Organic Citrus – a Growers’ Manual –

Organic Citrus – A growers’ manual –

ISBN 1 74151 841 5 ISSN 1440-6845

Organic Citrus – A growers’ manual by David Madge Publication No. 09/050

The information contained in this publication is intended for general use to assist public knowledge and discussion and to help improve the development of sustainable regions. You must not rely on any information contained in this publication without taking specialist advice relevant to your particular circumstances. While reasonable care has been taken in preparing this publication to ensure that information is true and correct, the Commonwealth of Australia gives no assurance as to the accuracy of any information in this publication.

The Commonwealth of Australia, RIRDC, the authors or contributors expressly disclaim, to the maximum extent permitted by law, all responsibility and liability to any person, arising directly or indirectly from any act or omission, or for any consequences of any such act or omission, made in reliance on the contents of this publication, whether or not caused by any negligence on the part of the Commonwealth of Australia, RIRDC, the authors or contributors. The Commonwealth of Australia does not necessarily endorse the views in this publication.

This publication is copyright. Apart from any use as permitted under the Copyright Act 1968, all other rights are reserved. However, wide dissemination is encouraged. Requests and inquiries concerning reproduction and rights should be addressed to the RIRDC Publications Manager on phone 02 6271 4165

Researcher Contact Details David Madge Research Officer Plant Protection Department of Primary Industries Victoria Box 905 Mildura VIC 3502

Phone: 03 50514500 Fax: 03 50514523 E-mail: [email protected]

RIRDC Contact Details Rural Industries Research and Development Corporation Level 2, 15 National Circuit BARTON ACT 2600

PO Box 4776 KINGSTON ACT 2604

Phone: 02 6271 4100 Fax: 02 6271 4199 Email: [email protected]. Web: http://www.rirdc.gov.au Bookshop: 1300 634 131

Electronically published by RIRDC in July 2009 Print-on-demand by Union Offset Printing, Canberra at www.rirdc.gov.au or phone 1300 6343 13

ii Foreword

Within the citrus industry—one of Australia’s major horticultural producers and exporters—there has been growing interest in improving the industry’s overall environmental performance and in organic production specifically. This has been driven by market demands, the global trend towards reduced impact of agriculture and concerns regarding soil health. The main barriers to increased adoption of organic practices have typically been the lack of relevant information, or ease of access to that information. To address that information requirement, RIRDC co-funded the development of this manual for organic citrus production in Australia. The manual is intended to address the specific information needs of organic citrus producers and growers who are interested in conversion to organic, while also bridging the gap between ‘standard’ and organic methods to ease the transition for growers who seek to change selected practices for environmental and marketing reasons. This project was funded by RIRDC core funds which are provided by the Australian Government, together with funds from the Department of Primary Industries Victoria and the Murray Valley Citrus Board. This manual is an addition to RIRDC’s diverse range of over 1800 research publications. It forms part of our Organic Produce R&D program, which aims to facilitate the development of a viable organic industry through increasing adoption of sustainable organic farming systems. Most of RIRDC’s publications are available for viewing, downloading or purchasing online at www.rirdc.gov.au. Purchases can also be made by phoning 1300 634 313.

Peter O’Brien Managing Director Rural Industries Research and Development Corporation

iii Acknowledgements

The author gratefully acknowledges the following organisations and people who supported the development of this manual through the project Organic citrus technical manual: building supply capability: • the Department of Primary Industries Victoria, Rural Industries Research and Development Corporation and Murray Valley Citrus Board who jointly funded the project • the organic certifiers—Australian Certified Organic, National Association for Sustainable Agriculture Australia, Organic Food Chain, Organic Growers of Australia and Tasmanian Organic-Dynamic Producers, who distributed survey forms and information about the project to their certified organic citrus growers • the growers from all states who responded to a survey of the organic citrus industry • the following growers who shared their knowledge and experience with the author during orchard visits in four states—Ian Armstrong, Philip Burkett, Blake Dorrington, Glen & Linda Chislett, Colin Furniss, Lyn Harvey, Humphrey Howie, Michelle Medhurst, Dawn and Rob Klok, Greg Lancaster, James Mosher, John and Dorothy Priestly, Peter Smith, Robert Ridgwell and Jan Denham, Alasdair Smithson, Jeromy Wallis The following researchers and others who provided technical information and/or reviewed sections of this document: • Dr Michael Treeby (DPI NSW) – soil and tree nutrition • James Altmann (Biological Services, Loxton SA) and Dan Papacek (Bugs for bugs, Mundubbera QLD) – pest management • Peter Dixon and Bruce Mackie (DPI Victoria), Deanna Chin (DPIFM Northern Territory) and Bill Woods and Shirani Poogoda (DAF Western Australia)—fruit flies • Dr Bob Emmett (DPI Victoria) – disease management • David Rumbold and Jane Rhodes (DPI Victoria) – pesticide use • Lyn McMahon (DPI Victoria) – English expression throughout the entire manual Photograph credits. Any photographs not taken by the author are labelled as follows: • DPI Staff of the Department of Primary Industries Victoria (photographer unknown) • JH Julie Hawtin • MP Miriam Pywell • GL Greg Lancaster

iv Contents

Foreword...... iii Acknowledgements...... iv Contents...... v 1. Introduction...... 1 What is Organic?...... 1 Management approaches...... 3 Livestock...... 5 Certification & standards...... 7 Orchard inputs...... 13 The grower as researcher...... 15 2. Establishment and conversion...... 17 Orchard establishment—optimising organic management...... 17 3. Environment and landscape management...... 23 4. Soil management...... 25 Managing the soil as a resource...... 26 Managing the nutrient cycle...... 31 5. Water management...... 57 6. Pest, disease and weed overview...... 63 A whole system approach...... 63 Aiming for a balance...... 65 Integrated management...... 66 7. Weed management...... 75 Pre-conversion weed management...... 75 Pre-planting weed management...... 75 What is a weed anyhow?...... 76 Volunteer plant or weed?...... 76 Benefits of volunteer plants...... 77 Integrated weed management...... 78 Weed management techniques...... 79 Timing timing timing!...... 87 Couch: Cynodon dactylon...... 87 8. Pest Management...... 91 Invertebrate pests...... 91 Ants...... 95 Aphids...... 97 Apple weevil...... 98 Citrus butterflies...... 99 Citrus gall wasp...... 99 Citrus leafminer...... 100 Fruit fly...... 101 Fruit-piercing moths...... 106 Fuller’s rose weevil...... 107 Lightbrown apple moth...... 109 Mealybugs...... 112 Mites...... 113 Nematodes...... 114 Scale insects...... 116

Snails...... 119 Spined citrus bug...... 121 Thrips...... 122 Vertebrate pests...... 124 Rabbits & hares...... 125 9. Disease management...... 127 Anthracnose...... 127 Brown rot...... 128 Brown spot...... 129 Greasy spot...... 129 Melanose...... 130 Septoria spot...... 130 10. Managing contamination risks...... 133 11. Machinery, energy and wastes...... 143 12. Useful resources...... 145 12.1. Organic industry regulation...... 145 12.2. Organic industry representation...... 145 12.3. Organic certifiers...... 145 12.4. Citrus industry representation...... 146 12.5. State fruit fly contacts146 12.6. Pest & disease diagnostic services...... 146 12.7. Soil & plant analysis services...... 147 12.8. Biological control suppliers...... 147 12.9. Other suppliers...... 147 12.10 Pesticide registration & use...... 148 13. References...... 149 14. Bibliography...... 159 15. Index...... 162

vi Production of quality fruit in a sustainable way is the aim of organic citrus growers. 1. Introduction Ever since the introduction of chemical-based pest, weed, disease and nutrition management in agriculture, some growers have questioned that approach. Many have opted for non-chemical methods of production IFOAM Principles of organic centred on more natural systems of pest regulation and nutrient cycling. agriculture ‘Organic agriculture’ as it is called, continues to attract growers for many Principle of Health and varied reasons. These range from concerns about environmental Organic Agriculture should impacts, soil degradation, personal health and product quality, to interest sustain and enhance the health in market access and price premiums. of soil, plant, animal, human and Within organic agriculture, the citrus industry is well-represented by planet as one and indivisible. growers who strive to produce high quality crops with minimal adverse Principle of Ecology impacts on the environment. Being generally hardy, citrus seems well Organic Agriculture should suited to organic production. It has in fact been considered one of the be based on living ecological more profitable crops to grow using organic methods[1] and the quality of systems and cycles, work with the end product can benefit measurably from this approach[2; 3; 4; 5]. them, emulate them and help sustain them. What is Organic? The International Federation of Organic Agriculture Movements Principle of Fairness (IFOAM) defines organic agriculture as “Utilising both traditional and Organic Agriculture should build scientific knowledge, organic agricultural systems rely on ecosystem management on relationships that ensure rather than external agricultural inputs. It is a system that excludes the use of fairness with regard to the synthetic inputs, such as synthetic fertilizers and pesticides, veterinary drugs, common environment and life genetically modified seeds and breeds, preservatives, additives and irradiation. opportunities. Organic agriculture is a holistic production management system which Principle of Care promotes and enhances agro-ecosystem health, including biodiversity, biological Organic Agriculture should be cycles, and soil biological activity. It emphasizes the use of management practices managed in a precautionary and in preference to the use of off-farm inputs, taking into account that regional [6] responsible manner to protect conditions require locally adapted systems.” . the health and well-being of While this definition focuses on the production system itself, organic current and future generations agriculture in the 21st century has a much broader scope as indicated by and the environment. the IFOAM principles[7] (see box opposite).

As these definitions and principles suggest, organic production focuses as much as possible on the use of natural processes and cycles for pest, disease, Organic management is weed and nutrient management. about a different approach to management, not simply the It is very important for growers to recognise that organic management ‘standard’ approach based on is about a different approach to orchard management, not simply the different inputs. ‘standard’ approach based on different inputs. This approach should involve the deliberate design and management of production systems to minimise the need for repeated intervention (e.g. cultivation) and repeated use of inputs such as pesticides. The goal is to eliminate or at least minimise the need for such inputs, not simply switch to their organic version. Also important is the fact that while organic standards and the principles they embody are applied globally or country-wide, the details of how those principles are put into practice are largely site specific. It is up to each grower to translate the principles and standards into a practical on-ground management approach that suits their orchard with its particular crop, soil, water, climatic and environmental characteristics. The search for ‘organic’ information Whatever the reasons, growers from all industries are seeking more information about reduced-chemical or organic approaches to production. Much of this information exists, but is widely dispersed and often documented in detailed technical form or embodied in grower knowledge and experience. In many cases, the overall ‘package’ of information that growers seek needs to be pulled together, interpreted and integrated by those growers—a time- consuming task. A manual for the citrus industry With support from the Victorian Department of Primary Industries, Rural Industries Research and Development Corporation and Murray Valley Citrus Board, this manual was developed to help address the citrus industry’s requirements for information on organic production. The information presented here was collated from a range of sources including Australian and international scientific and industry literature, researchers’ knowledge and the experience of organic citrus growers in New South Wales, Victoria, South Australia and Western Australia. “The principles of organic The author sincerely thanks those orchard managers who willingly shared citriculture are applicable their knowledge and experiences in order to help others in the industry world-wide. The details of learn and advance. organic citriculture are location specific” [8] Who will benefit from it? This manual is intended to assist citrus growers who are moving towards full organic production, as well as those who just seek to change selected aspects of their management. It is also hoped that the information provided may help existing organic citrus growers in the ongoing refinement of their orchard systems. Scope of this publication This manual is not intended to replace existing publications on the basics of citrus production. Rather, its purpose is to help growers consider and interpret those basics from an organic perspective.

Growers are likely to gain best value from this manual by using it in conjunction with existing guides such as the ‘Citrus growing manual: a manual for quality decision making’[9] and the Australian pest management ‘bible’, ‘Citrus pests and their natural enemies: Integrated Pest Management in Australia’[10]. For inquisitive growers Growers interested in researching the more detailed information that lies behind this manual will find the sources listed in the ‘References’ section and cited in the text by number. The Bibliography also contains further sources of information that may be of interest, including economic analyses of organic citrus production. Wherever possible, links have been included to relevant information sourced from the Internet. In the event of broken or lost links, please contact the author who has archived copies of most documents referred to in this manual.

Management approaches As mentioned above, organic agriculture is about a different approach to management. Every grower will have their own view on how an organic citrus orchard could or should function. What is important is for growers to think outside the square; wonder about all the possibilities they could pursue in their orchard; trial techniques and approaches that seem promising; and design and develop orchard systems that work for them. In this process there is no single ‘recipe’ for success, just a range of management options and practices to be pieced together into the most appropriate system for each grower and site. The following concepts are worth considering in the context of organic production, ecosystem management, reduced inputs and less intervention. They focus on awareness of how natural systems function, and use conscious design to maximise the natural robustness, resilience and productivity of agricultural systems. Orchards are ecosystems When we manage a citrus orchard we manage an ecosystem comprised of many components including citrus trees, possibly other crop plants and native vegetation, volunteer plants, water, soil, soil organisms, birds, reptiles, beneficial and pest invertebrates such as insects, and beneficial and disease-causing microbes. Most of these components, or the management activities associated with them, are closely interrelated. Intervention in one component is likely to affect the function or management of other components. Growers who keep this in mind are more likely to consider and plan their management activities more carefully, to maximise the desirable consequences and minimise any undesirable consequences of those activities (e.g. off-target pesticide impact). Permaculture Permaculture was conceived in Australia in the mid 1970’s and has since spread globally. Permaculture in agriculture is about design based on what we learn from observation and from natural systems and processes. It involves thoughtful choice and arrangement of the components of a system, such as an orchard, to maximise positive interactions between

those components and minimise the need for human intervention to maintain the system. Following are some definitions of Permaculture from its originators: “Permaculture (permanent agriculture) is the conscious design and maintenance of agriculturally productive ecosystems which have the diversity, stability and resilience of natural ecosystems. It is the harmonious integration of landscape and people providing their food, energy, shelter and other material and non-material needs in a sustainable way. The philosophy behind Permaculture is one of working with, rather than against, nature; of protracted and thoughtful observation rather than protracted and thoughtless action; of looking at systems in all their functions rather than asking only one yield of them; and of allowing systems to demonstrate their own evolution.” 11]. “Consciously designed landscapes which mimic the patterns and relationships found in nature while yielding an abundance of food, fibre and energy for provision of local needs.” [12]. Agroecology Agroecology is an ecology-based approach to agriculture that considers the interactions between all the agricultural system’s components when designing and managing the system. Mineral cycles, energy transformations, biological processes and socioeconomic relationships are viewed and analysed as integral parts of a whole system, rather than as individual components. “Agroecology is concerned with the maintenance of a productive agriculture that sustains yields and optimises the use of local resources while minimising the negative environmental and socio-economic impacts of modern technologies” (see http://www.agroeco.org/doc/what_is_agroecology.html)

The relevance of agroecology to the design of environmentally-sound organic systems is shown by the following principles upon which Agroecological design is based[13,14]. • “Enhance recycling of biomass and optimizing nutrient availability and balancing nutrient flow. • Secure favorable soil conditions for plant growth, particularly by managing organic matter and enhancing soil biotic activity. • Minimise losses due to flows of solar radiation, air and water by way of microclimate management, water harvesting and soil management through increased soil cover. • Species and genetic diversification of the agroecosystem in time and space. • Enhance beneficial biological interactions and synergisms among agrobiodiversity components thus resulting in the promotion of key ecological The manager of this organic orchard is processes and services”. trialling interplants of leguminous trees For more details on these approaches to agricultural design and for summer sun protection and nutrition benefits. management, see ‘Management approaches’ in the Bibliography.

One idea that fits the Permaculture and Agroecology models and is being used by organic citrus growers is the grazing of livestock to reduce the need for weed and pest control while contributing to tree nutrition and diversifying income. Another is the interplanting of different trees amongst citrus for a range of potential benefits. Bio-dynamics Bio-dynamic agriculture is a mindful and holistic approach to agriculture based on teachings of the Austrian philosopher Rudolf Steiner in the 1920’s. Steiner believed that soil, plants, animals (including humans) and the cosmos are all intimately connected. Amongst other things, he considered that enhancing that connectivity was the key to healthy soil, and therefore to the health of the plants and animals that rely upon the soil. The Bio-dynamic approach involves a strong commitment to its philosophy, and includes use of a series of special soil, compost and plant health preparations referred to as the BD500 series, and careful attention to the timing of management activities in the orchard. Any meaningful discussion and analysis of Bio-Dynamics requires some in- depth knowledge and preferably experience of the approach, and is outside the scope of this manual. Suffice to say, many crops including citrus are produced successfully using the Bio-Dynamic approach. Useful starting points for contacts and information on Bio-dynamics are listed in the Bibliography.

Livestock Livestock traditionally played important roles in agriculture, relating to nutrient-cycling, weed and pest management and income diversification. They have now been largely displaced by chemical fertilisers, herbicides and pesticides, and the change from mixed farms to specialised enterprises. Where it can be practically managed, the reintegration of livestock into organic farms can yield many benefits, including the Livestock traditionally played important roles in agriculture, relating to nutrient- development of more diverse and interesting production systems. A ‘more cycling, weed and pest management and interesting workplace’ is one of the benefits of organic farming according income diversification. They have now been to some growers, and the value of this point should not be underestimated. largely displaced by chemical fertilisers, herbicides and pesticides, and the change A few organic citrus orchards have incorporated livestock into their from mixed farms to specialised enterprises. systems, and for others the potential benefits of this approach are worth considering. Poultry seem to be the stock of choice, represented by geese, chickens and guinea fowl. The choice of poultry type for a particular property depends on their purpose. Geese, largely being grazers, are chosen for weed management. Guinea fowl are used for control of certain pests including weevils, and have the benefit of being less destructive than chickens. Chickens will eat almost anything that moves and graze on or scratch up many ground-cover plants and ‘weeds’. Even at moderate stocking rates, chickens can turn areas of an orchard into dustbowls, so they need to be managed thoughtfully.

Ducks have been recommended for snail control in Californian citrus, but don’t seem to have been adopted for the purpose in Australia, possibly because snails are not considered a major issue except by export growers. Poultry are discussed later specifically in relation to nutrition, weed and pest management in citrus. Some general points regarding poultry management are listed below and may also be applied to other stock. Poultry require management: Running poultry or other stock in citrus adds an extra element to orchard management. Like Guinea fowl contribute to pest management in this organic citrus orchard. any other aspect of the orchard, they need to be managed, and managed appropriately, if their integration is to be a success. Attention needs to be paid to their housing, provision of feed and water, and control of their movement and stocking rate, especially to manage impacts on the orchard such as disruption of cover crops and distribution of manure. This all needs to be done within the context of organic standards. Marketing of products such as eggs and meat birds also requires attention, if the benefits of poultry are to be maximised. Poultry require protection from predators: Raptors do attack grazing poultry, but foxes and dogs are the main concern. The heartbreak and disruption arising from the overnight slaughter of a poultry flock can be avoided by paying attention to housing and fencing. An important point to remember is that fencing needs to contain the poultry as well as exclude predators. An electrified netting fence has been known to keep marauding dogs out of a chicken run, but may not prevent the panicking hens from escaping the run and being killed by the dogs.

Permanent or mobile housing and yards? • Permanent housing may be easier to establish with regards to such aspects as water supply and fox-proofing • Manure deposits and groundcover disturbance are usually concentrated around housing and need Protection from predators is one to be managed carefully to requirement for success in managing avoid problems, especially livestock in citrus. near permanent housing

• Mobile housing helps to avoid the above issue and allows more management flexibility, but may be more difficult or expensive to construct • Mobile housing and fencing can be configured to concentrate stock in particular areas of the orchard at different times, but moving them when necessary is an additional and ongoing task • Permanent fencing should require no adjustment once installed, but allows less flexibility in locating the stock • A combination of permanent and mobile fencing may be an effective compromise between maximum flexibility and minimum ongoing labour requirement Manage movement with water: Most poultry seem happy to wander considerable distances during the day, but they always need access to drinking water. The strategic location of water points can help to manage their movement while minimising the time spent returning to a central water source.

Certification & standards The what? and why? of organic certification Organic certification is an accreditation system based on standards, inspections and audits, that allows the ‘organic’ nature of production systems and other aspects of the agricultural supply chain to be independently verified. This verification gives the consumer some assurance as to the authenticity of the product, and is increasingly necessary as the organic marketplace becomes more competitive and consumers more discerning. Organic certification is required for produce exported as organic, and will most likely become a requirement for locally marketed produce after changes are made to the way Australia’s national organic standard operates. Certification is therefore of interest to citrus producers who seek to use the organic approach to add value and integrity to their product in the marketplace. By becoming certified organic, producers gain credibility, assistance and some marketing advantage for themselves while contributing to the development and standing of the organic industry. They also support the efforts of organic agriculture organisations who are working towards: • providing practical marketing information and linkages for growers • developing and refining standards for organic production, processing and handling • promoting organic agriculture, the certification schemes and organic produce to the public.

Organic standards Organic standards are publicly available, documented standards against which certified organic growers are audited for compliance. They are comprised of definitions, requirements, recommendations and restrictions regarding the practices and materials that can be used within certified organic production and processing systems. They also cover such aspects as the transport, storage and marketing of organic products. Organic standards typically list in brief and generalised form, a range of recommended, restricted and prohibited inputs and practices applicable to a wide range of issues facing organic growers. As such, they provide some general guidance on organic management but do not offer advice or ‘recipes’ on management of specific issues. Materials and substances not listed in the standards should be considered as prohibited unless the relevant certification organisation specifically approves their use. As well as considering the technicalities of agricultural production and processing, organic standards address such broader aspects as biodiversity, native vegetation retention, waterway management, animal husbandry ethics and waste management. Several organic standards may apply directly or indirectly to certified Australian producers. These are: • The National Standard for Organic and Bio-Dynamic produce. This is the minimum standard that must be met by organic certifiers and producers operating in Australia[15]. Organic certifiers are audited and accredited under this standard, by the Australian Quarantine Inspection Service (AQIS) which also regulates organic exports from Australia.

The National Standard is maintained by the Organic Industry Export Consultative Committee (OIECC), a body through which AQIS consults with the organic industry. The OIECC is comprised of representatives of the organic industry and relevant government agencies. The National Standard is available on the AQIS Internet site (see section 12.1).

Note: The industry is developing a new ‘standard for organic and biodynamic products’ to be managed by Standards Australia. This will replace the current ‘National standard for organic and biodynamic produce’ and will make it easier for organic standards to be enforced within Australia. • Standards of individual Australian organic certifiers. Individual certification organisations (see section 12.3) develop their own standards that match or exceed the requirements of the National Standard. These individual industry standards are the ones with which certified producers have to comply. • IFOAM Basic Standards for Organic Production and Processing. IFOAM, The International Federation of Organic Agriculture Movements (see section 12.2) sets a basic standard against which individual certification organisations in any country can become accredited[16]. IFOAM accreditation has been achieved by some Australian certifiers and has the advantage of being recognised in some key international markets. • Market-specific standards. Some countries, including key markets for Australian citrus like USA, Japan and China, have developed their own organic standards that must be met by produce exported into those

countries[17; 18; 19]. Australian certifiers can become accredited under these foreign standards. However, certified Australian producers are still required to complete extra documentation to satisfy the requirements of some of these standards. To achieve and maintain organic certification, growers must comply with the relevant standards while implementing them in a practical way that suits their particular enterprise. Organic standards are under constant review to keep up to date with national and international requirements. Industry input into the revision process is welcome, and is in fact necessary to ensure the standards remain practical while adhering to organic principles. Producers should feel free to provide their certifier with feedback on their particular standard. Comments on the National Standard can be made through individual certifiers or direct to the OIECC through the AQIS Organic and Biodynamic program (see section 12.1). Reference to standards in this manual Most sections of this manual begin with a reference to Australia’s national organic Standard. “What the National Standard says” contains brief, pertinent extracts from the Principles and Standards sections of that Standard. The actual ‘Standard’ lists the minimum criteria that must be satisfied for the orchard and its produce to achieve and maintain organic certification. The ‘General principles’ of the Standard provide a brief outline of some key principles of organic agriculture that underlie the standards relating to the specific topic. To develop a sound organic orchard, growers should understand and apply the principles, not just comply with the standards. Certified growers should consult the Standards of their particular certifier for a complete listing of recommendations and requirements. Who can certify organic enterprises? Organic certification in Australia is regulated by the AQIS Organic and Bio-dynamic Program. AQIS accredits independent organisations to operate organic certification schemes. A current list of accredited certifiers is maintained by AQIS on its Internet site (see section 12.1) The certification process Organic certification organisations may vary in the way they handle certification, but the following points are a general guide to the process. Standards First obtain a copy of the organic standards and fee structure from one or more of the certifying organisations. Some certifiers have this information available free of charge from their web site. It is important to read and understand the standards. They are the ‘rules’ that have to be complied with to achieve and maintain certification. If any aspects of the standards are unclear, clarification should be sought from the relevant organisation. Contact & application To decide which certification scheme to join, speak with other certified growers for advice or contact a number of the certifiers for more information to judge their suitability.

Obtain an application form from the preferred certification organisation. This and other relevant information is available freely from some certifiers’ web sites. The completed application form, and fee if required, is returned to the organisation if the applicant agrees with the standards and agrees to comply with them. Questionnaire A comprehensive questionnaire will be provided (or can be accessed from the certifier website), requesting information on the management of the orchard to be certified. This includes chemical use, cultivation practices, fertiliser inputs and other nutrient management strategies, pest control methods, crop types and rotations. The risk of chemical contamination from neighbouring properties and other sources is also of interest. The questionnaire is to be completed and returned together with a map of the property clearly showing the location of areas to be certified. Some organisations require a statutory declaration to be signed, to add legal strength to the certification and licensing process. Inspection The applicant is then contacted to arrange a visit by an experienced inspector. The inspector will usually: • help fill in any gaps in the questionnaire • inspect the area or facility to be certified and note any problems such as major weeds and risks of contamination (e.g. spray drift) • examine the soil condition and management practices • collect samples of soil or products if required for chemical residue analysis.

Application review The questionnaire, inspection report and soil or produce test results will then be considered by the certifying organisation which will either offer certification, or reject the application if there is good reason to do so. Contract Once accepted, the applicant will be offered a contract of certification. This states the obligations of the applicant and certifying organisation in the event that the contract is accepted. The contract may include conditions necessary for the maintenance of certification, information on the use of certification labels or logos and annual licence fees or levies if they apply. Organic certification and the right to use the certifying organisation’s labels or logos and to promote produce as certified may be withdrawn if the contract is broken. This could occur for example if a product or practice prohibited under the organic production standards is used. Certification levels There are currently two levels of certification relevant to primary production, preceded by a pre-certification ‘lead-in’ period: ‘Pre-certification’ commences once the initial contract is signed and applies for one year. During pre-certification, no claims can be made regarding the organic status of the enterprise or its products. This means that certification cannot be sought to cover a crop that is about to be harvested. This lead-in period allows applicants to demonstrate that they can manage their enterprise in compliance with the organic standards and ensures that

10 certified produce carrying an ‘In conversion’ label has been managed under the standard for at least a full year. ‘Conversion to organic’ and ‘Conversion to Bio-dynamic’ are achieved when an enterprise successfully completes pre-certification and the associated audits and inspections. The length of the conversion period depends on the history of the enterprise and current management practices. It could last several years as it takes time to develop a good organic production system. Produce from enterprises in the conversion phase can carry a ‘Conversion to organic’ label and can be promoted as being in conversion to organic. ‘Certified Organic’ and ‘Certified Bio-dynamic’ are the top levels of certification and are achieved once all relevant requirements of the standards have been met for a minimum of three years. Produce can be labelled and promoted as being Certified Organic or Bio-dynamic. Annual audit Once certification is achieved, compliance with the standards must continue for the certified status to be maintained. Certified enterprises are reinspected annually to verify that the standards are being met. Things to consider BEFORE applying for certification Seek information Read as much as possible on the subject. Join a local organic grower group—they are there to support growers. Certification organisations and agriculture departments should be able to help growers contact these groups. Speak with people who are familiar with organic/sustainable agriculture and who use organic methods. Speak to someone who is familiar with organic certification. Get an idea of what is involved, including costs, in applying for certification and maintaining certified status. Find out about the application fee, farm inspection, soil tests and licence agreements. Ask to see the sort of questionnaires involved. Consider conversion issues for the specific property If a neglected property has been obtained especially for organic production because it has not had chemicals applied recently, remember that organic/sustainable agriculture is about best practice management not just chemical-free management. Organic certification organisations want to see good management practices in operation, and place some emphasis on the development and implementation of organic management plans for certified enterprises. Develop a conversion plan for the property. This should document the phases that each area of the property will go through during conversion to organic management. Aspects such as the establishment of windbreaks, There is no such thing as ‘organic by neglect’. cover crops and crop rotations would be included. Good organic management is much more than just the absence of prohibited inputs.

11 Consider the scale of the potential organic enterprise. It may need more capital input, labour and bulk materials such as compost, manures and mulch. Are the resources and experience available to convert the whole property at once? Organic techniques may be trialled on a small area first before being applied on a larger scale. However, with this approach, the organic area may have a high risk of contamination from adjacent crops or from spray vats used for other crops. If a small trial area for organic management is to be established and certified, is there any guarantee that produce from the organic and conventional areas would not get mixed up? See ‘Parallel production’ in section 2. Specific concerns about a property that is to be certified should be addressed before the application is made and fees are paid. For example, if the area is surrounded by properties on which heavy chemical use occurs, the application may fail because of an unacceptably high risk of chemical contamination. Notify neighbours and other relevant people Neighbours should be informed of what is involved in the conversion to organic. Try to reach some agreement on what they will do as good neighbours to minimise or eliminate any effects that their use of chemicals may have on the organic system. For more information see section 10. Consider marketing and economic aspects All growers, regardless of the production methods they use, should investigate the distribution and marketing aspects of a new enterprise before they develop that enterprise. This is particularly important for organic growers because the organic market, while expanding rapidly, is still small and easily oversupplied with certain products. Small-scale growers intending to sell through farmer markets or organic retailers may receive a better response to a mixed line of produce (including non-citrus), rather than to just one or two varieties of citrus. An organic grower has pointed out that while bulk bags (e.g. 10kg) are attractive to families, they do not necessarily suit couples or single shoppers. A variety of packaging will help to broaden the potential market. Recent analyses of the domestic and export market potential for Australian organic products have rated citrus reasonably highly because of our seasonality, production ability and a shortage of organic citrus juice[20; 21; 22]. It was also found however, that market access was difficult for small-scale producers, and that some form of cooperative ‘alliances’ may be needed to assist in this area[23; 24]. Analyses of world markets for organic citrus fruit and juice indicate that the current small market size together with increasing production, provide an opportunity for considerable market growth[25; 26]. Other aspects to consider Rather than have your fruit collected by the local co-op or company, will you need to deliver your organic fruit to a specialist packer or processor and so require your own forklift, trailer etc? To supply direct to markets or retailers, will you require your own packing line?

12 Orchard inputs Organically acceptable or not ? Each grower is responsible for ensuring that their particular certifier approves of the input products used in their certified organic orchard. Use of non- allowed inputs can result in suspension of organic certification, so growers should check with their certifier if there is any doubt about a particular product. This applies to fertilisers and soil amendments as well as pesticides. Organic standards published by the certification organisations usually contain lists of the general types of products that are permitted or prohibited under those standards. It is important to note that not all products based on the same major Growers should confirm the acceptability of ingredient, such as sulphur or pyrethrum, are acceptable under organic input materials with their certifier, before standards, as some products contain additives prohibited under those using them in the orchard. standards. Some products are specifically certified as allowable organic inputs by organic certifiers. Lists of those inputs or the suppliers are available from the certifiers. Reference to inputs in this manual Where relevant, pesticides registered with the Australian Pesticides & Veterinary Medicines Authority (APVMA) for weed, pest and disease control are listed as ‘Acceptable registered inputs’ if one or more of Australia’s organic certification organisations has approved their use in certified organic production systems. These substances are referred to by their generic name, like ‘mineral oil’ and ‘pyrethrum extract’ rather than by the trade names of all the individual products that are currently registered. Lists of registered inputs in this manual are correct at the time of printing. Current information on registered pest control products is available on the APVMA website listed in section 12.10. Input products that are organically acceptable and do not require APVMA registration are listed as ‘Acceptable inputs’. Because organic certifiers may differ in the input products they accept, and because similar products may contain different additives, it is important for certified growers to confirm the acceptability of specific inputs with their particular certifier. Alternative and off-label pesticides Most pesticides registered for use in citrus are not acceptable under organic standards, so organic growers may seek ‘alternative’ products or alternative uses for registered products for pest, disease and weed management.

13 Alternative pesticides Alternative pesticides could include such things as homemade insecticidal plant extracts or commercial products that are not registered by the Whenever using APVMA as pesticides. The APVMA defines an agricultural chemical agricultural chemicals, product as any substance or organism used to: organic or otherwise, • destroy, stupefy, repel, inhibit the feeding of, or prevent pests on plants always read and follow the or other things label directions. • destroy a plant or modify its physiology • modify the effect of another agricultural chemical product, or • attract a pest for the purpose of destroying it. This encompasses all herbicides, insecticides and fungicides. Fertilisers are not considered agricultural chemical products for the purposes of registration unless they modify the physiology of a plant. Any alternative pesticide that falls under this classification must either be registered by the APVMA, have a permit for the use of an unregistered chemical issued by the APVMA or be deemed by the APVMA to be exempt from classification. Growers should be mindful of the following issues that could arise from the use of ‘alternative’ pesticides: Legal: It is illegal to use unregistered products that are classified as agricultural chemicals for pest, weed and disease control. Commercial: Detection of residues of un-registered pesticides on fruit could possibly result in rejection of the fruit from processing and marketing. Technical: ‘Unofficial’ pesticides may not provide the desired level of control of the target pests. Also, without thorough evaluation, the health and environmental impact of wide-spread or long-term use of the substances would be unknown. The best approach, and one that matches the spirit of organic production, is to minimise the use of all pesticides including organic ones, thus minimising the potential for negative environmental and other impacts. Off-label pesticide use There are certain pesticides that are APVMA-registered and organically acceptable, but are not specifically registered for use on citrus. Others that are registered for citrus may not be registered specifically for use against the The best approach, and one that target pest or disease that the organic grower wants to control. Use of those matches the spirit of organic pesticides in such situations would be considered as ‘off-label’. production, is to minimise the use of all pesticides including Off-label use of a registered pesticide is any use that is not specified on the organic ones, thus minimising label of the product, i.e. any variation from the label ‘Directions for Use’. the potential for negative Off-label uses may involve crops, pests, rates of use or application methods environmental and other that are different to those listed on the label. Regulations controlling off- impacts. label use vary between states. For example, off-label use is permitted in Victoria as long as the application: • does not involve the use of substances classified by the Victorian Department of Primary Industries as ‘restricted use chemicals’ (none of the ‘restricted use chemicals’ are acceptable under organic standards in any case) • does not exceed the maximum label rate for that use

14 • does not exceed the label frequency of application for that use • complies with any specific label prohibitions (i.e. the label’s ‘DO NOT’ statements) regarding the use. In other states an off-label use permit may be required from the APVMA. Anyone using a registered pesticide in an off-label manner accepts full responsibility for the efficacy or lack of efficacy of that use, and also for any environmental or human health and safety impacts of that use. Growers should familiarise themselves with the relevant legislation and at least be aware of how their use of organically acceptable inputs relates to those regulations. Information on chemical use regulations should be accessible through the relevant state agriculture department.

The grower as researcher Every organic grower is a researcher in some way, observing interactions between different components of their orchard, noting the effects of their management actions and trialling new approaches to solve the issues they face on a day-to-day basis. Most growers have tested new products or techniques to determine if they have a useful and cost-effective role to play in the orchard. On-farm ‘research’ such as this is particularly valuable for organic growers, given the relatively very small amount of ‘official’ research directed towards their industry[27]. On-farm experimentation can be a very valuable exercise, but only if it is done in a way that provides the grower with real and useful information. Applying a treatment to the whole orchard for example, makes it difficult to attribute subsequent changes in the orchard to that particular treatment. Any such changes may have resulted from other factors such as weather conditions or irrigation regime that affected the whole orchard. To perform a basic evaluation of treatments, whether they are nutrient sprays or cultivation techniques, growers need to at least: • Separate the effect of treatments from other influences in the orchard Leave a portion of the orchard or block (same variety, soil type, irrigation method etc) untreated for comparison. Manage the treated and untreated areas in the same way except for the treatment, so that differences in the end result may be attributed more confidently to the treatment itself. • Measure the effect of the treatment—don’t rely on eyeball comparisons Take some simple measurements and photos; make notes. Do the treated trees really have larger fruit? …greener leaves? …fewer pests? …fewer weeds? • Compare the effect of the treatment with the result achieved from current practices Weigh up any benefits (e.g. improved weed control; larger fruit; better juice quality; less time input) against the costs (e.g. $ cost compared to current practice; extra time requirement). Do the benefits make the treatment worthwhile economically or otherwise? Following these basic points need not be a difficult task, but will help growers to get the most from their trials and to make judgements about new practices or inputs with greater confidence.

15 16 Isolation helps to reduce the risks to an organic orchard of chemical contamination and introduction of pests, diseases and weeds from adjacent orchards. 2. Establishment and conversion Should a new orchard be established organically from scratch, or established conventionally, with access to a wide range of fertilisers, What the National Standard pesticides and herbicides, then converted to organic? The ‘right’ answer for says: any grower depends on the balance between: General principles: • their philosophy (do they mind using non-organic inputs) Land is converted to organic status • their ability to manage new plantings organically (especially nutrition by the application of organic and weed management) management practices. • the relative costs involved. Standards: Young citrus plants are more prone to suffer from moisture stress Where the whole farm is not and nutrient deficiencies because of their limited root system. Both converted at the same time problems can result from competition from weeds, and inadequate weed (possibly resulting in parallel management can be a cause of poor tree establishment. The time from production), certified product planting to first harvest influences the economic viability of an orchard, complying with this Standard so growers should aim to avoid any setbacks in the establishment and must be distinguishable from early growth of trees. This is especially relevant to organic growers, whose product that does not comply. production costs can be higher. The management system must demonstrate, through management Many organic growers establish new citrus organically from the start, using practices and record keeping, the practices like those outlined in this publication. To do this well requires segregation of harvested material good management of: from the certified and non-certified • weeds, with mulch or precision cultivation (including hand-weeding) enterprises and the precautions • nutrition, with high quality compost and/or commercial organic taken to avoid contamination of the fertilisers. certified product with substances and practices not permitted under Orchard establishment—optimising organic this Standard. management Operators engaged in parallel Organic standards restrict the inputs and management options available to production must develop a certified organic orchards. It is therefore even more important for organic program of converting their whole growers to design and manage orchards in ways that make them inherently farming operation within 10 years more robust and resilient against ‘adversaries’ such as pests, diseases and to comply with this Standard.

17 weeds. This approach will help minimise the orchard’s dependence on material inputs and management interventions. The location, placement and design of an orchard may influence its susceptibility to weeds, diseases and pests as well as the range of acceptable management options that are suited to the particular site. In this context, the following aspects are worth considering. This list is by no means comprehensive but is intended to stimulate some thought on optimal orchard establishment. Geographic location Climate A major difference between regions is climate, which strongly influences pest, disease and weed pressure. High rainfall coastal districts for example, have high disease and weed pressure compared to drier inland areas. Conversely, the hot, dry and often dusty conditions of inland districts can be more conducive to red scale infestation. Such factors should be taken into account together with local experience, so that regions or districts with unduly high pest, disease or weed pressures are either avoided, or entered into with a good knowledge of effective strategies to manage those pressures. Local site selection Microclimate Disease expression on citrus is influenced by tree and fruit physiology which in turn can be affected by environmental conditions. Symptoms of septoria spot and anthracnose for example, are more likely to develop after fruit has been subjected to cool or frosty conditions in the orchard. Choice of frost-free sites and provision of shelter against cold winds will help to reduce the risk of these diseases developing and so reduce the need for fungicide applications. Soil type Soil is an orchard’s most important resource. It should be selected carefully because it has an ongoing influence on tree development and organic management, for example: • heavier, poorly-drained soil increases the risk of phytophthora and other root rot diseases for which there are no ‘easy’ organic solutions • light soils of low fertility require considerable levels of management and inputs to improve organic matter and nutrient levels, water holding capacity and so on. • highly alkaline and acid soils often lead to deficiencies or excesses in nutrient availability, and while these can be managed organically, it can be more difficult than with ‘conventional’ inputs.

Weed status By avoiding land that is infested with difficult weeds, especially perennial species, citrus growers will make organic orchard establishment and management significantly easier. This is an important consideration, given the scarcity and cost of ‘organic’ herbicides and the fact that organic standards discourage excessive cultivation. External infection/infestation sources Pest infestation levels may be influenced by an orchard’s proximity to

18 external infestation sources. A new orchard established with clean planting material and managed with good hygiene is more likely to remain pest-free for longer if it is geographically isolated from other orchards. Contamination risks Sources and management of contamination risks are discussed in section 10. Because of the impact that contamination issues have on an orchard’s organic status, the current and potential future risks should be taken into account during site selection. The risks inherent in a particular site will largely relate to surrounding land use and may typically be higher adjacent to intensive horticulture and lower adjacent to pasture or bushland. Orchard design Several aspects of orchard design relate specifically to weed, disease and pest management. These are covered in section 6. Other aspects to consider are: Row orientation Where citrus trees will grow together to form hedgerows, a north-south row orientation will allow for better sunlight access to the foliage of each tree, and to inter-row cover crops which are an important aspect of organic soil management. With well-spaced free-standing citrus trees, row orientation is not an issue with regards to solar access. In hilly country, it may be necessary to manage the risk of soil erosion by interrupting the downslope flow of water, by contour planting for example. This is an important consideration when determining row orientation, as responsible soil management is a basic requirement of organic standards. Irrigation system To some degree, irrigation type determines the ease with which ‘preferred’ organic soil and nutrition management practices can be implemented. These practices largely relate to the development or use of ground cover vegetation, green manures, enhanced soil biological activity and bulk organic nutrient inputs such as compost. All of these rely to a large degree on appropriate soil moisture management, and are likely to be more suited to, or easier to manage, under sprinkler irrigation compared to drip irrigation. Drip irrigation does however allow a high level of control over water application, soil moisture levels in the tree rootzone and water use efficiency. It is up to the individual grower to prioritise water and soil management issues and manage their orchard accordingly. See section 5 for more discussion of irrigation systems. Field efficiency Field efficiency is the ratio between the theoretical time required for a task (e.g. mowing) and the actual time taken. This efficiency is reduced by anything that increases the time taken for the actual task, such as turning, refuelling, rest breaks and overlapping of mowing passes. Reductions in soil impacts and pollution, and savings in fuel, time and other resources may be achieved by maximising the field efficiency of orchard operations. This is assisted by thoughtful orchard design, taking into account all the anticipated tasks. Long rows for example, reduce the amount of time spent lifting implements and turning, and so help to increase field efficiency.

19 Conversion to organic

Remember—conversion to Risk management organic means changing Conversion from ‘conventional’ to organic production requires some risk management. This is because the conversion phase may require to a different management fundamental changes to orchard management, including the use of SYSTEM, not simply management approaches, practices and inputs with which the grower is changing INPUTS. unfamiliar. Care needs to be taken to ensure that the orchard is not put at undue risk by the withdrawal of nutrient and pesticide inputs combined with ‘immaturity’ of the organic system. Figure 2‑1 highlights some typical changes and areas of risk associated with conversion. The conventional orchard characteristics tend to suit, and are reinforced by, conventional practices. Those characteristics may not be well suited to organic management. The manager’s job is to ensure that the functions performed by old practices and inputs are adequately maintained in the short-medium term, until the appropriate orchard characteristics such as good biological controls are developed. Two risks to production that may be encountered during conversion are: • inadequate weed management—resulting from insufficient time, materials or specialised equipment to replace herbicides • reduced yields—as a result of weed competition and inadequate nutrient inputs or soil improvement to replace a nutrition program based on water-soluble fertilisers. With careful management, these problems can be avoided. Growers should recognise the difference between ‘low input’ (e.g. low levels of nutrients added to the soil) and ‘minimal input’ (e.g. nutrient inputs kept to the minimum that will satisfy tree requirements). If tree requirements are not met, a decline in tree health and vigour may be expected.

Conventional Conventional orch ard Desired orchard Organic practices practices & inputs characteristics characteristics & inputs

Reliance upon Poor nutrient Biologically active Slow release nutrients, highly soluble cycling & soil, good cover cropping, fertilisers storage nutrient buﬀering compost, organic capacity of soil & cycling capacity matter

Bare soil & Reliance upon Cover cropping, mulch, monocultural ‘Weeds’ tolerated herbicides light mowers, grazing cover crop or out -competed

Reliance upon Low level of High level of contact natural Monitoring, biological natural biological pesticides biological controls & restricted control control range of pesticides

'Cheapest Minimal input, Relatively cheap Relatively expensive option' orchard most appropriate nutrients & inputs including labour pesticides management options

Figure 2‑1. Examples of typical changes initiated during conversion to organic management, and orchard characteristics that require careful management during that period.

20 Approaches to conversion One way to minimise the risks associated with conversion while evaluating and fine-tuning organic methods in the orchard, is through partial conversion. This can involve full conversion of a small trial section of the orchard, or conversion of selected management practices over the whole orchard, or a combination of both. Managers new to citrus culture or to organics may benefit from the lower- risk experience of partial conversion. Some advantages and disadvantages of the various approaches are listed in Table 2‑1. Parallel production Growers interested in trialling full organic management on a portion of their orchard, and obtaining certification on that portion, need to familiarise themselves with any restrictions that their certifier places on ‘parallel production’. Parallel production means production of one product such as navel oranges, by a single producer, under different levels of organic certification, i.e. conventional and ‘in conversion’, conventional and organic, or ‘in conversion’ and organic. Parallel production is a restricted practice and is closely monitored because of the increased risk of accidental or fraudulent mixing of products of different certification status.

Table 2 1. Approaches, advantages and disadvantages of full and partial organic conversion

Apply to whole orchard area Apply to small part of orchard

Establish full • Switch whole orchard to organic management • Apply full organic management program to a small organic mgt approach, practices and inputs at one time. test area. When confident with the approach, expand the program to the whole orchard. Highest management risk Shortest certification timeframe Lower management risk No internal cross-contamination risk Medium certification timeframe Whole orchard can be certified Highest cross-contamination risk Organic section may qualify for certification

Trial selected • Convert a key practice to organic over the whole • Convert a key practice to organic in a small area of organic orchard, e.g. pest management. When confident with the orchard, e.g. weed management. When confident practices the approach, convert another practice. Repeat until with the approach, expand the practice to the whole full organic management is achieved. orchard and convert another practice over a small area. Repeat until full organic management is Lower management risk achieved. Medium certification timeframe Cross-contamination irrelevant Lowest management risk No certification until the end Longest certification timeframe Cross-contamination irrelevant No certification until the end

21 Care of remnant vegetation is as important as establishing new plantings. On this organic orchard, a patch of native scrub has been fenced for protection.

Apart from wind shelter, some Eucalypts provide habitat for predators of citrus mite pests.

22 Rather than replant citrus, a cleared area of this organic orchard has been revegetated with native species, providing biodiversity and aesthetic benefits. 3. Environment and landscape management Organic producers can help to minimise environmental impacts, reverse environmental degradation and contribute to more sustainable landscapes through careful planning and management of their enterprises. This role What the National Standard of ‘environmental stewardship’ includes management of biodiversity and says: landscapes. As the value of this role has become recognised more, it has been progressively incorporated into organic standards. General principles: An organic production unit can Australian standards currently require five percent of a certified property enhance biodiversity by: to be developed to non-crop, non-intensively grazed vegetation within • establishing and/or retaining five years of ‘in-conversion’ status being achieved. The intent is for organic native vegetation on farms properties to include an area of semi-natural habitat to increase or at least maintain the natural diversity of the farm and broader landscape. • managing rangelands, waterways, floodplains, rivers, Good environmental management by citrus producers helps to conserve or streams and wetlands enhance the inherent values and characteristics of the broader environment in which the citrus orchard operates. While some of those values may • provision of wind breaks and not appear to benefit the orchard directly, they are deemed worthy of non-cultivated buffer zone protection as part of our natural heritage. areas. In other ways, the natural environment does contribute positively to our Standards: production systems and work environment, and provides services that Operators must include landscape would otherwise have to be provided via material or energetic inputs. management and biodiversity within organic/bio-dynamic These contributions are termed ‘ecosystem services’, some examples of management planning. which are: • Insect pest control: Some common predators including ladybirds, Operators must develop 5% of their mites and lacewings found in our citrus orchards, are examples of property as treed areas, grasslands Australian species which provide ‘free’ biological control of citrus pests. or other reserves which are non- These and other beneficial species make use of non-citrus habitat for cultivated and non-intensively food sources and shelter. grazed within five years from the • Water filtration: Vegetation belts filter surface or drainage water before date the production unit attains in- it re-enters natural waterways. conversion status • Regulation of groundwater levels: Natural and artificially established

23 plantings, especially of trees, are used as ‘pumps’ to regulate groundwater levels in areas where irrigation practices or vegetation clearance has resulted in raised water tables. • Aesthetics: The monocultural aspect of citrus orchards can benefit from the presence of natural vegetation in and around the orchard. Other ecosystem services include: maintenance of healthy waterways, soil health and soil fertility; prevention of soil erosion; provision of shade and shelter; maintenance and regeneration of habitat; maintenance and provision of genetic resources; regulation of microclimate; breakdown and absorption of waste, and river flow regulation[28]. Two common approaches to demonstrating environmental responsibility in agriculture are to revegetate non-crop areas and to maintain the quality of existing native habitat. The former approach is more common amongst organic citrus orchards, due largely to the lack of remnant native vegetation in intensive horticultural districts. The latter approach may require active management to: • prevent weed incursions from the orchard • exclude grazing stock • avoid spray drift • remove and avoid pollution • avoid degradation through discharge of drainage water and excess nutrients.

24 Slashing for cover crop management adds a considerable amount of organic matter to the soil in this organic orchard. 4. Soil management Healthy soil is the organic orchard’s biggest and most influential asset What the National Standard says: and is involved in complex interactions with most other aspects of orchard management. The soil influences management choices, and is General principles: affected by orchard practices related to: Healthy soil is the prerequisite for healthy • weed management (e.g. cultivation or mulching) plants, animals and products. With • pest management (e.g. insectary cover cropping) organic farming, the care of a living soil • disease management (e.g. fungicide residues) and consequently the maintenance or improvement of soil structure, fertility • mechanisation (soil compaction by heavy machinery) and nutrient cycling is fundamental to all • nutrition management (e.g. green manure crops or fertiliser measures adopted. inputs) • irrigation (e.g. application method, moisture levels and erosion Sufficient organic material should be potential). regenerated and/or returned to the soil to improve, or at least maintain, humus levels. This connectivity between soil and other elements of the orchard Conservation and recycling of nutrients is a needs to be kept in mind when management decisions are made. major feature of any organic farming system. Because of its focus on reducing or eliminating chemical inputs and A high or routine use of off-farm inputs is not improving soil health, organic management of soil alters many soil encouraged by this standard. parameters. As an example, when conventional and organic citrus orchards in Spain and Italy were analysed, the organically managed Standards: soils were found to be higher in such factors as organic matter, The fertility and the biological activity of the humic substances, carbohydrate, aggregate stability, microbial gums, soil must be maintained or increased… microbial biomass and enzymatic activity – an indicator of soil The use of off-farm fertilisers shall be [29; 30] metabolism . All of these differences are of benefit to the citrus regarded as a supplement to nutrient trees. recycling, not as a replacement for good soil To change the soil significantly does take time however, so organic management practices… producers need patience and persistence. Cultivation of soils is to be undertaken with care and consideration. Implements and techniques chosen must maintain or improve soil structure.

25 Managing the soil as a resource Where are the citrus roots? Citrus are known for their shallow roots—they will even grow masses of small feeder roots into mulch layers above the soil surface if conditions are suitable. This shallow rooting habit presents the organic producer with some opportunities and challenges in relation to nutrient, water and weed management. Citrus also grow deeper roots. The soil zone in which the majority of root activity occurs has been found to extend to only 20cm below the surface in some situations, and well over one metre in others[31]. This highlights the subsoil’s potential value as a resource—especially so for organic orchards. Its moisture and nutrient stores can help to buffer trees against the surface soil’s extremes of nutrient and water availability. Lateral roots in citrus can extend well into the mid row – an area that is handled differently by different organic producers. Some manage the mid row as an intensive production area, covered with solid stands of irrigated cover crop. Others manage it as rain-fed pasture, focusing their water and nutrient inputs within the tree row. The choice depends on each producer’s priorities, largely in relation to water management. Soil assessment Soil assessments are a good starting point for soil management. They provide valuable information on soil status and how it changes over time, and encourage producers to observe their own soil and note how it responds to different management practices. In conjunction with professional soil tests, soil assessments can help growers to evaluate and refine their management approach to achieve the soil-related outcomes they desire. Soil assessments involve simple observations and tests to determine the status of soil in relation to factors such as: • percent ground cover • root development • soil structure • compaction • pH • water infiltration rate • activity of earthworms and other soil organisms. When repeated over several years, soil assessments may provide some useful evidence to producers and organic certifiers as to the progress being made towards improving soil condition. Locally-developed guides and checklists are available and make good starting points for producers interested in performing their own soil assessment[32; 33; 34]. Soil organic matter Soil organic matter, usually measured as soil organic carbon, includes all living and dead organisms in the soil, from microbes to plant roots. It is one of the most important components of soil because of the major influence it has on the water and nutrient-holding capacity, biological activity and physical structure of soil. Living and dead organic matter is also food for soil organisms whose

26 activity is responsible for vital soil functions including nutrient recycling, pest and disease suppression, structural development and decomposition of contaminants like pesticides. A soil organic matter level of about 2% is considered the minimum required to be useful in holding water and nutrients in the soil. Levels can be increased by bulk additions of compost and mulch or grown on-site as green manure or cover crops, but it is typically a slow process. After conversion to organic management, a compost of cattle feedlot manure (20%), corn meal and husk (20%) and mixed leaves, wood chips and crop residues (60%) was banded under the tree drip lines of a Texas citrus orchard at 2.5-5 t/ha/year. After 17 years the soil organic matter level had increased from 0.3% to 1.25%[35]. During trials in Australia’s Sunraysia district, medic cover crops added about 3.4 t/ha/year of dry matter to the soil and increased soil organic matter levels from 1.11% to 1.47% over four cropping seasons[36]. In another Sunraysia example, organic matter levels in soil of an organic citrus orchard were raised from 0.2% to 2.3% in 16 years by application of about 8 t/ha/year of compost. Assuming a typical moisture content of 50% for composts, the three examples above and others[37] equate to an additional 0.02-0.03% soil organic matter for each tonne of dry matter added. These values are only approximate but give some indication of what may be expected from bulk applications of organic material to the soil. Soil biology Soil biology – involving the living component of soil organic matter—is a vast topic that encompasses multitudes of interactions between beneficial Stable humus: organisms, pests and pathogenic organisms, tree health, soil structure, • is considered most likely nutrient cycling and so on. Functional soil biology is critical to soil and to develop from the tree health and plays a role in the suppression of certain citrus pests and decomposition of woody diseases. plant material (e.g. shrubs Most organic management practices are intended to minimise negative and trees), rather than soft impacts on soil life and optimise conditions for soil organisms. It is beyond material (e.g. annual weeds the scope of this manual to investigate soil biology to any useful extent, and grasses) but excellent introductions can be found on the University of Western • forms strong associations Australia ‘Soil health’ website (see Bibliography) and in the publications with clay particles and so [38] [39] ‘Life in the soil’ and the ‘Soil biology primer’ . is difficult to build up or Humus maintain in sandy soils Another critical part of soil organic matter is humus—a very fine, dark- • decomposes more rapidly coloured collection of complex organic molecules. Humus results from the when soil is disturbed microbial decomposition of plant and animal matter to the point where (cultivated), heated or that material has lost all trace of its original structure. Amongst other subjected to frequent dry/ benefits, humus has excellent water and nutrient-holding capacity, can wet cycles. bind toxins such as heavy metals, and helps to hold soil aggregates together. These points need to be taken Soil contains humus in different forms. Short-lived humus decomposes into account in the choice of relatively easily and provides a source of food for soil organisms, but soil management practices contributes little to soil structure in the longer term. ‘Stable’ humus is and materials for mulch and more resistant to decomposition, can persist for thousands of years and compost, if the aim is to [40]. contributes greatly to soil structure and function increase soil humus levels effectively.

27 Stable humus: • is considered most likely to develop from the decomposition of woody plant material (e.g. shrubs and trees), rather than soft material (e.g. annual weeds and grasses) • forms strong associations with clay particles and so is difficult to build up or maintain in sandy soils • decomposes more rapidly when soil is disturbed (cultivated), heated or subjected to frequent dry/wet cycles. These points need to be taken into account in the choice of soil management practices and materials for mulch and compost, if the aim is to increase soil humus levels effectively. Techniques used by organic citrus producers to increase organic matter levels in their soil are discussed later in more detail. They include minimising soil disturbance, on-site growth of green manures and cover crops, and import of such materials as compost, mulch and coal. Surface cultivation How to check if your soil moisture level Where surface cultivation is required, e.g. for cover crop sowing or weed is suitable for cultivation management, it should ideally be as shallow as possible and minimise Squeeze some soil into a ball then try to mixing of the soil layers. roll it into a rod about 3mm thick. This approach will help to preserve the structure of the soil profile. • If the rod forms easily, the soil is Different soil organisms tend to be distributed through the soil profile likely to be too wet for cultivation, and could be easily compacted. according to their requirements regarding temperature, moisture, light, pH, nutrients and oxygen. Deep cultivation that mixes soil layers will have • If the best you can make is a a more disruptive effect on this soil life and so will reduce the benefits crumbly rod, the soil moisture obtained from soil biological activity. content is likely to allow cultivation without compaction occurring. As well as redistributing and destroying soil organisms, cultivation • If no rod forms, the soil is probably destroys the food source for some (plants), and their structures like worm too dry to cultivate. and ant tunnels. It also disrupts the physical soil structure by destroying soil aggregates, and can reduce organic matter levels by speeding the mineralisation of organic matter. Some of these negative impacts are greater when cultivation is carried out on soil that is excessively wet or dry. Erosion control Organic standards require soil erosion to be minimised if not eliminated. This is usually achieved through the use of windbreaks, cover crops, mulch, contour planting, careful management of irrigation, rainfall and drainage water, and practices that maintain good levels of soil organic matter. Where summer cover crops are not maintained because of insufficient water, at least the dry stubble or other crop residue should be left as a protective soil cover against the erosive force of wind, irrigation and rainfall. In a high rainfall citrus orchard with up to 10% slope, soil movement during rain was reduced by over 99% by mulch and 79% by a cereal green manure crop[41]. Even a partially established, young legume cover crop still reduced soil loss by 65%.

Compaction & deep cultivation Heavy orchard traffic, particularly tractors and spray carts can result in soil compaction, leading to reduced aeration, gas exchange and permeability to water, and increased bulk density (hardness). These changes make the soil less favourable for many desirable organisms including tree roots. Organic

28 growers need to be aware of, and take measures to avoid compaction, as a How to check your soil for compaction biologically active soil is the basis of their nutrient management system. • Use a shovel to dig a hole at least Permanent cover crops, minimum cultivation, varied cultivation depths 30cm deep. If there is a layer of hard, compacted soil you should and exclusion of heavy machinery from wet soils will help reduce the risk be able to feel it as you dig. Look of soil compaction. Establishment of deep-rooted cover crops like lucerne for signs of restricted root growth, and/or deep ripping with soil renovation implements like the Yeomans i.e. a layer of soil that roots are not plow® or Agroplow® will help reverse soil compaction. penetrating; or • push a 3-4mm diameter metal rod Deep cultivation or ‘ripping’ can be an important part of land preparation into the soil, feeling for resistance. before planting a new orchard. Good soil preparation at that early stage If the rod doesn’t penetrate at least is particularly important for organic growers. They need to maximise 30cm relatively easily, the soil may the benefits they obtain from well-structured, well-functioning and be compacted or dry; or biologically active soil with regards to nutrient storage and cycling and pest • use a penetrometer. This is a purpose-built device available and disease suppression. from agricultural suppliers or crop consultants, used to measure the A range of soil problems including compaction, poor structure, poor strength or hardness of the soil. drainage and high or low pH can be improved by deep ripping when Note: Results from the last two tests it is done correctly, especially in conjunction with other soil modifying can vary significantly, depending on soil practices. moisture levels at the time of testing. Moisture The moisture content of soil strongly influences many of its key properties and behaviours, particularly biological activity. From the organic viewpoint, a critical function of irrigation is to maintain soil moisture at the optimum level for biological activity. Because of water limitations, organic citrus producers are increasingly opting to maintain moisture levels within the main tree root zone and leave the mid row area to ‘fend for itself’ under natural rainfall. Mulch Mulch is used by many organic citrus producers to suppress weed growth, conserve soil moisture and protect the soil from temperature extremes. A benefit of using organic material as mulch is that it adds valuable organic matter to the soil as it decomposes. The benefits of mulch can often be observed in a relatively short time and include increases in activity of earthworms and other organisms, water infiltration rate and soil moisture retention, and reduced soil hardness. These benefits, together with a moderation of soil temperature and increased organic matter levels, help create soil conditions that are more favourable for biological activity including tree root growth. This is especially useful in citrus with its many shallow feeder roots. More information on mulching appears in section 7 on Weed management. Remember that uncomposted off-farm mulch materials such as straw may be a source of weed seed. The cleanliness of such materials should be confirmed before they are brought into the orchard. Salinity/sodicity/pH Salinity, sodicity and pH can have marked effects on biological activity, structural integrity, nutrient availability and other critical soil characteristics. Excessive salinity, sodicity or acidity are commonly associated with soil degradation. Organic standards require that problems such as these be guarded against or remedied by appropriate management

29 practices. See the publication by Ayers and Westcot[42] for detailed descriptions and management approaches for salinity, sodicity and other water-related soil problems. Salinity relates to the amount of dissolved salts, usually sodium chloride (common salt), in the soil. Soil salinity usually results from rising saline groundwater tables and application of salts in irrigation or rainwater. Salinity affects plants and other soil organisms directly as a toxin and indirectly by reducing the availability of water. Practices that help reverse or reduce the risk of localised soil salinity include: • minimise the amount of water applied—to minimise additions to the groundwater table • irrigate with low-salt water—to minimise the amount of salt added to the soil • apply sufficient leaching irrigations—to wash salt below the root zone and • use subsurface drainage where necessary—to remove excess water and salt from the soil. Sodicity refers to the amount of sodium in the soil, usually as the percentage of the cation exchange capacity (CEC) that is occupied by sodium. The CEC is a measure of the soil’s capacity to hold cations (positively charged elements like sodium, calcium, magnesium and potassium) by electrical attraction. Soils are considered sodic if more than six percent of the CEC is occupied by sodium, and highly sodic if the figure is greater than 15 percent. Sodic soils typically occur if concentrations of salt (sodium chloride) develop to the point where sodium replaces the calcium held in clay How to check your soil for its particles. Sodic clay particles tend to disperse rather than stick together likely response to gypsum when they are wet. This results in unstable soils that are prone to collapsing Not all clay soils will respond to gypsum and erosion when wet, and setting hard when dry. – only those that disperse readily when wet. The most common treatment for sodic soils is the application of gypsum, To check a soil for its tendency to either broadcast or dissolved in irrigation water. The high calcium content disperse: in gypsum helps to displace sodium from the clay particles and restore • Gently drop some dry soil crumbs soil stability. If subsoils are sodic, deep ripping may be necessary to help (aggregates) about 5mm in distribute the gypsum. diameter, into a glass of clean water. Rainwater is preferred. Organic growers need to be aware that some sources of gypsum contain • If the clay disperses, the water high levels of the undesirable heavy metal, cadmium. Organic certifiers set around the crumbs will become maximum allowable concentrations of cadmium and other contaminants cloudy. If the clay is highly in fertilisers and soil conditioners. These should be consulted before dispersive, the whole glass of water may become cloudy. materials like gypsum are purchased or applied to organic orchards. • If any cloudiness develops within pH (a measure of Hydrogen ion concentration in a solution) refers to the an hour or two, the clay is likely to acidity or alkalinity of the soil and has a major bearing on the availability be improved by the application of gypsum. This can be confirmed by a of nutrient elements within the soil. The pH scale ranges from zero soil laboratory test. (extremely acid) to 14 (extremely alkaline), with seven being neutral. Depending on pH, some elements can be so strongly attached to soil If gypsum is needed, a soil analysis particles that they are unavailable to plants, or so freely available that they should be used to determine the become toxic. The optimum pH for citrus appears to be between 6 and 7, application rate, as the requirement but values outside that range are common in Australian orchards. will depend on the soil type and actual sodium content. Lime or dolomite is often used to raise soil pH, with the application rate dependent upon current and preferred soil pH, soil type and lime quality. The following table gives approximate lime application rates.

30 Lime products are less likely than gypsum to be contaminated with heavy metals. Organic growers should however be aware of the risk, and confirm the acceptability of any product with their certifier before use. Soil pH tends to be reduced by legume cropping (e.g. as green manures or cover crops), increased soil organic matter and nitrogen fertilisers—some of the reasons why soil acidification is common in many of our naturally acid soils. On alkaline soils, these standard management practices may help to moderate the effects of high pH. Table 4‑1. Approximate lime application rates (tonnes/hectare) according to soil type and current soil pH[43]. Current soil pH Soil texture 4.0 – 4.5 4.6 – 5.0 5.1 – 5.5 Sand 4.0 2.5 1.5 Loam 5.5 3.25 2.0

Clay sand 9.5 6.25 3.5

Managing the nutrient cycle

Organic crop nutrition Acceptable inputs ‘Feed the soil, not the plant’ is a common saying within the organic industry. The intent of this approach to crop nutrition is to mimic natural • Animal manures and by- soil development and nutrient cycling, where soil is ‘provided’ with mineral products such as fish meal nutrients from the base material (rock) and organic matter from such and blood and bone sources as leaf litter, animal manure and the bodies of microbes, insects and • Compost other animals. • Minerals from natural The decomposition and recycling of these materials by organisms sources including gypsum, including plants, microbes, insects, worms and other animals gradually lime, clays, rock phosphate, converts the nutrient elements they contain into forms that tree roots can rock potash, epsom salts absorb and use for their own growth. Nitrogen is also extracted directly and zeolites from the atmosphere by free-living soil bacteria and by Rhizobium bacteria associated with nodules on the roots of such leguminous plants as clovers • Organisms (e.g. worms) and and medics. their by-products Natural nutrient cycling within soils relies upon soil biological activity and • Biological preparations, wetting/drying cycles. This contrasts with the soluble fertiliser approach including microbial and in which water-soluble forms are applied to soil with the intent of feeding botanical the plant directly. The latter approach largely bypasses the nutrient cycling role of soil microbes and other organisms—one reason why water-soluble • Plant by-products such nutrients are generally not permitted under organic standards. as sawdust, wood wastes, wood ash and straw As a first step in nutrition management, organic citrus growers should consider balancing their yields against the orchard’s inherent production • Seaweed and algal capacity (related to the scion-rootstock combination, and soil, water and preparations climatic factors) and their own capacity to provide the orchard with the • Mined carbon-based required inputs, taking into account input costs. The most economically materials ( e.g. coal and environmentally sustainable yield may not be the maximum possible humates) yield. • Trace elements (only natural Nutrient budgeting chelating agents allowed) Nutrient budgets are not simply nutrient input—crop output calculations. • Perlite and vermiculite (in They involve complex interactions between the rootstock, scion variety, potting mix only)

31 Table 4‑2. Nitrogen and crop load, applied inputs, soil texture and chemical properties, and the phosphorus inputs in Murray physical, chemical and biological processes taking place in the soil. Some Valley irrigation water. understanding of these interactions and their relative importance for kg/ha/year (and % of soil, tree and fruit development is necessary for growers to be able to annual requirement) develop effective and efficient nutrition programs consistent with organic principles. Swan Hill Lower S.A. Riverland Using nitrogen as an example, Figure 4-1 indicates typical nutrient Nitrogen (N) 3.7 (3.7) 8.1 (8.1) pathways into and out of the tree and soil ‘system’. Most nutrient additions Phosphorus 0.46 (2.1) 2.33 (10.8) to these systems will be obvious and deliberate, i.e. applied by growers in (P) the form of compost, fertiliser or mulch. Nitrogen is an exception, because Calculations based on data from the significant amounts can be added to the soil via bacterial fixation of Murray Darling Basin Commission ‘Murray River Water Quality Monitoring atmospheric nitrogen. Program’ and recommended annual irrigation (10ML/ha) and N and P Depending on its source, irrigation water may contribute small amounts requirements of mature citrus[9] of nitrogen and other nutrient elements. Some indicative levels of nitrogen and phosphorus input in Murray Darling irrigation water are shown in Table 4‑2. Some nitrogen also enters the orchard in rainfall, but Australian studies have shown this to be a minor source, in the order of 1-2 kg/Ha/ year[44; 45; 46]. Optimising the input and recycling of nutrients, while minimising losses, are important goals for organic growers and are addressed below.

Rainfall

Gaseous losses Exported in fruit

Runoff Mobilised from woody tissues & older leaves Applied nutrients & Fixation of atmospheric N mulches by symbiotic & free-living Released from decomposing microbes plant matter and soil Irrigation organisms water Leaching Leaching

Inputs Cycling within the system Losses

Figure 4‑1. Typical nitrogen flows in a citrus orchard system:

32 Soil & plant analysis Some organic standards require periodic soil analyses because of their value in monitoring long-term trends in such parameters as fertility, pH and the vitally important organic matter levels. These trends give an indication of the long-term sustainability of the organic orchard. Monitoring the soil also benefits growers. It helps growers to detect, and work to correct, undesirable trends such as element depletion or accumulation that can be slower and more difficult to address under organic management compared to non-organic management. Because changes to soil properties are relatively slow, soil analyses are usually performed every three years or so, rather than every year. Leaf analyses are used to monitor the nutrient status of trees and to assess their responses to changes in soil and nutrient management practices. Leaf analyses may also be used to confirm visual symptoms of a nutrient excess or deficiency. Many organic citrus growers use annual leaf analysis and occasional soil analysis to fine-tune their management with the aim of maximising resource use efficiency and fruit quality. Figure 4‑2 shows the trends for some mineral nutrients in Valencia leaves for an orchard in the Murray Valley. Also included are some less frequent measurements of soil organic matter. The orchard was converted to organic management in 1989 with a nutrition program initially based on composts that included amongst other things, pig and poultry manure and grape marc. Two trends most likely attributable to that program are seen in Figure Valencia orange on Citrange 4‑2; increasing potassium levels (possibly due to high-potassium 5 grape marc) and high phosphorus levels during the mid 1990s, most 4 likely from the poultry manure. A change from poultry manure to 3 cow manure helped to address the converted to organic issues of excess phosphorus. 2

Analytical services % P, N, K, Ca, Soil Organic Matter 1 Numerous soil and plant tissue analysis services are available 0 through state agriculture 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 departments and agricultural Phosphorus 0.14-0.18 Nitrogen 2.4-2.8 Potassium 1.0-1.5 Calcium 2.5-5.5 SOM Linear (Nitrogen 2.4-2.8) Linear (Potassium 1.0-1.5) Linear (Calcium 2.5-5.5) suppliers. It is preferable to develop a long-term relationship with one Figure 4‑2 Results of nutrient analysis before, during and after of these services rather than ‘shop conversion to organic management. Element data is from leaf around’ from season to season. analysis. SOM=Soil Organic Matter. The numbers after each This is because there is value in element indicate the ‘adequate’ range for that element[47; 48] and assembling a history of comparable the dashed lines indicate the overall trend for each element. analyses from a single laboratory, using the same sample handling procedure and equipment from year to year. It is also important to inform the chosen laboratory that the analyses are for organically managed trees. This allows them to make appropriate recommendations on input requirements and orchard management.

33 There is considerable interest within the organic industry in soil analysis and management using the ‘Albrecht system’ devised by William Albrecht, a professor of soils at the University of Missouri in the 1930’s. Amongst other things, Albrecht researched the importance of calcium and of the balance between some of the major soil elements, for soil health and crop nutrition. Although there is debate as to how applicable the Albrecht system is to all soils, the system continues to attract followers interested in an alternative approach to soil health and crop nutrition. As it is beyond the scope of this publication to review the ‘Albrecht system’ in detail, growers should seek further information from such sources as ‘The Albrecht papers’ and ‘Hands-on agronomy’ as listed in the Bibliography. Some soil laboratories using this approach are listed in Section 12.7. Further information may be obtained from the laboratories directly or through their Internet sites. Nitrogen mineralisation & availability Maintaining adequate soil and tree levels of nitrogen (N) can be more of a challenge under organic management because it must be achieved without the soluble, high-analysis fertilisers that can be used by non- organic growers. Nitrogen supply is likely to be the greatest limitation to production. Much of the nitrogen in organically acceptable inputs such as green manures, cover crops and compost is initially unavailable to plants because it is ‘bound up’ in complex organic compounds such as proteins. Nitrogen and other nutrient elements contained in this organic matter become available to plants when the organic material decomposes. This includes material arising from the death and decomposition of plant roots that occurs when a cover crop is slashed or grazed. Decomposition is greatly assisted by incorporation of the organic matter into the soil. The release of this ‘organic nitrogen’ in a plant-available form relies largely upon biological processes in the soil. Soil organisms break down the organic compounds in plant and animal matter and convert the nitrogen into simpler mineral forms that are more easily absorbed by plant roots. These processes are collectively referred to as ‘mineralisation’ (Figure 4‑3). Organic growers need a reasonable understanding of this process, as it is fundamental to the management of tree nitrogen nutrition. As indicated in Figure 4‑3, while the mineral forms of nitrogen are available to plants, these forms are also susceptible to loss from the soil. Nitrogen mineralisation needs to be managed to minimise losses and to optimise the levels of plant-available nitrogen. NH 3 Ammonia gas lost to the atmosphere Importance of the carbon:

Nitrification nitrogen ratio Ammonification mostly by bacteria by many soil organisms Given suitable temperature and Organic nitrogen NH 4 NO2 NO3 moisture conditions, the rate at (Proteins etc in plant Ammonium Nitrite Nitrate & animal matter) taken up by taken up by which nitrogen becomes available plant roots plant roots from organic material depends largely on the ratio of carbon to

Susceptible to leaching nitrogen (the ‘C:N ratio’) in the Figure 4‑3 Mineralisation of organic nitrogen. material (Figure 4‑4).

34 The importance of the C:N ratio Rapid breakdown - C:N less than 20:1 e.g. medics N is mineralised to ammonium and nitrate which are is that to function and reproduce, 30 then released into the soil microbes need an energy source. n Moderate breakdown rate - C:N 20:1 - 30:1 In the soil this energy source is 20 e.g. wheat No short-term change in soil the carbon-rich compounds (e.g. ammonium or nitrate sugars) in dead plant material. 10 To access the energy in those Net mineralisation compounds requires proteins, 0 Net which are largely made up of immobilisation carbon and nitrogen. Carbon is Plant-available Nitroge Slow breakdown - C:N greater than 30:1 -10 e.g. woody prunings lost during this process as carbon N is extracted from the soil and immobilised for dioxide. Soil bacteria have a C:N some time by incorporation into soil organisms ratio of 6:1, and so to grow, these -20 Time bacteria must be able to access and Figure 4‑4. General relationships between C:N ratio of organic consume more than double the matter and rate of nitrogen mineralisation (adapted from[49; 50]) carbon they need to maintain the 6:1 C:N ratio. Organic matter with a C:N ratio greater than 30:1 doesn’t contain sufficient nitrogen for soil microbes to build proteins to access the energy in the material’s carbon-rich compounds. To meet this shortfall, the microbes extract mineral nitrogen from the soil. The resultant drop in available nitrogen is the ‘nitrogen draw-down’. The mineral nitrogen is incorporated into the microbes’ cells and is unavailable to plant roots until the microbes themselves decompose. In contrast, organic material with a relatively high nitrogen content (C:N less than 20:1) usually contains all the nitrogen necessary to allow rapid decomposition by microbes, and results in nitrogen being released into the soil early in the decomposition process. These same processes and relationships apply during the decomposition of mulch, compost, manures and commercial fertilizers based on organic materials – the nutrient inputs upon which most organic citrus producers rely. So, depending on their C:N ratio and other factors such as their state of decomposition when applied, the soil moisture content and soil temperature, different organic materials can exhibit very different rates of nitrogen release. An experiment conducted in California assessed the decomposition of 31 manures and composts in soil after 12–16 weeks incorporation, and showed that the proportion of organic nitrogen that had become mineralised and available to plants ranged from 2% to 20%[51] (Table 4‑3). Table 4‑3. Example mineralisation rates of N in organic wastes[51; 52].

Organic nitrogen % mineralised Organic waste material Initial %N in 12–16 weeks

Dry poultry manure 3.0–3.9 20

Aged poultry or feedlot manure 2.0–2.9 9 Poultry, feedlot or dairy manure compost 1.2–3.6 6–10 Green waste compost 1.0 –1.7 2

35 Generally the percentage of organic nitrogen mineralised in the short to medium term (up to one year) is related to the initial nitrogen content (and hence the C:N ratio) of the organic matter[51; 52; 53; 54; 55]. This means that lower nitrogen materials not only release less nitrogen overall, they release it more slowly than higher nitrogen materials. Composts and manures with less than 3% organic nitrogen showed low rates of nitrogen release over 12-16 weeks[51]. While largely dependent upon the qualities of the organic matter, mineralisation rates of nitrogen in organic matter applied to the soil are also influenced by soil properties (Table 4‑4). These in turn may be influenced by management practices. Table 4‑4. Major soil factors influencing nitrogen mineralisation[56]

Soil N mineralisation characteristics Moisture Inhibited by very wet or dry conditions pH Inhibited by pH below 5 or above 8 Temperature Generally increases as soil temperature increases C:N ratio N draw down if soil C:N above 11 N released if soil C:N below 9 Cultivation Soil disturbance decreases mineralisation and increases N losses

Nutrient cycling

Organic standards emphasise the recycling of nutrients as a fundamental aspect of organic farming. Nutrient cycling can be achieved by the return of as much orchard ‘waste’ as possible to the orchard, the use of green manure and cover crops, and incorporation of livestock where appropriate.

Recycling of citrus tree nutrients A significant proportion of the nitrogen and other nutrient elements in older leaves are redistributed within citrus trees before leaf drop occurs[57]. The nutrients in fallen leaves and dead roots are also recycled, through the decomposition and mineralisation process described earlier. One Florida study of 20-year-old orange trees in a sandy soil found that mineralisation of organic nitrogen from leaves and roots made up to 153 kg of N/ha/year available for re-use by the trees[58]. Up to 84 kg/ha/year was recycled under 4-7 year old orange trees. When pulverised citrus leaves were incorporated into sandy soil, their nitrogen started to become plant-available within days. Ammonium nitrogen levels peaked after 20 days and about 60% of all nitrogen in the leaves was mineralised after nine months[59]. While the rate of nitrogen mineralisation is likely to be less under the drier conditions prevailing in most of Australia’s citrus districts compared to Florida, the cycling of nitrogen from mineralised tree residues should be taken into account when developing nutrient budgets. Wherever possible, tree prunings should be dropped where they are cut, and mulched to aid decomposition and to destroy any infestations of pests. If prunings are to be burnt for pest and disease control or for other reasons, then ideally the ashes would be returned to the orchard. This at least returns some of the mineral content of the prunings to the soil.

36 Cover crops & green manures Cover and green manure crops play a vital role in organic agriculture because of their many benefits to the soil and cropping system. Some of these benefits are illustrated in Figure 4‑5. Cover crops can be defined as crops grown as a ‘living mulch’ specifically to benefit the soil, by, for example, protecting from erosion and high soil temperatures and improving important properties such as soil structure, permeability, nutrient levels and biological activity. The improvement As well as suppressing weeds in this organic in soil organic matter is the basis of some of these effects. Cover crops orchard, the lucerne cover crop recycles can also provide additional benefits such as habitat, food and shelter for nutrients, fixes nitrogen and produces bulk organic matter. beneficial insects, suppressing weeds and maintaining orchard accessibility after rain or irrigation. Perennial plant species are commonly used for cover crops, and these may be left undisturbed, apart from slashing, for many years. Annual plants are also used, and are left to regenerate naturally by self-seeding, rather than being resown annually. Green manure crops may be considered as annual cover crops that are incorporated into the soil before they mature. As their name implies, green manures are intended to act as ‘manure’ to boost soil fertility, especially in relation to nitrogen. For this reason they are incorporated while still young and green, while their nitrogen content is relatively high. Green manure crops also provide short-term increases in organic matter levels, with benefits to soil structure and biological activity. A general introduction to the use and benefits of green manures applicable to a range of cropping systems can be found in the Agriculture Note “Organic farming: Green manures for vegetable cropping”[60]. Cover and green manure crops often contain a mix of plant types. Cover crops typically include legumes like medic, clover and lucerne for their nitrogen-fixing ability, and grasses such as ryegrass. Cereals like millet, barley, rye, ryecorn and oats, and legumes such as field peas, beans and lupins are often grown as green manures. In reality, a very wide range of plants may be used. The grower’s choice is determined largely by crop requirements in relation to, for example: • nitrogen balance (legumes for nitrogen input in poor soils vs grass- legume mix in fertile soils) • organic matter production (cereals generally produce more dry matter than legumes) • pest management (grasses do not host lightbrown apple moth; the pollen of some grasses is food for predatory mites; the nectar of certain flowering plants is food for beneficial insects) • growth habit (prostrate species are less likely to interfere with low-level sprinklers) • active season (winter-active/summer-dormant species will help to reduce competition with trees during summer) The Agriculture Note “Organic farming: Which green manure should I grow ?” [61] lists useful characteristics of over 50 green manure and cover crop plants suitable for use in most temperate regions of Australia. Some of that information was sourced from the extensive cover crop database maintained by the University of California (see ‘SAREP’ in the Bibliography under ‘Organic/ sustainable agriculture’). Knowledge of these plant characteristics will help growers to choose the crops most suited to their specific objectives and orchard situation. 37

, , and

supply s . n erosion . root

with pollen

s sources for

re fibrou ves soil moisture by groundcover arthropods food soil from crusting temperature extremes s s and extra income orage for grazers A groundcover ‘blanket’ protects the soil surface from and conser reducing evaporative losses. Protect soil from heat, wind & rain rovide A diverse groundcover ca beneficial nectar and alternative prey. Plant growth slows runoff and prevent P beneficial species Improve water infiltration ot exudates and Build soil aggregates Ro help to bind soil particles together. Provide f Grazing (eg. with geese or sheep) may be used for management

. water and

a dense rooted plants recycle some of desirable plants p- un Dee the nutrients and water that leach past the crop root zone Capture deep nutrients . with nual weeds are poor competitors an s

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protection for including many into d

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an in nutrient cycling and ts root growt . . s groundcover d parasites benefit from the g. organisms an physical shelter d protec d d living an habitat for soil organisms habitat y add organic matter to an ll beneficial . nutrients for later usable form s s t - urface litter Predators humidity mulch and S continua the soil Live and dead plant matter hold release and against leachin Symbiotic bacteria in legume root nodules fix nitrogen plan A diversity of plant types creates a richer habitat for soil species pest & disease suppression. Provide beneficial specie Add organic matter to soil Store nutrient Fix atmospheric Enhance 5 Some benefits of orchard cover crops cover 4 ‑ 5 Some benefits of orchard Figure

38 Nitrogen fixation by leguminous green manures and cover crops The extraction of nitrogen from the atmosphere is a major reason for the long-standing role of legumes in organic agriculture. This ‘free’ service is a valuable component of organic nutrition programs as it can provide significant amounts of nitrogen to cropping systems. Nitrogen fixation occurs when Rhizobium bacteria form a symbiotic relationship with the roots of legumes. When these bacteria infect the plant root, the root forms a gall (nodule) around the infection site. The bacteria live within the nodules and incorporate ‘free’ atmospheric nitrogen into their own bodies and supply the host plant with nitrogen in a usable form. The bacteria benefit by being supplied with sugars and other nutrients by the plant. When the nodulated roots die, after cultivation for example, the nodules and bacteria decompose, allowing their nitrogen content to be mineralised into plant-available form. To ensure effective nodulation, legume crops usually need to be inoculated with the bacteria at the time of sowing. As specific strains of Rhizobium bacteria infect Root nodules on legumes are the powerhouse specific types of legumes, it is important to match the bacteria and legume of nitrogen fixation in organic orchards. correctly. Advice and inoculum should be sought from the seed supplier. The amount of nitrogen fixed by legume crops varies greatly and relates to the crop type and variety, and soil moisture, temperature and nutritional status. As an indication of this variability, the nitrogen fixation estimated in Californian studies ranged from 50 to over 220 kg N/ha for vetches and from 100 to over 330 kg N/ha by strawberry clover[62]. During trials under dryland conditions in the Victorian Wimmera, medics, fenugreek, vetch, faba beans and field peas produced 100 to over 220 kg N/ha[63]. During trials in Sunraysia vineyards, medic cover crops covering 62% of the ground area produced 70 to 80 kg N/ha[36]. Under suitable conditions, increases in soil nitrogen can be detected soon after legume crops are cultivated or cut. In the Sunraysia trials mentioned above, soil nitrate levels peaked around three weeks after mowing and five weeks after incorporation into the soil, of a Paraggio medic cover crop (2.9% N). As would be expected, the overall release of nitrogen from the cultivated crop far exceeded that of the mown crop. Using these times of nitrogen release as a guide, combined with experience, cultivation, grazing or mowing of leguminous green manures or cover crops may be timed to give trees a natural nitrogen boost prior to critical periods such as flowering and growth flushes. Table 4‑5 provides a guide to the nitrogen content and C:N ratio of some common leguminous green manures and cover crops, along with cereals and brassicas.

39 Cover crop or green manure ? How to determine the nitrogen content of a cover crop or This choice depends on the green manure priorities and objectives of the To calculate the approximate nitrogen content of a cover or green orchard manager. manure crop requires a laboratory analysis of the percentage dry For soil improvement prior to matter and percentage nitrogen of a sample of the crop, and a orchard establishment, a well grown simple calculation. To do this: green manure is likely to boost 1. Harvest whole plants, tops and roots, from a total of one square short-term soil organic matter and metre of the crop. This can be done in several small patches. nutrient levels more rapidly than a 2. Weigh the freshly harvested sample to get the FRESH WEIGHT cover crop and more cost-effectively (kg per square metre). than applied compost or other soil amendments. Green manures are 3. Send a sub-sample of whole plants to a soil/plant analytical less suitable for established orchards, laboratory for analysis of DRY WEIGHT % (the fresh weight with as they need to be incorporated water removed) and DRY WEIGHT NITROGEN % (how much of through cultivation, which may the dry weight is nitrogen). The laboratory will advise on how disrupt the shallow roots of citrus. much to send and how to package the sample. Longer-term cover crops have 4. Calculate the kg of nitrogen per hectare the advantage of reduced or nil = FRESH WEIGHT x DRY WEIGHT % x DRY WEIGHT NITROGEN % cultivation once established. This is of real value to organic growers Example: A FRESH WEIGHT of 4kg is harvested from one square because it reduces negative impacts metre. The laboratory analysis shows a DRY WEIGHT % of 15% and a on the soil while fostering soil DRY WEIGHT NITROGEN % of 2.5%. development and providing a The crop’s nitrogen content is 4 x 15 x 2.5 = 150 kg per hectare of more stable habitat for beneficial cover crop. invertebrate species within the orchard. If the cover/green manure crop only covers a proportion of the orchard floor, then the crop nitrogen content can be adjusted A disadvantage of summer-active accordingly, to determine the nitrogen content per hectare of cover crops is their competition for orchard. water—an important point where these factors are limiting. In the above example, if the cover crop covered only 50% of the orchard floor, it would contribute 75 kg (50% of 150 kg) of nitrogen Compost per hectare of orchard. Composting is an ideal way to recycle nutrients extracted from the orchard, such as in cover crops that are harvested, or ‘wastes’ like citrus prunings and peel from juicing plants[64]. The production and use of compost is dealt with below under ‘Applied nutrient inputs’.

Grazing livestock One of the traditional roles of livestock on mixed farms was the conversion of ‘weeds’ and ‘wastes’ into manures. Poultry in particular produce nutrient-rich manure and many of the commercial organic fertilisers used on citrus are based on composted poultry manure. The running of poultry in citrus orchards for any reason (weed or pest management, egg or meat production) will contribute directly to the nutrition of trees and cover crops. As a guide, some indicative values of nutrient deposits by hens are shown in Table 4‑6. These were calculated from manure analyses and production rates developed for the Western Australian poultry industry[65].

40 Table 4 5 Nitrogen content and C:N ratio of selected green manures and cover crops (Wheatley and Treeby, unpublished data). %N1 C:N ratio Pulses Faba bean (Vicia faba) 3.4 13 Field pea (Pisum sativum) 2.3 19 Sandplain lupin (Lupinus cosentinii) 2.4 18 Medics Burr medic (Medicago denticulata) 2.8 17 Kasbah medic (M. truncatula) 3.9 11 Paraggio medic (M. truncatula) 2.9 15 Prostrate lucerne (M. sativa) 3.6 12 Cereals Wheat (Triticum aestivum) 0.8 52 Oats (Avena sativa) 0.9 49 Triticale (T. aestivum x Secale cereale) 1.1 41 Perennial ryegrass (Lolium perenne) 0.6 78 Brassicas Nemfix™ (Brassica spp.) 4.3 9 Weedcheck™ (Raphano sp x Brassica sp) 3.0 13 1 Calculated as % of dry matter

Table 4‑6 Approximate nutrient deposits by laying hens Amount Recommended Amount removed in 50t/ application deposited by ha crop[66; 67; 68; 69] rate for mature 150 hens/ha citrus[9] (from[65])

Element kg/ha/yr kg/ha/yr kg/ha/yr Nitrogen N 50-83 80-125 107* Calcium Ca 7-50 # 91 Magnesium Mg 5-10 # 12 Phosphorus P 7-13 18-24 47 Potassium K 83-125 80-125 49 g/ha/yr g/ha/yr g/ha/yr Boron B 38-75 # 47 Copper Cu 16-25 # 47 Iron Fe 33-58 # 7000 Manganese Mn 10-13 # 702 Zinc Zn 33 # 819 * after an assumed 25% loss as ammonia # depends on orchard-specific leaf analysis

In Table 4-6, a stocking rate of 150 hens/ha was selected to match the rate of nitrogen deposition with the recommended nitrogen input for mature citrus. This allows the other nutrients to be compared easily. Stocking rates for commercial free-range poultry are much higher—a maximum 1500 birds/ha is suggested for egg production under conventional management[70] and 1000 under organic management[71]. The figures in Table 4‑6 are provided only as a guide and are based on birds that are supplied with all their feed requirements ‘out of a bag’. The actual amount of nutrient in manure and potentially available to trees

41 in a free-range situation will depend on several factors including poultry breed, quality of feed, the distribution of manure in relation to trees and irrigation management. Growers also need to distinguish between nutrient imports into the orchard and nutrient cycling within the orchard. The amount of nutrient that is a ‘new’ import will depend on the ratio in the diet of on-site forage to purchased feed (such as pellets and wheat). Two points to note from Table 4‑6 are: • Relatively low poultry stocking rates can make a significant contribution to citrus mineral nutrient needs • Depending on the balance of elements in commercial feed, manures can contain levels of micronutrients like iron, zinc and manganese far in excess of citrus requirements. This issue has been identified in South Australian citrus orchards but does not appear to have resulted in excessive levels of those elements in trees[72]. This may be due to the low availability of those elements under our typically high pH soil conditions. It should be noted that some organic standards and quality assurance schemes restrict the application of raw animal manures to food crops for specified periods prior to harvest, where there may be a risk of microbial contamination of the crop. The US NOP standard for example requires a ‘withholding period’ of 90 days for crops not in direct contact with the soil. These restrictions may also be interpreted as applying to direct deposition of manure by livestock, which need to be managed accordingly. Mycorrhizae Mycorrhizae (a mix of Greek and Latin meaning ‘fungus roots’) are the result of a symbiotic relationship between fine plant roots and specialised soil fungi. Over 90% of all known plant species are mycotrophic, i.e. they live in association with mycorrhizal fungi. The fungal spores germinate and penetrate root cells of citrus and most other cultivated plants, and extend out into the soil. The fungi benefit from the association by obtaining carbohydrates and other substances from the plant. The benefits to plants are due in part to a simple increase in absorptive area of their root system (plant roots plus fungal hyphae). Mycorrhizal hyphal networks can be very extensive. The total length of hyphae in some natural and agricultural systems has been estimated to be many kilometres per kilogram of soil[73]. Mycorrhizae are also considered to be involved in decomposition of mineral and organic materials through the production of organic acids and other substances[74]. This means they can increase the actual availability of some mineral nutrients, not just the volume of Conversion of weeds into manure is one soil accessible to plant roots. benefit of grazing livestock in organic orchards.

42 The major nutrient elements influenced by mycorrhizae include nitrogen, sulphur, copper, zinc, iron, calcium and magnesium[75; 76; 77], but phosphorus is usually considered the most important. It has been estimated that in tropical citrus, mycorrhizal infection of roots can effectively supply as much phosphorus as would be supplied by an application of 500kg per hectare[75]. Being adapted to low-nutrient soils, mycorrhizae tend to thrive and provide benefit to their host plants only under conditions of low to moderate nutrient availability. For this reason, rock phosphate (naturally slow-release) has been recommended as a suitable phosphate source to encourage mycorrhizal development in citrus[78]. Rock phosphate is the main mineral source of phosphorus available to organic producers. Other than increased nutrient availability, the benefits of different mycorrhizae can include enhanced stability of soil aggregates, reduced soil pH, improved nodulation and nitrogen-fixation by legumes, greater drought tolerance and improved defence or resistance against root pathogens[75; 77; 79]. Plants like citrus, with relatively coarse roots, are usually more dependent upon mycorrhizae for adequate nutrition[75]. Within citrus, different rootstocks show different degrees of dependency on mycorrhizae[80]. Of the rootstocks commonly used in Australia, Troyer citrange, Carrizo citrange, rough lemon (citronelle) and sweet orange are known to be mycorrhizal dependent[81]. Mycorrhizae have an important role to play in organic citrus production, where natural nutrient cycles need to be encouraged in place of soluble fertiliser inputs. Although the role of mycorrhizae in phosphorus availability could be replaced by high phosphorus inputs, the multiple benefits of mycorrhizae warrant appropriate nutrient management to ensure those benefits are maximised. Managing mycorrhizae It is possible to increase the natural level of mycorrhizal infection of crop plants by pre-conditioning the soil with a crop of alternative host plants that help to boost the fungal population. Maize, millet and soybean were used as pre-crops in one study, to enhance the subsequent mycorrhizal infection of citrus seedlings[82]. This is considered a way to exploit the natural mycorrhizal potential of soils and could possibly be used to boost mycorrhizal levels in established orchards if that was considered desirable. Orchard management practices influence the mycorrhizal infection rates of citrus and other crops so can be used to manipulate mycorrhizal development. As a guide to fostering mycorrhizae in the citrus orchard, Table 4‑7 lists some common practices and their positive or negative impacts on mycorrhizae. It is important to note that the abundance and diversity of mycorrhizal fungi can be strongly influenced by the diversity of vegetation, including ground cover and ‘weeds’ in the orchard, not simply the density of ground cover. A more diverse ground cover means more opportunities for root associations with a wider range of mycorrhizal species and tends to reduce soil nitrate levels and produce more biomass, all of which favour mycorrhizae[83; 84].

43 Table 4‑7. Orchard practices and their effects on mycorrhizal fungi (MF) (from[79; 83; 84; 85; 86; 87; 88; 89; 90]). Beneficial practices Effects Use of low solubility fertilisers Low concentration of available nutrients encourages MF colonisation Exclusion of most biocides Avoids toxic effects of some biocides Cover cropping Encourages build up of MF population Diversity of cover crops Encourages build up and diversity in MF community Mowing instead of cultivation Encourages build up of MF population Application of mature compost Avoids nutrient excesses Detrimental practices Effects Mechanical cultivation Destroys mycorrhizal hyphal networks Bare ground Lack of host plants results in decline in MF population Non-mycorrhizal cover crops Lack of host plants results in decline in MF population Use of copper-based fungicides Directly toxic to MF Incorporation of uncomposted organic Decomposition suppresses MF through matter anaerobic conditions and possibly production of toxins

In a study of citrus and other fruit orchards[87], marked drops in mycorrhizal infection levels were linked to fungicide applications in bare- ground orchards but were not observed in one sprayed orchard that had over 75% ground cover. This may have been due simply to the ground cover reducing the amount of spray directly entering the soil. One study of comparable citrus orchards found greater microbial biomass and mycorrhizal diversity under organic management compared to non-organic[91], while another study found differences in mycorrhizal communities between mature and young orchards but not between organic and conventional management[92]. These observations suggest that: • regardless of orchard management, mycorrhizae may develop adequately as long as the critical factors (i.e. soil nutrient levels, pesticide flows to the soil and ground cover) are right, and • it may be worthwhile actively promoting mycorrhizal development in new orchards using practices such as those listed above. These practices, especially cover cropping and minimal cultivation, may also be used to regenerate mycorrhizal populations over relatively short periods where adequate levels of inoculum are present in the soil[93]. Companies that offer soil tests including mycorrhizal assessments are listed in section 12.7. Applied nutrient inputs The nutrient sources most commonly used for organic citrus in Australia are: • commercial organic fertilisers which are mostly pelletised or granulated and based on composted poultry manure and other animal wastes • composted animal manures from production systems such as feedlots, piggeries and poultry sheds; produced on-site or purchased • crushed rock (rock dust) including rock phosphate • seaweed and fish-based foliar fertilisers, produced on-site or purchased.

44 Organic growers should be aware that some sources of rock phosphate contain high levels of contaminants such as cadmium and lead. Organic certifiers set their own limits on the level of contaminants permitted in fertilisers and soil amendments, and these should be consulted to confirm the acceptability of such inputs. Other inputs include: • earthworm casts and worm farm leachate • allowable trace elements • bio-dynamic preparations • compost tea. The latter two are used as soil activators as opposed to nutrient inputs. Their purpose includes enhancing soil biological activity by inoculating the soil with a range of microbes. It can be challenging to satisfy citrus nutrient needs cost-effectively, with organic inputs that contain a broad and variable range of elements. Whether it be on-farm compost or purchased fertiliser, continual use of particular nutrient inputs may result in nutrient excesses or deficiencies. Grape marc for example is high in potassium. As shown earlier in Figure 4‑2, long-term use of marc as mulch or in compost can lead to accumulation of potassium and excessive levels in the tree. Ideally, like our own diet, a range of different inputs would be used, either simultaneously or varying over time. Compost Composting is the management of a natural biological process during which organic material is decomposed into humus. The composting process and product has always been highly regarded within organic agriculture as an effective way to manage crop and livestock ‘wastes’ and improve soils. Compost is not just a source of nutrients and organic matter. Good compost is also rich in soil microbes, and as such it helps maintain or re-establish soil microbial communities. Composting has an important role to play in modern organic citrus production. The benefits of compost have been well researched and include weed control, moisture conservation and soil improvement as well as improved tree growth. The cost-effectiveness of on-site composting will depend on such factors as the purchase and transport cost of bulk ingredients, availability of suitable space, time and equipment, and how these compare with the cost of alternatives such as commercial fertilisers. Some key points critical to successful production and use of compost are discussed below. There are many useful introductions to composting (e.g.[94; 95; 96]) but producers interested in commercial-scale composting should consult more detailed literature on the subject, such as the composting ‘Guide to Best Practice’[97]. Managing the composting process Compost making can be considered both an art and a science. Successful composting requires management of the following aspects in order to control the speed of the natural decomposition process, maximise the retention of nutrients and ensure effective control of pathogens and weeds:

45 Major ingredients: Most material of plant or animal origin is acceptable for composting. The onus is on the grower to show that material brought in from non-organic farms does not pose a contamination risk. Certain materials such as coloured paper and colour print, are not permitted by some organic standards. C:N ratio: If the C:N ratio of the compost mix is too low, a large proportion of the nitrogen can be lost during the composting process as volatile ammonia or soluble nitrate. Most nitrogen in raw compost ingredients can be conserved if high-carbon material (e.g. straw, grape marc, orange peel, green waste, sawdust, wood chips) is added to the nitrogenous material to adjust the C:N ratio[98; 99]. A C:N ratio of about 25:1 is considered ideal to minimise nitrogen losses and support microbial activity in a compost mix. As examples, the C:N ratio of pure poultry manure is 7:1; cow manure 12:1; fresh green grass, food wastes and grape marc 15:1 to 20:1; straw 100:1 and sawdust 450:1[94; 100]. A blend of different materials is desirable and is usually required to achieve the correct C:N ratio and a broad nutrient content. Element balance: Because of the mix of viticulture and citrus in many Remember that the districts, grape marc is one material used by many organic growers as a formation of long-lived, mulch or compost ingredient. Growers should however be aware that high stable humus requires soil potassium levels might result from the application of large amounts of woody plant material such grape marc, as marc is relatively high in potassium (Table 4‑8). Only four as that present in sawdust, to six tonnes of grape marc per hectare, and possibly even less grape marc wood shavings and fine compost (more concentrated), may be enough to replace the potassium woodchips. removed in a 50t/ha orange crop. Supplementary ingredients: Many compost producers supplement their mix with such things as microbial preparations, bio-dynamic preparations, coal humates, rock dust, ground rock phosphate or trace elements, depending on their requirements. Phosphate in particular will help address soil deficiencies as well as aiding the composting process itself. Clay has also been added to improve sandy soils and enhance the persistence of stable humus. Particle size: If the particle size of compost ingredients is made smaller, Table 4‑8. Typical elemental microbes have a larger surface area to work on, and this speeds up the content of grape marc as decomposition process. Slashers, flail mulch-mowers, chippers and percent of dry weight[100]. mulching machines are used to break up larger material before mixing. Mixing: Effective mixing is necessary to ensure even distribution of Carbon 47% moisture, supplementary ingredients and high and low C:N materials. Nitrogen 2.2% Front-end loaders are typically used for mixing and turning during on-site compost production, but purpose-built mixers help ensure more thorough C:N ratio* 21 and rapid mixing.

Potassium 2.7% Moisture content: A moisture content of about 50 percent is required to support the high levels of microbial activity needed for rapid composting. Calcium 0.43% The compost needs to feel moist but not wet. Dry compost will stop decomposing and wet compost will become anaerobic and putrid. Phosphorus 0.25%

Sulphur 0.14% Growers have obtained effective moisture levels by using fresh, moist ingredients, mixing during rainfall and sprinkling the material during Magnesium 0.1% and after mixing. Covering compost during heavy rains will help prevent waterlogging but routine covering is not recommended as it interferes with Sodium 0.05% aeration.

46 Aeration: Good aeration of the compost mix is critical to support the activity of aerobic microbes and avoid the compost becoming anaerobic. This is achieved by having a mix of coarse and fine material and by periodic turning of the compost heaps. Turning and mixing helps to ensure that all the material is subjected to the microbial decomposition and high temperatures occurring in the centre of the heap. Slotted pipes can be embedded in compost heaps to aid aeration. Temperature: Temperatures of around 60° C are required to kill weed seeds and pathogens, and will occur naturally in an effective compost heap due to high levels of microbial activity. Small heaps may not maintain such high temperatures as they lose their heat too rapidly.

As a guide, heaps or windrows should be between one and one and a half metres high. Smaller heaps are less likely to heat effectively and larger heaps may become anaerobic in the centre. For rapid and effective composting, heaps should be turned when their inner temperature reaches 60° to 65° C. Note that the US NOP standard requires windrow compost heaps to remain “between 55° C and 77° C for fifteen days, during which time, the materials must be turned a minimum of five times”. The intention is that all material in a compost heap is exposed to temperatures lethal to pathogens (55° C or more) for at least three days (not 15) during the composting process. Compost variability The raw materials that are used in compost typically vary in their nutrient content, depending on their growing conditions, age and treatment after harvest. Because of this and variations in the composting process, composts can vary widely in their mineral and biological characteristics. Composts should therefore not be treated as uniform products like processed fertilisers, unless they have been produced under carefully managed conditions and analysed.

One worthwhile analysis for The compost at this bio-dynamic orchard compost is the C:N ratio. This factor largely determines the performance is based on cow manure with added rock of the compost in relation to nitrogen availability, as discussed earlier. phosphate, basalt, quartz dust, coal dust Compost with a C:N ratio of 30:1 or more is most likely to bind up soil and Bio-dynamic preparations (502-506). nitrogen temporarily, thus reducing the availability of nitrogen to the crop. It is mixed and windrowed with a front- end loader and matures over about eight Apart from this potential but avoidable drawback, any well-produced months. The compost is applied over the compost is likely to benefit the soil because of its nutrient and organic whole orchard floor at 5–7t/ha. It is spread matter content. Its actual contribution to a nutrition program won’t, as a single application in late winter or split however, be known without analysis. between late winter and late summer. Local compost production Some of Australia’s larger organic citrus growers produce about 130-300 tonnes of compost on-site each year and apply it at the rate of 5-10 t/ ha/ year.

47 Manure spreaders are typically used to apply the compost, either broadcast or directed along the tree row. In some cases, compost has been applied by hand under the canopy of each tree. This is labour- intensive but delivers the compost where it is of most use. Nutrient release from compost Further decomposition of well- composted materials is generally slow, and may add little plant- A manure spreader makes light work of compost application in this organic orchard. available nitrogen in the short term. These materials do have long-term value in building soil structure. To provide available nitrogen in the shorter term, more rapidly decomposing materials such as leguminous green manures or semi-mature compost with reasonable C:N ratio (<20) may be more suitable[101]. Reviews of nitrogen dynamics in composts show that about 15- 20% of total nitrogen in compost can be expected to become plant- available within the first year, with the percentage halving in each subsequent year[56; 102; 103]. Most potassium is released from compost in the first year after application, and most phosphorus becomes available over three years. In the Some spreaders can be easily controlled to absence of local data, growers may start with the assumption that nutrient deliver compost just to the base of small trees, avoiding the need for manual applications. release from one application of compost roughly follows the pattern determined overseas as shown in Table 4‑9. Growers can use this guide to estimate the annual application rates required to supply citrus with the desired nutrients from their own compost supply, taking into account the cumulative availability of each element from multiple compost applications over time, e.g. for nitrogen: • Year 1 N availability = 20% of total N added in year 1 compost application

This compost contains on-site forage, cow • Year 2 N availability = 20% of manure, grape marc and sawdust in the total N added in year 2 compost application + 10% of total N added in ratio 2.5:1:1:0.5 and matures in about year 1 compost application ten weeks after being turned six times. The producers monitor the compost temperature • Year 3 N availability = 20% of total N added in year 3 compost regularly and turn it with a purpose-built application + 10% of total N added in year 2 compost application + mixer-windrower when the core temperature 5% of total N added in year 1 compost application, and so on. approaches 70°C. They apply the compost to their organic citrus at 6.5–10t/ha in A spreadsheet-based nutrient calculator is also available to help growers late winter. They would prefer early winter determine the nutrient contributions of mulch and compost[104] applications but don’t have forage available in time to prepare the compost earlier.

48 For any particular orchard, the pattern of mineralisation and availability Table 4‑9. Approximate rate of of nitrogen depends on the range of compost and soil factors mentioned macro nutrient release from [103] earlier. Trials with mature compost (C:N below 25:1) under Florida’s warm compost over time . moist conditions found that the nitrogen was mineralised, and therefore N P K [105] available to trees, in 90 days . Year 1 20% 40% 80% To minimise nutrient losses, compost should generally be incorporated Year 2 10% 40% 20% into the soil and moistened to encourage the microbial activity that drives Year 3 5% 20% mineralisation (see ‘Nutrient losses’ below). Remember, however, that Year 4 3% compost with a C:N ratio considerably higher than 25:1 should be used Year 5 2% with caution as there is a risk of nitrogen draw-down, resulting in a short- Total term nitrogen deficiency. becoming 40% 100% 100% available An important part of nutrient management is monitoring of how trees, yields and fruit quality respond to the nutrition program. Good observation and records allow growers to associate nutrition and other management aspects with crop behaviour, allowing them to modify their management as necessary. This is especially important when changing to a new management approach such as organic. Animal manures Animal manures have traditionally played a useful role in organic crop nutrition. Not only do they contain vital mineral elements, but also a range of complex organic compounds, microbes and organic matter, the latter of which is deficient in many Australian soils. Organic citrus growers use a variety of animal manures as nutrient inputs, typically as compost ingredients. The most common manures used are from poultry and cattle. The feasibility of using manures depends largely on their availability and cost including transport, both of which vary according to location. Before purchasing or using animal manures, growers should consider the following points: • Manure should be considered like other nutrient inputs, in that an analysis of its nutrient content is required if an appropriate application rate is to be determined. The nutrient content of animal manures varies greatly (Table 4‑10), and depends on the livestock type and diet, and whether the manure includes urine, is fresh or dry, new or aged, and pure or mixed with bedding, litter or other material. Growers should obtain an analysis to ensure that the manure suits their particular requirements and is cost-effective. • Manure from non-organic sources may be a contamination risk for the organic orchard. Documentation should be obtained from the supplier as to the likely contaminants in the manure. These could include chemical treatments applied to livestock housing, and internal or external drenches applied to the animals themselves. • Organic standards generally require that animal manures be composted before use. This helps to minimise any contamination risks to the organic orchard. • The application of animal manure to land is restricted by some organic standards, to rates that could be expected naturally if the land was a livestock holding. As with any input, the use of manure must not cause soil degradation, by for example, creating excessive nitrate levels.

49 Table 4‑10. Variations in elemental nutrient levels of some animal manures (from[106; 107; 108; 109; 110]).

Nutrient content—elemental Manure type % % % nitrogen phosphorus potassium C:N ratio (N) (P) (K)

Cow 0.5—2.0 0.1—0.7 0.3—1.5 11:1—30:1

Horse 0.4—0.5 0.1 0.3—0.6 15:1—50:1

Sheep 0.6—3.0 0.1—0.7 0.2—2.6 13:1—26:1

Goat 1.0—1.4 0.2 1.0 11:1—16:1

Pig 0.5—0.6 0.2 0.1—0.3 9:1—24:1

Chicken 1.2—4.0 0.4—1.3 0.4—1.7 6:1—14:1

Broiler litter 1.6—3.9 1.3 1.7 12:1—15:1

Growers should monitor the situation regarding high levels of micronutrients in animal manures, and their accumulation in soil. Micronutrients can be supplied in excess when the volume of manure applied is based on the requirement for macronutrients like nitrogen, as indicated earlier (Table 4‑6). Whether these micronutrients ever accumulate to problematic levels will depend on soil conditions, especially pH. Orchards on acid soils in particular should be monitored for this issue, because of the greater availability of many micronutrients at lower pH. Microbial inoculants Microbial inoculants contain large numbers of selected strains of bacteria, fungi or other microbes and are intended to boost natural microbe populations or introduce new microbe strains to compost or soils. The goal is higher levels of beneficial biological activity. Benefits may include more rapid and complete decomposition during composting, or higher rates of nitrogen fixation or phosphorus solubilising in the soil. For example, trials in Egypt did find that the yield and quality of navel oranges and limes growing in poor, alkaline sandy soils were improved by applications of ‘biofertilisers’ containing nitrogen-fixing bacteria and phosphorus-dissolving bacteria along with farmyard or poultry manure[111; 112]. Many commercial microbial preparations are available in Australia and may offer numerous benefits, especially while converting an orchard to organic management. Even with the benefits of these and other convenient products however, the basics of good soil management, such as improving organic matter levels and managing moisture and ground cover vegetation appropriately, still need to be addressed. Commercial fertilisers A wide range of commercial organic fertilisers is available to today’s organic growers. These include pelletised base nutrients for soil application, foliar-applied nutrients, rock minerals and trace elements. Current lists of certified organic input manufacturers and their products are available

50 from the organic certification organisations listed in section 12.3. Growers need to be aware that some fertilisers promoted as ‘organic’ or ‘organic based’ are in fact blended with water-soluble nutrients such as urea, which makes them unacceptable for certified organic production. Before using commercial fertilisers, growers should confirm that the product is acceptable to their certification organisation, unless the product itself is clearly certified by that organisation. Pelletised composted manure is the most Commercially processed organic fertilisers are generally costly. It is a common nutrient input in organic citrus orchards. worthwhile exercise for growers to calculate the cost of purchasing such fertilisers, compared to producing their own compost on-site. Regardless of the nutrient source, growers should remember the organic standards condition that: “The use of off-farm fertilisers shall be regarded as a supplement to nutrient recycling, not as a replacement for good soil management practices”. To the greatest extent possible, cover crops, green manures, livestock and composting of orchard ‘wastes’ should be used to maximise the orchard’s capture of its own nitrogen and carbon requirements. Elements apart from nitrogen and carbon will still need to be imported onto the orchard to replace those removed in the crop. Trace elements Trace elements, or micronutrients, are generally permitted by organic production standards as long as they contain no prohibited substances and are used on a ‘needs’ basis, i.e. to correct a known nutrient deficiency. It is the producer’s responsibility to show that a need exists (e.g. through leaf analysis or documented deficiency symptoms) and to confirm that the products to be used comply with the relevant standard. Sulphates of magnesium, manganese, iron and zinc in particular, are commonly used to correct citrus nutrient deficiencies in Australia, and are listed as permitted inputs by Australian and USA standards.

Nutrient ‘losses’ from the orchard In various ways, nutrient elements are ‘lost’ from the orchard in that they become unavailable for recycling and reuse by the trees, cover crops and soil organisms. Major areas of loss are described below. Some are inevitable, others need to be managed and minimised by the organic producer. Removal in the citrus crop The simple measure of element removal from the orchard in harvested fruit shows the nutrient inputs needed to replace those ‘lost’ elements. Although soils may support fruit production for some time without the harvested mineral nutrients being replaced, such ‘mining’ of the soil’s fertility is unsustainable, and inconsistent with the philosophy of organic farming.

51 As there is considerable variation in the nutrient content of citrus fruit between varieties and regions, fruit composition tables should be used only as rough guides to element removal in fruit. The element removal data shown in Table 4‑6 above was compiled from several sources and gives an indication of the amounts of important nutrient elements removed in orange crops. Incorporation into tree structures The nutrients incorporated into leaves and fine roots are continually recycled as those organs die and decompose. Others become locked up in the permanent structure of the tree (trunk, major branches and roots) and are unavailable for the life of the tree. It has been estimated for example, that in the order of 20kg/ha/yr of nitrogen is deposited in the permanent structure of mature citrus trees[113; 114]. Leaching and volatilisation Nitrogen (N) in particular is easily lost from the orchard through volatilisation as ammonia gas or leaching of water-soluble nitrite and nitrate. Incorporation of nitrogenous materials into the soil helps to reduce the loss of ammonia nitrogen. Compared to surface application, incorporation of compost (1.9%N) into soil virtually eliminated the loss of nitrogen as ammonia (but may have resulted in nitrogen draw-down), while losses from a high-N (5%N) pelletised product were reduced by 75%[54]. Incorporation improved the mineralisation of N by 64% for the pellets and 8-fold for the compost. Loss of ammonia from the surface-applied compost and pellets continued for at least 180 days. These losses mean wasted time, money and nutrients, and increased environmental impact, all of which are important issues for the organic grower. If incorporation is not possible or practical, nitrogen losses may be reduced by applying mulch over the nitrogenous material as soon as possible after it has been spread. Salinity is also known to dramatically increase the rates of nitrate leaching from sandy soils[115], a point of particular relevance to Australian producers. These points highlight the need for good overall soil and water management to maximise the efficiency of applied nutrients. Analysis of drainage water or groundwater from below the tree root zone (e.g. sampled with ceramic tip suction samplers) can be used to determine whether, and to what degree, soluble nutrients are being lost through leaching. Nutrient pollution Stockpiles, processing and application of nutrient-rich materials like compost and animal manures can pose a risk of soil or ground and surface water contamination. Nitrogen and phosphorus in their water-soluble forms in particular are easily leached. To avoid this loss and the associated environmental impacts, common sense and organic standards require that nutrient-rich materials be managed carefully. This includes: • effective storage of raw and composted material to prevent excessive wetting and leaching of water-soluble components

52 • effective composting to avoid excessive free nitrogen in the finished product • appropriate application rates to avoid excessive soil nutrient levels, and • efficient irrigation practices to minimise leaching of nutrients beyond the tree root zone.

Nutrient uptake and use In relation to nitrogen nutrition of citrus, it has been stated that ‘The purpose of fertilisation is to ensure proper development of the tree, not the current fruit yield’[113]. This is a useful point to remember when planning a nutrition program. It is particularly relevant for organic producers who aim to achieve good crops by building soil fertility and tree health. To see the link between nutrient inputs and tree and crop development, let’s consider the nutrient flows in reverse order – from their accumulation in fruit, back to their application in the orchard. Nutrient accumulation in fruit Peak rates of accumulation of major nutrient elements in orange fruit occur from late spring through to late summer, with nitrogen and potassium continuing to accumulate into winter[66]. This timing of peak accumulation coincides with fruit cell division and expansion, and root growth (Figure 4‑6). Nitrogen mobilisation within trees It is important to note that in citrus trees, up to 85% of nitrogen accumulating in flower buds, flowers, developing fruits and new leaves comes from the trees’ nitrogen reserves that were deposited during the prior season[57; 114; 116]. Nitrogen is stored in leaves, branches, trunks and roots, and is mobilised during growth flushes and flowering. Even in over- fertilised mature trees with abundant available nitrogen in the soil, about 80% of nitrogen in young fruit and leaves comes from tree reserves and the remainder from recently absorbed soluble nitrogen. So… soil nitrogen should be available when the trees can absorb and store it most efficiently. Nutrient uptake by roots Studies of radioactive nitrogen applied to the soil found that the rate of absorption of nitrogen by citrus roots was lowest during winter-early spring So… soil nitrogen should (dormancy) and high during mid spring (flowering) and the summer be available when the trees growth flush[117; 118]. Peak absorption was in late spring-early summer (fruit can absorb and store it set) for Valencias and mid-late autumn for mandarins. most efficiently. This makes sense, as the nutrient absorption and translocation efficiency of citrus roots is inhibited by low soil temperatures, e.g. below 13°C[47] . As an example, soil temperature to a depth of 20cm in the Sunraysia district is typically below 13°C from late May to late August (long-term averages). Increased absorption of nitrogen from spring onwards coincides with higher soil temperatures. So… in temperate and inland districts with cold winters, nutrients So… in temperate and should be available to trees between spring and mid autumn. inland districts with cold winters, nutrients should Nutrient release from organic fertilisers be available to trees As shown earlier, about 20% of the total nitrogen in organic ‘fertiliser’ between spring and mid such as mature compost is expected to become plant-available (through mineralisation) within a year of application. Most of this release seems to autumn.

53 occur within the first 3-4 months after application, given adequate soil So… compost and moisture levels and temperatures. compost-based organic So… compost and compost-based organic fertilisers should be applied fertilisers should be 3–4 months before nitrogen is required by the trees. applied 3-4 months before nitrogen is required by the Timing of nutrient applications trees. For the organic citrus grower, this means that compost or similar organic material needs to be applied in mid-late winter/early spring to have nitrogen available in late spring/early summer – the peak period for root absorption of nitrogen. Late spring/early summer applications would also provide nitrogen during the summer/autumn period of absorption. The same application timing can be applied to commercial organic fertilisers based on pelletised composted animal manure.

Winter Spring Summer Autumn

Shoot flush Shoot flush Shoot flush

Root flush Root flush

Floral initiation Flowering & set

Fruit cell division Fruit cell expansion . . .

. . . Fruit maturation

May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May

Figure 4‑6. General phenological cycle of citrus in south east Australia[119]

If heavy stands of leguminous cover crops are slashed two to three weeks before citrus flowering or fruit set starts, the nitrogen released from their decomposing roots and root nodules should peak early in the bloom/set period and provide the trees with an extra ‘boost’.

Nutrient management program It may be useful to pull together the relevant information on growth and nutrition requirements of organic citrus into a ‘nutrition management plan’. A general example of a plan is given in Table 4‑11. Growers would need to customise this example to suit their own orchard situation, due to differences in climate, soil and management practices. Nutrient inputs in particular will vary according to each orchard’s reliance upon green manure/cover crops, compost or commercial fertilisers.

54 Table 4-11. Example nutrient management plan for organic citrus

Month Information collection Management action/application

May gypsum

June gypsum

July compost/organic fertiliser

August compost/organic fertiliser

compost/organic fertiliser September slash legume cover crop 2-3 weeks before trees flower cover crop sowing

October soil analysis cover crop sowing

November soil analysis compost/organic fertiliser

December compost/organic fertiliser

January

February leaf & soil analysis foliar zinc & manganese

foliar zinc & manganese March leaf & soil analysis cover crop sowing

April cover crop sowing

Whenever record yields exclude livestock from 90 days pre-harvest relevant monitor groundwater N & P prune as required; mulch prunings

55 56 Drip irrigation allows precise management of water but limits the potential of cover crops. 5. Water management This section highlights aspects of water management What the National Standard says: of interest to organic certifiers and regulated to some degree by organic standards. Specific General principles: techniques of irrigation design, application, Water and agriculture are inextricably linked. The harvest, scheduling and monitoring are not covered here as storage, use and fate of waters are integral components they are dealt with by specialised publications and of an organic farm. Management of water will include irrigation management courses. These courses are management of vegetation, soil and drainage on the recommended for all growers interested in using organic or bio-dynamic farm. water efficiently and in an environmentally sound way. Recycling of water should be carried out as much as possible. Because of water’s effect on other components of the orchard, its management is also discussed briefly Surface water leaving an organic farm should not contain in sections 3 (Environment), 4 (Soil) and 6 (Pests, greater levels of nutrients, salts and turbidity than when the diseases and weeds). surface water entered the farm. Water is a vital component of natural and Standards: agricultural landscapes and is coming under On-site harvest of water for agricultural use must allow increasing pressure as a valuable resource around for maintenance of on-farm and local ecosystems that are Australia. The organic industry recognises this and under the immediate influence of the operator. aims to manage water carefully to achieve the best Provision must be made for environmental flows to environmental and production outcomes. maintain existing riverine health, wetlands and biodiversity. The primary aims of water management in the Where appropriate, operators shall design, measure and orchard are to: monitor irrigation water application to minimise water loss. • provide the crop’s water requirements • prevent salts from accumulating to harmful levels in the soil Acceptable inputs • maintain sufficient soil moisture to support green • Chlorine (bleach) for cleaning drip irrigation systems manure or cover crops and soil biological activity • minimise any negative environmental impacts • Hydrogen peroxide for cleaning drip irrigation from water use. systems

57 Organic standards generally approach water management from the angles of: • environmental management to minimise any negative impacts of water use (e.g. extraction, use, disposal, interference with natural flow) • resource use efficiency to minimise water wastage • impacts of water use on the orchard, including factors like soil, weed and disease management, salinity and contaminants.

Environmental management Organic agriculture, as reflected in organic standards, has the broad objective of maintaining the health of our natural water systems including ground water, rivers and streams. In complying with organic standards, growers need to satisfy a range of environmental criteria by demonstrating, for example, how their approach to water management: • maintains environmental flows and the quality of riparian areas and natural wetlands • avoids contaminating groundwater or natural surface water systems when reclaimed water (e.g. from drainage or waste recycling) is used • avoids soil erosion, waterlogging and salinity • avoids the leaching of nutrients and salt into groundwater or natural surface water systems • ensures that any surface water leaving the orchard is of equal or better quality than that entering the orchard. These issues are largely addressed by good water management in the orchard. Resource use efficiency Organic citrus growers are required to use water wisely to minimise wastage and maximise the efficiency of use of this increasingly valuable resource. Water wastage often has implications for environmental flows, negative soil impacts and energy consumption (in pumped systems). Management of environmental flows is usually addressed at the national, regional or district level. At the orchard level, maximising water use efficiency can help address environmental flow concerns by minimising the need for water extraction from the environment. For optimum water use efficiency, irrigators need to demonstrate good management in relation to the following points. Choice of irrigation system. Irrigation systems need to suit each orchard’s characteristics such as soil type, water quality, water availability and climate, as well as the grower’s objectives in relation to organic management of the soil, tree nutrition, groundcover, pests and diseases. Because these aspects of organic orchard management are influenced by water management, the correct choice of irrigation system is obviously important. The various irrigation methods all have their advantages and disadvantages, some of which are: • Pressurised systems (sprinklers or drip) are more costly than furrow, but allow more precise application of water. • Overhead sprinklers suit cover cropping and broadcast nutrition

58 programs but suffer relatively high evaporation losses, are prone to uneven water distribution and can increase tree stress if the water contains dissolved salts. • Furrow is cheap but not recommended on light or unevenly textured soils because of wastage and difficulty in obtaining uniform water distribution. • Drip provides high water use efficiency but requires water on demand, is less suited to nutrition programs based on broadcast compost or manure and makes cover crops more difficult to establish and maintain in dry districts. Drip irrigation lines also require maintenance or treatment to prevent blockages. • Low level sprinklers suit cover cropping and broadcast nutrition programs but require good canopy and groundcover management to minimise interference with water distribution, and are more prone to mechanical damage. Irrigation system design. Correct layout of the system is necessary to ensure good application efficiency through even coverage of the irrigated area. This helps avoid excessively wet and dry patches and the associated problems of soil water logging and tree stress. To ensure the quality of irrigation system design, the Irrigation Association of Australia operates a Certified Irrigation Designer program—see the Bibliography for details. Irrigation scheduling. Accurate irrigation scheduling is required to ensure For the best outcomes in the right amount of water is applied at the right time. This is to avoid under-watering resulting in tree stress, and over-watering resulting in such water use efficiency and problems as water wastage, waterlogging, nutrient leaching and raised crop performance, the water tables. irrigation method, system design and irrigation Irrigation scheduling requires knowledge of such aspects of the tree/ scheduling all need to soil system as soil water holding capacity, tree water requirements and be matched to the soil rooting depth. Scheduling also requires monitoring of the orchard water characteristics and crop balance or moisture status, through, for example, monitoring of applied water, rainfall, evaporation or soil moisture levels (some of the aspects of needs. To achieve this irrigation management covered by irrigation management courses). may require a soil survey, preferably by a qualified Growers interested in comparing the techniques available for monitoring soil specialist. soil moisture levels can find useful technical reviews and comparisons at the Internet sites listed in the Bibliography. Soil improvement. This includes management of the orchard floor and sub-surface soil through such practices as mulching, cover-cropping, cultivation and addition of soil amendments like gypsum if needed. The aim is to reduce water loss, improve water infiltration and distribution, and raise water-holding capacity where this is desirable. Orchard impacts Water use can have direct impacts on orchard health, crop quality and organic integrity. At least the following aspects of water use should be addressed to minimise any potentially negative impacts within the organic system and to comply with organic standards: Monitoring. To demonstrate that negative impacts of water use such as nutrient leaching, increased salinity and raised water tables are being avoided, or at least minimised, it may be necessary to monitor such factors as: • soil and groundwater quality within the orchard and on adjacent land

59 • local watertable levels • the volume and quality of irrigation and drainage water. Testing off-site water sources for contamination. Irrigation water is a potential source of contamination for the organic orchard. Australian organic standards require that off- site water sources including shared public sources like channels and rivers be tested for contamination. The type and frequency of testing should be appropriate for each specific situation. In districts where public water sources are routinely tested, growers may be able to obtain useful information on water quality from their local water authority. Cautious use of reclaimed water. On-site water recycling is encouraged. However, the use of off-site reclaimed water is tightly regulated by organic standards because of the risk of orchard or environmental contamination with chemicals, pathogens, salts or heavy metals. Growers should note that some certifiers do not permit the use of water reclaimed from industrial or human wastes. Where reclaimed water is permitted, testing is necessary to confirm that any Apart from protecting shallow citrus roots, contaminants are at acceptable the surface mulch used in this organic levels. orchard greatly improves water use efficiency. The use of reclaimed water is also regulated by Environment Protection Authorities (EPA’s), so growers considering reclaimed water for irrigation should familiarise themselves with the requirements of their state EPA. Drainage management. The two primary aims of irrigation are to provide the crop’s water requirements and to prevent salts from accumulating in the soil to a level that is harmful to the crop. Where salinity is a potential issue, a sufficient ‘leaching fraction’ should also be applied to prevent the build-up of salts in the tree root zone by leaching salt deeper into the soil profile. The leaching fraction is an extra amount of water, commonly ten to 15 percent, in excess of the crop’s water requirements. Methods for calculating leaching fractions are available (e.g.[120]) but it should be noted that a leaching fraction may not be necessary with each irrigation. The requirement depends on soil type, water quality, irrigation method, rainfall, salt tolerance of the rootstocks and the efficiency of leaching to remove salts from the root zone.

60 A review of research[121] indicated that to improve leaching efficiency, irrigators should aim to: • let the whole root zone dry to the refill point before irrigating, to keep salt moving downwards • maintain a surface cover of mulch or cover crop residue to improve water infiltration and minimise evaporation • apply a leaching irrigation at the end of winter when the soil profile is already moist and evaporation is low • water slowly and try to avoid ponding on the surface. Techniques such as re-use on woodlots, trees or salt-tolerant crops, or disposal in authorised evaporation basins should be used to minimise any negative on- or off-site impacts of drainage water disposal. Soil management. Soil compaction, surface run-off and erosion are risks associated with irrigation and rainfall. These risks are addressed in part through groundcover management, timing of cultivation and soil development (e.g. through cover cropping or organic matter addition) to reduce the physical impact of water on the soil and improve water infiltration rates. In addition, water and nutrition management needs to be coordinated to prevent excessive nutrient loss and the associated pollution of ground and surface water.

Irrigation system maintenance Drip irrigation systems usually require some sanitation treatment to prevent algal growth that can block dripper outlets. Chlorination (using sodium hypochlorite) and hydrogen peroxide are suitable for this purpose. Both are currently permitted as sanitation agents by the National Standard for Organic and Bio-Dynamic Produce. Before using them for irrigation system maintenance however, growers should confirm their acceptability with the relevant organic certifier and check for restrictions on residue levels in the flush water. Occasional high-pressure flushing is also used to help keep irrigation lines clean. Maintenance of irrigation systems is also necessary to ensure that correct application rates and high distribution efficiency are maintained and to help avoid water wastage. This includes paying timely attention to leaks, blocked outlets and ‘weeds’ that interfere with sprinkler water distribution.

61 62 Ibis is a natural predator of pests 6. Pest, disease and weed overview The National Standard states that producers can use allowable inputs for What the National Standard crop protection “Only in cases of imminent or serious threat to the crop” says: and where the approved measures listed in the right hand panel are, or would be ineffective. The emphasis is clearly on managing pest, disease and The reliance on substances rather weed threats without automatically resorting to applied substances. than management practices for the control of pests and A whole system approach diseases is not in accordance In agriculture generally, including citrus orchards, pest, disease and with the principal aims of organic weed management tend to be approached in a curative way, using toxic agriculture. substances or management activity to kill or suppress the offending Where used, mulches should be of organism. The replacement of ‘hard’ chemicals with ‘softer’ alternatives, natural materials. including microbial pesticides, plant extracts, cultivation and so on, tends to perpetuate this curative approach. Pests, diseases and weeds must be controlled by any combination of Some disadvantages of this approach are: the following: • Many treatments, including cultivation, have undesirable off-target • choice of appropriate species impacts on non-pest organisms and the broader environment. and varieties Cultivation in particular is very disruptive to soil structure. • light and sound • Many treatments, especially ‘organic’ ones, are relatively short-lived and • biological control require repeated use (e.g. weekly to annually). This is largely because • mechanical cultivation treatments are often ‘neutralised’ by inherent characteristics of the • appropriate rotation programs orchard and surrounding ecosystem. For example: • mulching and mowing – 'banks' of long-lived seed produce a new flush of weeds after • specific bio-dynamic measures cultivation • grazing of livestock – genetic variability supports selection for pest resistance against • mechanical controls such as applied pesticides traps & barriers – the impact of pesticides on beneficial species results in pest • flame/steam weeding resurgence or development of secondary pests after a pesticide • protection of natural enemies application, and as one eminent pest management specialist said, of pests through provision “When we kill off the natural enemies of a pest, we inherit their of favourable habitats (e.g. work” hedges, nesting sites)

63 – The energy costs of input-based programs are high, largely because of their reliance on petroleum products (it was estimated in 1983 “When we kill off the that an oil spray program for red scale on citrus was about 50 natural enemies of a pest, times more energy expensive than an Aphytis-based program[122]). we inherit their work” • The habitual reliance on sprays and other management actions to (Carl Huffaker, University of California, tackle pest, disease and weed problems is more likely to distract busy Berkeley) growers from an important step—the careful observation and thought as to why the problems arise and how they might be reduced by better design of the production system. The challenge is for researchers and growers to design and build better orchard systems that rely more heavily upon built-in regulation of undesirable organisms—weeds, diseases and pests. In tackling this challenge, critical aspects are to investigate why weed, disease and pest problems arise, and to respond with thoughtful management and redesign of the orchard system wherever possible, rather The challenge is for researchers than to perpetuate an ultimately unsustainable curative approach. In and growers to design and build asking “Why is the pest a pest?” we need to “address underlying weaknesses better orchard systems that in ecosystems and/or agronomic practice(s) that have allowed organisms to reach rely more heavily upon built- pest status” [124]. in regulation of undesirable organisms—weeds, diseases The same author correctly states that “…as a matter of fundamental and pests. principle, application of external corrective actions into a system can be effective only for short term relief. Long term, sustainable solutions must be achieved through restructuring the system…The use of pesticides and other ‘treat-the- symptoms’ approaches are unsustainable and should be the last rather than the first line of defence”. A useful discussion on ‘redesigning agroecosystems for environmental sustainability’ is put forward by Professor Stuart Hill[123] who suggests that our approach can pass through several phases on its way towards sustainability. Table 6‑1 suggests how our approach to pest management could evolve through those phases. Citrus producers generally are operating in the ‘efficiency’ or ‘substitution’ phase. Organic citrus producers are in ‘substitution’ because of their philosophical approach or restrictions imposed by organic standards, or both. Their aim should be to move towards the next step – modification or Table 6‑1. Approaches to pest management in a move to sustainability (adapted from[123])

‘Old conventional’ Techniques refined for Input substitution for Redesigned/restructured approach greater efficiency reduced environmental for inherent stability impact Routine, blanket Pest monitoring; targeted Targeted & efficient Favourable pest application of broad- application of broad- application of ‘soft’ balance maintained by spectrum pesticides spectrum pesticides chemical and bio- released or naturally using efficient equipment pesticides; release of regenerating biological to deliver accurate doses biological controls controls supported by resource-rich habitat; appropriate crop mix; ‘soft’ intervention when essential Curative Curative Curative Preventative

Unsustainable Sustainable

64 design of orchard systems that are inherently more robust and stable, and less reliant on intervention by the grower. To take this step, growers should use organic standards as foundations for building better production systems, rather than simply complying with their minimum requirements as often occurs[125]. Some of the tactics needed to meet the challenge are addressed in more detail elsewhere in this publication, and include care with orchard location, design and layout, choice of variety and soil and habitat management including cover crops and other vegetation.

Aiming for a balance An objective of organic management is to develop naturally ‘balanced’ systems, the maintenance of which does not require high levels of intervention. Weeds for example often fill an environmental niche that has been left vacant, i.e. bare soil. In natural systems, given adequate water, bare soil is generally rare – a sign of disturbance and imbalance – and is often exploited by rapidly growing species that we consider as ‘weeds’. A more stable, balanced state is one where the soil is covered. Given this situation, the orchard manager can choose to: • maintain a soil cover of mulch or desirable plants, or • continually struggle (e.g. via cultivation) to maintain the unstable situation of bare soil. Most organic citrus orchards maintain sown or volunteer inter-row cover crops which are slashed as necessary, with the tree row slashed or mulched. Some cultivate, especially around young trees, to reduce competition for water and nutrients. Pests are often maintained in balance with their natural enemies. Aiming to develop or retain this balance is a more rational approach than aiming for pest eradication, which is usually an impossible task. Modifying the orchard environment to favour beneficial species helps to achieve the required balance. This can involve the use of shelterbelts to reduce wind and dust; flowering cover crops to provide shelter and food for predators and parasites; and minimising sprays of any sort that disrupt beneficial activity. It is important for growers to remember that because rational pest Ladybird larvae are amongst the many management usually involves a balance between pests and their natural beneficial species that help to keep pests in enemies, pests will be present. Learn to live with them! The objective is to balance in organic citrus orchards. have the balance in the grower’s favour.

65 Diseases generally differ from most pests and weeds (in our perception at least), in that they are more difficult to control once established, and under the right conditions have a high capacity for spreading and damaging crops. Because of this, the aim of disease management is usually prevention or eradication rather than achieving a ‘balance’ that includes the disease organism. In reality, disease eradication is rare and adequate suppression is what is achieved. The level of intervention required to maintain this situation can be minimised by designing and managing the orchard environment to reduce its susceptibility to disease.

Integrated management Integrated management of weeds, diseases and pests involves pulling together a range of different but appropriate techniques and approaches, as a strategy to tackle issues in the most cost-effective way, given the grower’s desired outcomes. For organic citrus growers, these outcomes commonly include: • reduced environmental impact • reduced risk of chemical residues in produce • lower risk to personal health (through avoidance of synthetic pesticides) • a greater understanding of the orchard ecosystem providing more personal interest and satisfaction. All these outcomes are important and influence each grower’s perception of ‘cost-effectiveness’ when it comes to practical management decisions. An integrated approach is of particular value to organic growers because of the restricted range of agricultural inputs permitted under organic standards. Some basic principles of integrated weed, pest and disease management in citrus are outlined briefly below. Any citrus grower with an interest in pest management should have a copy of ‘Citrus pests and their natural enemies: Integrated Pest Management in Australia’[10]. ‘Biointensive integrated pest management’[126] also provides a very good general introduction to pest management with an ecological focus. Identification: know your pest and beneficial species Correct identification of the target species (weed, pest or disease) is critical to ensure that a relevant and effective preventative strategy or management technique is used. In particular, this helps avoid unnecessary and ineffective pesticide applications. Correct identification of beneficial species is also valuable, as it allows growers to monitor biological control activity in the orchard and gauge positive and negative impacts of management actions on those desirable species. The ‘Citrus pests and their natural enemies’ A larva of the mealybug predator book mentioned above and Cryptolaemus montrouzieri feeding on a publications and web sites listed small mealybug. These larvae are sometimes in the bibliography are good places to start for identification of pests and mistaken for mealybugs themselves. Correct beneficial species. identification is vital! Photo: DPI

66 Monitoring: know what your beneficial and pest species are doing Orchard monitoring is the tool that helps growers to determine whether a management action is needed, which action or strategy should be used, when and where it should be applied, and how effective it was. Monitoring for the latter point—treatment effectiveness—is important as it allows ineffective strategies, actions or inputs to be modified or replaced. Monitoring of beneficial species and pest parasitism levels is just as important because at any one time, higher pest populations can usually be tolerated if their natural enemies are also increasing in activity. Effective monitoring is particularly important in organic orchards. It helps to avoid unnecessary treatments (e.g. pesticides or cultivations) by maximising their effectiveness through accurate timing and by showing when treatment is not needed. Monitoring also helps to meet organic standards’ requirements for proof of the need for applied treatments. The requirements for monitoring and the thresholds for treatment action depend on the specific pest, citrus type, time of year and geographic region. For most pests, these are detailed in the ‘Citrus pests and their natural enemies’ book. Management techniques: choose the most appropriate combination More specific details for the management techniques discussed here are given in sections 7–9 under each pest, disease and weed issue to which they are relevant. Quarantine & Hygiene Prevention is better (and cheaper) than cure! Quarantine and hygiene are the best defences against the introduction and spread of unwanted species. They are also cost-effective when compared with long-term management of pests, especially in organic orchards where control options are limited. Simple techniques like restricting vehicle access and plant or soil movement into orchards; equipment wash-down after off-site use; using clean, accredited propagation material and destroying infected plant material where necessary, can help avoid weed, disease and pest introductions or limit their spread. Post-harvest control Post-harvest treatments such as washing and brushing can remove light to moderate infestations of some pests, honeydew and sooty mould from fruit. This approach should be used to the maximum extent possible to reduce the need for applied treatments in the orchard, and so avoid their negative impacts on beneficial species. Biological control The first known use of biological control to tackle insect pests in agriculture was on citrus in China in about the year 300[127]. Since then, biological control has played a major role in pest regulation. The establishment of effective biological controls should be a key objective of organic citrus growers. This will help to minimise the level of intervention required to keep pests below damaging levels. Weeds and diseases are also suppressed by their own natural enemies, but biological control in citrus is most applicable to insect and mite pests.

67 In situations where particular beneficial species have never been established, their introduction may be useful. Annual releases of some beneficial species may be necessary where the climate or orchard environment does not support their season-to-season survival and reproduction. The ‘ideal’ regarding natural pest management is ‘conservation biological control’ where populations of beneficial species are self-perpetuating, and supported by a range of resources within and around the organic orchard. See ‘Habitat management’ below for more on this topic. Low levels of parasite or predator activity may indicate that orchard Most spiders in the citrus orchard are conditions are less than optimum general predators and perform a useful pest for these species and need modifying. Some key factors worth considering management function. and discussed further below, include wind, dust, pesticides, physical disturbance, exposure and lack of food resources.

Cultural control Cultural control of weeds, diseases and pests involves thoughtful design and management of the orchard’s physical and biological environment, to make it less suitable for undesirable species while encouraging the diversity and population levels of beneficial species. Cultural control can incorporate many different techniques and practices. Some common practices are listed briefly below. More detail appears later under the relevant pest, disease and weed sections. Wind reduction: Wind inhibits the flight of many insects, so it is likely that dispersal and foraging by beneficial species will be reduced in windy conditions. Exposure of citrus trees to cold conditions, usually worsened by cold winds, increases their susceptibility to some diseases. For these reasons, protection of citrus from winds may contribute to reduced pest and disease pressure, apart from reducing wind-rub blemish on fruit. Dust minimisation: Dusty conditions reduce the effectiveness of some beneficial species such as small predatory ladybirds and parasitic wasps. This is one reason why citrus trees next to dirt roads or headlands often carry heavier scale infestations. Dust has also been linked to increased mite problems in citrus overseas. Overall, dust management in the orchard seems to be worthwhile. This can be achieved through groundcover vegetation, windbreaks, minimising orchard traffic, sealing major dirt roads and watering dirt tracks and headlands during periods of heavier activity. Sand, gravel and organic mulches have also been used on unsealed tracks to reduce dust levels. Applying old engine oil, left-over oil spray or similar materials to the ground to settle dust would not be acceptable under organic standards.

68 Irrigation type: Irrigation type can influence pest, disease and weed development through its effect on humidity, foliage washing and soil wetting. Overhead irrigation has the benefit of washing dust and honeydew off foliage and allows for full ground cover establishment, but encourages weed growth and may increase the risk of soil splash (including fungal spores) onto foliage. Under-tree sprinklers can support ground cover establishment and reduce soil splash but do not wash foliage. Drip irrigation helps to minimise weed growth, but does not wash foliage and limits the potential for establishing ground covers and other beneficial plants including ‘insectary’ species. It also limits the availability of moisture for beneficial insects and so may reduce their survival rates under harsh summer conditions. With regard just to pest, disease and weed management, the best irrigation system for any one orchard would depend on the potential pest, disease and weed risk and the grower’s priorities. Where they are practical, dual watering systems could be established as is done in some locations for frost management. With a dual system, drippers can allow for highly efficient irrigation while overhead sprinklers are used occasionally as needed to combat frost in winter and to wash trees and provide free moisture to the whole orchard during hot dry summer weather. Irrigation management: Water stressed citrus trees are more susceptible to phytotoxicity from oil sprays. Irrigation management should be used to maintain healthy tree water status to avoid this problem. Tree nutrition: The nutritional status of plants can influence the development of pests feeding on those plants. Also, excessive nitrogen leads to more vigorous growth flushes, the growth phase favoured by leaf miner, aphids and certain other insect pests. Nutrient deficiencies and excesses therefore should be avoided to help improve the trees’ ability to resist or tolerate attack by a range of pests. Inadequate nutrition can also result in poor canopy growth, leading to more weed growth because of lack of shading. Extensive shelterbelts help to protect this Tree hygiene: Keeping trees free of dead wood and free of residual fruit organic orchard and its beneficial insects and after harvest will reduce the inoculum source for diseases and food sources mites from excessive wind and dust. for some pests. Habitat management: This generally relates to provision of non-crop vegetation including cover crops, to support beneficial species[128; 129]. Most of the beneficial insects and mites active in citrus have food requirements other than the pest species that they attack. Several predatory mite species for example feed on pollen, while nectar is an important food for green lacewing adults, mealybug parasites and scale parasites. Beneficial species are more likely to live longer and reproduce more in orchards that contain a diversity of suitable pollen and nectar resources

69 (flowering plants including grasses). Such resources are included in the following characteristics “typical of farms that host plentiful populations of beneficials”[130]: • fields are small and surrounded by natural vegetation • cropping systems are diverse and plant populations in or around fields include perennials and flowering plants • crops are managed organically or with minimal agrichemicals • soils are high in organic matter and biological activity and during Nectar, pollen, shelter and sites for egg-laying the off-season are covered with and pupation are some of the benefits that mulch or vegetation. beneficial insects andmites obtain from areas of non-crop habitat in the orchard. Under European conditions, it is considered that the success of conservation biological control is linked to the presence and quality of resources for beneficial species, within 100–200m, because many of those species are most effective over distances up to about 50m[131]. It is also thought that 15% of a landscape dedicated to ‘natural areas’ is around the optimum for conserving biodiversity, including those beneficial species. How relevant these guidelines are in Australia’s citrus-growing environment is not yet known, but the organic standards requirement for at least 5% of each property to be under non-crop management is probably a step in the right direction. Not enough is yet known about species-specific interactions between pests, parasites, predators and flowering plants in Australia to make many firm recommendations on habitat management in citrus. However, enough information is available to allow producers to make some educated guesses and evaluate this approach for themselves[129; 132; 133; 134]. Also refer to Table 8‑1 that lists plants that support beneficial species. Agroecology publications and websites (see the Bibliography) are also useful sources of information on the principles and practices of habitat management for enhanced pest management. It has been suggested that pollen availability in the late winter-early spring period is particularly important for building up populations of beneficial species in citrus[128] and this should be a consideration when choosing potential resource plants. Local experience of bloom periods and resources like the ‘Australian pollen calendar’[135] may be used to optimise the value of resource plantings. Other valuable resources provided to beneficial species by non-crop habitat include egg-laying and pupation sites, and shelter. Shelter may be especially important in young orchards that have relatively little canopy area. It is also useful as a refuge for beneficial species when the citrus are being sprayed, because of the physical disturbance created by the sprayer. Habitat management may also be used to encourage larger predators. Nesting and roosting boxes can attract insect-eating birds and bats[136], especially where their natural habitat has been reduced by agriculture and other development. Flowering plants that provide nectar for insectivorous

70 birds such as spinebills will also help to attract those species into the orchard. Planting material: Choice of fruiting variety and rootstock can have a major impact on ongoing pest and disease management because of different susceptibilities to above and below-ground pests and diseases such as fruit fly, nematodes and root rots. Some of these are mentioned under the relevant pests. Regarding rootstocks, Table 6‑2 lists the common stocks and their relative tolerance of major soil-related issues. Mating disruption The females of many insect species such as lightbrown apple moth produce sex pheromones to attract males for mating. Mating disruption is a pest management technique that ‘floods’ crops with a synthetic version of the pheromone. This confuses the males and reduces the chance of them meeting and mating with a female. Mating disruption has no direct effect on beneficial species because pheromone activity is specific to each species.

Pesticides Pesticides are applied to orchard ecosystems, not just to pests. This is a critical point to remember for organic growers who want to develop the biodiversity of their orchards for biological control purposes. Many adverse impacts, including secondary pest problems, have resulted from the off- target effects of pesticide use including fungicides. This can equally apply to organically acceptable pesticides such as spinosad, pyrethrum, oil and sulphur which are harmful to a range of beneficial species[137; 138]. The impact of pesticides on beneficial species depends in part on the timing and rate of application and the species in question. Direct contact with an oil spray for example appears to be hard on most beneficial species inhabiting the trees, but the runoff seems not to affect important soil-dwelling predators[139]. To avoid or minimise adverse effects of organic pesticides, growers need to make an extra effort to: • choose the most appropriate, selective and lowest impact pesticide for the job • follow the label directions • apply pesticides only when their use is really justified, as indicated by monitoring • use the right spray equipment in the right way at the right time, to maximise the application efficiency and minimise the need for repeat treatments • monitor the effectiveness of any pesticide use to allow future applications to be fine-tuned. Where practical, growers should avoid spraying the whole orchard at the one time and focus instead on treating just those areas infested by pests. This will allow untreated areas to act as safe refuges for mobile beneficial species. This may mean spraying selected trees, rows or varieties. Border rows in particular may be targeted for treatment separately from the rest of the orchard, where their greater exposure to wind and dust makes them more prone to pest infestation. To help refine their use of any type of pesticide, growers should ask themselves the following questions:

71 • What was the target ? white louse scale on the trunks ? black scale at the top of the trees ? • Did the spray reach the target ? was the machine suitable ? was it set up correctly ? was spray coverage of high foliage adequate ? did the spray coat both sides of the leaves ? • Was the spray mix correct for the target pest ? was the concentration correct ? was the tank mix well agitated ? – (especially important for oil sprays) • Was the timing optimal ? did the spray target the most susceptible stage of the scale, e.g. new-generation crawlers and young scales ? • Did the spray have the desired result ? was there a high kill rate of the target pest ? It is worth answering these questions as far as possible to determine if and how the efficiency of an existing spray program may be improved. The following basic monitoring ideas are a good start: • Where non-toxic materials are used (e.g. a test spray of water), observation of freshly sprayed trees will help show the extent of spray coverage. Look for wet leaves and twigs high and low in the tree and throughout the canopy. • Water and oil sensitive papers obtained through agricultural suppliers may be used to monitor spray distribution. These can be stapled to leaves throughout the canopy before spraying. They change colour when wet and their degree and pattern of colouring indicates the penetration and distribution of the spray at that point. • The real test of spray effectiveness is the level of pest mortality. To assist all growers to apply sprays more effectively, improved methods for calibrating spray machinery were documented in recent years in the ‘Orchard & vineyard spraying handbook for Australia & New Zealand’[140]. The handbook includes a guide for spraying citrus, relating the spray volume required to the canopy density and tree height. Correct calibration of spray application will help to minimise undesirable environmental impacts, even of ‘organic’ sprays, while maximising their effectiveness. In developing better pest management systems based on biological control, most growers would benefit from expert advice from an experienced IPM practitioner. The organisations listed in sections 12.4 and 12.8 should be able to provide contact details and advice regarding IPM specialists in different districts.

72 Table 6‑2 Common citrus rootstocks and their relative tolerance of soil conditions, pests and diseases[141; 142]

Soil Compatible Soil type Phyto- Citrus Scion status rootstocks Tristeza Exocortis Poor phthora nematode Saline Alkaline Sand Loam + # drainage Rough lemon 4 2 1 4 4 3 1 3 5 Troyer citrange* 2 1 4 3 3 4 2 2 2 N & D Poncirus trifoliata* 1 1 5 1 5 5 2 2 1 Oranges Sweet orange 5 2 1 4 3 2 2 1 4 Swingle citrumelo* 2 1 2 1 2 4 2 2 1 Troyer citrange* 2 1 4 3 3 4 2 2 2 R or S Swingle citrumelo* 2 1 2 1 2 4 2 2 1 Rough lemon 4 2 1 4 4 3 1 3 5 N & D Troyer citrange* 2 1 4 3 3 4 2 2 2 Grapefruit Swingle citrumelo* 2 1 2 1 2 4 2 2 1 R or S Swingle citrumelo* 2 1 2 1 2 4 2 2 1 Troyer citrange* 2 1 4 3 3 4 2 2 2 N & D Poncirus trifoliata* 1 1 5 1 5 5 2 2 1 Ellendale Sweet orange 5 2 1 4 3 2 2 1 4 R or S Troyer citrange* 2 1 4 3 3 4 2 2 2 Rough lemon 4 2 1 4 4 3 1 3 5 Cleo. mandarin 3 1 1 4 1 1 3 2 3 N & D Murcott Troyer citrange* 2 1 4 3 3 4 2 2 2 Sweet orange 5 2 1 4 3 2 2 1 4 R or S Troyer citrange* 2 1 4 3 3 4 2 2 2 Cleo. mandarin 3 1 1 4 1 1 3 2 3

Imperial N & D Troyer citrange* 2 1 4 3 3 4 2 2 2 & other Sweet orange 5 2 1 4 3 2 2 1 4 mandarins Cleo. mandarin 3 1 1 4 1 1 3 2 3 R or S Troyer citrange* 2 1 4 3 3 4 2 2 2 Rough lemon 4 2 1 4 4 3 1 3 5 Villa Franca N & D & Lisbon Troyer citrange* 2 1 4 3 3 4 2 2 2 lemon R or S Troyer citrange* 2 1 4 3 3 4 2 2 2 Rough lemon 4 2 1 4 4 3 1 3 5 Eureka N & D Benton citrange* 2 1 4? 3? 4 4 2 2 2 lemon R or S Benton citrange* 2 1 4? 3? 4 4 2 2 2 Meyer N & D Rough lemon 4 2 1 4 4 3 1 3 5 lemon R or S Troyer citrange*? 2 1 4 3 3 4 2 2 2 Rough lemon 4 2 1 4 4 3 1 3 5 N & D Troyer citrange* 2 1 4 3 3 4 2 2 2 Lime Poncirus trifoliata* 1 1 5 1 5 5 2 2 1 R or S Troyer citrange* 2 1 4 3 3 4 2 2 2 + Soil situation: N=New, i.e. not previously used for tree crops; R=Replant; D=Deep (over 75cm); S=Shallow (less than 75cm) # Carrizo citrange can generally be considered the same as Troyer citrange * = to maximise tree life & productivity, use propagation material certified free of viruses and viroids 1 = best of the listed stocks, 5 = worst of the listed stocks, ? = performance uncertain

73 74 Full ground cover managed by slashing is the typical approach to weed management in organic citrus. 7. Weed management Organic farmers usually rate weed control as one of their biggest problems, Acceptable inputs and citrus producers are no exception. Growers considering a switch to organic citrus management also rate weeds as their major concern. This • Pine oil herbicide concern may relate to the ease with which weeds are controlled with herbicides in conventional orchards, compared to the need for organic producers to achieve effective control of weeds without using synthetic herbicides and ideally with minimal disruption to the soil. Weed management under an organic regime is typically seen as labour- intensive, and indeed the study of Riverland citrus orchards[72] found the labour requirement for weed management on organic groves (11.5 hours/ha/year) was three times that of non-organic groves. To keep this in perspective however, weed management only accounted for 3–7% of the total labour input on those organic orchards.

Pre-conversion weed management It may be useful for citrus growers to consider whether they should tackle their major weed issues with conventional non-persistent herbicides before joining an organic certification scheme. The use of this approach depends on the individual producer’s philosophy but may have merit, especially where invasive perennial species are well established and would be more difficult to manage under an organic regime.

Pre-planting weed management Because it is easier to tackle weeds in open ground than amongst established trees, a serious effort should be made to suppress, or if possible eradicate, major weed issues before planting a new orchard. This is especially important with infestations of perennial weeds like couch grass (Cynodon spp), kikuyu (Pennisetum clandestinum), Johnson grass (Sorghum halepense) and nutgrass (Cyperus rotundus), given that organic producers cannot use systemic herbicides.

75 Managing these weeds before planting also reduces competition with new trees and the risk of tree damage from weed control activity.

What is a weed anyhow? Depending on their management approach, citrus producers could define plants as weeds if they exhibit some of the following qualities: • compete with trees for water (most plants) • compete with trees for nutrients (most plants, especially non-legumes) • interfere with water distribution from low-level sprinklers (all except prostrate plants) • interfere with picking or other operations • compete with more desirable cover crops (e.g. suppression of clover by capeweed) • increase the pest risk (e.g. many plants support lightbrown apple moth; tall weeds give Fuller’s rose weevil access to the tree canopy) • produce spiky seeds that inconvenience or injure workers (e.g. Caltrop, Tribulus terrestris) • have the potential to invade neighbouring properties including areas of native vegetation • affect orchard aesthetics. The definition of weeds varies as much as producers themselves. Each producer must determine their weed management priorities and objectives in the context of their own orchard. A possible exception is that highly invasive plants may be universally considered as weedy because even a little of them is too much. As a first step in developing a weed management program, organic citrus producers should reconsider their definition of weeds. In doing this, they should remember that it is of no practical or economic benefit to spend To optimise their management, organic time, energy, money and other resources combating ‘weeds’ that are in fact producers should make the effort to separate ‘real weeds’ like caltrop (top photo) from causing no practical or economic harm to the orchard. As with any pest, ‘other plants’. the control of weeds is only warranted when those weeds cause, or are very likely to cause, economic or other loss to the orchard or neighbouring properties.

Volunteer plant or weed? Volunteer plants are often defined as ‘weeds’ simply because they were not deliberately planted. That definition alone however, does not justify efforts to control those plants. Many agricultural weeds have been defined as such because of their negative impact in pasture and grain cropping systems, the dominant form of agriculture in Australia. Their impact, or role, in citrus orchards can be quite different. This heavy weed growth steals water and nutrients from the trees and interferes with To determine their real ‘weed’ status, the characteristics of all plants need sprinkler water distribution. to be considered in relation to the objectives of the orchard manager. The

76 manager’s job is made easier by classifying orchard vegetation as ‘real weeds’ that require attention, and ‘other plants’ that can be ignored.

Benefits of volunteer plants Any potential negative impacts of volunteer plants on organic citrus orchards need to be weighed against benefits they may provide, before they are targeted as weeds. Some of these benefits are listed below. Soil protection—Most plants protect otherwise bare soil from the effects of sun, wind and rain.

Food source for beneficial What weeds? The mixed growth of grasses, invertebrates—Many flowering plants produce pollen or nectar that is legumes and other flowering plants in the used as food by the natural enemies of citrus pests. Others carry aphids midrow provides numerous benefits to this organic orchard. and other alternative prey that help to maintain populations of beneficial parasites and predators in the orchard. Nutrient recycling—Deep-rooted plants absorb nutrients from lower in the soil profile and redistribute them when the plants decompose. Weed suppression—Heavy growth of volunteer plants helps to suppress the development of undesirable ‘real’ weeds like Emex (three-cornered jack) and caltrop. Indicators of soil conditions—Unlike crop plants that grow where we force Wireweed (Polygonum aviculare) thrives in dense soil and so may be a useful indicator them to grow, volunteer plants tend to thrive under conditions to which of soil compaction problems. Also, its they are well adapted. Because of this, they may be used to some degree as flowers are used as a nectar source by many indicators of underlying soil conditions such as compaction or salinity[143]. beneficial insects[144] Altering the soil conditions to be less suitable for undesirable weeds may be a practical way to improve the competitiveness of more desirable cover crop species. Diversity is important in relation to benefits of volunteer plants or sown cover crops. Differences in habit, root structure and depth, height, flower type and timing, root exudates and so on, add to the complexity of interactions between ground cover plants, the soil, soil organisms and invertebrates, and are likely to provide greater benefits than single-species plantings. Under subtropical conditions for example, increased biomass production, soil organic matter and mycorrhizal activity occurred as increased numbers of ‘weed’ species were allowed to develop as groundcover in a citrus orchard[84]. With five or more weed species present, the characteristics of individual species (e.g. nitrogen and carbon fixation), became more important than the actual number of species.

77 Integrated weed management Integrated weed management (IWM) helps growers to achieve the most effective weed management outcomes in the short and long-term. Like integrated pest management, successful IWM relies upon some basic principles that include: • correct identification of weeds – know what you are dealing with • some understanding of weed ecology – know why the weeds grow where they do, and how they get there • appropriate orchard design – e.g. choice and layout of irrigation system can influence weed development and weed management approaches • choice of appropriate management methods – use effective techniques that minimise negative impacts on the orchard environment • correct timing of management activity – weed management needs to be timed effectively, e.g. to prevent seed set or interference with sprinklers • monitoring – know where and when weeds are a problem and how effective the control strategies have been.

Weeds require management before they IWM makes use of any appropriate methods to deliver the best outcome. cause problems such as disruption of The integration of several weed control techniques into a program makes irrigation. sense, as no one method can control all weeds cost-effectively, all the time.

This is because: • some weeds are easier to control than others • some weeds are annual and some perennial • some are spread by cultivation, others by wind or water • some are avoided by grazing animals • some are very competitive against cover crops. A combination of weed control techniques also helps to reduce the risk of particular weeds dominating the orchard. Some good manuals on integrated weed management are freely available (e.g.[145; 146]) and these provide useful guides to producers wanting to develop a more holistic approach to weed management. When selecting techniques, producers should consider potential long-term impacts of their choice and ideally move away from high-impact activity like continual cultivation. In subtropical citrus for example, levels of soil microbial biomass, organic matter, nitrogen and activity of mycorrhizal fungi and phosphorus-solubilising bacteria have been found to be greater after only three years of mowing for weed control, compared to cultivation or herbicide use[85]. All of these parameters are important for the organic citrus producer. Short-term & long-term approach Growers should consider their short- and long-term approaches to weed management carefully, to ensure they remain practical and complementary. Short-term aims are likely to involve reducing the quantity of weed growth during critical periods in the orchard, such as flowering, fruit set and times

78 of water stress when competition from weeds can affect tree and crop development. Long-term aims might relate to changing the ‘quality’ of orchard floor vegetation by, for example, suppressing or eradicating couch and encouraging perennial legumes. This eventually makes the short-term management easier. Both approaches—quantitative and qualitative regulation of weeds—are required in most organic citrus orchards to maintain tree productivity while developing a more desirable mix of plants on the orchard floor[147]. Total property weed management IWM needs to consider the whole property to minimise the risk of ‘clean’ areas being continually reinfested by weeds carried by wind or machinery from infested areas such as roadsides, headlands, irrigation channels and habitat reserves. Weed management must also be integrated with overall orchard management. Weeds, pests, diseases, soil, water and trees are all interrelated aspects of the orchard system and need to be managed as a whole for best results. Keep weed management objectives realistic For orchard managers and their workers to implement and maintain a weed management program, their objectives need to be realistic and achievable. The eradication of mallows (Malva spp) from an orchard in the short to medium term may be an unrealistic objective, given that some Malva seeds can remain viable for over 100 years[148]. Preventing further seed set would be a more realistic goal, and more likely to be followed up rather than abandoned in frustration. Also, to be forewarned is to be forearmed - where a herbicide program was in place before conversion to organic management, one weed issue likely to be faced is the re-emergence of weeds that were most sensitive to the herbicides being used[149]. This should be considered in the weed management program.

Prevention of seed set should be a priority in Weed management techniques the management of noxious weeds such as caltrop. Quarantine Quarantine can minimise the introduction of new weeds into orchards, and their spread between blocks. Being a preventative measure, quarantine is very cost-effective compared to the ongoing input of resources required to suppress weeds once they become established. An effective quarantine approach may require orchard managers to: • restrict the movement of machinery, people and livestock onto and across the whole property, especially those coming from high-risk, weed-infested sites

79 • establish buffers including windbreaks and surface water diversion, against wind and water-borne seed.

Hygiene Like quarantine, hygiene involves practices that reduce the introduction and spread of weeds. Orchard managers should: • select clean sources of potted trees, mulch, compost ingredients and other materials that may be weed-infested • avoid spreading weeds vegetatively, e.g. avoid cultivating from infestations of perennial Good hygiene can prevent weeds from being weeds like nutgrass and couch into clean areas of the orchard spread on machinery. • clean equipment of plant material, bulbs, roots and soil before it is taken into the orchard • prevent weed seed set • destroy seed of noxious weeds by deep burial, burning, etc. Grazing is not always reliable as the seed of many weeds is viable after passing through grazing animals[150; 151]. Animal manures can contain large amounts of weed seed, so when manure is brought in to the orchard there is a real risk of weed introductions. When mature seed heads of marshmallow (Malva parviflora) for example are eaten by sheep, about 20% of the seed excreted in manure is viable[151] and viable seed continue to be excreted for up to seven days. An eight day ‘holding period’ would be required after grazing on marshmallow, for sheep manure to be free of its seed. The importance of hygiene as a weed management tool was highlighted by an overseas trial that found sheep manure to contain 330,000 seeds per tonne, including wild radish, marshmallow and amaranth[152]. Effective composting, during which temperatures exceed 60°C, is known to greatly reduce if not eradicate viable weed seed and should be used to address the weed risk of manures[150; 153; 154]. Monitoring Cost-effective weed management relies on monitoring. Monitoring allows the producer to identify the orchard’s major weed issues and hotspots, select the most appropriate management techniques and timing (e.g. soon after germination to prevent weed establishment or before flowering to prevent seed set) and determine the effectiveness of weed control techniques. Monitoring relies on correct identification of weeds, and guides are available to help with this. Surveys and mapping of important weeds are also useful tools for weed management programs and should be timed appropriately, e.g. a few weeks after summer rain to detect summer annual Monitoring is necessary to detect weed issues weeds. such as a new flush ofEmex seedlings so that appropriate action can be taken.

80 Water and nutrition management In low rainfall districts, irrigation and nutrition programs can minimise the supply of water and nutrients to weeds by concentrating these inputs within the tree rows rather than broadcasting them over the entire ground area. Reduced nitrogen input into the mid-row is also likely to favour legume growth there, which may be more desirable than grasses and other non-legumes. In high rainfall areas where mid- row growth is abundant, the broadcasting of nutrient inputs over the whole orchard floor may be more beneficial, supporting heavier cover In this high rainfall organic orchard, growth crops which can be cut and used as mulch for weed suppression in the tree of the spreading plant ‘wandering dew’ is encouraged to suppress weeds in the tree row. row[155]. Competition In most ecosystems with adequate water resources, bare soil is unnatural, a sign of imbalance or disturbance. In 350BC, Aristotle proclaimed that “nature abhors a vacuum”. In terms of weeds his idea certainly applies – ‘nature’ will usually do whatever it can to cover bare ground with plants. Many of the plants that are adapted to colonise and cover bare soil quickly and effectively are considered weeds. As a result, producers who try to maintain their orchard in a state of imbalance, i.e. with bare soil, generally find themselves in ongoing conflict with these colonising ‘weeds’. Alternatively, weed growth can be suppressed by competition from more desirable plants for water, light, nutrients and space. Many weeds are poor competitors and their establishment, growth or seed production can be This organic orchard’s sward of Argentine reduced by competition from other plants. Wherever possible, producers paspalum has suppressed weeds for several should design bare soil out of their orchards. years. In this warm, moist climate it requires six cuts in summer and three in winter. Perennial and annual cover crops are used in organic citrus to improve soil structure and fertility and suppress weeds in the mid-row. Annual crops may be more effective in some situations because of their rapid growth and the effect of the cultivation required for their sowing. The most appropriate crops will depend upon local climate, soil conditions and water availability. A wide range of annual and perennial cover crops is available to growers[61] and local expertise and experience should be used to make the right choice. When selecting cover crops for weed suppression, the following characteristics should be considered[156]: • time to develop full ground cover (the sooner the better) • density of cover (the greater the better) • duration of cover (the longer the better) When grown well, dense crops can suppress even tenacious weeds like couch. One crop showing this ability under subtropical-tropical conditions Perennial cover crops such as this one of [156; 157] lucerne are commonly used for mid-row is sunn hemp (Crotalaria juncea) . weed suppression in organic orchards wherever rainfall or irrigation allow for their establishment.

81 For effective weed suppression, cover crops need to be managed well to cover the soil as quickly as possible to smother emerging weeds. Particular attention should be given to irrigation, nutrition and pre- and post-planting weed management. Allelopathy Allelopathy is a special form of competition, where seed germination or plant growth is suppressed by chemical substances produced by another plant. These substances may be leached from Offset slashers are commonly used to mow foliage or secreted from roots of the cover crops under the tree canopy. allelopathic plant, or released when the plant dies and decomposes. Many plants produce allelopathic substances[158]. Green manure crops may be the most appropriate way to use allelopathy in citrus, and of these, barley and cereal rye are known to suppress numerous weed species and are considered to have the greatest allelopathic potential. Slashing Slashing is the most common approach used by organic citrus producers to keep cover crops and weeds to a manageable height. It is relatively fast and causes minimal soil disturbance, although soil compaction may become an issue where slashing with tractor-mounted equipment is frequent. Timing and height of slashing are important considerations and are chosen to suit the weed management objectives. Slashing during or before flowering of weeds will prevent seed production. A high cut (e.g. 20cm above ground) will reduce or prevent seed set in medium to tall weeds while allowing useful species including non-grasses, to regenerate. A low cut tends to favour grasses over many other desirable plants, because the growing point of grasses is low. For the same reason, low cutting is not effective against weeds with very low crowns, like capeweed, caltrop and wireweed. As well as tractor-mounted and ride-on mowers, brush cutters are commonly used by organic producers – usually to cut weeds closer to sprinklers and trees. Slashing can be used to produce mulch for weed suppression along the tree row. When cutting for mulch, slashers are preferable to mulchers (e.g. flail mowers). The coarser material produced by slashers will break down more slowly and extend the life of the mulch. Mulch mowers are also much harsher on beneficial insects living in cover crops[131]. Organic citrus producers should consider slashing alternate rows, allowing the uncut rows to provide resources such as pollen for beneficial insects and mites in the orchard. Grazing Grazing can contribute to citrus weed management programs and conforms to organic standards which encourage the incorporation of livestock into organic farming systems.

82 In citrus, poultry are most commonly used because of their ease of management and low risk of tree damage. Side benefits of grazing include nutrient recycling and income diversification. Producers who use grazing need to address several stock management issues including: • control of movement and stocking rate to avoid over- grazing in specific areas • protection from predators (e.g. foxes & dogs) Temporary fencing is used to manage grazing by geese in this organic orchard. Slashing • selective grazing (e.g. geese prefer grass and seem to dislike nightshade, of the mid-rows encourages the geese to pigface, onion weed and fat hen) that leads to dominance of specific concentrate under the trees. The producer’s weeds aim is to use geese to replace manual under- • crop damage – most stock can damage citrus trees by feeding on the tree weeding. leaves and small twigs. Even geese will damage the bark of young trees and jump to pick ------Fence line ------mandarins from trees if they acquire a taste for them. Appropriate stock management, ensuring for example that there is always ample ground cover to graze, will help to avoid these issues. Heat Thermal weeding uses heat in various forms (radiant, flame, steam, hot water) to kill plant tissue. This technique has been researched and used for weed control for many years, but is generally economically effective only against Grazing can be an effective tool forweed small seedlings. Thermal weeding is therefore used most commonly on management. In this organic orchard, geese (kept on the right of the fence) have stripped row-crop seedbeds to kill the new flush of weed seedlings before the crop almost every leaf from this caltrop plant. germinates, although it has also been used in orchards. A benefit of thermal weeding is that it does not disturb the soil. Organisms below the soil surface are generally not affected, as the heat does not penetrate far into the soil. A disadvantage of thermal weeding is its high energy cost—it is usually based on fossil fuel such as diesel or bottled gas. It is also a relatively slow operation to achieve a good weed kill and may create a fire risk in dry districts or seasons where flame is used and the ground cover or mulch is dry. For these reasons, although some organic citrus producers have tried thermal weeding, none appear to use it routinely. Rolling Weeds, cover crops and green manures may be flattened with a crimping roller instead of being mown. Rolling leaves the plants largely intact, so they break down more slowly and create a longer-lasting mulch layer. Rollers can be cheap to manufacture and maintain and can be towed by a light four-wheel ATV.

83 Mulching Mulch inhibits weed seed germination by blocking sunlight from reaching the soil surface. It is also a physical barrier to weed growth. Almost any organic matter can be used as mulch, but straw, compost and chipped green waste are the materials used most commonly in citrus. Grape marc is used when available. Chipped Eucalyptus wood has also been used successfully for weed suppression and soil improvement in citrus (e.g.[159; 160]). Mulch is typically used for weed control along the tree row and provides numerous benefits. Mulches generally: • provide a source of nutrients (some mulches such as composted green waste) • add organic matter to the soil • enhance soil biology (e.g. increase microbial activity and inhibit citrus nematode[160]) • protect shallow citrus roots from excessive heat and dryness A mulch of straw suppresses weed growth • conserve soil moisture by reducing evaporation (e.g. citrus soil moisture around this young organic tree. tension reduced by up to 20%[160]) • avoid cultivator or slasher damage to trees • are convenient where tree trunks, sprinklers and irrigation tubing make cultivation and mowing difficult in the tree row. Depth of mulch is an important factor in its success. Weeds will generally not be suppressed effectively if the mulch is too thin, while overly thick mulch can shed sprinkler water and light rainfall away from the trees. Local trials will help to determine the best mulch depth for a particular orchard situation. Based on Australian and American trials in citrus orchards and vineyards, a 7.5cm depth of chipped or composted green waste is all that is required for suppression of annual weeds[41; 160; 161].

‘Mulch’ mats of thick cardboard and other The optimum depth for mulch will be influenced by characteristics of long-lasting materials are used by some the material used, such as its allelopathic properties or its ability to block organic producers to keep weeds clear of low- sunlight. Egyptian trials on weed management in citrus found for example, level sprinklers. Brush cutters are often used that a 6cm mulch of rice straw (15t/ha) gave much better control of grasses to manage weeds around the mat. and broadleaf weeds than a mulch of wild oats (Avena fatua) applied at the same rate, possibly due to allelopathic activity by the rice straw[162]. Mulches do have some disadvantages: • mulch may harbour pests such as snails • partly decomposed mulch may create an ideal seedbed for weeds • weeds at the mulch/mid-row interface can be awkward to manage without disturbing the mulch. In this organic orchard, geese graze most Regarding the latter two points, if weeds alongside a mulched area are weeds except onion weed which needs to be permitted to mature and drop seed onto the mulch, the weed-suppressing managed to prevent it from dominating. Twelve geese/ha make the difference between role of the mulch will be severely compromised. slashing once each month or only three times in a year.

84 When considering mulch as a long-term weed management option, producers need to take account of the cost of reapplication of mulches, possibly every one to three years. Also, as most organic mulch material is bulky, the cost of transport and handling needs to be considered. Another consideration is the influence of mulch on soil microbial communities. ‘Rich’ materials such as mature compost and slashed green cover crops are likely to favour bacterial decomposers, while fungi are more This organic producer cuts his own pasture likely to be encouraged by ‘hard’ materials with a high Carbon:Nitrogen for mulch and compost – an ideal way to ratio such as chipped wood. Producers who aim to fine-tune their soil minimise costs and contamination risks. biology need to take these differences into account. On-site production of organic matter can reduce the cost of mulching, especially if the slashing-mulching operation is performed in a single pass with a side-throw slasher that delivers the material directly under the tree. This approach particularly suits organic orchards as it reduces both the need for external inputs and the risk of introducing new weeds in mulch material. Synthetic mulches Synthetic woven weed mat suppresses many weeds and has been used effectively during the establishment of new organic citrus. A temporary mulch of black plastic can also kill difficult weeds including couch grass by starving them of water and light. Organic standards generally prohibit the use of solid plastic sheeting as mulch for weed control but special permission may be granted for this use in certain situations. Woven plastic matting is generally allowed—this should be confirmed with the relevant certifier. All such material must eventually be removed from the environment and not be cultivated in or left on-site to decompose. Temporary mulching with matting can be used to weaken tenacious weeds such as couch before cultivation or other treatment. Photo: Biological control CJ Weeds have their own natural enemies that include root, stem and seed- eating insects, mites and diseases. Green caltrop seed for example is attacked by weevil larvae (but unfortunately not severely enough to reduce populations of the weed). In some cases after considerable research, natural enemies of weeds are officially imported and released to help control introduced noxious weeds. Bridal creeper (Asparagus asparagoides)—a serious weed of citrus orchards and native bushland—has been targeted by such a biological control program in Victoria, using a rust fungus and leafhoppers. Biological control programs are run by government bodies but often involve community groups and landholders. Information on these programs should be sought from State agriculture departments.

85 Solarisation Solarisation involves the destruction of plants, seeds, pests and pathogens by the solar heat trapped when soil is covered by clear plastic sheeting during hot weather. While this technique is more commonly used to kill disease organisms in the soil it is also effective against many weeds and their seeds, although deep tubers or rhizomes are unlikely to be killed. To be effective, solarisation requires good transfer of heat into the soil. This is aided by high levels of soil moisture, so dry soil should be irrigated before the plastic is laid down. Air gaps between the plastic and soil should be minimised as they inhibit heat transfer into the soil. To prevent the plastic being lifted by wind and to reduce the leakage of heat, the edges of the sheet should be buried. Solarisation for at least four weeks is likely to be needed for effective weed kill. This will vary according to the quality of plastic sheet used, the prevailing temperatures and weed species. Winter weeds are likely to be less A mixture of cultivation and solarisation tolerant of high temperatures than summer weeds, and so more strongly is being used here to control couch prior to establishment of a new organic orchard. affected by solarisation. To avoid reinfestation of treated areas with weeds, the soil should be mulched or sown to a green manure/cover crop as soon as possible after removal of the plastic. Mechanical cultivation Cultivation destroys or buries weeds, disrupting their growth and preventing seed set. Most forms of cultivation are very disruptive to soil structure and to soil organisms. Cultivation can also spread seeds, tubers and rhizomes of noxious weeds, is relatively energy-expensive and increases the risk of soil compaction. Citrus develop many shallow roots, especially under mulch where cooler, moister conditions are maintained, so their root system Mechanical cultivation is used to manage will be affected by under-tree cultivation. Some organic producers do, weeds along the interface between mid-row and tree-row in this organic orchard. nevertheless, use shallow cultivation to maintain a weed-free strip along the tree row, especially with young trees that are less tolerant of competition. Manual cultivation Many organic citrus producers do some manual weeding (hand pulling, hoeing and brush cutting) to remove weeds from around young trees and sprinklers where cultivation and slashing is too risky. Although manual weeding is time-consuming and therefore expensive, it is effective and gives producers an opportunity to observe their soil and trees closely—a vital aspect of good organic management. Chemical weed control An organic knock-down herbicide based on pine oil is commercially available in Australia and several others using natural acids and plant oils have been evaluated overseas[163]. These herbicides disrupt the cuticle of plants and cause them to desiccate.

86 Although these herbicides are permitted by some organic standards they still involve the application of chemical substances to the ecosystem, and should be used with care as the effects of their long-term use are not known. Routine use of organic herbicides to replace synthetic ones also diverges from the spirit of the organic approach, which involves considering and managing the orchard differently, rather than simply substituting allowed inputs for prohibited inputs.

The pine oil herbicide works best On this organic property where cover against small seedlings and would require many repeat applications to cropping is standard practice in established suppress a perennial weed like couch, so its likely cost-effectiveness should blocks, weeds in the mid-row of a new be assessed carefully by producers. Also, before using organic herbicides, planting have been controlled by cultivation in preparation for a vegetable intercrop. certified producers should clarify any restrictions with their certifier.

Timing timing timing! In some situations, the timing of weed control in relation to the weeds’ developmental stage or weather conditions is critical. Weed management actions should be prioritised, scheduled and performed at the optimum timing for best results. If the management priority is prevention of seed set, then control treatments must be applied before or during flowering. Whenever weeds produce a new generation of seed, the problems they cause will be perpetuated, as will the need for ongoing control. A single plant of blackberry nightshade (Solanum nigrum) for example may produce over 170,000 seeds, some of which can remain viable for over 20 years[164]. Timing is also important when cultivation is used to disrupt weed seedlings or the rhizomes of perennial weeds. A greater kill rate will be achieved if the cultivation is followed by hot, dry weather rather than cool, wet weather. Priority should therefore be given to timing the cultivation according to prevailing weather conditions.

Couch: Cynodon dactylon Couch (also ‘Bermudagrass’) is rated as one of the world’s worst weeds and causes problems for organic and non-organic citrus producers alike. This weed not only competes for water and nutrients – it also suppresses citrus and other crops through allelopathic effects. Couch can retard the growth of young citrus plants significantly, and this effect can last for months after the weed is killed as allelopathic substances are released from decaying couch stems[165]. Mature citrus are also strongly affected by heavy infestations of couch, which have been recorded to markedly reduce soil moisture levels (down to 90cm), trunk and shoot growth, leaf area (by 80%), leaf nitrogen levels and yield (by over 70%)[166]. It is clear from research trials and field observations that couch is a real weed that requires effective management.

87 Numerous investigations around the world have determined the following about couch: • Its rhizomes (underground stems) can be up to 75cm deep[167] but are mostly much shallower. In sandy loam under high rainfall (600mm), almost 50% of the rhizomes were in the top 5cm of soil and only 10% below 15cm[168]. • The growth rate of new plants sprouting from stem fragments (after cultivation) increases rapidly after four weeks[167]. • Rhizomes can survive submersion in water for a month[169]. Flaming has killed most of the surface growth in this couch patch but regrowth will appear • Rhizomes buried deeper than 10cm had poor shoot emergence soon. Repeated thorough flaming would be and vigour[168]. needed to eradicate the patch. Photo: CJ • No new plants have been observed emerging from rhizomes buried deeper than 40cm[169]. • It took two weeks for new shoots to appear from rhizomes buried 5cm deep, and over a month from those buried 30cm deep[169]. • New plants growing from rhizome fragments developed their own new rhizomes once they had ten leaves[169]. • 90% of rhizome buds (at stem nodes) died when the rhizomes were exposed to dry conditions for at least seven days and lost half of their original weight. Under higher humidity 90% of buds died after two to four weeks[170]. • Ploughing in winter then spring gave better control than ploughing twice in spring. The main benefit came from drying of exposed rhizomes after the winter ploughing then deep burial (20cm) by the spring ploughing[171]. • A higher proportion of nodes sprouted from smaller stem fragments (with fewer nodes) and those shoots emerged later, compared to larger fragments (with more nodes)[172]. • Shaded couch grew stems with longer internodes, which should result in fewer nodes per fragment after cultivation[172]. • With a 40% reduction in light intensity (from shading) couch biomass production is reduced by up to 75% and a greater proportion of plant resources go to leaf development[173; 174]. • Spread of couch by cultivation depends on soil type and density of the infestation. In heavy soil, 30cm deep chisel ploughing spread stem fragments up to 30m from a dense couch patch and only 3m from a light patch. In sandy soil, stem fragments were spread up to 60m. 50% of fragments were dropped by the plough within 4m of their origin. Subsequent disc or tine harrow cultivation cut the stem fragments smaller but didn’t spread them further from the original patch. Only 5% of the redistributed stem fragments survived—these were the ones partially buried during cultivation[175].

88 • Cutting of couch (at least every two weeks) to completely remove all regrowth reduced rhizome biomass by 99% after eight cuts, and eliminated regrowth after 15 cuts[176]. • Under tropical/subtropical conditions, a dense planting of sunn hemp (Crotalaria juncea) ‘virtually eliminated’ couch[156]. • A 6cm deep mulch of rice straw (15t/ha) applied in early spring, had reduced above-ground dry matter production of couch by 96% after six months[162]. The observations above come from a range of climates and soil types and may not all reflect the behaviour of couch in all areas of Australia. They do however suggest One innovative organic producer uses this large portable ‘chicken tractor’ to graze couch that the following approaches may be of value in couch management: heavily before smothering it with mulch. • Because the bulk of couch plant matter can be quite shallow, it is vulnerable to cultivation or other shallow treatment – but follow-up treatment is needed to tackle the regrowth. • Cultivation should aim to bury stems deeply (40cm?) or leave them exposed on the surface. • Shallower cultivation (at least 20 cm) should suppress regrowth significantly but is unlikely to prevent it. • Cultivation to expose rhizomes should be done prior to a period of dry weather and the rhizomes should be left exposed for one to four weeks to ensure they dry. • Alternatively, cultivation may be intended to cut the stems into smaller fragments with fewer nodes. A higher proportion of these nodes should then sprout, depleting the fragments’ reserves more rapidly. To assist this, shading with mulch or dense green manure or cover crops may encourage couch to produce stems with longer internodes, resulting in fewer nodes per fragment after cultivation. • Shading or mulching may be used to generally deplete couch reserves and weaken infestations before cultivation or other treatment. • Cultivation from couch patches towards clean areas should be avoided to minimise spread of the weed. After passing through a patch, raise the implement and ensure it is clear of couch stems before proceeding. • After cultivation, regrowth should be interrupted with further cultivation or other treatment within four weeks, or before the new plants have developed ten leaves, whichever occurs first. • Repeated and frequent removal of all regrowth (e.g. by cutting, burning, organic herbicide) will eventually eradicate an infestation— this could take almost a year.

89 90 Cosmos can provide valuable nectar to beneficial insects in the orchard. 8. Pest Management Invertebrate pests Integrated pest management (IPM) has a long history within Australia’s citrus industry, and by necessity organic producers rely on this approach to pest management. Within IPM, the focus of organic growers should be on preventative strategies and biological control because of their emphasis on natural regulation of pests and their low environmental impact. These approaches are especially important for organic producers because of the very restricted range of pesticides permitted for use under organic standards. Important aspects of the biology and control of Australia’s significant citrus pests are well documented in ‘Citrus pests and their natural enemies: Integrated Pest Management in Australia’[10], ‘The Good Bug Book’[177] and the website of Australasian Biological Control (see section 12.8). All serious citrus growers should use these as valuable guides to effective and environmentally sound pest management. A good 10X hand lens is also a valuable tool. Rather than duplicate the descriptive and biological information found in those excellent references, this section focuses on the optimisation of IPM from an organic perspective. The pests discussed in this section are those most likely to cause problems in citrus. In reality, relatively little action is taken against pests by organic citrus growers in Australia. Less than 10% apply treatments for lightbrown apple moth, mealybug or thrips for example, while the most troublesome pest group – scale insects – is actively treated by only 30% of organic growers[24]. A note on sooty mould Sooty mould is a common problem associated with several sap-feeding insect pests on citrus. These pests including soft scales, mealybugs and aphids excrete a sugary solution called honeydew. Honeydew forms a

91 sticky coating on leaves, twigs and fruit, providing an ideal food source for certain fungi. When the fungi produce black spores, they develop an unsightly appearance referred to as ‘sooty mould’. Sooty mould reduces fruit quality by staining the rind and is a concern to growers aiming for high value fresh markets. Severe infestations of sooty mould also affect tree health by covering leaves and reducing photosynthesis. Honeydew causes additional problems by attracting ants Heavy sooty mould growth can affect tree onto citrus trees. Ants seek honeydew as an energy-rich food and while health. they forage for honeydew they disturb beneficial insects. This disrupts biological control of hard and soft scales and other pests. The problem of sooty mould is addressed through management of the various honeydew- producing insects, as outlined below in this section. Also remember as mentioned in section 6, post-harvest cleaning of fruit can reduce the level of field control required for sooty mould.

Resources for beneficial species As mentioned earlier many beneficial insects and mites require, or at least benefit from alternative food sources like pollen and nectar. Table 8‑1lists plants that have been found to provide these food resources to a range of beneficial species. This list is provided as a guide to the types of plants that may enhance the longevity or performance of beneficial species in citrus. It is important to note that in most cases, the work has not yet been done to positively associate particular food plants with the beneficial species found on Australian citrus. Because of this, the plants listed are mostly those that are known to provide suitable food for closely related species (other species in the same genus as those on citrus in Australia). Table 8‑1 only lists plants whose pollen or nectar is known to be used directly by parasitic and predatory species. It must be remembered that many other plants can also support these beneficial species by hosting alternative prey or providing shelter.

Alyssum can also provide valuable nectar to beneficial insects in the orchard.

92 Table 8‑1. Food plants known to be used by beneficial insects and mites

Beneficial species Citrus pest attacked Food plant Food* Ref.

Parasitic wasps Anagyrus pseudococci Citrus mealybug buckwheat (Fagopyrum esculentum) N [178] Coccidoxenoides sp Citrus mealybug shell ginger (Alpinia zerumbet) N

angel’s trumpet (Datura candida) [179; 180] Russelia equisetiformis Grevillea bipinnatifida x banksii agapanthus Agapanthus praecox

Ooencyrtus sp Fruitpiercing moth, fruitspotting bug, vetch (Vicia angustifolia) N [181] planthoppers fleabane (Erigeron annuus) Trissolcus basalis Green vegetable bug canola (Brassica napus) N marigold (Tagetes patula) basil (Ocimum basilicum) buckwheat (Fagopyrum esculentum) cosmos (Cosmos bipennatus) [182] calendula (Calendula arvensis) coriander (Coriandrum sativum) nasturtium (Tropaeolum majus) phacelia (Phacelia tanacetifolia) Diachasmimorpha sp Queensland fruit fly cotton (Gossypium hirsutum) EFN [183]

Trichogramma sp Corn earworm, native budworm, light peach (Prunus persica) EFN [184; 185; 186;

brown apple moth, citrus butterflies cotton (Gossypium hirsutum) EFN 187] alyssum (Lobularia maritime) N maize (Zea mays) P Predatory ladybird beetles

Coccinella sp Scale insects, aphids, thrips Compositae (daisy, dandelion, sunflower family) P [188] Umbelliferae (carrot, parsley, dill family)

Harmonia sp Black citrus aphid, some scales and rye (Secale cereale) P [189; 190] mealybugs maize (Zea mays)

Micraspis frenata Hard wax scales, aphids Rhodes grass (Chloris gayana) P [191; 192] Windmill grass (Chloris truncata) P Vasey grass (Paspalum urvillei) P Slender pigeon grass (Setaria gracilis) P Forage sorghum (Sorghum bicolor) P Kangaroo grass (Themeda australis) P Perennial ryegrass (Lolium perenne) P

Balloon cottonbush (Gomphocarpus physocarpus) N [193] Red head cottonbush (Asclepias curassavica) N

Micraspis sp maize (Zea mays) P [194; 195; 196] rice (Oryza sativa) P Predatory hover flies Melangyna sp Aphids, leafhoppers, mealybugs, soft wireweed/knotweed (Polygonum sp) P scales daisies (Asteraceae) lilies (Liliaceae) grasses (Poaceae) dandelions (Taraxacum sp) gooseberry, currant etc (Ribes sp) Myrtaceae [197; 198] pines (Pinus sp) cabbage family, canola etc (Brassica) stonefruit, apples, pears, brambles (Rosaceae) Dock Rumex Yarrow Achillea millefolium Phacelia Phacelia tanacetifolia Predatory bugs Citrus pest attacked

Orius sp Corn earworm, native budworm, two- maple (Acer) P [199; 200; 201;

spotted mite, aphids, thrips Maize (Zea mays) 202; 203; 204;

Sweet pepper (Capsicujm annuum) 205] Rosaceae cotton (Gossypium hirsutum)

93 Table 8‑1. Food plants known to be used by beneficial insects and mites (continued)

Beneficial species Citrus pest attacked Food plant Food* Ref.

Lacewings

Mallada sp Aphids, scales, whiteflies, mealybugs, Roxburgh sumac (Rhus semialata var. P [206] moth eggs roxbrughiana)

Micromus sp Black citrus aphis, black scale, citricola buckwheat (Fagopyrum esculentum) P&N [207] scale, soft brown scale Preying mantid

Tenodera sp General predators of bugs, moths, Mixed pollen P [208] caterpillars and beetles Predatory mites Euseius victoriensis Mites: brown citrus rust, citrus rust, broadleaf cumbungi/ bullrush (Typha orientalis) P citrus bud, broad, oriental spider, two- Rhodes grass (Chloris gayana) [209; 210] spotted spider. Also Australian citrus whitefly, scale eggs and crawlers Euseius sp Mites, whitefly, scale eggs and crawlers poppy (Papaver rhoeas) P cherry, peach, apricot, walnut date palm (Phoenix dactylifera)

castor oil plant (Ricinus communis) [211; 212; 213;

maize (Zea mays) 214; 215; 216;

tulip (Tulipa gesnerana) 217; 218; 219;

angular pigface (Malephora crocea) 220; 221; 222] live oak (Quercus virginiana) apple (Malus domestica) Hottentot fig, pigface (Carpobrotus edulis) cumbungi/bullrush (Typha angustifolia) almond (Prunus dulcis) Amblyseius sp Brown citrus rust mite, citrus rust mite, castor oil plant (Ricinus communis) P broad mite, two-spotted mite cumbungi/ bullrush (Typha angustifolia) narrow-leaf cumbungi/bullrush (Typha

domingensis) [223; 224; 225;

pygmy date palm (Phoenix roebelenii) 226; 227; 228] cucumber (Cucumis sativus) coast live oak (Quercus agrifolia) live oak (Quercus virginiana) Livingstone daisy/ice plant (Dorotheanthus bellidiformis)) Typhlodromus sp Two-spotted mite rosemary (Rosmarinus officinalis) P Oxalis sp. holly/holme oak (Quercus ilex) [209; 216; 221; Hottentot fig, pigface (Carpobrotus edulis) 229; 230; 231] almond (Prunus dulcis) broadleaf cumbungi/ bullrush (Typha orientalis) Agistemus sp Brown citrus rust mite, citrus rust mite, cumbungi/bullrush (Typha angustifolia) P

flat mites castor oil plant (Ricinus communis) [215; 232; 233;

tea (Camellia sinensis) 234] date palm (Phoenix dactylifera) maize (Zea mays) angular pigface/ice plant (Malephora crocea) * P=Pollen, N=Nectar from flowers, EFN=nectar from Extra-Floral Nectaries (usually on leaf petioles or stems) Note: Where ‘sp’ is given in place of a beneficial species name, the food plants have not been evaluated against the particular beneficial species that are active in Australian citrus, but are used by other closely related species (i.e. in the same genus).

94 Pesticides Readers should keep in mind that although organically allowable insecticides are listed for many of the following pests, they should be considered as the last resort (as dictated by organic standards and common sense). Some successful inland organic citrus producers have managed to do without any insecticide applications at all since the early 1980s. As mentioned earlier, a major drawback of many pesticide sprays is their impact on the beneficial species on which we rely for biological pest management. To reinforce this point, Table 8‑2 indicates the level of impact of common organic pesticides on different biological control agents.

Table 8‑2 Level of impact of organic pesticides on beneficial species[137; 177; 235; 236] Predatory Other Parasitoid mites predators wasps Petroleum oil mod mod mod-high Pyrethrum high high mod-high Soap low-mod low high Spinosad mod mod mod-high Sulphur mod-high mod mod-high

A caution on Pyrethrum and piperonyl butoxide Extracts from the pyrethrum plant are an allowable insecticide under organic standards and products containing pyrethrum are registered for use on citrus as noted in the ‘Acceptable registered inputs’ boxes. Most pyrethrum pesticides also contain the synergist piperonyl butoxide which is a prohibited input under organic standards. Growers should ensure that products they intend to use do not contain piperonyl butoxide. If in doubt, certified growers should confirm the acceptability of any input with their relevant certifier. Growers should also remember that pyrethrum is a broad-spectrum pesticide that is highly toxic to most beneficial species and therefore should be used with caution, if at all, to avoid disruption of biological control systems. Commercially available biocontrol Wherever there is mention of biological control agents being commercially available, growers should refer to ‘The Good Bug Book’ mentioned above, and the biological control suppliers listed in section 12.8.

Ants About 1,300 ant species have been identified in Australia to date. Ants are found in almost every environment across Australia including citrus orchards. It is relatively easy to find over 30 species in inland citrus orchards. In most situations, most ant species are beneficial. Many are general predators and many improve soil condition, especially aeration and permeability, through their tunnelling activity. Sticky trunk barriers can be used to prevent ants from entering tree canopies. These As mentioned above, some ant species cause problems on citrus when their barriers consist of sticky polybutene gel (e.g. activity disrupts the biological control of certain insect pests. This occurs Tac-Gel®, Trapp-it®, Tanglefoot® and Stikem Special®) applied to form a continuous band when large numbers of ants are attracted to honeydew. While foraging on around the trunk.

95 trees, ants attack or disturb the pests’ natural enemies including ladybirds, lacewings and parasitic wasps. The pests are then free to build up large populations. Of the numerous ant species seen in citrus orchards, very few are found in large numbers associated with honeydew-producing insects. The two most common culprits are a small black ant in the Iridomyrmex rufoniger group and the larger meat ant Iridomyrmex purpurea. If any control action is considered necessary against ants, only those species causing problems should be targeted. Management techniques Monitoring At any time of year, high levels of ant activity within a citrus canopy are easily detected by observing ant activity on the trunk. An occasional ant is not an issue, but trails of ants indicate a problem. A closer look should expose the reason for all the activity, such as an infestation of soft scales. An exception to this is that when citrus trees are flowering, sugar-loving ants are attracted to the nectar. Cultural management

Some pest ant species including meat Acceptable inputs ants seem to prefer undisturbed bare • Sticky trunk barriers ground – most people will have (polybutene gel) noticed their bare nesting sites and their trails cleared of all debris. Heavy mulch and cover crops may be expected to discourage these species, as would cultivation.

The sticky band technique is very effective where tree skirts and weeds are managed to ensure the trunk is the only path into the canopy. However, sticky bands are also messy and labour intensive. They require occasional scraping to prevent the surface becoming sealed over with dust and leaves, and are unlikely to be cost-effective except on a small scale. The sticky gel should not be applied directly to tree trunks as damage to the bark can occur. This may result from sunburn through the clear gel or moisture accumulation under the gel. Suitable underlays for sticky bands include elastic bandage (see photo) and foil-backed fibreglass insulation. The planting of common vetch as a nectar source has been used experimentally in California to attract some IPM-disruptive ant species out of grape vine canopies[237]. This approach has merit but would need evaluation against the pest ants of Australian citrus orchards and against the attractiveness of honeydew from citrus pests. Pesticides Boric acid baits have been used to Acceptable registered reduce ant populations in organic inputs for ants citrus orchards overseas[238; 239], and • Baits based on boric acid can be formulated appropriately to attract sugar or protein-seeking ants[240]. Baits such as these should be in containers to prevent soil contamination and access by non-target animals. Approval for their use should be obtained from the appropriate organic certification body, as some certifiers may not permit the use of boric acid.

96 The best approach for ant management is effective control of the honeydew-producing insects that are invariably the reason for increased ant activity on citrus. Refer to the sections on mealybugs and scales for more information.

Aphids Four aphid species commonly infest citrus in Australia. Toxoptera citricida and Toxoptera aurantii, both known as black citrus aphid, occur in all citrus regions. Aphis gossypii (cotton or melon aphid) can be found in most regions except Western Australia while Aphis spiraecola (spiraea or apple aphid) is restricted to the coastal regions between lower Queensland and central NSW. Aphids may be found on young citrus growth throughout the year. However, they strongly prefer new flush growth and it is on the spring and autumn flushes that large This parasitoid wasp laying an egg in an populations can develop. On a range of crops, aphid development is aphid is one of the many allies that organic citrus growers have against insect pests. The favoured by high crop nitrogen levels. inset shows a parasitised aphid from which an adult wasp has emerged. Photos: MP Mature trees should tolerate sporadic heavy aphid infestations, as a relatively small proportion of their foliage will be ‘new flush’ at any one time. Young or reworked trees however may at times have most of their foliage susceptible to aphid attack. These trees should be monitored more closely and managed accordingly. In most cases, growers should tolerate minor aphid infestations as they provide useful food resources for a range of beneficial predators and honeydew-feeders. Heavy aphid infestations may cause distortion of flowers, leaves and shoots. The most common problem though is sooty mould from infestations present during autumn. Management techniques Monitoring Flowers, spring and autumn growth flushes and flushes induced by pruning should be inspected for heavy aphid infestations. Parasitised aphids and the activity of beneficial species should be noted. Biological control In mature orchards, aphids should be managed effectively by their natural enemies that include parasitic wasps and predatory ladybirds, lacewings and hover flies. Aphid parasites and predators are commercially available but this is unlikely to be necessary as they are naturally widespread. Growers should keep in mind that aphid populations grow very rapidly —an entire generation can develop in less than a week. Populations of parasites and predators take longer to catch up so it is important to monitor and wait as long as possible before taking any control action.

97 Cultural management Refer to section 6 regarding the key aspects of cultural management applicable to aphid control, particularly the avoidance of broad- spectrum pesticides and excessive nitrogen levels in trees. Pesticides

Acceptable registered inputs for aphids • Insecticidal potassium soap

Use of pesticides against aphids on Maggot-like hoverfly larvae are often seen citrus is unlikely to be warranted except in the case of heavily infested attacking aphid infestations. Photo: DPI young or reworked trees. Soap insecticides are non-selective and will affect beneficial species that are hit directly by sprays. For this reason especially, these products should only be used when necessary, after orchard monitoring has shown a real need for control and a lack of beneficial insect activity.

Apple weevil Apple weevil (Otiorhynchus cribricollis) also known as curculio beetle and cribrate weevil is usually a minor pest of citrus, but heavy infestations can defoliate young trees. After pupating in the soil, adult apple weevils emerge during early to mid summer to begin feeding on tree foliage. During the day, the flightless adult weevils shelter in crevices on the tree, under bark and in loose soil at the base of trees. They may also shelter inside tree guards. At night they climb the trees and feed on leaves. Management techniques Monitoring Chewed leaf margins may indicate the presence of the weevil, but to be sure of the cause, damaged trees should be inspected at night when the weevils are active. Apple weevil may also be monitored by observation of adults sheltering in leaf litter, under bark or in loose soil at the base of trees during the day. Bands of corrugated cardboard wrapped loosely around tree trunks will be used as daytime shelter by some of the adult weevils. This makes their presence easy to detect. Hygiene As these weevils are flightless they are most commonly spread by human activity, for example, as larvae in soil or adults on equipment and plant material. Attention to hygiene will reduce the chance of clean orchards becoming infested. Biological control No effective biological control agent is known for apple weevil. Birds are natural enemies of beetles generally, and poultry (chickens, turkeys

98 and guinea fowl) have been used to manage garden weevil in Australian vineyards[241] but this approach has not been evaluated against apple weevil. Cultural management Sticky trunk bands may be used to Acceptable inputs prevent adult weevils from climbing • Sticky trunk bands the tree trunk to reach the canopy, but this option is time-consuming and messy, and so is unlikely to be economic on a medium to large scale. Apple weevil populations may be reduced if alternative host plants such as capeweed and dock are removed from the orchard. Pesticides There are currently no organic Acceptable registered pesticides registered for apple weevil inputs for apple weevil control. • None

Citrus butterflies Caterpillars of the small citrus butterfly Papilio anactus and large citrus butterfly Papilio aegeus can defoliate small trees, but generally these are minor pests. Both species over-winter as pupae and emerge as adults in spring when they mate and begin laying eggs on young foliage. Management techniques Monitoring Young trees should be inspected for caterpillars from mid spring to mid autumn, especially if butterflies are observed in the orchard. Biological control Many natural enemies including birds, diseases, predatory bugs and parasitic wasps attack citrus butterflies. Some of these enemies such as lacewings and Trichogramma wasps are commercially available. However, because the caterpillars can defoliate small trees rapidly once established, they are unlikely to be controlled satisfactorily through the reactive release of biological control agents. Pesticides Acceptable registered No organically acceptable pesticides have been registered for controlling inputs for citrus citrus butterflies specifically, butterflies possibly because they are a minor • None problem. Citrus gall wasp The citrus gall wasp Bruchophagus fellis is less than 3mm long but can cause loss of production and dieback in trees when infestation levels are high. The female wasp lays numerous eggs into small twigs during spring. As the wasp larvae develop, the twigs swell and become galled. The larvae complete their development and pupate in late winter, emerging as adult wasps in spring. Gall wasp is mostly a problem in the QLD and NSW coastal districts but appears to be increasing in southern Victoria and the Sunraysia district. Lemons are particularly favoured by this pest.

99 Management techniques Monitoring Trees should be inspected for obvious galls in mid-winter. To determine if parasites of the gall wasp have been active, collect some galls from across the orchard in late winter and keep them at room temperature in a container with a fine mesh lid (e.g. facial tissue). Black gall wasps should start emerging first, followed about two weeks later by honey-coloured parasitic wasps about 2.5mm long.

Some organic growers have pruned heavily Biological control to remove gall wasp galls, but the wasp has Where parasitic wasps (Megastigmus sp.) are active, a large proportion returned. This strategy may possibly work of gall wasp larvae can be parasitised and galling reduced. Parasites are with small isolated occurrences of the wasp. available commercially in limited supply. Cultural management Where small infestations occur, the galls can be pruned off and destroyed before the new generation of adult gall wasps emerges in spring. Pesticides There are currently no organic Acceptable registered pesticides registered for gall wasp inputs for citrus gall wasp control. • None Citrus leafminer The citrus leafminer Phyllocnistis citrella is a moth about 2mm long that occurs in most citrus regions across Australia. This pest can usually be found all year round, although it is rare in late winter and early to mid-spring. Leafminer activity typically begins to build up from mid to late spring, peaking in late summer to early autumn. Female moths lay individual eggs on new leaves. After hatching, the larvae burrow into the leaf and begin feeding, producing the characteristic silvery ‘mine’. Although unsightly, leafminer damage Damaged leaves usually become distorted. A complete leafminer is unlikely to have a significant effect on generation takes about two weeks under favourable conditions. mature trees. Photo: JH Severe infestations of leaf miner may affect young, reworked or heavily pruned trees where the majority of foliage is damaged. Generally though, the most important growth flush in citrus, the spring flush, rarely suffers serious damage. Because of this, growers should consider the need for leaf miner control carefully, even where summer and autumn flushes are damaged.

100 Management techniques Monitoring As leafminer eggs are difficult to see, early flush growth should be inspected for active mines instead, during summer and early autumn. Biological control Citrus leafminer is attacked by several parasitic wasps and predators such as lacewing larvae. To encourage this natural control, contact pesticides should be avoided wherever possible. Cultural management Leafminer can be managed to some Acceptable registered extent by managing the trees to inputs for citrus leafminer encourage spring growth and • Mineral/petroleum oil minimise summer and autumn growth flushes that are more likely • Botanical oil (canola) to be damaged. The key points are • Insecticides containing to avoid excessive water and the compounds spinosyn nutrient inputs during summer and A and spinosyn D (known early autumn, and to maintain a as Spinosad; produced balanced crop load to encourage the by the soil actinomycete diversion of tree resources into fruit Saccharopolyspora rather than flush growth. The focus spinosa) should be on nutrition management in late autumn and winter to ensure that the trees’ nutrient status in spring will support good growth. Pesticides A considerable research effort has been directed towards management of citrus leafminer on susceptible trees. The least disruptive option appears to be the use of low concentration spray oils to protect new foliage. A light coating of oil deters female leafminer from laying eggs on the sprayed leaves. Because of the continual growth of new leaves during a flush, several sprays may be needed to protect the entire flush. Spinosad-based insecticides (usually applied with horticultural oil) are also registered and acceptable for use against citrus leafminer, but are known to have a slightly greater negative impact than oils, on a range of beneficial species.

Fruit fly Fruit flies are amongst the world’s worst pests of fruit. They are present in See section 12.5 for state most countries and attack many types of fruit, as well as fruiting vegetables, government contacts regarding ornamentals and some nuts. Feeding by fruit fly larvae (maggots) damages fruit fly identification. the fruit internally, causing it to ripen prematurely and rot. Up to 100% of fruit may be damaged by fruit fly when infestations are uncontrolled. The presence of fruit fly can also result in the loss of valuable interstate and export markets. While over 80 species of fruit fly are known in Australia, the following two are of major concern: Queensland fruit fly (Qfly) - Bactrocera tryoni. This species is native to the humid regions of north-eastern Australia, extending from Queensland into the Northern Territory and New South Wales. Its extensive host range includes many cultivated and wild plants[242] and the adults can fly many

101 kilometres. This allows Qfly to maintain heavy populations in forest and bushland areas and move from there into commercial fruit crops and backyard trees. Mediterranean fruit fly (Medfly) - Ceratitus capitata. Medfly originated in Africa and was introduced to Australia many years ago. It is currently restricted to south west Western Australia. Unlike Qfly, Medfly prefers drier regions. Medfly infests a wide variety of fruits and vegetables and although it can Queensland fruit fly (Qfly) Bactrocera- disperse locally in search of suitable egg-laying sites, it is much less mobile tryoni. Photo: Department of Primary than Qfly. Industries N.S.W While most citrus can be affected by Qfly and Medfly, this crop is not a preferred host for either pest. The thick skin of citrus can be a deterrent to egg-laying and eggs and larvae can be killed by oil in the citrus rind, especially in immature fruit. Higher levels of damage to citrus may be expected where the citrus are thin-skinned or already damaged (e.g. from hail or splitting), or when there are no other suitable fruits available for egg-laying. Qfly and Medfly are most active from October to May, but some activity will continue in warmer periods during the winter months. Both species overwinter as adult flies in sheltered locations. Medfly also overwinters as eggs or larvae in fruit, or pupae in the soil. Adults of both species become active again in spring and begin laying eggs in mature fruit. The danger of Mediterranean fruit fly (Medfly) Ceratitus- capitata. Photo: Department of Agriculture fruit fly infestation is heightened when ripe fruit is present and conditions and Food W.A. are warm and moist. For both species, preferred hosts such as stone fruit can support a build-up in populations before citrus fruits become available as egg-laying sites. The adults can live for a few months and lay hundreds of eggs, several at a time, a few millimetres into the fruit. A Medfly may lay up to 1000 eggs during her life. Eggs hatch in a few days and the larvae eat through the fruit, growing to about 9mm long when mature. Depending on temperature, this takes one to several weeks for Qfly and two to six weeks for Medfly. Infested fruit often ripen and drop prematurely. Mature larvae leave the fruit, drop to the ground and burrow into the top few centimetres of soil to pupate[243]. Pupation depth is an important factor for growers who are considering cultivation or livestock as part of their fruit fly management strategy. Results from a range of trials indicate that pupation depth varies with soil texture and moisture content. In moist or dry sand, Medfly pupated within 3cm of the surface. In soil, several other species were observed to burrow to a maximum depth of 7.5cm. When Medfly pupae were buried in compacted soil or moist loose soil, no adults emerged from deeper than 7.5cm, while in dry loose soil, some Medfly adults emerged successfully from as deep as 32cm. Qfly have been noted to rarely pupate deeper than 5cm, with no adults emerging from pupae buried 15cm deep. The pupal stage lasts one to several weeks for Qfly and two to seven weeks for Medfly. When pupation is complete, the new adults emerge from the soil and take about a week to mate, feed and begin laying eggs. Adult female Qfly and Medfly need a source of energy and protein before they can mature their eggs. For this, they may feed on nectar, honeydew from sap-sucking insects such as scales and aphids, bird droppings and bacteria.

102 Qfly generally lays eggs in citrus that is at the ‘silver green’ stage or more mature, while Medfly prefers fruit that has started to colour. Skin colour may develop prematurely around the egg-laying site (the ‘sting’) and fungal decay can infect stung fruit under humid conditions. Stung fruit can fall, even if no fruit fly larvae develop. Populations of fruit fly continue to build up through successive generations over the spring and summer months until temperatures drop in autumn. Management techniques Regional exclusion A region of NSW, Victoria and SA (see Figure 8‑1) has been designated a Landholders within the FFEZ ‘fruit fly exclusion zone’ (FFEZ) for the purpose of maintaining access to must not use sprays or traps for important markets that are sensitive to fruit flies. The grower’s approach fruit fly unless authorised by a to managing fruit fly depends on whether they are within or outside the state agriculture department, FFEZ. as they may compromise the effectiveness of the official Within the FFEZ, state agriculture departments apply quarantine monitoring program. restrictions, operate an intensive fruit fly monitoring program, and when necessary run eradication programs, to maintain the fruit-fly-free status of the zone. The situation outside the FFEZ is summarised in Table 8‑3. Where fruit fly is present, it is up to individual landholders to minimise the risk of damage to their crops.

Figure 8‑1. The Riverland and Murray Valley fruit fly exclusion zone

103 Area-wide suppression In some districts, area-wide suppression of fruit fly may be attempted through the use of bait sprays, mating disruption with pheromones, and mass release of sterile male flies. Organic growers should actively participate in any such programs, as long as organically acceptable treatments are used. The following practical management strategies should be applied to home garden trees as well as commercial orchards. Hygiene Exclude fallen and damaged fruit from the harvest. Because larvae can develop successfully in fallen fruit, collect and destroy all such fruit quickly, e.g. by cooking or by sealing in plastic bags in the sun for several days. Fallen fruit can also be slashed to destroy or expose any fruit fly eggs and larvae and to speed decomposition of the fruit. Remember – do not bury suspect fruit as fruit fly larvae may survive. Inspect trees after harvest, collect any missed fruit and use or destroy it promptly. Remove unwanted and unmanaged fruit trees to reduce the source of breeding sites for fruit fly. This may be especially important for preferred hosts such as stone fruit. Biological control Newly emerged flies need up to 24 hours for their wings to harden before they can fly, so are prone to predation on the soil surface by birds, ants, bugs and earwigs. Birds including domestic poultry may also contribute to the control of fruit fly larvae in fallen fruit and shallowly buried larvae and pupae. Cultivation would increase the exposure of larvae and pupae Table 8‑3 Occurrence and to these and other predators, but is not desirable where it would be needed management of fruit fly – right under the trees. outside the fruitfly exclusion zone. Parasitic wasps and nematodes also attack various stages of fruit fly. While State/Region Fruit fly Control all of these natural enemies help to reduce fruit fly numbers, they are very status by land- unlikely to provide economic levels of control. holders Cultural management Western Australia free not Harvest as early as possible - Kununurra required Acceptable inputs Western Australia Medfly permitted As the season progresses, fruit fly - elsewhere • Pheromone or protein- numbers, the attractiveness of fruit South Australia free not based attractants for traps to fruit flies and the risk of damage required all increase. • Food lures for traps Victoria - Qfly permitted permanent fruit fly Keep tree size manageable zone* Tall trees are more likely to carry unharvested fruit, providing egg laying Victoria - free not sites for fruit flies. elsewhere required Tasmania free not Physical exclusion required Individual fruit, branches or whole trees can be protected against fruit fly New South Wales Qfly permitted by bagging, but this is a labour-intensive approach warranted only for very Queensland Qfly permitted small or valuable crops. In some situations, whole-orchard netting may Northern Territory free not be justified where protection is required against a number of pests such as -Ti Tree required fruit fly, lightbrown apple moth and birds, as well as hail. Northern Territory Qfly permitted - elsewhere Trapping * Roughly the region east of a line drawn Traps are generally used for monitoring fruit fly numbers rather than between Wodonga and Paynesville (near controlling them. However populations of Bactrocera fruit flies and fruit Bairnsdale). For a map see www.dpi. damage in olives have been reduced by mass trapping, so this approach vic.gov.au Agriculture & Food/Plant [244] Standards Branch/Queensland Fruit Fly may have some merit .

104 Traps attract fruit flies by using pheromones, food scents or visual cues. Pheromone traps contain a sex pheromone that attracts male flies. Depending on the trap type, the flies drown in liquid bait, get caught on a sticky layer or are killed by a contact insecticide. In the latter case, the insecticides commonly used are not permitted under organic standards. However, liquid and sticky pheromone traps suitable for use on organic properties are available commercially (see Section 12.9). Food lure ‘wet’ traps are used by some growers. These traps contain an aromatic liquid food attractive to fruit flies (see recipes below). The acidity of the food attractant may be important - fruit flies seem to prefer a pH around 9 and are less attracted if the lure becomes more acidic[245]. Traps need to allow flies to enter easily while excluding rain as much as possible. Clear plastic bottles with several 1cm diameter holes are one option[246]. The holes need to be far enough above the base to allow the bottle to hold a few cm of liquid lure. For safety and maintenance purposes, the bottles should have their original labels removed and be clearly labelled as ‘fruit fly traps’ with the label stating the trap contents, date of placement and name of the person responsible for the trap. The traps should be kept out of the reach of children. Food lure traps are best placed from 1.5 to 2 metres above the ground in areas where fruit flies rest or feed. This is usually in shady areas within or near the trees being protected. Some traps should also be placed in nearby non-fruiting trees where flies may shelter. One organic citrus grower tackled an The attractiveness of food lures extends over just a few metres, so these isolated fruit fly outbreak by stripping off traps should ideally be no more than five or six metres apart. all fruit and setting bottled baits of water, vegemite and flour. Another uses wet baits An alternative trapping approach uses fruit mimics - coloured spheres of cloudy ammonia, vanilla and water every coated with a sticky gel such as TacGel® or Tanglefoot®. Australian research summer to reduce the fruit fly risk. indicates that for spheres, blue or white appear to be the best colours for Qfly[247] and yellow for Medfly[248]. Also, it seems that larger spheres (eg 10cm diameter) are more effective than smaller ones. Because the visual range of fruit flies is about 6m, coloured traps should be placed within 6m of the trees being protected. A disadvantage of sticky traps is that the gel becomes less sticky with age, especially in dusty conditions, and during overseas trials many flies were observed escaping after landing on this type of trap. In addition, sticky sphere traps appear to be much less effective than liquid food lure traps, even when the spheres are baited with an attractant. Pesticides Bait sprays Acceptable registered inputs for fruit fly Organically acceptable fruit fly bait containing a food attractant and • Spinosad-based bait the insecticide Spinosad is available sprays (derived from soil commercially (see section 12.9). bacteria) The bait is applied as a coarse spot spray, ‘splashed’ onto tree foliage throughout the orchard. The proteins and sugars in the bait attract both male and female Qfly and Medfly. After feeding on the bait, the flies are killed by the insecticide. Bait sprays tend to attract fruit flies from several metres away. They are Sticky-coated coloured spheres have been used to attract and kill fruit flies.

105 usually applied to about 25% of all trees in the orchard, eg every second Lure recipes tree in every second row. Baiting should begin when fruit flies are detected The following recipes have (e.g. in traps) and the fruit is susceptible to egg laying, or at least six weeks been used to make attractant before ripening. Fruit flies are most active in the morning so bait sprays [250] solutions for the wet food lures will be more effective if applied at that time . The sprays need to be mentioned above. reapplied after rain. Bait spray mixtures may damage the rind of citrus so should be applied to foliage only. Qfly wet trap lure recipe[249] • 1 litre water Spinosad-based baits are generally considered more benign than the • 1 tablespoon bakers yeast traditional formulations containing organophosphate insecticides, but they • 1 cup brown sugar are known to kill certain beneficial species such as the red scale parasitoid [251] • 1 tablespoon Vegemite Aphytis melinus and lacewings . Although the spot-splash method of • 1 cup urine application should help to minimise any undesirable impact of these baits, growers should remember that the baits are still insecticidal and treat them Mix ingredients and let stand for with appropriate caution. five days before using. Change every week. Cover sprays Medfly wet trap lure recipe[248] These are insecticide sprays applied to whole trees to kill various stages of (orange-ammonia) fruit fly. Currently there are no organically-acceptable materials registered • 280 ml fresh orange juice for use in Australia as cover sprays against fruit flies. • 25g ammonium carbonate Post-harvest management • 1g potassium sorbate • 600ml water Fruit treatment There are currently no organically-acceptable post-harvest dips registered Mix ingredients then dilute in for use against fruit fly in citrus in Australia. The only acceptable post- the ratio of one part to 10 parts harvest treatment is cold disinfestation, most commonly used for export of water. fruit. Fruit inspection In fruit fly areas, the chance of identifying stung fruit and excluding them from packing may be increased by storing the fruit for a few days after harvest. This time allows the sting to become more obvious and so more easily detected. In some situations, untreated organic citrus from fruit fly infested areas can be shipped within or between states if it is inspected, packed and transported according to strict protocols. The protocols may also require that a baiting and trapping program is in place. Because such protocols can vary from state to state, growers should refer to their state agriculture departments for details.

Fruit-piercing moths Citrus in the NT, QLD and northern NSW are attacked by three species of fruit-piercing moths: Eudocima fullonia, Eudocima materna and Eudocima salaminia. These large moths lay eggs on and near certain native plants in bush and When using bait forest areas, often distant from orchards. Their larval stage (caterpillars) sprays, follow the label feed and develop on the plants then pupate, after which the adult moths instructions fly in search of fruits. Remember, fruit fly bait sprays The moths feed on a wide range of fruit, flying into orchards to feed at and traps should not be used night and returning to refuges outside the orchards where they rest during within the Fruit Fly Exclusion the day. In citrus, early-maturing varieties are most prone to attack. Zone unless authorised by a state agriculture department. Feeding by the moths is typically most prevalent in the outside two rows of

106 trees. Fruit attacked by fruit piercing moths start to ripen prematurely and decay, then drop. Management techniques Monitoring Maturing fruit, especially in outer rows, should be inspected from late summer to early autumn for puncture marks, bruising, rots and drop. Hygiene It is recommended that fallen fruit be collected and disposed of, possibly to remove it as a source of odour that attracts fruit-piercing moths to the orchard. This practice would also help in the management of fruit fly. Biological control Several parasitic wasp and fly species attack fruit-piercing moths but apparently not to the extent that numbers are reduced to non-economic levels. Cultural management The pest status of fruit-piercing moths can be reduced by avoiding the culture of early maturing citrus varieties in tropical areas and by harvesting crops as early as possible. Netting (20mm) to exclude the pest from trees is effective, but likely to be economic only on high value crops. Attract-and-kill baits are a possibility for reducing moth numbers – these have been evaluated but are not yet commercially developed[252]. In some situations, traps consisting of inverted sacks or cones of material baited with over-ripe or fermenting fruit (bananas have been suggested) may assist in reducing moth numbers locally. By providing moths with shelter, these traps may encourage them to stay on site rather than leave the orchard in search of a daytime refuge. The traps would need to be checked daily and cleared of any moths. Host plants for fruit-piercing moths include species of Erythrina (e.g. coral tree) and vines in the Menispermaceae (moonseed) family[253]. Removal of such host plants has been suggested as contributing to control of the pest overseas[254]. Pesticides No organic (or conventional) Acceptable registered pesticides are registered for control inputs for fruit-piercing of fruit-piercing moths. Spray- moth applied pesticides are unlikely to be • None effective anyway, because of the limited contact that the moths would have with sprayed fruit.

Fuller’s rose weevil Fuller’s Rose Weevil (FRW) Asynonychus cervinus is not a serious damaging pest of citrus but is a major quarantine issue in some of Australia’s important export markets. Growers involved in export programs to those markets are required to comply with protocols that include FRW monitoring and management. Current information on export protocols should be sought from local citrus boards.

107 FRW is flightless and reproduces without mating. Adult females emerge from pupae in the soil and climb trees in search of food and egg-laying sites. Emergence seems to occur for most of the year, but is highest during summer, autumn and winter. In Sunraysia, numbers of FRW on citrus trees is lowest during very late spring and early summer. Eggs are laid in crevices, under fruit calyces and in the navel of navel oranges. When the eggs hatch, the larvae drop to the ground and burrow into the soil where they feed on citrus roots until they pupate. In the soil, the larval and pupal stage can take up to one year. Adult FRW feed on a wide range of plants including weeds such as nightshade. Management techniques FRW management is only required when fruit is destined for sensitive export markets. Monitoring Saw-tooth margins on lower citrus leaves are typical of FRW feeding damage. Adults on trees are easily detected by sharply knocking some lower branches over a white tray or groundsheet. Hygiene Because FRW is flightless it naturally disperses slowly. It is distributed mainly by human activity, e.g. carried on equipment, clothing, bins and infested nursery stock. Attention to hygiene will reduce the chance of new orchards being infested. Biological control Wasp parasitoids attack FRW eggs, predators such as birds, assassin bugs and preying mantids eat the adults and parasitic nematodes and fungi attack larvae in the soil. This natural control however does not suppress FRW populations enough to meet export quarantine requirements. Cultural management Because FRW cannot fly, good Acceptable inputs management of groundcover and • Sticky trunk barriers weeds and skirting of trees will (polybutene gel) minimise the pathways for adults to enter the trees. Care needs to be taken to ensure that things like dry grass, tumbleweed and light prunings cannot blow under the trees where they may form bridges between the ground and tree foliage. FRW access to foliage and fruit via tree trunks can be blocked by sticky trunk bands. These bands can be very effective in preventing FRW access to the trees, but are messy to apply and maintain and are unlikely to be cost-effective except on small numbers of trees. Refer to ‘Ants’ above for more information. Any treatment to block FRW access to citrus trees should be applied by very early summer to ensure it is in place before the new generation of adults emerges from the soil. Pesticides Acceptable registered inputs for FRW • None

108 Lightbrown apple moth Description Lightbrown apple moth (Epiphyas postvittana; LBAM) is a native Australian leafroller moth that has a very wide host range including native and introduced weeds, crops and ornamental plants. LBAM can be a pest of citrus in most regions. Up to four generations occur each year, with peaks in egg hatch typically occurring in winter, spring, early- mid summer, and the fourth during late summer/early autumn LBAM larva and feeding damage caused to in warmer districts. LBAM larvae (caterpillars) can be a threat to citrus an orange rind. Photo: DPI because they: • damage flowers and small fruitlets, causing them to drop • chew the rind of small fruits under the calyx, resulting in an unsightly ‘halo’ scar when the fruits grow • hide under the calyx or tunnel into mature fruit where they become a quarantine issue for some export markets.

Management techniques Monitoring LBAM activity can be monitored Acceptable inputs with pheromone or port wine traps • Pheromone or port wine and tree inspections. Monitoring is traps for population used to determine the timing of egg monitoring hatch (for spray timing), the level of parasitism of LBAM and the level of infestation of the crop by caterpillars. Pheromone traps are available commercially and while relatively expensive they have the benefit of being specific to LBAM. They contain a small rubber plug impregnated with a sex pheromone that attracts the male moth. Moths that enter the trap get caught on a sticky card and can be counted easily. Port wine traps can be made from any suitable container about 15cm in diameter and 20cm deep. The container is partly filled with a solution of ten percent port wine. A cap of wire mesh with at least 1cm holes will help exclude birds, preying mantids and other larger animals from the trap. Port wine traps attract a wide range of insects including other small moths, so the user needs to be able to identify LBAM correctly. Ideally the traps should be checked twice a week to allow freshly caught moths (still floating) to be counted easily. Regular inspections of pheromone or port wine traps allow the level of moth activity to be charted. A significant increase in moth numbers over a couple of weeks indicates that a peak in moth flight activity, mating and egg-laying is imminent. This will be followed after a week or two by a peak in egg hatch, which is the best time to apply a biological insecticide if one

109 is needed. Note however, that there is not necessarily a good association between moth numbers and the subsequent population level of LBAM on trees. For this reason, it is preferable that peaks in moth activity be used to time a more detailed inspection of trees rather than the application of sprays. Tree inspections involve searching foliage and fruit for LBAM egg masses and caterpillars. Particular attention should be paid to[255]: • young leaves, flowers and fruits that are webbed together • more mature fruit that are touching other fruit or leaves (look for bore holes) • under the calyx of all fruit. LBAM egg masses are difficult to detect, but any fresh egg masses that are found can be circled using a permanent marker, and the twig tagged with coloured tape. These marked egg masses may then be monitored easily to determine their hatching date and rate of parasitism. Biological control LBAM eggs and larvae are eaten by numerous predators including spiders, lacewing larvae, predatory shield bugs and some earwig species. Trichogramma wasps parasitise LBAM eggs while other parasitic wasps and flies attack the larvae. These beneficial species are endemic in most areas and are often observed in insecticide-free orchards. Some, including Mallada signata (green lacewing) and species of Trichogramma, are commercially reared by Australian insectaries and can be purchased for release into crops. Trichogramma carverae are available in convenient release capsules, which are perforated cards each containing 1000 moth eggs parasitised by the wasp. These cards can be stapled onto leaves. As the wasps mature, they emerge through the perforations and begin their search for LBAM eggs to parasitise. By distributing Trichogramma cards during the peak period of LBAM flight activity, the wasps should be emerging when fresh LBAM eggs are present. Trichogramma’s longevity and egg-laying performance relies in part on the availability of nectar on which the adult wasps feed. This is also likely to apply to the green lacewing, the adult stage of which is a nectar feeder. Growers should consider the practicality of establishing a diverse cover crop that includes flowering plants to provide food and habitat to these beneficial species. Mating disruption

Acceptable registered inputs for LBAM • Sex pheromone for mating disruption

A synthetic version of the LBAM sex pheromone is available in twist- tie dispensers that can be wrapped Several species of predatory bugs attack around small branches. The ties release their contents slowly over the LBAM larvae. Photo: DPI

110 season and flood the orchard with the pheromone. This confuses the male moths who then find it hard to locate a female moth to mate with. This approach has been used successfully to reduce infestation and damage levels in organic citrus in Australia[256]. Because mating disruption has no effect on beneficial species, increased activity of these species may be observed in orchards where mating disruption replaces insecticide sprays[257]. A limitation to mating disruption is that its effectiveness will be reduced if mated female LBAM move into the treated area from nearby untreated areas such as bushland, vineyards or other orchards. Another limitation for very small orchards is that a minimum area of 3-4 hectares needs to be treated as one block. Both limitations may be overcome by extending the treated area beyond the boundary of the organic orchard. Pesticides Biological insecticides based on Acceptable registered inputs Bacillus thuringiensis (B.t.) and for LBAM spinosad can be used to manage • Biological insecticides LBAM. Because B.t. sprays based on the soil selectively kill caterpillars without bacterium Bacillus harming beneficial parasites and thuringiensis predators, they can be used to control LBAM without disrupting • Insecticides containing biological control. Spinosad the compounds spinosyn insecticides, also of microbial origin, A and spinosyn D (known should be used more cautiously as as Spinosad; produced they have a wider target range and by the soil actinomycete also affect bees. B.t. sprays have a Saccharopolyspora very short residual life so spray spinosa) timing is critical if good results are to be achieved. Both insecticides will have greatest effect if applied when most LBAM larvae are very young. At this stage, the caterpillars are very small, exposed and most easily controlled. After a relatively short period, the caterpillars start to produce webbing to make sheltered feeding sites. Once in these sites, they are much harder to control with sprays.

Cultural management On citrus, LBAM prefers young leaves, so limiting the autumn flush may help to limit build-up of the spring generation of this pest. Removal of broadleaf weeds like capeweed and dock is often recommended as part of LBAM management programs, because LBAM can feed and reproduce on those plants. A difficulty with this approach is that LBAM has a very large host range, encompassing hundreds of plant species from trees to clover, but excluding monocotyledons (grasses and grains). Cost- effective removal of all the host plants in and around an orchard would be impractical, if not impossible. A conflicting theory is that diverse cover crops including broadleaf ‘weeds’, legumes and other host plants may draw LBAM away from the trees, especially as citrus is not LBAM’s preferred host. Diverse cover crops may also support natural enemies of LBAM in the orchard.

111 This latter approach would suit organic management because it allows full ground cover to be maintained and potentially aids biological control of pests generally. Unfortunately, not enough is yet known about the ecological interactions between LBAM, ground covers and citrus in different regions, to develop scientifically-based recommendations on groundcover management specifically for LBAM control. At this stage, growers need to be guided by the experience of others along with site-specific observation and experimentation. One compromise approach would be to maintain a grass- dominated mixed ground cover to limit the population potential of LBAM while still providing useful resources to beneficial species in the orchard.

Mealybugs Mealybugs are sap-feeders that produce honeydew which encourages sooty mould growth. Fruit quality is reduced by contamination with honeydew and moulds. The presence of mealybugs under the calyx of fruit and in the navel of navel oranges also poses a quarantine risk for some export markets. Our main mealybug pests on citrus are: • citrus (Planococcus citri) • citrophilous (Pseudococcus calceolariae) • long-tailed (Pseudococcus longispinus) Another two are minor or occasionally important pests in particular regions. These are: • spherical (Nipaecoccus viridis) • rastrococcus (Rastrococcus truncatispinus). Although these pests will infest all citrus varieties, some varieties suffer more than others. Long-tailed, citrophilous and citrus mealybugs affect grapefruit and navel oranges the worst, while rastrococcus mostly infests oranges and mandarins. Typically three to four generations of mealybugs develop each year in the southern states, with closer to six generations developing in Queensland and the Northern Territory. Female mealybugs overwinter on the trees and lay eggs in spring (except longtailed mealybugs which produce live young). The eggs hatch into mobile crawlers in a few days to two weeks. In late spring the crawlers disperse. Citrophilous, long-tailed and citrus mealybug crawlers settle largely on fruits. Spherical mealybug crawlers move to fruits, twigs, shoots and leaves while rastrococcus crawlers settle on leaves. Management techniques Monitoring From late spring onwards, fruit should be inspected for the new generation of mealybug crawlers and young mealybugs (leaves for rastrococcus mealybug). A high level of ant activity on trees may indicate mealybug or soft scale infestations, as ants are attracted to the honeydew produced by these pests. Hygiene Care should be taken to ensure that new orchards are established with plant material free of mealybugs and that the pest is not introduced on equipment, workers’ clothing etc.

112 Biological control Mealybugs have many natural enemies that include parasitic wasps and predatory flies, ladybirds and lacewing larvae. Some biological controls such as the mealybug ladybird Cryptolaemus montrouzieri, green lacewing Mallada signata and leptomastix wasp are available commercially for mealybug control. Biological control of mealybugs is commonly disrupted by the use of broad-spectrum insecticides that are highly toxic to parasites and predators. These include materials like pyrethrum that are permitted The mealybug ladybirdCryptolaemus for use under organic standards. montrouzieri is a very effective predator of mealybug pests on citrus. Photo: DPI Biological control of mealybugs can be severely disrupted by ant activity, so ant control may be warranted where mealybug and ant infestations coexist. Cultural management For organic growers, the best approach to mealybug management is the conservation of their natural enemies, including ant control where necessary. A key factor is the avoidance of broad-spectrum pesticides that will suppress beneficial species. Diverse groundcovers are likely to help encourage the natural enemies of mealybugs by providing resources such as pollen and nectar. Pesticides Acceptable registered Oil sprays are really only effective inputs for mealybugs against very young mealybugs, so if oil is used, it should be applied in • Mineral oils late spring to target the crawlers. • Insecticidal potassium soap

Mites Citrus fruits in Australia are damaged by several species of mites. The main ones causing minor to major problems in different citrus districts across the country are: • brown citrus rust mite (Tegolophus australis) • citrus rust mite (Phyllocoptruta oleivora) • citrus bud mite (Aceria sheldoni) • broad mite (Polyphagotarsonemus latus) • two-spotted mite (Tetranychus urticae) • oriental spider mite (Eutetranychus orientalis) Citrus red mite (Panonychus citri) and citrus flat mite (Brevipalpus lewisi) also occur but are generally more minor pests. The feeding action of these mites results in discoloured surface scarring on fruits, except for bud mite which causes distortion of fruit, leaves and shoots. Most species prefer warm humid conditions and can multiply rapidly with up to 30 generations per year.

113 Management techniques Monitoring For broad mites, fruit should be monitored from set until fruit is fully sized. Inspection of fruit for other pest mites (or shoots for bud mite damage) should be carried out from late spring to late autumn in Queensland and coastal NSW, and mid summer to mid autumn elsewhere. Biological control Pest mites are attacked by predatory mites, flies and bugs, and are often kept under good control unless these natural enemies are knocked out with broad spectrum pesticides. The key predatory mite Euseius victoriensis may be available commercially. Cultural management A key to organic management of mites on citrus is the conservation of natural enemies by avoidance of broad-spectrum pesticides and the provision of alternative food sources such as pollen (see Table 8-1). Effective management of some mites in Queensland citrus orchards was achieved simply by altering the mowing program so that the orchards always contained flowering Rhodes grass – a valuable pollen source for the predatory mites[210]. It is suggested that annual and perennial ryegrass serve the same purpose[10]. Californian experience indicates that dusty conditions worsen certain mite problems. Dust management in orchards therefore seems to be worthwhile and is included in recommendations for insect and mite management[258]. Also, water stressed citrus appear more susceptible to infestation by some pest mites, so good irrigation management should be maintained. Pesticides Any use of permitted organic Acceptable registered pesticides for mite management inputs for mites should be based on monitoring • Mineral oil results, keeping in mind that fruit damage may only become apparent • Sulphur (wettable and some weeks after it was caused and elemental) that the offending mites may no longer be present. • Insecticidal potassium soap The use of pesticides is often a cause of mite infestations in citrus because of their effect on mite predators. Mites seem to be rarely treated by organic citrus producers.

Nematodes Citrus trees worldwide suffer root infestations of parasitic nematodes. The main pests of citrus orchards in Australia are the citrus nematode Tylenchulus semipenetrans and root lesion nematodes – various species of Pratylenchus. Citrus nematodes insert their head into new citrus roots and remain there, feeding and laying eggs. The eggs hatch into larvae that disperse over several metres in search of new roots to infest. Citrus yields can be reduced because of the lower efficiency of nematode-infested roots. Root lesion nematodes enter the roots fully and remain mobile, feeding and laying eggs within the root system. They can also leave the roots and

114 disperse through the soil, laying eggs and searching for more roots to feed upon. Root lesion nematodes can cause reduced tree health and tree decline because damaged roots are prone to infection by root rotting fungi. Management techniques Monitoring Monitoring of soils for nematodes is best done by having soil samples professionally analysed. This can be arranged through the diagnostic services listed in section 12.6. Hygiene Although citrus-infesting nematodes are present in most soils, it is still recommended that new orchards be established with clean planting material to give the trees the best possible start. This relies on good nursery hygiene, as there are no organically acceptable nematicides available to treat nursery stock. Biological control Nematodes that infest citrus are attacked by a range of soil organisms including fungi and predatory nematodes and mites. There are not currently any biological control agents for nematodes available commercially. Cultural management Prevention is the best approach to pest and disease management for the organic grower, so rootstocks should be the first (and main) line of defence against citrus-infesting nematodes. To make the best choice of rootstock, the crop variety, soil type and presence of nematodes and soil diseases need to be considered together with the rootstock characteristics. Refer to Table 6‑2 for a summary of suitable rootstock, variety and soil combinations. The next most important approach is to plant into clean ground. This can be: • virgin ground, or • ground that has been cropped only to non-host plants, or • used ground (such as a previous orchard site) that has been rested for at least two years and kept clean of any nematode host plants, including citrus roots. Because nematodes attack and reduce the efficiency of the root system, good management of water and nutrition will help to counter the effects of nematode infestations. It is generally accepted that higher soil organic matter levels are associated with greater biodiversity of soil organisms, resulting in greater pressure by natural enemies on soil-borne plant pests such as nematodes. For example, a large group of soil-dwelling predatory mites, the ‘mesostigmatid’ mites which are known to feast on nematodes, are much more prevalent in citrus soils with higher soil carbon levels[72; 259; 260]. Populations of predatory mites including mesostigmatids have been increased in citrus soils by the addition of organic mulches and manures[261; 262] so this may be a useful strategy to help manage populations of nematodes and some other soil pests. ‘Biofumigant’ crops – often in the Brassica (cabbage) family – have also been investigated for their effect on nematode pests of citrus. These

115 crops are incorporated into the soil to suppress nematodes and other disease organisms through the release of organic compounds as the plants decompose. In laboratory studies, citrus nematodes have been suppressed significantly by incorporation of brassica residues (canola and cultivated and wild turnip)[263]. However, field trials at citrus orchards in the SA Riverland found that the incorporation of weeds had generally the same effect[264]. Major ‘weeds’ at the sites were capeweed (Arctotheca calendula), wireweed (Polygonum aviculare), burr medic (Medicago polymorpha), salvation jane (Echium spp.), wild oats (Avena fatua), barley grass (Hordeum leporinum) and soursob (Oxalis pes-caprae). The key may have been the amount of plant material incorporated – the fresh weight of weeds and brassica crops was in the order of 150-220t/ha. Pesticides There are currently no organic Acceptable registered pesticides registered for nematode inputs for nematodes control in citrus. • None

Scale insects Scale insects are often the most significant pest of citrus in Australia. Effective management of most scale pests is necessary for the production of high quality fruit, and in some cases is necessary for tree health. Two types of scale affect citrus: • Armoured or hard scales, like the ubiquitous red scale and the citrus snow scale, produce a hard waxy cover that protects their soft body. Red scale injects toxins into the tree as they feed, resulting in dieback of twigs, branches and eventually the whole tree. • Soft scales, like citricola, soft brown, black and pink wax scale, do not produce a hard cover, but some become quite tough and leathery when they mature. Soft scales do produce honeydew, resulting in ‘sooty mould’ as discussed earlier. Some scale species produce several hundred eggs, others a few thousand – this gives them great potential for population increase. Eggs are usually laid under the adult scale where they are well protected from sprays. It is not until the mobile stage (crawlers) leave the shelter of their mother that they are susceptible to sprays. Cottony cushion scale and cottony citrus scale differ from other species by producing a waxy cottony sac under their body, into which the eggs are laid. Management techniques Monitoring The best time to monitor most soft scales for population levels and timing of reproduction is mid-late spring (mid-October to November) and late spring-early summer (February to March). Leaves, twigs and fruit stalks should be inspected, depending on the scale species. For hard scales, fruit should be inspected from fruit set to harvest. The one These eggs under a black scale will soon exception is citrus snow scale for which the trunk and branches should be develop into crawlers that will disperse inspected during November/December. throughout the tree. Photo: JH

116 Active reproduction in scale insects is indicated by the presence of eggs and/or crawlers under mature scales, and crawlers wandering around on leaves and twigs. A magnifying glass is useful as the crawlers and new scales are only about 0.2mm long. Hygiene Scales can be introduced to clean orchards on infested planting material, workers’ clothing, machinery and possibly itinerant birds. Good hygiene, especially with new plantings, will help to reduce the likelihood of infestation with scales and hence the need for ongoing scale management in the organic orchard.

Biological control Scales are attacked by a wide range of parasites and predators including parasitic wasps, and predatory ladybirds, mites, wasps, caterpillars and lacewings. A number of these beneficial species are available commercially in Australia. These natural enemies make a significant contribution to This wasp larva Scutellista( caerula) has control of scales in citrus orchards, where it is common to find over 50% eaten all the eggs laid by the black scale. of scale are parasitised. Photo: DPI Disease also helps to suppress scale populations in warm, wet coastal areas, where high levels of scale mortality can result from fungal infections. Detecting beneficial activity Because of their small size, the activity of parasitoid wasps is more easily detected through the tell-tale signs of parasitism. Some scales become thin shells when they are parasitised, with wasp grubs or pupae visible inside the scale body. Other scales turn black and shiny when parasitised. Another obvious sign of parasitism is dead scales from which adult wasps have emerged after pupating. These scales are punctured by ‘exit holes’ cut by the wasps - a good sign that the natural cycle of parasitism is continuing. Red scales infected by the ‘red-headed fungus’. Samples of scales on leaves and twigs may be collected from the orchard and stored for one to two weeks in a jar with very fine gauze over the opening (facial tissue is suitable). This allows emerged parasites to be seen easily. Predators like adult hoverflies, lacewings and ladybird beetles are often easily observed in the orchard. Closer inspection is needed to find their larvae, usually on shoots and leaves infested with scales, aphids and other soft-bodied pests. It is important that natural enemies of scales and levels of biological control are observed and recorded as part of the orchard monitoring program. In many situations, the need for applied controls will depend upon the degree of biological control in action. Many wasp parasitoids are less than 1mm long, so are difficult to see in action. Photo: DPI

117 Cultural management Cultural management options applicable to scale pests have been detailed above under ‘Ants’ and in section 6. These include minimising the use of pesticides, reducing dust and wind, skirting trees and applying trunk bands where necessary. Dusty conditions in particular appear to reduce the effectiveness of some beneficial species such as small predatory ladybirds and parasitic wasps, including Aphytis and Metaphycus wasps, important parasitoids of citrus scale pests[265]. Over-fertilising with nitrogen should be avoided, as high leaf nitrogen levels have been noted to favour soft scale development and reproduction in Australian citrus orchards[266]. Pesticides Spray materials Two parasitised soft scales: one (top) still Acceptable registered containing the developing black wasp, the inputs for scales Mineral spray oils give very good other showing exit holes from which adult control of most scale insects when wasps have emerged. Photo: DPI • Mineral oil timed and applied well, and they fit well with an IPM approach. • Sulphur & lime sulphur Sulphur and lime sulphur are used against citrus snow scale (white louse scale). All three materials are allowed under Australian organic standards, but because of differences between products, certified growers should confirm the acceptability of specific products with their certifier. Sulphur, and lime sulphur in particular, are toxic to many beneficial species so their use should be minimised. Spray timing Correct spray timing based on field monitoring is essential for The effectiveness of oil sprays varies greatly between different stages of a good control of scale insects. scale’s life cycle. Scales are best targeted soon after a reproduction period while the new generation is very young and exposed. An oil applied at this stage will have greater effect than one applied to mature, well- established scales. As the exact timing of reproduction varies seasonally, calendar-based spraying should be avoided as it can give unpredictable results. Regular monitoring will highlight reproduction periods and allow sprays to be timed accurately. Spray application Monitoring is required to target oil sprays Oil sprays work by suffocating insects, so spray applications must be against the susceptible juvenile stage of scale thorough enough to coat the insects entirely with oil. High spray volumes insects. are usually required to achieve this, with up to 10,000 litres/ha needed to fully wet the canopy in a mature orchard. The high volumes needed for effective use of oil sprays can be achieved with specialised equipment such as oscillating boom sprayers or ‘hydra’ sprayers. Effective delivery of these high volumes is more difficult with the common air-blast sprayers but can be achieved, especially with low ground speeds (less than 1.2km/hour[236]).

118 When growers have trouble managing scales, it is very likely that their spray units, including oscillating booms, are not set up adequately to achieve good spray coverage and distribution. Growers should contact their equipment supplier/manufacturer, consultant or agriculture department for advice on sprayer calibration and set-up. Up-to-date recommendations on application rates of petroleum oil (or any other spray), should always be obtained from the product label. Useful information on the use of oil sprays to manage honeydew-producing insects can also be found in ‘Citrus pests and their natural enemies’[10]. When monitoring to determine the efficiency of an oil spray, the following points should be kept in mind: • it may take several days for the death of young scales to become obvious, and up to two weeks for mature scales • insect mortality (especially of very young insects) can also result from high temperatures • to clearly determine the effect of a spray and distinguish it from temperature or other effects, scale mortality on sprayed trees needs to be compared to the mortality occurring at the same time on unsprayed trees.

Weather conditions Hot weather is an important factor in scale management: • It may coincide with the best timing for oil sprays against scales. Oils can damage water-stressed trees, and water stress is more likely during hot, dry weather. Before applying oil during hot weather, check the label for temperature restrictions. • High temperatures can kill crawlers and very young scales to the extent that a spray may be unnecessary. Where a planned spray is preceded by hot weather (e.g. several days over 39°C), scale survival should be monitored to determine whether the spray is still required. • High temperatures can also kill tiny scale parasitoids. During hot summers, citrus growers need to be particularly vigilant with their monitoring to ensure they detect decreases in parasitism or increases in scale populations at an early stage. This will allow the most appropriate action (parasitoid release or spray application) to be planned in a timely way.

Snails Several species of snails cause problems in Australian citrus orchards. Some, like the common garden snail Helix aspersa (up to 30mm diameter) cause considerable damage by eating the bark off twigs and chewing on the rind of fruit. Others, like the small brown snail Microxeromagna armillata (up to 7mm diameter) create a major quarantine issue for some export markets when they are detected on fruit, cartons, pallets or shipping containers. During autumn and winter, mature snails lay eggs into the top few centimetres of soil. After a few weeks, small snails hatch from the eggs and start feeding. Snails take up to one year to mature and start egg-laying, but under the right conditions the small brown snail can start laying within three months[267]. Snails are most active in moist, mild conditions. During hot, dry periods they tend to climb posts or trunks to escape from the hot ground, then seal their shells and remain inactive until the next wet period. The common garden snailHelix aspersa can cause considerable damage

119 Management techniques Monitoring Snail activity is most easily detected if the orchard is inspected when conditions are most favourable for snails, i.e. damp, especially after overnight rainfall or sprinkler irrigation. Most activity is likely to be detected in Autumn and Spring. In drier conditions, monitoring can be made easier if snails are provided Significant dieback of twigs in this young with hiding places such as cardboard sheets on the ground[268]. This saves orchard was caused by snails feeding on the growers the task of searching for snails in leaf litter and ground cover. bark up to 3m above the ground. Damage was worse on trees that were surrounded by Biological control dense grass growth. Although snails have many natural enemies including birds, rats, mice, lizards, beetles and predatory snails, biological control alone is usually not sufficient to prevent snail populations from building up in some situations. An exception is that well-managed poultry can provide effective snail control. Khaki Campbell and Indian Runner ducks are often referred to as the most efficient snail hunters as they are active breeds. Stocking rates of one to eight ducks per hectare have been suggested as sufficient for snail control[269; 270]. Cultural management Cultural management techniques Other acceptable inputs for snail control mostly involve • Copper trunk bands skirting, cultivation, weed management and barriers to snail movement. Skirting to keep all foliage and fruit off the ground reduces the opportunity for snails to enter the tree canopy. It also makes it easy to monitor and apply treatments under the trees and to apply and maintain trunk bands. Cultivation destroys some snails and their eggs, and exposes others to predation by natural enemies including birds and lizards. Weed control also reduces the snails’ food source and shelter. Simple snail barriers include dry and/or coarse materials such as rock dust, sawdust, ash, diatomaceous earth and lime. These materials can be applied around the base of trees and work by interfering with the snail’s ability to lay down a slime trail as it moves. However, they are labour-intensive to apply and only work when dry, which would effectively limit their use to drip-irrigated orchards. Even then, they would not be very effective in wet weather, when snails are most active. Copper in various forms has a strong repellent effect against snails because of a chemical reaction with the snail’s slime. Copper tape or foil (available commercially) can be wrapped around the trunk of trees as a snail barrier[258; 271]. However, like the other barriers mentioned above, this product also would be labour intensive as well as expensive to apply. Irrigation type and timing may influence snail activity in low-rainfall districts. By wetting a relatively small area, drip irrigation does not create such a favourable environment for snails as sprinkler irrigation, and so

120 would not encourage the build-up of snail populations to the same extent. Overnight sprinkler irrigation has the benefit of reduced losses from evaporation, but growers with snail problems need to remember that keeping the soil wet overnight can be expected to encourage snail activity, compared to morning shifts that allow the soil surface to dry before nightfall. Hygiene Snails shelter and breed in areas like rubbish heaps, piles of prunings and dense weed growth. Removal of these situations from within and around the orchard will help reduce snail populations in the long term. The use of mulch and cover crops will generally improve conditions for snails, so the importance of snails as a pest should be taken into account when these practices are being considered. Pesticides The commercial snail baits Acceptable registered approved for use under organic inputs for snails standards can be applied around the • Snail baits based on iron base of trees or broadcast across the phosphate orchard, depending on the nature of the snail problem. As with other • Snail repellents based pests, if the snail problem occurs in on copper alone or in isolated pockets, only those areas combination with silicate should be baited. Baits will be most salts effective if applied just before a wet period (rainfall or irrigation) which will stimulate snail activity. Snail populations will be reduced most effectively if baiting is carried out in Autumn before the autumn/winter rains begin in earnest. At that time, snail numbers will be at their lowest after summer, and egg-laying will not have begun. Commercial snail repellents can be applied as a spray to the tree trunk. The copper silicate in these repellents deters snails from climbing the trunk. Some copper sprays have the effect of repelling snails from trees and killing some young snails. Where these sprays are used for disease management, snail mortality may be increased by laying baits under the trees after the copper sprays have dried. If the baits themselves are sprayed with copper, they may become repellent to snails.

Spined citrus bug Spined citrus bug (SCB) Biprorulus bibax is a shield bug that feeds on citrus fruit and causes drying and discolouring of fruit segments. SCB prefers lemons and mandarins but will also feed on oranges. Eggs are laid from mid spring to mid autumn with peak laying in late spring and late summer/early autumn[272]. Young SCB (nymphs) can usually be found all year except late winter/early spring. In early autumn, SCB adults migrate from lemon trees to the nearest non-lemon citrus trees where they spend winter. Most (up to 80%) of the population gather on the first row of non-lemons, sometimes in groups of several hundred[273]. The grouping is in response to an aggregation pheromone produced by the males.

121 Management techniques Monitoring Population levels of adults and eggs should be checked over the peak egg-laying period, from late spring to early autumn. Egg parasitism levels should be noted. Biological control Several wasps attack SCB eggs and can parasitise up to 100% of a single egg batch. None of these are commercially available, so biological control relies on conservation of natural enemies, especially by avoiding the use of Hand collection of spined citrus bug adults broad-spectrum pesticides. Numerous predators including ants, spiders, during routine orchard activities has been used by some organic growers to reduce bugs and lacewings also attack different stages of SCB. numbers of the pest. Cultural management Where small numbers of lemons or mandarins exist in orchards of predominantly other citrus types (e.g. oranges, grapefruit), some benefit may be gained from the removal of those lemons and mandarins. This will reduce the orchards’ overall attractiveness and suitability for SCB. Also, fruit should be harvested completely, with none left on the trees as an ongoing food source for SCB. Non-lemon citrus trees, especially those in the first two rows nearest to lemons, should be checked in winter for groups of adult SCB. Collection and disposal of these groups is a key to minimising SCB populations in the following season. The sunny side of trees should also be inspected on cool- cold days for bugs that are sunning themselves. Because SCB uses an aggregation pheromone to form groupings during late autumn, it is possible that caging a few live bugs in selected trees may trigger the grouping process in those trees, thus making the location and destruction of the groups easier. Please let the author know if you have tried this! Pesticides There are currently no organic Acceptable registered pesticides registered for use against inputs for SCB spined citrus bug. • none

Thrips Economic damage can be caused to citrus fruit in Australia by the following thrips: • Kelly’s citrus thrips (KCT) (Pezothrips kellyanus) • scirtothrips (Scirtothrips albomaculatus) • citrus rust thrips (Chaetanaphothrips orchidii) • greenhouse thrips (Heliothrips haemorrhoidalis) The plague thrips (Thrips imaginis) can sometimes be found in citrus flowers in large numbers but does not cause economic damage.

122 Adults of the pest thrips are 1.5-3mm long and lay eggs in soft young fruit or leaf tissue. Immature and adult thrips affect the cosmetic quality of fruit by damaging the surface cells as they feed. The damage often occurs where the thrips have been feeding in protected areas such as under the calyx and where fruit touch other fruit or leaves. Citrus rust thrips and KCT are known to pupate in the soil. Thrips in California citrus are noted to be less of a problem in orchards that receive minimal pesticide treatments[258]. This is due in part to better biological control and less ‘pesticide-induced stimulation’ of thrip reproduction compared to heavily treated orchards. Management techniques Monitoring Fruit inspections for thrips are timed according to the species: from petal fall to calyx closure for scirtothrips and KCT; January to harvest for citrus rust thrips; and October to March for greenhouse thrips. Careful attention should be paid to checking under the calyx and where fruit are touching each other. Biological control Thrips have numerous natural enemies including parasitic wasps, predatory thrips, mites and bugs, and fungal diseases (in humid areas). A study in the South Australian Riverland found lower KCT populations to be linked with higher numbers and species diversity of soil-dwelling predatory mites[259]. Cultural management Ongoing research is investigating the value of soil management to improve biological control of thrips in citrus, as the Riverland study mentioned above found that higher predatory mite numbers appear to be associated with higher soil carbon levels and greater prevalence of grass cover in orchards. Associated research[72] found the following characteristics to be common across orchards with or without significant thrips problems. Orchards with thrip problems tended to have: • inter-rows of bare soil or occupied by annual weeds or a monocultural ground cover • low (520/sq m) average annual populations of predatory soil mites. Orchards without thrip problems tended to have: • dense, diverse inter-row swards of perennial grasses and herbs • high (4,147/sq m) average annual populations of predatory soil mites. The research to date suggests that some key points for thrip management may be: • maintain diverse ground cover including grasses for pollen production • improve soil organic carbon levels through addition or growth of organic matter • add organic mulch to maintain favourable soil conditions and increase organic carbon levels. Along those lines, New Zealand researchers found that 10cm of mulch (about 75% woody material and 20% compost) applied under the canopy area of lemon trees doubled the number of predatory mites in the soil after four months. The mulch significantly reduced numbers of KCT adults

123 emerging from the soil after pupation, but whether this was due to higher levels of predation or to a physical effect of the mulch or both was not determined[262]. Greenhouse thrip populations are known to increase with excess nitrogen levels in some crops, and it is possible that this relationship also occurs in citrus[130]. Avoiding excessive nitrogen levels may therefore assist in thrip management. Pesticides Although oil is suggested for Acceptable registered managing greenhouse and citrus inputs for thrips rust thrips[10], and other organic • Insecticidal potassium insecticides are registered against soap thrips on citrus, organic growers • Pyrethrum extract generally don’t apply treatments for (greenhouse thrips) thrip management. The avoidance of disruptive pesticides is likely to encourage more biological control activity.

Vertebrate pests Birds Description Crows, cockatoos, galahs and corellas are amongst the birds known to damage citrus fruit. Crows appear to eat the actual fruit while cockatoos, galahs and corellas tend to demolish fruit to get to the seeds which they eat. Although these birds occasionally cause significant damage, in most situations they are not major pests of citrus and rarely warrant any control action. Native birds are protected and with very few exceptions their destruction without a special permit is illegal. Management techniques At the locations and times when Acceptable registered birds are a problem, the inputs for birds management objective should be to • None repel or exclude damaging species from the crop during the susceptible period (e.g. towards fruit maturity) rather than attempt the impossible and undesirable task of eradicating them from the orchard. An important objective in bird management is to prevent pest species from damaging fruit in the first place. Once they develop a taste for it, they will be much more persistent in their efforts to re-enter the orchard, regardless of which management techniques are used. To develop an effective bird management program, growers need at least a basic knowledge of local pest species and their habits, much of which is well documented[274; 275]. They also need a systematic approach[276] which involves knowing or determining: • which birds are causing damage (identify the culprits) • when the damage is caused (when is protection required)

124 • where in the orchard the damage is being done (where is protection required) • what sort of damage is being done (helps to identify the culprits) • what else the birds are feeding on (may indicate useful ‘decoy’ foods) • what is the value of the damage (is it worth taking any action?) Regarding the last point, to justify any investment in bird control, the value of bird-related crop loss needs to be quantified and compared with the expected cost of control. Orchard management There are differing views on the value or otherwise of managing bird pests by manipulating their food sources. One approach is to provide birds with alternative food sources to reduce their desire or need to feed on citrus fruit. Where for example, galahs attack ripening mandarins to extract the seed, provision of a seed supply outside the orchard may satisfy their needs and distract them from the crop. In this situation, harvesting the crop as soon as possible, particularly from the tops of the trees, may also help to discourage the offending birds. This may also help to reduce fruit damage from crows, which appear to prefer over-mature fruit. Scare tactics Scare tactics are often used in other high-value crops such as grapes, but are not common and probably not warranted in citrus. For anyone contemplating their use, the following points are worth noting. The many bird-scaring devices currently available mostly rely on loud scary noise (like a gunshot), ‘psychological’ noise (e.g. bird distress signals), annoying noise (interferes with bird communications) or visual deterrence (e.g. scarecrows, kites, balloons, raptor shapes). An important aspect of this approach is to use as many different types of bird scarer as possible, switching between them randomly. The change from one type to the next can be done at unpredictable intervals, or as soon as the birds start to lose their fear of the device currently in use. One disadvantage of scarers is that they may deter all birds from the orchard, including beneficial species such as flycatchers, magpies and ibis that contribute to pest control.

Rabbits & hares Description Rabbits and hares can set back the development of young trees by damaging the leaves or bark. Severe or repeated damage may kill the tree. Larger established trees are not susceptible to this damage because new shoot growth is out of reach and the bark becomes tough and unpalatable.

Management techniques Acceptable registered Fencing is the most costly but also most effective and long-lasting way inputs for rabbits & hares to prevent rabbit and hare damage • None to citrus. It would usually be warranted only where ongoing protection is needed, for example where rabbit populations are high and

125 new plantings are to be established. Light wire netting fences are effective as long as they extend 15cm to 20cm into the ground or have an ‘apron’ over the soil surface to prevent rabbits from burrowing under the fence. Construction details can be found in the Landcare note ‘Rabbit-proof fencing’[277]. Although rabbit fences can be of light construction, the need for heavier duty fencing should be considered where larger animals such as sheep, cattle or kangaroos are present, as they may damage a light fence. Tree guards provide effective rabbit protection to individual new trees if the guards are tall enough. Rabbits will stand to chew leaves poking out of the top of short guards, so a minimum height of 40cm should be used. Up to 50cm may be required if hares are a problem. One organic citrus grower who noted that hares were chewing his low- level sprinklers (presumably to get a drink) now provides the hares with alternative water sources.

126 9. Disease management Disease management in organic citrus is a matter of prevention through good hygiene and cultural practices, and the application of copper sprays if and when they are necessary. Growers should not rely exclusively on copper sprays - in isolation they are unlikely to provide the required level of disease control. The use of copper has been restricted under organic standards in response to concerns regarding its accumulation in agricultural soils and its potential effects on earthworms and other important soil organisms. Currently, a maximum application rate of 8kg/ha/year is set under organic standards[15]. Depending on the formulation used, a single spray of copper fungicide applied to mature trees may deliver 4-6 kg/ha. Research is ongoing to find effective alternatives to copper, but as yet none are commercially available[278]. Copper is considered more benign than the other common ‘organic’ fungicide sulphur in relation to effects on beneficial species in citrus trees, although it should be expected to have some impact. As an example from studies on citrus in Florida, copper sulphate sprays delayed the development of a predatory ladybird, but were still considered unlikely to disrupt IPM systems there[279].

Anthracnose Anthracnose is the name used for any lesion in which the fungus Colletotrichum is growing. Some species of this fungus are very common and can infect fruit, leaves and twigs. Spores from established infections in dead wood are spread by water. In wet conditions, the spores germinate and develop a latent infection in the fruit rind. When the rind is damaged (e.g. by sunburn, frost or hail) or starts degrading because of age, the infection becomes active and symptoms develop.

127 Management techniques Hygiene Removal of dead wood from trees will reduce the source of spores. Ideally this should be done annually. Cultural management Development of the disease on fruit will be minimised if fruit damage is minimised. Trees and fruit should be protected from all forms of damage (e.g. wind, frost, insect) and fruit should be harvested and marketed before it becomes over-mature. Extended storage of fruit should be avoided. Pesticides Acceptable registered Copper sprays applied for other inputs for athracnose diseases may have some marginal effect on anthracnose but can not • None be relied upon. Prevention of the disease through good hygiene and care of the fruit is the only effective control.

Brown rot Brown rot is caused by several species of Phytophthora fungi. These fungi infect fruit during wet conditions associated with rains late in the fruits’ development, e.g. around colour break. Phytophthora species are typically soil-borne and cause root rot and collar rots. Low-hanging leaves and fruit can be infected by spores splashed up from the soil during rainfall or sprinkler irrigation, especially during hail storms that cause rind damage to the fruit. Management techniques Cultural management The risk of infection will be reduced if: • trees are skirted to keep fruit and foliage at least 60cm above the ground • weeds and groundcover are managed to maintain good air flow under the trees • irrigation and drainage are managed to avoid extended periods of wet soil[258; 280]. Pruning to open the tree structure will also assist with more rapid drying of leaves and fruit after moist conditions, and may help to reduce the risk of infection. If soil is covered with mulch, the risk of spores being splashed onto fruit should be reduced. Pesticides Acceptable registered A single application of copper at the time of colour break in the fruit inputs for brown rot should provide adequate protection • Cuprous oxide from brown rot. The spray should be concentrated on the lower portion of the canopy which is at higher risk of soil splash.

128 Brown spot Brown spot of mandarins is caused by the fungus Alternaria alternata which infects shoots, leaves and fruit. Infections can be worse on trees with lush growth. Although shoot infections are unlikely to affect tree development, they are important as they are considered a major source of spores for fruit infections. The production and germination of spores is encouraged by wet humid conditions. Infected leaves drop before they mature, while mature leaves are resistant to infection. Infection of young fruitlets causes them to drop. Fruit may remain susceptible to infection for several months after fruit set. Management techniques Cultural management Excessively lush growth should be avoided by good management of orchard nutrition and irrigation. Pruning should also be managed carefully to avoid having new lush growth present in the orchard for extended periods. Pesticides Copper sprays give some protection Acceptable registered from infection but are not fully inputs for brown spot effective. A full ‘conventional’ spray • Cuprous oxide program involving several sprays from budburst onwards may not be possible because of the organic standards limitation on annual copper applications (8kg/ha/year).

Greasy spot Greasy spot is caused by Mycosphaerella fungi that live in decaying citrus leaves on the orchard floor. To germinate and infect leaves or fruit, the fungal spores require periods of moderate to high temperature and very high humidity, as may occur in hot inland districts during periods of extended wet weather in mid-late summer and autumn. Disease symptoms appear three to six months after infection. Severe leaf infections can cause tree defoliation especially when trees are stressed. Management techniques Cultural management The source of greasy spot fungi may be reduced by the destruction or accelerated decomposition of leaf litter. Cultivation, mulching and application of nitrogen may help to achieve this. Managing factors that may stress trees (e.g. root rot and nutrient deficiencies or toxicities) should reduce the risk of tree defoliation. Pesticides No organically acceptable Acceptable registered fungicides are currently registered inputs for greasy spot specifically for control of greasy • None spot. Growers should seek further advice from their advisor or agricultural supplier.

129 Melanose Melanose is caused by the fungus Diaporthe citri which lives on dead citrus wood (in trees or on the ground). The fungus produces spores that infect young fruits at petal-fall and for the next few months. Where fruit is heavily infected, infected dead wood will usually be found higher in the tree. Extended wet warm periods are required for the spores to germinate and penetrate the rind of fruit, from eight hours at 25°C to 24 hours at 15°C[281]. For this reason, Melanose is more of a problem in tropical and coastal districts. Management techniques Hygiene Spores can be produced by the Diaporthe fungus growing in dead twigs and wood on the soil surface or still attached to the tree. Pruning to remove dead material from trees before flowering and removal of dead wood from the orchard will reduce the sources of inoculum. Cultural management Pruning to open the tree structure will also assist with more rapid drying of leaves and fruit after moist conditions, and may help to reduce the risk of infection. Pesticides Infection of new fruit is prevented Acceptable registered by a copper spray at petal-fall. If inputs for melanose prolonged wet conditions are • Copper sulphate, copper expected a month or so after this hydroxide, cuprous oxide spray, a second application may be needed to maintain a protective cover on the fruit.

Septoria spot Septoria spot, caused by one or more species of Septoria fungi and usually involving Septoria citri, is largely a superficial disease but is a concern if the appearance of the fruit is important, as it is in most fresh markets. Prolonged moist conditions are required for Septoria fungi to produce spores and for the spores to germinate and penetrate the surface of a citrus fruit or leaf. In dry inland districts, these conditions would normally occur with the ‘breaking rains’ of autumn, but infection can also occur during extended wet periods from mid summer onwards[280]. The small spots typical of a Septoria infection can be confused with damage from copper sprays, but close inspection will show fungal growth in the spots[258]. While initially inconspicuous, the spots of a Septoria infection may grow in size and join together during cold storage to become obvious dark blemishes. Frost is not necessary for infection to occur, but the disease is likely to develop more rapidly in frost-damaged fruit. Management techniques Hygiene Septoria fungi also infect leaves, so removal of dead leaves as well as wood from trees and mulching over the leaf litter may help to reduce the inoculum source of Septoria.

130 Cultural management As for Melanose. Also, because frost-damaged fruit is more susceptible to development of the disease, frost management should be undertaken where necessary.

Pesticides In inland (dry) districts, Septoria Acceptable registered spot should be easily prevented by a inputs for septoria spot single copper spray in early Autumn • Cuprous oxide – before the first Autumn rains occur.

131 132 Living shelterbelts are a preferred option as barriers against spray drift and also protect this organic orchard from excessive winds. 10. Managing contamination risks Primary production can be seen as an exercise in risk management, with What the National one objective being to minimise negative impacts on the production Standard says: system from markets, finances, weather, pests, diseases and other factors. In addition, certified organic producers need to manage the risk of Standards: contamination of their land and crops with substances prohibited under The operator must address organic standards. the potential risks from prior operations and consequences Vulnerability & consequences of external contamination with Organic orchards are vulnerable to contamination with prohibited substances not permitted by substances from a contractual and technical perspective. this standard. This may require the implementation of buffer Contractual: Contamination with substances prohibited under the zones/barriers and withdrawal relevant organic standard can result in the suspension of certification of contaminated product/land of affected land and crops and withdrawal of any potentially affected from certification. produce from the marketplace. This scenario is of particular concern for organic producers in intensive horticultural areas. This is because of the Water that is derived from real risk of spray drift involving ‘organically prohibited’ pesticides, and the sources that may introduce implications for the integrity and viability of organic enterprises, many of undesirable contamination to which depend on their organic certification for improved market access. the property must undergo a risk assessment to determine Technical: Heavy contamination with pesticides, e.g. from significant the level of monitoring and spray drift, may disrupt biological pest control by reducing populations of management required. beneficial parasites and predators. This scenario is less likely to occur. The contamination necessary to have such a significant impact would usually require direct spraying of the organic orchard, or a level of spray drift that is unlikely if good agricultural practice is followed. In some situations, the risk of contamination from activities on adjacent land may be minimal. In others, such as intensive horticulture or where government authorities apply treatments to control noxious weeds and pests, there can be a significant risk of chemical contamination. There may also be contamination risks associated with the import of compost, mulch or other materials onto organic orchards.

133 Because of these and other issues (see Table 10-2), most organic producers are likely to benefit from analysis of the contamination risks facing their enterprise and the development of at least a basic plan to minimise and manage those risks. Contamination caused by spray drift of agricultural chemicals is an offence under the Agricultural and Veterinary Chemicals (Control of Use) Act 1992. In Victoria, suspected cases of contamination can be reported to DPI - Chemical Standards via the DPI Call Centre on 136 186. GMO contamination Historically, the risk to organic properties has related to contamination with pesticides. The possibility of contamination with genetically modified organisms (GMOs) poses a new potential risk to organic producers if GMO crops become widespread. It is possible that GMO crops may cross-pollinate closely related green manure crops, cover crops or weeds in organic orchards. For example, mustard biofumigant crops or weeds could become contaminated from GMO canola pollen. If the mustard self-seeds, the subsequent plants could be considered as GMOs. Given the existence of GMO crops in Australia, the only way to prevent contamination of organic land with GMO plants is to avoid the growth of plant species that are related to and may be cross- pollinated by GMO species. Notification of contamination events Organic certifiers require prompt notification of contamination events. Such events are investigated seriously because of their potential impact on market and consumer perceptions of organic agriculture and organic certification. The certifiers should be able to provide advice on the best course of action to address a contamination event. Risk management The risk of contamination of organic orchards needs to be managed to minimise the likelihood and impact of contamination events. The need for growers to address these risks is assessed by certification bodies on a case by case basis, as is the most appropriate treatment for each risk. Orchards with a very high and unmanageable contamination risk may not qualify for organic certification. A useful approach to risk management is ‘Risk management planning’ - a common business practice that is applied to all types of risks and enterprises. This involves a series of steps through which risks to the enterprise are identified, analysed and treated, then monitored to determine the effectiveness of the treatment.

Table 10‑1. Typical risk rankings. Consequences Likelihood Insignificant Minor Moderate Major Catastrophic Almost certain High High Extreme Extreme Extreme Likely Moderate High High Extreme Extreme Moderate Low Moderate High Extreme Extreme Unlikely Low Low Moderate High Extreme Rare Low Low Moderate High High

134 Developing a contamination risk management plan should be easy for most producers, and will provide some peace of mind that potential risks to the organic enterprise have been addressed appropriately. The steps to risk management planning are outlined briefly below. For a more detailed description of how to work through each step, including real-life examples, visit the ‘risk management’ web site listed in the Bibliography. The planning steps Identify all the risks • What are the contamination risks, in terms of the types of contamination and the likely sources ? See Table 10-2 for examples of contamination risks for organic properties.

Analyse each risk • What is the likelihood of the risk occurring? • What would be the consequences if it occurred? The likelihood and consequence of a risk combine to give an overall risk ranking. Suggested rankings for use in typical risk management planning are shown in Table 10‑1. In reality, contamination of an organic orchard or citrus fruit with prohibited substances will usually have major consequences, e.g. suspension of the property from organic certification. Because of this, the ranking of individual risks is not so useful. All contamination risks are automatically ranked highly and so need to be addressed. If a certain risk has no likelihood of occurring in a particular situation, it can still be included in the plan to show that it has at least been considered. Evaluate each risk Once the contamination risks have been listed, they are evaluated as to which ones require special treatment, and which ones can be controlled easily through day-to-day management. A spray drift risk would warrant careful planning and control to avoid potential impacts on the organic enterprise. Treat the risks Risks can be treated in one of the following ways (see Table 10-2 for more examples): Avoid the risk • e.g. avoid unwanted residues of conventional fertilisers by using fertiliser spreaders that are dedicated to organic materials. Control the risk • e.g. supervise harvest to ensure produce from non-certified land is not mixed with certified produce. Transfer the risk to someone else • e.g. obtain insurance against contamination if possible or use only certified organic inputs (transfer the risk to the insurer or input manufacturer respectively).

135 Retain the risk • if it cannot be avoided, controlled or transferred cost-effectively e.g. keep purchasing compost ingredients from non-organic sources, but be prepared to dispose of any (and suffer the cost) if they are found to be unacceptably contaminated.

Monitor and review the treatments The last column of Table 10-2 shows examples of how risks and their treatments can be monitored to determine whether the risk event is in fact occurring and whether the treatment is addressing the risk effectively. If a treatment is not effective, it needs to be reviewed then modified or replaced so that the risk is managed appropriately. Following are some actions commonly used to address contamination risks. Good communication Good communication and relationships with neighbours, councils and government authorities helps to reduce contamination risks arising from their activities. When these individuals and organisations are informed of the basic principles and operation of an organic orchard, and understand the grower’s position and objectives, they are more likely to cooperate to minimise the likelihood of their actions causing unwanted contamination. In addition, this communication helps to raise the profile of organic agriculture within the community. Issues to communicate to neighbours and others, preferably in writing, include: • the organic status of the orchard, the basic nature of organic production, the likely consequences of contamination and a request to cooperate in minimising contamination risks; • potential sources of contamination; and • negotiation of management options and alternative approaches to minimise contamination risks. See the end of this section for an example of written communication for Good communication includes clear neighbours and others. property signage where appropriate. A power authority has provided this fence sign to Contractor management notify its workers of the organic status of a Contractor equipment is one potential source of contamination of organic property. Photo: GL land and crops. For example, fruit bins may contain traces of conventional fruit and fertiliser spreaders or spray equipment may be contaminated

136 with prohibited materials. As is the case with neighbours, organic growers should ensure that contractors are aware of the requirements of organic Because of the standards, and of the risks and consequences of contamination. contamination risk, some certifiers require spray Rather than prescribe specific clean-down procedures, organic standards tend to state the required end result, i.e. no residues of conventional crop equipment to be dedicated or prohibited substances. The onus is on the producer to ensure that a to organic production. suitable clean-down procedure is documented and used where relevant. Generally, a combination of visual inspection and steam or high-pressure water is used on equipment other than sprayers. Input selection Growers minimise the risk of introducing contaminants into their orchard, in seeds, mulch, fertilisers, other nutrients and compost ingredients, pesticides and other spray materials, by selecting inputs and input sources carefully. This may involve: • restricting inputs to products (e.g. fertiliser) or sources (e.g. farms) covered by organic certification; or • obtaining documentation from suppliers to verify the contamination status of inputs. Even apparently desirable inputs like composted municipal waste can introduce contaminants like heavy metals so should be checked carefully[282]. Residue analysis Chemical analysis can be used to test input materials for unwanted residues if there is any doubt about their contamination risk. It can also be used to confirm whether or not a crop has been contaminated through spray drift or some other event. To ensure the relevance and acceptability of test results, advice on the types of analysis and laboratories to use should be obtained from the relevant certifier before any such testing is arranged. Buffer zones/spray drift barriers Buffer zones are identifiable, unsprayed areas of land between organic crops and contamination sources such as conventional cropping areas. These zones are intended to protect organic crops from contamination. Contaminants typically move by way of spray drift, surface water flow or soil movement during wind and water erosion. Buffer zones usually contain: • an area of uncropped and unsprayed land that can include roads and road reserves; and/or • a physical spray drift barrier such as a vegetative barrier or artificial windbreak; and/or • a portion of the crop excluded from organic certification. These buffer options can be used in various combinations to protect organic orchards. The configuration of buffers is determined on a case-by- case basis and depends on the contamination risk and the presence of a physical barrier to spray, dust and water movement. Vegetative barriers Research indicates that the best type of living spray/dust barrier is one that is permeable to airflow, consisting of bushy trees with fine branches

137 and leaves. Sheoaks (Casuarina spp.) and similar trees are ideal. For a basic introduction to vegetative barriers, see the Agnote “Using vegetation as a barrier to reduce spray drift”[283]. Because of the variability in spray equipment, chemical properties, wind speed and topography, no single recipe for buffer zones can be applied to all situations. A good guide however, is the buffer requirement developed by Queensland’s Department of Natural Resources and Mines to minimise the risk of agricultural spray drift to adjacent residential areas[284]. Their minimum requirement is a 40-metre wide buffer, comprised of a 20-metre wide band of trees and other plants bounded on each side by a 10-metre wide strip clear of vegetation (Figure 10‑1). Height of barrier trees should be at least double the height of the spray source - the higher the better. Significant protection from drift extends downwind only three to ten times the buffer height[285]. Management of barrier trees Before establishing vegetative barriers, it is vital for growers to acknowledge that the trees themselves will require management, usually in the form of irrigation, nutrition, hedging and root pruning. This is necessary to ensure that the barriers perform effectively and to minimise any negative impact they may have on orchard productivity through competition with the citrus trees. Crop-area buffer zones In many situations, especially where physical barriers cannot be established, areas of crop may be designated as buffer zones. Because of their role in trapping contaminants, buffer zones themselves are not included in the property’s organic certification. Any fruit or other crop from buffer zones has to be harvested and handled separately from the certified crop and not be marketed as organic. External buffers - shared management of adjacent land One approach to risk management used by some organic viticulturists and applicable to citrus is for the organic grower to share management of a portion of the neighbouring property that is adjacent to the certified land. If that adjacent land is managed with organically-acceptable inputs, the risk of contamination of the certified land is reduced. This effectively shifts the buffer zone from the certified land to the neighbouring property and avoids the need for the organic grower to harvest and sell a portion of their crop as ‘non organic’.

At least twice the height of the neighbour’s sprayer

10m 20m 10m

Figure 10‑1. Design for a ‘best bet’ spray drift buffer, based on Queensland Government planning guidelines to minimise spray drift into residential areas[284].

138 Such ‘external buffers’ can be arranged in several ways such as: • The neighbour agreeing to supply and use only organically-acceptable sprays in the buffer area • The organic grower supplying the neighbour with acceptable sprays to use • The organic grower spraying the buffer area for the neighbour. The adjacent land may also be a road verge, water channel or similar. Here the organic grower could agree to manage weeds, by slashing for example, in exchange for the council, road authority or water board avoiding herbicide use on that land. This approach requires a good level of trust and communication between the organic producer and their neighbours, and good communication and agreement with the relevant certifier.

Legal recourse Because unwanted contamination can have negative economic and other consequences for an organic orchard, organic growers may need to familiarise themselves with the legalities of a contamination event. Three good places to start are the relevant organic certifier, the state agriculture department and the Environmental Defenders Office (see the Bibliography).

139 Table 10‑2. Examples of sources, treatment and monitoring of contamination risks for organic citrus orchards.

Source of contamination risk Possible treatments to minimise the risk Monitoring to determine risks and effectiveness of treatments Production phase Water Irrigation (e.g. Negotiate with water authority re: enforcement of Water analysis contamination of restrictions on chemical use near channels; water supply channel analysis with pesticides) Fertigation (if used Separate supply system, main line flushing before Document fertigation and irrigation on non-organic irrigation or water analysis during irrigation events blocks of a mixed enterprise) Surface runoff Water diversion or buffer zone for absorption of Inspect for surface flow after irrigation from adjacent land runoff on upper borders of organic orchard or rain Soil Windblown dust Shelterbelts Note weather conditions; inspect for dust from adjacent land contamination of crop Old dip or chemical Remove contaminated soil or quarantine the area and Residue tests of soil from suspect sites storage area within maintain permanent ground cover to prevent dust the property Soil carried on Clean machinery before use Inspect machinery before use machinery Air Spray drift from Spray drift barrier/buffer zone; drift avoidance Note weather conditions; observation adjacent property measures negotiated with neighbours and authorities of drift; notification of spray activity by like council or water authority (e.g. grower neighbours and authorities; residue test responsible for roadside weed management; no of crop spraying under certain wind conditions) Dust drift from As above As above fertiliser spreading on adjacent land Pollen from GMO Avoid crops, cover crops and green manures related Ascertain local GMO crop status and crops to locally-grown GMO species (e.g. canola) as choose crops accordingly; monitor and recommended by organic certification bodies. control related weeds Mulch & Pesticide residues Source clean, non-GMO materials Check details of source before purchase; compost on plant material; obtain documentation from supplier; ingredients antibiotics etc. in request residue tests if purchasing in animal manures; bulk GMO plant material Fertilisers Prohibited Confirm acceptability of nutrient products with As above & soil ingredients or certifier amendments heavy metal contamination Seeds Covercrop/green Source non-treated seed or seed with acceptable As above manure seeds treatment treated with prohibited pesticides Genetically- Source non-GMO seed As above modified seed Machinery Pesticide residues Equipment dedicated to organically-acceptable Confirm equipment history in spray equipment materials Fertiliser residues Equipment dedicated to organically-acceptable Confirm equipment use or clean-down in spreading materials; approved cleaning procedure (check with history equipment certifier) Pest/weed Herbicides on Negotiate alternative approaches, e.g. cultivation for Maintain good relations and control by roadsides or water weed control; organic fruit fly baits & locust sprays, communication with the relevant authorities (e.g. channels; Sprays spraying in non-certified border areas of property; government department or authority fruit fly) for fruit fly or alternative termite treatment or sealing of treated locusts; termite poles treatments for timber power poles

140 Table 10‑2. Examples of sources, treatment and monitoring of contamination risks for organic citrus orchards (continued)

Source of contamination risk Possible treatments to minimise the risk Monitoring to determine risks and effectiveness of treatments Harvest & post-harvest phase Soil Windblown dust from Spray drift barrier/shelterbelt; buffer zone; Note weather conditions; inspect for dust adjacent land minimise time between harvest and pick-up; contamination of produce use bin covers Air Spray drift from adjacent Spray drift barrier; buffer zone; drift Note weather conditions; observe land avoidance measures negotiated with drift; notification of spray activity by neighbours/authorities (e.g. council or water neighbours and authorities; residue test authority); no spraying under certain wind of produce conditions; grower responsible for roadside weed management) Dust drift from fertiliser As above; minimise time between harvest As above spreading on adjacent land and pick-up; bin covers Produce Fruit from non-certified Very clear documentation and labelling of Supervise harvesting closely buffer zone bins; harvest of organic/non-organic blocks on different days Machinery Residues from non-organic Dedicated bins; approved clean-down Inspect bins; confirm clean-down and/or produce in fruit bins, trucks procedure; inspection by grower; plastic bin certification status of transporter etc. liners; certified transporters

141 Example letter for neighbours or authorities. Below is an example of the type of communication used to notify neighbours and others of the organic status of a property and to request cooperation in minimising contamination risks.

Notification of organic status.

(Neighbour/Authority name and address) (Date)

Dear ……………..

I manage the citrus orchard located at (location) and am currently certified as an organic producer (or converting it to organic management) with (certifier). This entails managing the property in accordance with (certifier’s) documented organic standards. Because you manage land adjoining my property, I would like to inform you of my objectives and obligations as an organic grower. I strive to produce high quality fruit from a system which emphasises natural nutrient cycling and non-chemical pest, disease and weed management. My orchard relies upon biological pest control, and where necessary, a limited range of non-synthetic inputs to manage specific nutritional, pest, disease and weed issues. The organic standards strictly regulate the types of inputs allowed. The use of synthetic fertilisers, pesticides, herbicides and genetically-modified organisms (GMO’s) is not permitted. Contamination of my orchard or citrus crop with non-permitted substances would result in the loss of organic certification of the crop and land for up to three years. That would translate into an economic cost due to the loss in premium price attracted by the certified organic crop. As a certified organic producer, I need to manage the risk of contamination of my property. I would like to request your help in minimising any risk of accidental contamination of my property with substances not permitted under the organic standards. If you transport, store or use synthetic fertilisers, pesticides or herbicides on land adjoining my property, please take the precautions necessary to prevent accidental contamination of my property through, for example, spills, run-off, spray drift, over-spray or wind-blown dust. Please notify me immediately if you believe such contamination may have occurred. Thank you for your cooperation. Do not hesitate to contact me if you would like more information about my organic orchard or organic certification.

Yours sincerely,

142 Light mowers are a soil-friendly alternative to heavy tractor-mounted slashers. 11. Machinery, energy and wastes Careful choice and use of machinery, and management of waste, allows the What the National Standard organic orchardist to address some issues of environmental impact that are says: considered important under the philosophy of organic agriculture. These include the following. The principal objectives of the certified operator include: Soil compaction The use of lighter machinery, lower tyre pressures and wider tyres to spread • the avoidance of pollution the load can help to reduce the risk of soil compaction. Caterpillar-tracked resulting from agricultural machinery provides the least risk of soil compaction but is expensive and practices and processing less manoeuvrable than standard tractors. Lower tank volumes and broader tyre configurations on spray vats also help to reduce soil compaction. • the co-existence with, and the protection of, the environment Where orchard floor management is based on mowing of cover crops, it may be possible to replace heavy tractor-slasher combinations with much lighter ATV slashers. ATV-mounted fertiliser spreaders and sprayers may also be practical in some situations. An obvious limitation is the small load capacity of ATVs compared to standard tractors, when it comes to towing sprayers or spreaders. Pollution The level and type of air pollution generated by powered machinery depends largely upon the engine condition and the type of fuel used, which is determined by the choice of machinery. Research on the lifecycle emissions of a range of fuels has been evaluated and compiled by the CSIRO[286]. Although the data relates to heavy transport vehicles rather than tractors and other agricultural machinery, it may provide a useful guide for growers interested in alternative fuels. Table 11‑1 provides a very brief summary of these fuel comparisons. Regardless of which fuel type is used, good engine maintenance is important to ensure that emission levels are as low as possible. Energy efficiency Field efficiency as discussed in section 2 is one consideration for growers aiming to minimise their energy usage in the orchard. To help achieve the

143 best energy efficiency with powered machinery, growers should also, to the greatest extent possible: • match the engine to the job, to avoid overloading small engines or wasting the power output of larger engines • maintain the most efficient engine speed, according to the manufacturer’s specifications • maintain engines in good condition. Another aspect of energy consumption is embodied energy - the energy required to produce something like a tractor. Embodied energy use can be reduced by reusing and recycling materials and equipment, and by minimising the purchase of materials and equipment in the first place. An example is the use of a single, versatile tractor to perform all the necessary orchard operations, rather than the use of several single-purpose tractors, which collectively possess much more embodied energy. Waste Although organic standards do not yet address the management of wastes generated during crop production, responsible waste management is Table 11 1. Emission embodied in the principles of organic agriculture, in relation to efficient performance of fuels compared resource use and minimal environmental impact. to standard diesel Fuel type Greenhouse Particulate Nitrous Toxins Some orchard wastes have the gases pollution oxides potential to cause air, soil and water pollution if they are not handled Biodiesel much lower slightly lower higher equal-higher* or disposed of correctly. Local Natural Gas much lower much lower much lower much lower councils and relevant Environment Liquid lower much lower much lower lower Protection Authorities (EPA) Petroleum Gas regulate recycling or disposal of Ethanol lower-much similar similar lower-much many waste types. Organic growers lower* higher* should familiarise themselves with * the range of values reflects variation within the requirements of those bodies. the fuel type, e.g. biodiesel from vegetable oil vs animal fats. The best approach to waste management is RRR - Reduce, Reuse, Recycle, with disposal being a last and least preferred option: • Reduce waste by avoiding the introduction and use of materials that will ultimately become waste and by maintaining equipment to minimise damage, wear and the need for replacement, e.g. – purchase inputs in returnable drums, boxes or bags – use biodegradable or long-life tree guards to reduce the need to dispose of a short-life, non-biodegradable product – install irrigation lines out of the way of slashers and cultivators to minimise damage • Reuse potential waste products wherever practical, including sale to other growers, e.g. – plastic tree guards • Recycle wastes on- or off-site, e.g. – mulch prunings in the orchard – use official recycling schemes for polypipe, machinery oil, tractor batteries, tyres etc. • Dispose of real wastes as a last resort. – Wastes such as batteries and oil that are to be recycled or disposed of should be stored in a way and location that prevents environmental degradation or pollution. Monitoring of the types and amounts of waste generated, recycled, reused, stored or disposed of will allow orchard managers to highlight areas for improvement in their purchasing and waste management.

144 12. Useful resources 12.1. Organic industry regulation Peak Australian industry body Australian Quarantine and Inspection Service: AQIS Organic Federation of Australia (OFA) Organic Program Postal: PO Box 369, BELLINGEN NSW 2454 Postal: GPO Box 858, CANBERRA ACT 2601 Phone: 1300 657435 Phone: 02 6272 3928 Email: [email protected] Email: [email protected] Internet: Internet: 12.3. Organic certifiers AUS-QUAL Limited National Standard for Organic and Bio-dynamic Postal: PO Box 3403 Produce: TINGALPA DC QLD 4173 Internet: Fax: 07 3361 9222 Email: [email protected] AQIS-approved organic certification organisations: Internet: Internet: Australian Certified Organic Postal: PO Box 530 12.2. Organic industry CHERMSIDE QLD 4032 representation Phone: 07 3350 5706 Fax: 07 3350 5996 Peak international industry body Email: [email protected] International Federation of Organic Agriculture Internet: Movements (IFOAM) Postal: Charles-de-Gaulle-Str. 5, 53113 Bio-Dynamic Research Institute Bonn - Germany Postal: PO POWELLTOWN VIC 3797 Phone: +49 228 926 50-10 Phone: 03 5966 7333 Fax: +49 228 926 50-99 Fax: 03 5966 7433 Email: [email protected] Internet:

145 National Association for Sustainable Agriculture 12.5. State fruit fly contacts Australia Use these contacts for fruit fly identification or to Postal: PO Box 768 STIRLING SA 5152 report suspected fruit flies in fruit fly free districts: Phone: 08 8370 8455 Fax: 08 8370 8381 New South Wales Email: [email protected] Your nearest DPI office or 1800 084 881 Internet: Northern Territory Organic Food Chain Your nearest DPIFM office or 08 8999 5511 Postal: PO Box 2390 TOOWOOMBA QLD 4350 Queensland Phone: 07 4637 2600 Department of Primary Industries and Fisheries Fax: 07 4696 7689 Phone: 13 25 23 Email: [email protected] Internet: South Australia The Fruit Fly Hotline Safe Food Production Queensland Phone: 1300 666 010 Postal: PO Box 440 SPRING HILL QLD 4004 Phone: 07 3253 9800 Tasmania Fax: 07 3253 9810 Department of Primary Industries and Water, Email: [email protected] Quarantine Centre Internet: Phone: 03 6233 3352 Email: [email protected] Tasmanian Organic-dynamic Producers Postal: PO Box 13 Victoria CAMPBELL TOWN TAS 7210 Department of Primary Industries, Plant Standards Phone: 03 6381 2004 Phone: 1800 084 881 Fax: 03 6381 2008 Email: [email protected] Email: [email protected] Western Australia 12.4. Citrus industry representation Department of Agriculture and Food, Pest and Disease Information Service Australian Citrus Growers Phone: 1800 084 881 Postal: PO Box 5091, MILDURA VIC 3502 Email: < [email protected]> Phone: 03 5023 6333 Email: [email protected] Internet: services Horticulture Diagnostic Service Murray Valley Citrus Board South Australian Research and Development Institute Postal: PO Box 1384, MILDURA VIC 3502 Postal: GPO Box 397, Adelaide SA 5001 Phone: 03 5051 0500 Phone: 08 8303 9562 Fax: 03 5021 1905 Fax: 08 8303 9303 Email: [email protected] Internet: section.php?sectID=1097&tempID=1>

Riverina Citrus Plant Health & Plant Pathology Unit Postal: PO Box 1432, GRIFFITH NSW 2680 Department of Primary Industries, Water and Phone: 02 6962 4333 Environment Fax: 02 6964 2285 Postal: 13 St. Johns Avenue, New Town TAS 7008 Email: [email protected] Phone: 03 6233 6833 Internet: Fax: 03 6228 5123 Internet:

146 AgWest Plant Laboratories Soil, compost and compost tea microbial analyses Department of Agriculture Western Australia SWEP Analytical Laboratories Postal: 3 Baron-Hay Court, South Perth WA 6151 Postal: Box 583, Noble Park VIC 3174 Phone: 08 9368 3721 Phone: 03 9701 6007 Fax: 08 9474 2658 Fax: 03 9701 5712 Intenert: Internet:

NSW Agriculture Plant Health Diagnostic Service Soil and plant analysis and interpretation using an Orange Agricultural Institute alternative Albrecht-style approach Postal: Forest Rd., Orange NSW 2800 Phone: 02 6391 3980 12.8. Biological control suppliers Fax: 02 6391 3899 Australasian Biological Control Internet: agents in Australia and New Zealand. Internet: Plant Pathology Branch Department of Business, Industry and Resource Biological Services Development Postal: Box 501, Loxton SA 5333 Postal: Box 3000, Darwin NT 0801 Phone: 08 8584 6977 Phone: 08 8999 2311 Fax: 08 8584 5057 Fax: 08 8999 2312 Email: [email protected] Internet: Crop Health Services Department of Primary Industries Parasitic wasps, predatory mites, pheromone traps Postal: Private Bag 15, Ferntree Gully Delivery Bugs for Bugs Centre, Knoxfield VIC 3156 Postal: Bowen Street, Mundubbera Qld 4626 Phone: 03 9210 9356 Phone: 07 4165 4663 Fax: 03 9887 3166 Fax: 07 4165 4626 Internet: 8b394cfd3963e53cca256f7e007ac45a58abfc 55970d6824ca256f810082ac16> Parasitic wasps, predatory ladybirds, lacewings and mites, fruit fly control products 12.7. Soil & plant analysis services Australian Perry Agricultural Laboratory 12.9. Other suppliers Postal: Box 327, Magill S.A. 5072 Entosol (Australia) Pty Ltd Phone: 08 8332 0199 Postal: Box 28, Roselands NSW 2196 Fax: 08 8361 2715 Phone: 02 9758 4552 Email: [email protected] Fax: 02 9758 4882 Internet: Email: [email protected] Internet: Soil analysis and interpretation using the Albrecht approach Pheromone sticky traps for lightbrown apple moth, Soil Foodweb Inc. Qfly and Medfly Postal: 1 Crawford Rd., East Lismore NSW 2480 Organic Crop Protectants Phone: 02 6622 5150 Postal: 42 Halloran St., Lilyfield NSW 2040 Fax: 02 6622 5170 Phone: 02 9810 4566 or 1800 634 204 Email: [email protected] Email: [email protected] Internet: Fax: 02 9810 4674 Internet:

Organically certified crop protection products including horticultural oils and Spinosad fruit fly bait spray

147 Wild May Fruit Fly Attractant & traps Phone: 07 3349 5283 Email: [email protected] Internet:

Wild May Qfly wet traps Nutri-Tech Solutions Phone: 07 5472 9900 Email: [email protected] Internet:

Fly Bye Fruit Fly Lure for Qfly wet traps

12.10 Pesticide registration & use Australian Pesticides and Veterinary Medicines Authority (APVMA) Postal: Box 6182, Kingston ACT 2604 Phone: 02 6210 4700 Internet:

Information on registered pest control products

148 13. References

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Bangladesh Journal of Entomology 11(1/2), p 55-66. 210. Smith D, Papacek D (1991) Studies of the predatory mite Amblyseius victoriensis (Acarina: Phytoseiidae) in citrus 195. Anderson JME, Hales DF (1983) Micraspis lineata orchards in south east Queensland: control of Tegolophus (Thunberg) (Coleoptera: Coccinellidae) - seasonality and australis and Phyllocoptruta oleivora (Acarina: Eriophyidae), food. General and Applied Entomology 15, p 47-52. effect of pesticides, alternative host plants and augmentative release. Experimental & Applied Acarology 12, p 195-217. 196. Omkar (2006) Suitability of different foods for a generalist ladybird, Micraspis discolor (Coleoptera: Coccinellidae). 211. Abdallah AA, et al. (2001) Euseius finlandicus (Acari: International Journal of Tropical Insect Science 26(1), p 35-40. Phytoseiidae) as a potential biocontrol agent against Tetranychus urticae (Acari: Tetranychidae): life history and 197. Irvin NA, et al. (1999) The phenology and pollen feeding of feeding habits on three different types of food. Experimental & three hover fly (Diptera: Syrphidae) species in Canterbury, Applied Acarology 25(10/11), p 833-847. New Zealand. New Zealand Journal of Zoology 26, p 105-115. 212. Allawi T (1991) Biological and ecological studies on 198. Wratten SD, et al. (1995) Phenology and ecology of hoverflies indigenous and introduced phytoseiid mites: 1. Mass rearing (Diptera: Syriphidae) in New Zealand. Environmental and study of the effect of different pollen and other plant entomology 24(3), p 595-600. derivatives on the fecundity and longevity of Euseius scutalis (A.-H.). Dirasat. Series B, Pure and Applied Sciences 18(1), p 57-67.

155 213. Broufas GD, Koveos DS (2000) Effect of different pollens 227. Rasmy AH, Elbanhawy EM (1975) Biology and predatory on development, survivorship and reproduction of Euseius efficiency of two Phytoseiid mites as affected by long-term finlandicus (Acari: Phytoseiidae). Environmental entomology pollen feeding. Entomophaga 20(1), p 93-95. 29(4), p 743-749. 228. Yue B, et al. (1996) Development, survivorship, and 214. El-Halim SMA, et al. (2000) Evaluation of food type, reproduction of Amblyseius lagoensis (Acari: Phytoseiidae) availability of food and competition as factors affecting on selected plant pollens and temperatures. Environmental mass rearing of the predaceous mite Euseius scutalis (Athias- entomology 25(2), p 488-494. Henriot) (Acari-Phytoseiidae). Egyptian Journal of Biological 229. Liguori M, Guidi S, Simoni S (1996) Life history and Pest Control 10(1/2), p 33-38. potential for increase of a laboratory strain of the predaceous 215. Ferla NJ, Moraes GJ (2003) Oviposition of the predators mite Typhlodromus kerkirae Swirski and Ragusa (Acari Agistemus floridanus Gonzalez, Euseius concordis (Chant) and Phytoseiidae) reared on two different kinds of food. Redia Neoseiulus anonymus (Chant & Baker) (Acari) in response the 79(2), p 247-256. different kinds of food. Revista Brasileira de Zoologia 20(1), 230. Ragusa S (1981/1983?) Influence of different kinds of food p 153-155. substances on the developmental time in young stages of the 216. Ferragut F, et al. (1987) Influence of food and temperature predacious mite Typhlodromus exhilaratus Ragusa (Acarina: on development and oviposition of Euseius stipulatus and Phytoseiidae). Redia 64, p 237-243. Typhlodromus phialatus (Acari: Phytoseiidae). Experimental 231. Reuveny H, Palevsky E, Gerson U (1996) Laboratory life and Applied Acarology 3(4), p 317-329. history studies of the predaceous mite Typhlodromus athiasae 217. Momen FM (2001) Biology of Euseius yousefi (Acari: (Acari: Phytoseiidae). Systematic and Applied Acarology 1, p Phytoseiidae) life tables and feeding behaviour on different 45-53. diets. Acta Phytopathologica et Entomologica Hungarica 232. Borthakur M, Handique R, Banerjee B (1997) Effect of 36(3/4), p 411-417. pollen feeding on development and reproduction of Agistemus 218. Nomikou M, et al. (2002) Phytoseiid predators suppress hystrix Gupta (Acarina : Stigmaeidae). Two and a Bud 44(1), populations of Bemisia tabaci on cucumber plants with p 18-20. alternative food. Experimental & Applied Acarology 27(1/2), 233. Elghar A, et al. (1969) Studies on the feeding, reproduction p 57-68. and development of Agistemus exsertus on various pollen 219. Ouyang Y, Grafton-Cardwell EE, Bugg RL (1992) Effects species (Acarina : Stigmaeidae). Zeitschrift fur Angewandte of various pollens on development, survivorship, and Entomologie 63(3), p 282-284. reproduction of Euseius tularensis (Acari: Phytoseiidae). 234. Goldarazena A, et al. (2004) Biology of three species of Environmental entomology 21(6), p 1371-1376. Agistemus (Acari: Stigmaeidae): life table parameters using 220. Shih CIT, et al. (1993) Responses of Amblyseius ovalis (Evans) eggs of Panonychus citri or pollen of Malephora crocea as food. (Acarina: Phytoseiidae) to natural food resources and two Experimental & Applied Acarology 32(4), p 281-291. artificial diets. Experimental & Applied Acarology 17(7), 235. Davies RAH, McLaren IW (1977) Tolerance of Aphytis p 503-519. melinus DeBach (Hymenoptera : Aphelinidae) to 20 221. Shirdel D, et al. (2003) Comparison of rearing methods of orchard chemical treatments in relation to integrated control two predatory mites species Typhlodromus kettanehi Dosse and of red scale, Aonidiella aurantii (Maskell) (Homoptera : Euseius finlandicus (Oudemans) (Acari: Phytoseiidae). Applied Diaspididae). Australian Journal of Experimental Agriculture Entomology and Phytopathology 70(2), p 25-27. and Animal Husbandry 17, p 323-328. 222. Yue B, Childers CC, Fouly AH (1994) A comparison of 236. Altmann J (2008) (Personal communication) Loxton, S.A. selected plant pollens for rearing Euseius mesembrinus (Acari: 237. Flint ML (2006) ‘UC IPM Pest management guidelines: Phytoseiidae). International Journal of Acarology 20(2), Grape.’ (University of California Agriculture and Natural p 103-108. Resources, UC Statewide Integrated Pest Management 223. Abou-Awad BA, et al. (1998) Studies on development, Program: Davis). http://www.ipm.ucdavis.edu/PDF/PMG/ longevity, fecundity and predation of Amblyseius olivi Nasr & pmggrape.pdf Abou-Awad (Acari: Phytoseiidae) on various kinds of prey and 238. Greenberg L, Klotz JH, Rust MK (2006) Liquid borate bait diets. Zeitschrift fur Pflanzenkrankheiten und Pflanzenschutz for control of the Argentine ant, Linepithema humile, in 105(5), p 538-544. organic citrus (HYMENOPTERA: FORMICIDAE). Florida 224. Duso C, Camporese P (1991) Developmental times and Entomologist 89(4), p 469-474. http://www.fcla.edu/FlaEnt/ oviposition rates of predatory mites Typhlodromus pyri and fe89p469.pdf Amblyseius andersoni (Acari: Phytoseiidae) reared on different 239. Greenberg L, Klotz JH, Rust MK (2006) Ants take the bait foods. Experimental & Applied Acarology 13(2), p 117-128. for less toxic solution. UC IPM Online - In the news. [cited 225. Lofego AC, Moraes GJ (2005) Oviposition ratio of the 2007/02]; Available from:http://www.ipm.ucdavis.edu/ predators Amblyseius acalyphus and Amblyseius neochiapensis NEWS/argentineants-news.html (Acari: Phytoseiidae) with various kinds of foods. Arquivos do 240. Ogg B (2000) Ant baits: a least toxic control. University of Instituto Biologico (Sao Paulo) 72(3), p 379-382. Nebraska, Lincoln. Report 267-95. http://lancaster.unl.edu/ 226. Pai KF, Shih CIT (2002) Effects of Bemisia argentifolii pest/resources/antbaits267-95.pdf (Homoptera: Aleyrodidae) and cucumber pollen on 241. Fisher D, Learmonth S (2003) ‘Garden weevil in vineyards. development and fecundity of Amblyseius ovalis (Acari: Farmnote 60/2003.’ (Department of Agriculture, Western Phytoseiidae). Plant Protection Bulletin (Taipei) 44(2), Australia). http://www.agric.wa.gov.au/pls/portal30/docs/ p 101-114. FOLDER/IKMP/PW/INS/PP/HORT/fn060_2003.pdf

156 242. Botha J, Hardie D, Power G (2000) Queensland fruit fly 256. Mo J, et al. (2006) Evaluation of mating disruption for - Exotic threat to Western Australia. Agriculture Western control of lightbrown apple moth (Lepidoptera: Tortricidae) Australia, Report Factsheet 43/2000. http://www.agric. in citrus. Journal of Economic Entomology 99(2), p 421-426. wa.gov.au/content/pw/ins/pp/hort/fs04300.pdf 257. Horsley P (2000) ‘The organic alternative: The complete 243. Dominiak B (2007) Queensland fruit fly. NSW Department guide to organic farming.’ (Kondinin Group). of Primary Industries, Report Primefact 520. http://www. 258. Flint ML (2006) ‘UC IPM Pest Management Guidelines: dpi.nsw.gov.au/__data/assets/pdf_file/0013/110902/ Citrus.’ (IPM Education and Publications, UC Statewide queensland-fruit-fly.pdf IPM Program, University of California.: Davis). http://www. 244. Broumas T, et al. (2002) The efficacy of an improved form of ipm.ucdavis.edu/PDF/PMG/pmgcitrus.pdf the mass-trapping method, for the control of the olive fruit 259. Baker G, et al. (2005) The biological control of Kelly’s citrus fly, Bactrocera oleae (Gmelin) (Dipt., Tephritidae): pilot-scale thrips in Australian citrus orchards by soil predatory mites. feasibility studies. Journal of Applied Entomology 126(5), In ‘15th IFOAM Organic World Conference ‘Shaping p 217-223. Sustainable Systems’’. Adelaide, South Australia. (International 245. Messing R (1999) Managing fruit flies on farms in Hawaii. Federation of Organic Agriculture Movements). Cooperative Extension Service, College of Tropical Agriculture 260. Beaulieu F, Weeks AR (2007) Free-living mesostigmatic mites & Human Resources, University of Hawaii., Report Insect in Australia: their roles in biological control and bioindication. Pests Brief IP-4. http://www.ctahr.hawaii.edu/oc/freepubs/ Australian Journal of Experimental Agriculture 47, p 460-478. pdf/IP-4.pdf 261. El-Banhawy EM, et al. (1997) Interactions of soil predacious 246. Broughton S (2004) Control of Mediterranean fruit fly mites and citrus nematodes (parasitic and saprophytic), in (Medfly) in backyards. Department of Agriculture Western citrus orchard under different regime of fertilizers. Effect on Australia, Report Gardennote 24. http://www.agric.wa.gov. the population densities and citrus yield. Journal of Pest Science au/content/pw/ins/pp/hort/gn2004_024.pdf 70(1), p 20-23. 247. Drew RAI, Prokopy RJ, Romig MC (2003) Attraction of fruit 262. Jamieson LE, Stevens PS (2006) The effect of mulching on flies of the genus Bactrocera to colored mimics of host fruit. adult emergence of Kelly’s citrus thrips (Pezothrips kellyanus). Entomologia Experimentalis et Applicata 107, p 39-45. New Zealand Plant Protection 59, p 42-46. http://www.nzpps. 248. Broughton S, Francis de Lima CP (2002) Field evaluation of org/journal/59/nzpp59_042.php female attractants for monitoring Ceratitis capitata (Diptera: 263. Walker GE (1997) Effects of Brassica residues and other Tephritidae) under a range of climatic conditions and organic amendments on abundance and sex ratio of population levels in Western Australia. Journal of Economic Tylenchulus semipenetrans in soil. Australian Journal of Entomology 95(2), p 507-512. Experimental Agriculture 37, p 693-700. 249. Wyatt T (2007) Fruit fly trap recipe. [cited May]; Available 264. Walker GE, Morey BG (1999) Effect of brassica and weed from:http://www.abc.net.au/queensland/stories/s1854840. manures on abundance of Tylenchulus semipenetrans and htm fungi in citrus orchard soil. Australian Journal of Experimental 250. Hardy S, Campbell G, Jessup A (2007) Managing Agriculture 39, p 65-72. Queensland fruit fly in citrus. NSW Department of Primary 265. Phillips P (1998) The impact of dust deposits on insectary- Industries, Report Primefact 752. http://www.dpi.nsw. reared and released parasites in transitional and organic citrus gov.au/__data/assets/pdf_file/0017/120608/Managing- orchards using perennial vs. annual tilled cover crops. Organic Queensland-fruit-fly-in-citrus.pdf Farming Research Foundation, http://ofrf.org/funded/ 251. Michaud JP (2003) Toxicity of fruit fly baits to beneficial reports/phillips_95-41.pdf insects in citrus. Journal of Insect Science. 3(8). http://www. 266. Beattie GAC, et al. (1990) Effect of nutrients on the insectscience.org/3.8/Michaud_JIS_3_8_2003.pdf growth and phenology of Gascardza destructor (Newstead) 252. Fay HAC, Halfpapp KH (1998) Baits for fruitpiercing moths and Ceroplastes sznensis del guercio (Hemiptera: Coccidae) - the state of play. In ‘Proceedings of the Sixth Workshop for infesting citrus. Journal of the Australian Entomological Society Tropical Agricultural Entomologists’. Darwin. (Department 29, p 199-203. of Primary Industry, Fisheries and Mines). http://www.nt.gov. 267. Lush A (2003) New facts on SBS lifecycle. Snail Mail 10, p au/dpifm/Content/File/p/Tech_Bull/TB288.pdf 2. http://www.sardi.sa.gov.au/pdfserve/ento/market_access/ 253. Herbison-Evans D, Crossley S (2008) Eudocima fullonia. cit_snailmail10.pdf [cited May]; Available from:http://www-staff.it.uts.edu. 268. Lush A (2000) Small brown snail monitoring. South au/~don/larvae/cato/fullon.html Australian Research and Development Institute, Adelaide, 254. French BR (2006) ‘Insect pests of food plants of Papua S.A., http://www.sardi.sa.gov.au/pdfserve/ento/market_ New Guinea: A compendium.’ (Bruce R French: Burnie, access/cit_snailmon2.pdf Tasmania). http://www.foodplantsinternational.com/index. 269. Davis P, Widmer M, Craven T (2004) Control of pest snails php?sec=home&page=resources and slugs. Department of Agriculture, Western Australia, 255. Mo J (2006) Light brown apple moth in citrus. NSW Report Garden Note 12. http://www.agric.wa.gov.au/ Department of Primary Industries, Report Primefact content/pw/ins/pp/gn2004_012.pdf 216. http://www.dpi.nsw.gov.au/__data/assets/ 270. Hely PC, Pasfield G, Gellatley JG (1982) ‘Insect pests of fruit pdf_file/0003/76206/Light-brown-apple-moth-in-citrus- and vegetables in NSW.’ (Department of Agriculture New Primefact-216-final.pdf South Wales).

157 271. Lush A (2002) Copper banding for snail management – a 285. Primary Industries Standing Committee (2002) Spray drift positive result. Snail Mail 7, p 2. http://www.sardi.sa.gov. management: principles strategies and supporting information au/pdfserve/ento/market_access/cit_snailmail7.pdf CSIRO Publishing, Collingwood Victoria, Report PISC (Formerly SCARM) report no. 82. http://www.publish.csiro. 272. Mo J (2006) Spined citrus bug. NSW Department of Primary au/nid/18/pid/3452.htm Industries, Orange, NSW. Report Primefact 217. http:// www.dpi.nsw.gov.au/aboutus/resources/factsheets/primefacts/ 286. Beer T, et al. (2001) Comparison of transport fuels. Final ?a=76733 report to the Australian Greenhouse Office on the stage 2 study of Life-cycle emissions analysis of alternative fuels 273. James DG The development of suppression tactics for for heavy vehicles. CSIRO Aspendale Victoria. Report Biprorulus bibax (Heteroptera: Pentatomidae) as part of an Report (EV45A/2/F3C). http://www.environment.gov.au/ integrated pest management programme in citrus in inland settlements/transport/comparison/index.html south-eastern Australia. Bulletin of entomological research 84(1), p 31-38. 274. Tracey J, et al. (2007) Managing Bird Damage to Fruit and Other Horticultural Crops. Bureau of Rural Sciences, Canberra., http://affashop.gov.au/PdfFiles/managing_bird_ damage_small.pdf 275. Temby I (2003) Problems caused by birds in grape, fruit and nut crops. Department of Sustainability and Environment, Victoria, Report Flora and Fauna Note FF0013. http://www.dpi.vic.gov.au/DPI/ nreninf.nsf/9e58661e880ba9e44a256c640023eb2e/ 2ab65e2c78c93ed6ca256e7200223d87/$FILE/FF0013.pdf 276. Sinclair R (2003) Guidelines for best practice bird management. Department of Water, Land and Biodiversity Conservation, South Australia, 277. Hay P (1999) Rabbit-proof fencing. Department of Primary Industries Victoria, Report Landcare Notes LC0342. 278. Van Zwieten M, Stovold G, Van Zwieten L (2007) Alternatives to copper for disease control in the Australian organic industry. Rural Industries Research and Development Corporation, Report Publication 07/110. http://www.rirdc. gov.au/reports/ORG/07-110.pdf 279. Michaud JP, Grant AK (2003) Sub-lethal effects of a copper sulfate fungicide on development and reproduction in three coccinellid species. Journal of Insect Science. 3(16). http:// www.insectscience.org/3.16/Michaud_and_Grant_JIS_3.16_ 2003.pdf 280. Barkley P (2003) Copper sprays for inland orchards. Australian Citrus News. http://www.australiancitrusgrowers. com/PDFs/export/Copper_Spray_Fact_Sheet.pdf 281. Whiteside JO, Garnset SM, Timmer LW (1988) ‘Compendium of citrus diseases.’ (The American Phytopathological Society: St. Paul, Minnesota). 282. Canet R, Pomares F, Tarazona F (1997) Chemical extractability and availability of heavy metals after seven years application of organic wastes to a citrus soil. Soil Use and Management 13(3), p 117-121. http://www.blackwell- synergy.com/doi/pdf/10.1111/j.1475-2743.1997.tb00569.x 283. Chemical Standards Branch (2002) Using vegetation as a barrier to reduce spray drift Department of Primary Industries, Victoria, Report Agriculture Note AG0860. 284. QLD Natural Resources and Mines (1997) Planning Guidelines: Separating Agricultural and Residential Land Uses. Queensland Department of Natural Resources and Mines, Report Publication DNRQ 97088. http://www.nrw. qld.gov.au/land/planning/pdf/public/plan_guide.pdf

158 14. Bibliography

The publications and Internet sites listed below contain information that may be of interest to growers looking at organic citrus production or organics generally. Most have not been cited directly in this manual.

Organic/sustainable agriculture Agroecology Geno L, Geno B (2001) Polyculture production: Principles, benefits Altieri MA (1989) Agroecology: The science of sustainable agriculture. and risks of multiple cropping land management systems for The ‘bible’ for anyone interested in agroecology. Boulder, Australia. Rural Industries Research and Development Colorado, USA: Westview Press. 433pp. Corporation, Canberra. Publication No 01/34. http://www. Altieri MA (2008) Agroecology in action. [cited 2008 May]; rirdc.gov.au/reports/ORG/01-34sum.html Agroecology web site featuring research and publications. Rural Industries Research & Development Corporation (2008) Available from: http://agroeco.org/index.html Organic Produce Research Program: Research results. [cited 2008 University of California (2008) Agroecology. [cited 2008 May]; May]; Available from: http://www.rirdc.gov.au/programs/org. Web site of the Centre for Agroecology and Sustainable html Food Systems. Research and education activities in the field United States Department of Agriculture (2008) Sustainable of agroecology. Available from: http://www.agroecology.org/ Agriculture Research and Education. [cited 2008 May]; Web index.html and http://casfs.ucsc.edu/ site containing activities, research and publications related to sustainable agriculture. Available from: http://www.sare.org/ Permaculture University of California (2008) Sustainable Agriculture Research Holmgren D (2008) Holmgren Design Services. [cited 2008 May]; and Education Program. [cited 2008 May]; A web site Web site featuring Permaculture information, activities and featuring research and education information on sustainable publications. Available from: http://www.holmgren.com.au/ and organic agriculture, including an extensive cover crop database. Available from: http://www.sarep.ucdavis.edu/ Mollison B (1988) Permaculture: A designers’ manual. A detailed description of wide-ranging aspects of Permaculture design: Organic citrus Tagari Publications. Mollison B, Slay RM (2000) Introduction to Permaculture. Tagari Chubb AG, Somarribas O (2000) Commercial organic citrus Publications. A good introduction. development, in Proceedings 13th International IFOAM Scientific Conference: IFOAM 2000: the world grows organic, Permaculture International Limited. [cited 2008 May]; A T. Alfoldi, W. Lockeretz, and U. Niggli, Editors: Basel, networking web site for international Permaculture Switzerland. p. 261-262. workers and activities. Available from: http://www. permacultureinternational.org/ Chubb AG, Somarribus O (2005) Commercial organic citrus development: post conversion, in First International Conference The Permaculture Research Institute. [cited 2008 May]; Web site on Ecological Citrus Growing: ‘Biocitrics’ IV Valencia Congress featuring Permaculture information, courses and projects. on Ecological Agriculture: Valencia, Spain. Available from: http://permaculture.org.au/ Gilbert A (2007) Citrus: A guide to organic management, Tagari Publications. [cited 2008 May]; Web site featuring propagation, pruning, pest control and harvesting. Flemington, Permaculture information, courses and publications. Available Victoria, Australia: Hyland House Publishing P/L. 167 pp. from: http://www.tagari.com/ Kilcher L (2001) Organic agriculture in Cuba: the revolution goes green. Journal of Agriculture in the Tropics and Subtropics. Bio-Dynamics 102(2): p. 185-189. http://www.fibl.org/archiv/pdf/kilcher- Biodynamic Agriculture Australia. [cited 2008 May]; Web site 2001-cuba.pdf featuring information, workshops and publications on Kilcher L (2005) Organic citrus - challenges in production and trade, biodynamics Available from: http://www.biodynamics.net.au/ in Cuaderno de Resumenes I Conferencia Internacional de Kemp, C (ed) (2004) Biodynamic resource manual. Byodynamic Citricultura Ecologica BIOCIITRICS: en Gandia, Spain. p. Agriculture Australia. Bellingen, NSW. 22-27. Proctor P, Cole G (1997) Grasp the Nettle - making biodynamic McCoy S, Parlevliet G (2001) Organic production systems guidelines: farming and gardening work. Auckland, New Zealand: Beef, wheat, grapes and wines, oranges, carrots. Rural Industries Random House. Research and Development Corporation. RIRDC Publication No 00/189. http://www.rirdc.gov.au/reports/ORG/00- Steiner, R. (2004) Agriculture course: the birth of the biodynamic 189sum.html method. (English translation of Steiner’s 1924 lectures). Morton A, Proebst D (2003) Organic citrus resource guide. Auckland. New Zealand: Soil and Health Association of NZ & Bio Dynamic Association in NZ Inc. 52pp. http://www. biodynamic.org.nz/guides/CITRESG_LR.PDF

159 Soil Land & Water Australia (2008) National Program for Sustainable Irrigation. [cited 2008 May]; A web site that includes Albrecht W (1996) The Albrecht papers, Vol 1: Foundation the publication ‘Irrigation Insights’, a series of technical concepts. Volume one of a four volume series covering much information packages relating to sustainable irrigation. of Albrecht’s work on soil and plant nutrition. Metairies, Irrigation Insights No. 1 reviews and compares soil moisture Louisianna, USA: Acres USA. monitoring techniques in detail. Available from: http://www. Hardy S, Huett D (2005) North Coast citrus nutrition workshop npird.gov.au/index.aspx report. CITTgroups Australia. Fruitgrowers Newsletter, Winter 2005, pp 1-10. http://www.australiancitrusgrowers. Pest, disease & weed management com/PDFs/resources/North_Coast_Nutrition_Workshop_ Altieri MA, Nicholls CI, Fritz MA (2005) Manage insects on your Report_2005.pdf farm - a guide to ecological strategies. Handbook Series Book 7. Kinsey N, Walters C (1995) Hands-on agronomy. A ‘grower- Beltsville MD, USA: Sustainable Agriculture Network. 130. friendly’ discussion of soil and plant nutrition using the http://www.sare.org/publications/insect/insect.pdf approach developed by William Albrecht. Metairie Louisiana, Bugg RL (1992) Habitat manipulation to enhance the effectiveness USA: Acres USA. of aphidophagous hover flies (Diptera: Syrphidae). Sustainable Magdoff F, Vanes H (2000) Building soils for better crops. Vol. Book. Agriculture Volume, 1-8 4, 2nd edition: Sustainable Agriculture Network Handbook Chase CA (2002) Soilborne plant pathogen and pest management Series. http://www.sare.org/publications/bsbc/bsbc.pdf with soil solarization. [cited 2008 May]; Available from: http:// Milton N (2001) Bacteria transform ammonium to nitrate in soil. www.imok.ufl.edu/LIV/groups/cultural/pests/solar.htm Soils are Alive Newsletter. 2(1): p. 1-2. http://www.soilhealth. Geiger G, Biellier H (1993) Weeding with geese. [cited 2008 May]; segs.uwa.edu.au/newsletters Useful description of the use and management of weeder O’Connor G, Strawhorn J, Orr K (1993) Soil management for geese. Available from: http://extension.missouri.edu/xplor/ orchards and vineyards. A useful Australian summary of soil agguides/poultry/g08922.htm assessment and management systems by Department of IOBC (2004) Guidelines for integrated production of citrus - IOBC Primary Industries, Victoria. Technical Guideline III. International Organization for School of Earth and Geographical Sciences (2008) Soil Health. Biological Control of Noxious Animals and Plants, (IOBC). [cited 2008 May]; An informative website that contains a http://www.iobc.ch/IOBC_Citrusguideline_english_ wealth of information on soil biology and soil management. definitive.pdf Available from: http://www.soilhealth.segs.uwa.edu.au/ Lamp C, Collett F (1989) Field guide to weeds in Australia. Soil Foodweb Institute Australia (2008) Soil Foodweb Institute Melbourne, VIC: Inkata Press. Australia. [cited 2008 May]; Website of SFIA. A useful Smith D, Beattie GAC, Broadley R (1997) Citrus pests and their source of information on soil biology and the biology, natural enemies: Integrated Pest Management in Australia. production and use of compost and compost teas. SFIA Brisbane: Queensland Department of Primary Industries and provides a commercial soil, compost and compost tea analysis Horticultural Research and Development Corporation. service. Available from: http://www.soilfoodweb.com.au/ Smith D, et al. (1997) Citrus pests: a field guide.: Queensland Srivastava AK, Singh S, Marathe RA (2002) Organic citrus: soil Department of Primary Industries and Horticultural Research fertility and plant nutrition. Journal of Sustainable Agriculture. and Development Corporation. 19(3): p. 5-29. Van Mele P, van Lenteren JP (2002) Survey of current crop Soil health knowledge bank [cited 2009 July] A useful knowledge management practices in a mixed-ricefield landscape, Mekong base of information on soil health, diagnosis and Delta, Vietnam—potential of habitat manipulation for improved management. control of citrus leafminer and citrus red mite. Agriculture, Travis J, et al. (2003) A practical guide to the application of compost in Ecosystems and Environment. 88 p. 35-48. vineyards – Fall 2003: Penn State University. http://fpath.cas. Wilding J, Barnett A, Amor R (1986) Crop weeds. Melbourne, VIC: psu.edu/frextension.html Inkata Press. Zublena JP, Baird JV, Lilly JP (1991) Soil Facts: Nutrient content of Zehnder G, et al. (2007) Arthropod pest management in organic fertilizer and organic materials. North Carolina Cooperative crops. Annual Review of Entomology. 52: 57-80. Extension Service. AG-439-18. http://www.soil.ncsu.edu/ publications/Soilfacts/AG-439-18/AG-439-18.pdf Contamination Water ACT Insurance Authority (2003) Risk management. [cited 2008 May]; Web site providing a useful description of risk Irrigation Australia. [cited 2008 May]; Web site of the IAA. The management and blank planning forms. Available from: IAA certifies irrigation system designers who demonstrate http://www.treasury.act.gov.au/actia/Risk.htm competence in the field and comply with the industry’s code of ethics. The site includes a list of certified designers. Australian Network of Environmental Defenders Offices Inc (2008) Available from: http://www.irrigation.org.au/ Australian Network of Environmental Defender’s Offices. [cited 2008 May]; Web site of the EDO - a good starting point for legal information about environmental contamination including spray drift. Available from: http://www.edo.org.au/

160 Economics of organic citrus Juliá Igual JF, Server Izquierdo RJ (2000) Economic and financial comparison of organic and conventional citrus-growing systems. Food and Agriculture Organization of the United Nations: Rome, Italy. Klonsky K, Tourte L (1997) Production practices and sample costs for fresh market organic lemons, South Coast 1997. University Of California, Department of Agricultural and Resource Economics: Davis California, USA. Klonsky K, Tourte L (1997) Production practices and sample costs for fresh market organic Valencia oranges, South Coast 1997. University Of California, Department of Agricultural and Resource Economics: Davis California, USA. Liu P (2001) Economic analysis of organic vs. conventional citrus production in Spain., in Conference on supporting the diversification of exports in the Caribbean/Latin American region through the development of organic horticulture. United Nations, Food and Agriculture Organisation.: Trinidad and Tobago. Peris Moll EM, Juliá Igual JF (2006) Production costs of the organic Clementine crop in the region of Valencia (Spain). Spanish Journal of Agricultural Research. 4(1): p. 17-25. http://www. inia.es/gcontrec/pub/PERIS_MOLL-JULIA_IGUAL_ 1141635926828.pdf

161 15. Index

A E agroecology 4 economics 161 Albrecht system 34 ecosystem services 23 allelopathy & weeds 82 environmental management Alternaria 129 water 58 animal manure 31, 49, 54 erosion 19, 24, 25, 30, 37, 58, 61, 137 anthracnose 18, 128 establishing organic orchards 17 ants 92, 95, 96, 104, 112, 122 aphids 93, 94, 97 F apple weevil 98, 99 fruit-piercing moths 106 APVMA 13–15, 148 fruit flies 10 1, 106 AQIS 8, 9, 145 fruit fly exclusion zone 10 3 Fuller’s Rose Weevil 107 B fungicides bermudagrass 154 copper hydroxide 130 bio-dynamic 5, 8, 61, 145, 149 copper sulphate 130 biofumigant crops 134 cuprous oxide 128–131 biological control 23, 67, 85, 97–104, 107–117, 120, 122, 123, 147 G birds 3, 6, 41, 70, 99, 104, 108, 109, 117, 120, 124, 125, 158 geese 5, 83, 84, 160 boric acid baits 96 GMO 134 brown rot 128 greasy spot 129 brown spot 129 green manure crops 25, 37, 134 buffer zones 13 7 guinea fowl 5, 99 gypsum 30, 31, 55, 59 C C/N ratio H compost 46 habitat management 65, 70 N availability 34 herbicides 5, 14–20, 75, 79, 86, 87, 142, 154 chlorine 57 honeydew 91 chickens 5, 6 humus 25, 27, 28, 45, 46 citrus butterflies 9 3, 99 hydrogen peroxide 57 citrus gall wasp 99 citrus leafminer 100, 101 I climate and microclimate 18 IFOAM 1, 8, 145, 149, 157, 159 compost 27, 40, 45 IPM 72, 91, 96, 118, 127, 153, 156, 157 contamination risks 19 irrigation 19 conversion to organic 11 chlorine cleanser 57 copper hydroxide 130 hydrogen peroxide 57 copper sulphate 130 nutrients in water 32 couch grass 75, 85 recycled water 60 cover crops 27, 37 thrip management 123 L cultivation 28 leaching of nutrients 52, 53, 58 cuprous oxide 128–131 lightbrown apple moth 37, 71, 76, 91, 104, 147, 157 Cynodon dactylon 87, 154 lime & soil pH 30 livestock 40 D disease management 25, 58, 66, 70, 115, 121, 127, 153 M diseases 127 machinery 25, 29, 72, 79, 80, 117, 140–144 Alternaria 129 management approaches 3 anthracnose 127 manure, See animal manure 80 brown rot 128 mealybugs. see pests 66, 91, 93, 94, 97, 112, 113 brown spot 129 melanose. See diseases 130 Colletotrichum 127 mites. See pests 23, 37, 69, 70, 82, 85, 92–95, 113–117, 123, Diaporthe 130 147, 155–157 greasy spot 129 mulch 12, 17, 26–37, 45–48, 52, 60, 65, 70, 80–89, 96, melanose 130 121–124, 128, 133, 137, 144, 150, 152, 154 Mycosphaerella 129 mycorrhizae 42–44, 151 phytophthora 128 Mycosphaerella. See diseases 129 Septoria spot 130 dolomite & soil pH 30 N ducks 6 nectar and pollen 92 ducks for snail control 120 nitrogen mineralisation 34, 35

162 nutrient birds 124 budgets 31 rabbits 125 cycling 31, 36 pH. See soil 26–33, 36, 42, 43, 50, 105 inputs 44 phenological cycle 53 trace elements 51 Phytophthora. See diseases 128 uptake 53 piperonyl butoxide 95 nutrition 31 plant analysis 33 and pest management 118 pollen and nectar 92 in irrigation water 32 poultry 40 management plan 54 ducks for snail control 120 nutrient losses 51 manure 40 poultry manure 40 weed management 120 O R on-farm trials 15 rabbits. See pests, vertebrates 125, 126 orchard design 19 research by growers 15 organic agriculture Rhizobium bacteria 31, 39 definition 1 risk management (contamination) 134 principles 1 root distribution 26 organic certification 7 , 9, 11, 13, 21, 51, 75, 96, 133–145 rootstocks 43, 60, 71, 73, 115, 151 organic conversion 21 organic standards 2, 6, 8, 9, 10, 13, 14, 18, 19, 23, 31, 33, 42, S 46, 49, 51, 52, 57–60, 64–70, 82, 87, 91, 95, 105, 113, salinity 29, 30, 52, 152, 153 118, 121, 127, 129, 133, 137, 142, 144 scale insects 91, 117, 118 Septoria spot. See diseases 130, 131 P snails. See pests 6, 84, 119–121, 157 parallel production 21 sodicity. See soil 29, 30 permaculture 3–5, 149, 159 soil pesticides 13, 71 assessment 26 Bacillus thuringiensis 111 biology 27 copper/silica 121 compaction 28, 143 impact on beneficials 9 5 erosion 28 iron phosphate 121 management 27 oil 101, 113, 114, 118 organic matter 26, 123 pheromone 110 pH 29 potassium soap 113, 114, 124 predatory mites 123 pyrethrum 124 salinity 29 Spinosad 101, 105, 111 sodicity 29 sulphur 114, 118 soil analysis 33 pest management soil type 18 effect of dust 6 8, 118 solarisation and weeds 86 effect of wind 6 8 sooty mould 91, 112 habitat management 69 spined citrus bug. See pests 121, 158 IPM 72 nutrition 118 T rootstocks 71 thermal weeding 83 pests thrips. See pests 91, 93, 122–124, 157 ants 92, 95, 96, 104, 112, 122 trace elements 51 aphids 93, 94, 97 Trichogramma 93, 99, 110, 154, 155 apple weevil 98, 99 trunk barrier (sticky) 96 citrus butterflies 9 9 trunk barriers 95, 96, 108 citrus gall wasp 99 copper 120 citrus leafminer 100, 101, 160 trunk barriers (sticky) 108 fruit-piercing moths 106 fruit flies 10 1, 103 V lure recipes 106 vertebrate pests. See pests 124 Fuller’s rose weevil 76, 107 invertbrates 91 W lightbrown apple moth 109 waste management 8, 144 mealybugs 112 weed management 6, 13, 17, 20, 21, 25–28, 63, 69, 75–85, mites 94, 113, 114 120, 140–142, 151, 153, 160 nematode 73, 84, 114–116 Weeds 65, 67, 78, 79, 83–85, 153, 154 scale insects 93, 116 weeds snails 119, 121 & LBAM 111 spined citrus bug 121 site selection 18 thrips 122, 123 vertebrates

163 Organic Citrus – A growers’ manual – by David Madge

RIRDC Pub. No. 09/050

The main barriers to increased adoption of organic practices have typically been the lack of relevant information, or ease of access to that information.

To address that information requirement, RIRDC co- funded the development of this manual for organic citrus production in Australia.

The manual is intended to address the specific information needs of organic citrus producers and growers who are interested in conversion to organic, while also bridging the gap between ‘standard’ and organic methods to ease the transition for growers who seek to change selected practices for environmental and marketing reasons.

This project was funded by RIRDC core funds which are provided by the Australian Government, together with funds from the Department of Primary Industries Victoria and the Murray Valley Citrus Board.

This manual is an addition to RIRDC’s diverse range of over 1800 research publications. It forms part of our Organic Produce R&D program, which aims to facilitate the development of a viable organic industry through increasing adoption of sustainable organic farming systems.

Most of RIRDC’s publications are avaible for viewing, downloading or purchasing online at www.rirdc.gov.au. Purchases can also be made by phoning 1300 634 313.

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