Lettuce Best Practice Integrated Pest Management Farm Services Victoria ii
A Guide to Integrated Pest Management for Lettuce - Insect Pest, Disease, Virus, Nematode and Weed Control Edited by Robert Dimsey, David Carey and Sally-Ann Henderson
Rob Dimsey, Department of Primary Industries, Bairnsdale, Victoria David Carey, Department of Employment, Economic Development and If you would like to receive this information/publication in an Innovation (Agri-Science Queensland), Indooroopilly Research Centre. accessible format (such as large print or audio) please call the Customer Service Centre on 136 186, TTY 1800 122 969, Queensland or email [email protected]. Sally-Ann Henderson, Sustainability Victoria, Mildura, Victoria Published by the Department of Primary Industries, Farm Services Division, December 2010. Purpose of this Guide © The State of Victoria 2010. This guide outlines the key issues that should be considered in relation This publication is copyright. No part may be reproduced by any process to the implementation of Integrated Pest Management (IPM) for lettuce except in accordance with the provisions of the Copyright Act 1968. crops on a whole of crop basis. The guide addresses the key control Authorised by the Department of Primary Industries methods and their rating in an IPM system for the major insect pests, 1 Spring Street, Melbourne 3000. disease, virus, nematode and weed control. ISBN 978-1-74264-593-3 (print) ISBN 978-1-74264-594-0 (online) The guide should be used in conjunction with the posters; “Lettuce Disclaimer crop protection products – A guide to potential impacts on beneficials” This publication may be of assistance to you but the State of Victoria and its employees and the “Best Practice IPM – Overview”. The guide should also be used do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other alongside other publications such as the, “Pests, Beneficials, Diseases consequence which may arise from you relying on any information in this publication. and Disorders in Lettuce – Field Identification Guide”. For more information about DPI go to www.dpi.vic.gov.au or phone the Customer Service Centre on 136 186. Contents
What is IPM (Integrated Pest Management)? 1 Disease How to monitor/scout a crop 3 Anthracnose 28 Botrytis (grey mould) 30 Farm hygiene 5 Downy Mildew 32 Generic IPM Practices 6 Rhizoctonia (bottom rot) 34 Designing the production system 7 Sclerotinia (lettuce drop) 36 Weed control – pest and beneficial habitat 8 Septoria spot 38
Insects Nematode 40 Aphids other species excluding CLA 10 Slugs and Snails 42 Currant lettuce aphid (CLA) 12 Virus Cutworm 14 (Lettuce, Cucumber and Turnip mosaic viruses, Lettuce Heliothis – Corn earworm or Native budworm 16 necrotic yellows, Tomato spotted wilt and Lettuce big vein) 44 Loopers and Cluster Caterpillar 18 Virus minimisation strategy 46 Sucking pests 20 Weed control 48 Western Flower Thrips (WFT) 22 Whiteflies 24 References 54 Wireworm / False Wireworm 26
Lettuce Best Practice iii Farm Services Victoria iv Acknowledgements
Technical Editors Department of Employment, Economic Development and Innovation (Agri-Science Queensland) The project team would like to acknowledge the following for their Denis Persley, Principal Plant Pathologist technical contribution without which the guide could not have been produced. John Duff, Senior Plant Protectionist Dr Lara Senior, Entomologist Department of Primary Industries, Victoria Dr Elizabeth Minchinton, Senior Plant Pathologist Primary Industries, Industry & Investment NSW, Dr Oscar Villalta, Senior Plant Pathologist Dr Sandra McDougall, Industry Leader (Field Vegetables) Dr Ian Porter, Principal Research Scientist, Plant Pathology Len Teserioro, Senior Plant Pathologist Dr Caroline Donald, Senior Plant Pathologist CSIRO Ecosystem Sciences, Brisbane, Queensland Dr Brendan Rodoni, Senior Plant Virologist Dr Cate Paull
South Australian Research & Development Institute (SARDI) Dr Barbara Hall, Senior Research Scientist Photos The project team would also like to acknowledge the Technical Experts Tasmanian Institute of Agricultural Research, (TIAR, UTAS) contribution of photos. Dr Frank Hay Senior Plant Pathologist What is IPM (Integrated Pest Management)?
IPM is an effective combination of chemical, cultural (such as, farm A range of issues must be considered when considering an IPM management practices) and biological methods to keep, weeds, insect production system: pest numbers, disease pressure and other crop production problems low • Identify the main pest and crop issues for the season and time enough to prevent significant economic loss. of production. • If not controlled, do the pests pose a production threat? In an IPM system the term pest includes insects, diseases, viruses, • Identify the actions required to minimise any potential impact nematodes and weeds. – eg. cultural, crop rotation, variety selection. • Know which pests, diseases and beneficials are in your crop - IPM tactics monitor for beneficials and insect pests and regularly scout your Good forward planning and the careful design of a production system crop for any disease incidence. will minimise the risk of pest, weed and other problems and reduce the • Understand the pest pressure to determine if control is need for chemical control. To implement IPM you must understand: necessary. • crop rotation • Identify whether or not there is a threat to production, or the • identification of your best production window potential impact, if the pests are not controlled. • efficient irrigation and drainage systems • Once a decision is made to apply a chemical control, then the • monitoring and pest thresholds choice of product will depend on the pest to be controlled • beneficials and pests versus the impact on beneficials, as well as other production • good farm hygiene issues. • available pest control techniques and products including their • Record yields and damage to assess effectiveness of control IPM rating. methods and review the IPM program.
“Beneficials” can be generalist predators such as spiders or more specialised like hoverflies whose larvae prefer to feed on aphids or they may be parasitoids such as wasps whose eggs may be laid in pest insect larvae or eggs which are then parasitized by the emerging larvae.
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Step by step guide to decision making and the improvement of IPM Practices 1 Understand Key weed, disease, pests, natural enemies and crop life cycles. 5 2 Results /Assessment Prevention and planning Harvest %, crop records, yields e.g. site selection, variety, crop and damage. Review crop rotation, farm hygiene, market monitoring records if production Best Practice needs, optimum production time break is needed. Continual Improvement and cultural practices Model 4 3 Control decision Observation What action is most appropriate Crop monitoring, weeds disease, for the crop stage and the pests and beneficials, prediction observed pest pressure. models, traps (pheromone and e.g. Biological, soft option sticky traps). products, targeted chemicals or Use all available mechanical control. monitoring tools.
Note: “Soft” pesticides are those chemicals or biological agents that provide effective control of a pest (insect, disease, nematode or weed) with reduced impact on beneficial species. How to monitor/scout a crop
The purpose of scouting/monitoring is to gain a good understanding during peak production periods check traps more frequently. For of insect pest, disease, weed and beneficial insect activity in your crop. example, if a large flight of moths occurs, then crops should be scouted Effective monitoring includes assessing the numbers of insect pests at least twice a week during the next few weeks. and beneficials in a crop as well as the incidence of diseases and weeds. Recording this information and any control actions taken, will Forecasting models help you to better understand your crop management practices over There are certain forecasting programs which are being developed time. A record of this information, allows you to refer to previous to assist in determining the likelihood of infection, once suitable monitoring results and determine the impact and effectiveness of your conditions are met. control decisions. For example, there are a disease forecast models for Downy mildew Crop monitoring disease, DownCast and BremCast predictive models are being evaluated. A number of tools are available for monitoring pests and beneficials, In the future such models can be useful to either trigger a control including: action or indicate the importance of increased scouting and vigilance • Pheromone traps (which attract males of specific pests such as the over the next few days of a crop’s production cycle. Heliothis). • Yellow sticky traps (which attract a broad spectrum of flying insects Crop scouting – blue sticky traps can be used for some thrips and leafminers). Scouting each area or block regularly, twice a week in warmer weather and once a week in winter, provides a picture of the beneficials, insect These tools will help provide information about the range and activity pest, disease, virus and weed levels in a crop. When scouting, cover of pests and beneficials present in your crop. Data from traps should a thorough cross section of a block, as pest problems can occur in be recorded to identify flights, or periods of peak activity. This data patches at one end or side of a block or at the crop edge. There may will assist in determining the frequency of crop scouting. Obviously, also be “hot” spots in different areas of a block.
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The number of plants to check will depend on a crop’s growth stage and Scouting pattern the total area of the planting. Growth stages can be grouped as one if Scouting involves moving through paddocks looking for pests and plantings are close together e.g., group together plantings at two and beneficials, measuring populations and then using this information to three weeks of age. make pest control decisions. The information helps growers know if a pest control treatment is needed, where it is needed and what options For some pests there are specific recommendations for thresholds are available and practical. When scouting a crop, it is important to and the number of plants to check. When scouting use a zigzag or M get a random sample using various patterns such as a zigzag, M or V pattern over a paddock (see diagram for examples) and generally check pattern as indicated below. at least three plants at a minimum of 10 random sites. There is more detailed information on scouting patterns in a range of publications on specific pests.
As you walk through a crop, you are likely to spread infection particularly if the leaves are wet. Always scout clean paddocks before moving into blocks that are known to be infected and remember to practice good hygiene between crops.
Diagram 1: A sample of some scouting patterns. Farm hygiene
Good farm hygiene is one of the simplest, but most often overlooked, If you have your own nursery it should be isolated from crops or host methods of managing weeds and pests. Good hygiene reduces the risk plants and free of weeds. Use soil-less potting mix, place trays up on of bringing new infections onto the farm, and reduces the spread of benches, maintain good air movement, control infection and manage existing problems. pests.
• Production areas of the farm should always have restricted access. Internal farm hygiene means avoiding the movement of soil, insects • Vehicles and equipment must be cleaned before entering and people and plant material around the farm. These can all spread infection should also be made aware of the risk they pose as potential carrier to clean areas. Spread usually occurs via dirty equipment, machinery, of pests. vehicles and soil on workers’ boots. Work from young to old plantings • Ensure clothing and footwear is clean. rather than the other way around or if there is a known infection site • Ensure all people entering the farm report to a central point away be sure to do that last, whether it is when you are crop scouting, from the production zone, such as a shed or office. This includes moving a tractor or hand weeding. suppliers, contractors, workers and visitors. Keeping headlands clear of weeds is good hygiene practice. It ensures • Be sure to explain how to comply with your hygiene practices. there is no place for insects and diseases to carry-over between crops. • Seedling trays, boxes, crates and other equipment are also a source Clean headlands also reduce weed seed sources contaminating a crop. of potential infection and should be inspected before entry. • Only accept clean transplants and ensure they are obtained from Removal of crop residues and self-sown plants also forms an important a quality nursery who complies with your pest management part of an efficient IPM hygiene routine as they too can act as habitat strategies. Avoid using transplants that are infected or for insect pests and diseases when the main crop has been removed. contaminated with pests. Note: Weeds may provide habitat for beneficial insects. Therefore you may need to consider the weeds that are present and the likelihood that they may cause production problems and / or be a host for pests.
Lettuce Best Practice 5 Farm Services Victoria 6 Generic IPM Practices
There are standard IPM practices that apply to all cropping issues, Isolate nursery: A nursery should be isolated from crops or host plants pests and weed control. and free of weeds.
A production break: Avoids a weed or pest problem being carried over Nursery hygiene: Use sterile soil-less potting mix, place trays up from one season to the next. on benches, maintain good air movement, control infection and manage pests. Land preparation: Good land preparation assists with plant establishment, weed control and reduces the risk of water logging and Use only clean healthy transplants: Avoid using transplants that are plant losses from soil borne diseases. infected or contaminated with pests.
Selecting the right crop and site: Select a crop and production site Post harvest: Destroy old crop residues and weeds promptly by that maximises your chance of success. ploughing in or spraying off, as these may be a reservoir for pests and diseases. Keeping records: Records help build a picture of weed and pest risks on different parts of the farm. Subsequent plantings: These should be up-wind (of prevailing winds), where possible, to minimise the chance of contamination. If feasible, Crop rotation: To break the life cycle of diseases and pests and control put a physical barrier between crops (such as a trap crop, alternate germinating weeds. crop or wind break) so pest and disease problems don’t migrate from one planting to the next. Green manure crops: Improve soil structure, water and nutrient holding capacity, as well as provide a break from intensive production. Green manure crops have the potential to suppress weed growth and may also act as a harbour for beneficials, but do not let green manure crops set seed as these can be another weed source. Designing the production system
Good farm management practices are vital in the control of pest Production window problems, such as: The key is to select a production period and site that will minimise • Healthy well-grown plants are less likely to suffer disease and weeds, insect pest and disease problems. For instance: pest problems than plants stressed from poor irrigation and / or • caterpillar problems are usually worse in warmer weather nutrition. • foliar diseases and bacterial head rots are usually worse in warm, • Overhead irrigation may, if timed incorrectly, increase the length of wet weather leaf wetness times and hence encourage disease. • club root also prefers warm conditions. • Furrow irrigation if timed incorrectly can delay follow-up sprays, which are needed to manage a pest outbreak, and encourage soil First select the right variety for a growing season and a particular borne diseases. market and then consider options for resistant varieties for insect pest • Drip irrigation saves water, allows quick crop re-entry after watering and disease issues. and doesn’t wet plant leaves. • Bedding-up improves drainage and air circulation around plants – both help reduce disease problems. • Good spray coverage is essential but more difficult to achieve in high-density plantings. • Poor air circulation in a crop increases disease risk. Ensure there is good airflow around plants so the leaves dry quickly and the humidity doesn’t build up.
Lettuce Best Practice 7 Farm Services Victoria 8 Weed control – pest and beneficial habitat
Weeds are a significant host of both pests and diseases in lettuce There can be a conflict in maintaining beneficial habitat and managing crops, some specific weeds are known hosts of viruses and the vectors the risk of disease presence and pest activity: of those viruses. • Monitor weeds and remove and control those which are critical hosts of pests. Weed control and control of pests such as aphids and thrips in weeds • Encourage beneficial habitat in areas adjacent to production areas on headlands may be a necessary management practice for virus but not within a crop. control. • Consider the use of native vegetation or the use of grass species in Weeds that are good hosts of viruses may also be good hosts for a headlands as alternative options for beneficial habitat. (For further range of pests which transmit the viruses. However, they may also be information refer to the “Re-Vegetation by Design” project.) a good host for beneficials such as parasitoids and predators of these pests.
It is important to control weeds that are virus hosts as well as pest hosts and green manure crops have the potential to significantly suppress weed growth.
It is vital that a beneficial habitat is encouraged in order to support an IPM program. The following tables indicate the key control methods, their IPM rating and management for the major insect pests, disease, nematode, virus and weed control issues. Each of the pest areas is colour coded.
Insects Disease Nematode
Snails and slugs Virus Weed control
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Aphids other species excluding CLA Including Brown thistle aphid (Uroleucon sonchi), Green sowthistle aphid (Hyperomyzus lactucae), Potato aphid (Macrosiphum euphorbiae), Green peach aphid (Myzus persicae), Foxglove aphid (Aulacorthum solani) Effective IPM Rating √ √ √ √ √ Critical Comments: There are very good aphid specific and soft options available – seedling drenches will prevent IPM from being effective. Infestation Risk Factors Cultural Practices Chemical Control Conflicts / Issues Increases the Reduces the Monitoring Beneficial Other Pest Lifecycle Chemical IPM Issues risk risk Control Insects Thresholds Mild weather. Cool /cold A control Predators: Plant with Aphids Range of Range of Seedling drench weather. threshold is ∙∙ Spiders spacing that reproduce targeted IPM suitable application Spring and 1-2 aphids ∙∙ Assassin bugs to allows for asexually most protectant and targeted may have autumn Good and no sign of ∙∙ Ladybird maximum air of the time so and systemic chemicals impact on the plantings. population of beneficials on beetles movement and most are clones chemicals available with survival of beneficials. Presence of most seedlings ∙∙ Lacewings spray coverage. of each other. available. good IPM some beneficial sow thistles Control weeds checked. ∙∙ Damsel bugs Rating. insects. (Nabids) Neighbouring Once Aphid specific in or near within crop and When scouting crops can be a insecticide and soft Choose Broad spectrum crop greatly around crop – a ∙∙ Hoverfly check for aphid larvae source of the resistance options are soft option products reduce increases range of weeds “mummies” aphid and the develops it available and products where beneficial chances of sow are hosts for to indicate Consider virus. can progress effective. additional insect numbers. thistle aphid both aphids parasitoid providing quickly. control is feeding on and viruses activity. habitat for Select a necessary Because aphids lettuce and (such as mosaic beneficial production and rotate are vectors transmitting and necrotic Monitor using insects. period that will correctly. for a range of necrotic yellows). yellow sticky minimise pest viruses control yellows virus. traps to check pressure. is important. pest levels. Infestation Risk Factors Cultural Practices Chemical Control Conflicts / Issues Increases the Reduces the Monitoring Beneficial Other Pest Lifecycle Chemical IPM Issues risk risk Control Insects Thresholds Parasitoids: Aphids are Evaluate other ∙∙ Aphid wasps generally not a pests present (Aphidiidae) problem during and beneficials cooler weather when deciding Naturally once the crop on control. occurring fungi is established can also infect CLA can still be and control active in cool aphid colonies. weather.
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Currant lettuce aphid (CLA) Nasonovia ribis-nigri
Effective IPM Rating √ √ √ √ √ Critical Comments: Use of broad spectrum chemicals can result in increased pest levels – seedling drenches will prevent IPM from being effective. Infestation Risk Factors Cultural Practices Chemical Control Conflicts / Issues Increases the Reduces the Monitoring Beneficial Other Pest Lifecycle Chemical IPM Issues risk risk Control Insects Thresholds Previous or Colder weather Physical Predators Plant with A seedling A seedling Year-round Broad spectrum nearby pest and frosts inspection and ∙∙ Spiders spacing drench has drench based production seedling drench presence. may reduce scouting is ∙∙ Assassin bugs that allows been widely on one increases will prevent occurrence. the preferred ∙∙ Ladybird maximum spray used as a insecticide the risk of IPM from being Spring and method of beetles coverage. preventative group is insecticide effective. autumn Resistant monitoring. ∙∙ Lacewings strategy for high risk for resistance. plantings. varieties are ∙∙ Damsel bugs Assess this pest to developing Other broad effective. Yellow sticky (Nabids) likelihood of date. resistance. Seedling drench spectrum Hearting traps can also pest pressure application sprays can lettuce more Cos type ∙∙ Hoverfly be used to larvae prior to This is the A soil / may have a knock out susceptible as lettuce. monitor for planting. main aphid seedling secondary beneficials. aphids colonise presence for Consider that will infest drench, impact on the within the Presence Select a Seedlings that of aphid beneficials, providing the internal followed by a survival and heart. however, less habitat for production heart of rotation with a reproduction of have been predators: period that will treated in a Use of non- ∙∙ Lacewings effective for beneficials lettuce. foliar spray is some beneficial CLA presence. adjacent to minimise pest now possible insects. nursery may resistant ∙∙ Damsel flies pressure. adversely affect varieties. ∙∙ Ladybird cropping areas. where aphids Destructive are observed. beneficials for beetles monitoring is a few weeks. ∙∙ Hoverfly required once larvae hearts formed. Infestation Risk Factors Cultural Practices Chemical Control Conflicts / Issues Increases the Reduces the Monitoring Beneficial Other Pest Lifecycle Chemical IPM Issues risk risk Control Insects Thresholds In spring, Cause for Naturally CLA can still be IPM techniques A new highly Systemic Use of broad these may be concern is 3-4 occurring problem during using natural systemic foliar soft option spectrum moving about aphids and beneficial fungi cooler weather predators spray from a aphicides are insecticides in relatively no sign of can infect periods. as a control new chemical available. can result in high numbers. beneficials on aphids. measure has group, will poorer control most checked Control weeds been effective allow a more Consider of the pest. seedlings. particularly in a number effective using targeted hosts such as of production insecticide aphicides for Monitor Hawksbeard sites. resistance open headed beneficials that and Wild management lettuce if are present, as lettuce. strategy. necessary. a small number can quickly Effective clear up CLA systemic outbreaks. soft option aphicides are Keep records available. of harvest volume, % damage as well as numbers of pests to fine tune thresholds.
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Cutworm Agrotis spp.
Effective IPM Rating √ √ √ √ √ Critical Comments: Control is best achieved with cultural and management practices, consistent with IPM practices but if chemical control is required it will not fit into an IPM system. Infestation Risk Factors Cultural Practices Chemical Control Conflicts / Issues Increases the Reduces the Monitoring Beneficial Other Pest Lifecycle Chemical IPM Issues risk risk Control Insects Thresholds A nearby crop At least one Monitor newly Parasitoids Good soil Soil-borne Chemical Good spray Chemical or a weedy season free of transplanted ∙∙Trichogramma preparation can insect. control still coverage is control can area could be a lettuce crops. seedlings for significantly Control as soon relies on broad essential as be difficult to source of insect any sign of Predators reduce as crop damage spectrum this is a soil achieve as the pests. Normally not root or stem ∙∙ Spiders numbers. detected. products. dwelling pest. pest hides in an issue in an damage. ∙∙ Assassin bugs These are not the soil. Warm weather. established ∙∙ Ladybird Select a Ground suited to IPM. High water cropping Act quickly to beetles production dwelling volumes give Management is Consider area, though control pest if ∙∙ Lacewings period that will pest so high best results. best achieved ground history. occasional it is observed. ∙∙ Predatory minimise pest water volume with cultural Increased risk infestations beetles pressure. application Late afternoon practices. if coming out can occur. Active at ∙∙ Common essential control of pasture night or early brown earwig Control (minimum applications rotation. If the paddock evening. important 600L/Ha). tend to give is a known during seedling best results. Uncultivated or problem area, to hearting. weedy ground. cultivate and have a fallow period before planting a crop. Infestation Risk Factors Cultural Practices Chemical Control Conflicts / Issues Increases the Reduces the Monitoring Beneficial Other Pest Lifecycle Chemical IPM Issues risk risk Control Insects Thresholds Control weed Look for Early detection Bt could be growth. damage and and action used late in curled up required if the the day if eggs caterpillars in pest is present. are observed the first few on plants centimetres of Plough in crop but needs to soil near plant residue. be applied stems. when eggs are hatching.
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Heliothis – Corn earworm or Native budworm Helicoverpa armigera or Helicoverpa punctigera
Effective IPM Rating √ √ √ √ √ Critical Comments: Monitor crops and use pheromone traps to assess moth activity – need to consider if corn earworm or native budworm are present as corn earworm has resistance to some chemical groups and broad spectrum chemicals will not provide good control. Infestation Risk Factors Cultural Practices Chemical Control Conflicts / Issues Increases the Reduces the Monitoring Beneficial Other Pest Lifecycle Chemical IPM Issues risk risk Control Insects Thresholds A nearby crop At least one 1 small Parasitoids Ensure good Control easiest There are Year-round If seedling or a weedy season free of caterpillar ∙∙Microplitis spp spray coverage. at small registered production and drenches area could be a host crops. in 20 plants. ∙∙Netelia spp caterpillar insecticides poor product have been source of insect 1 egg in 10 ∙∙Cotesia spp Good soil stage. and options rotation used these pests. Healthy plants. ∙∙Hyposoter spp preparation can with good IPM increases may affect beneficial ∙∙Trichogramma significantly Avoid spraying Rating. the risk of beneficial Warm weather insect Extreme heat spp reduce at large insecticide control of this increases the population. will cause ∙∙Telenomus spp overwintering caterpillar Biological resistance. pest. rate and speed young hatched ∙∙Tachinid fly pupae numbers. stage. options to of hatching Ploughing in caterpillars to assist control Be aware NPV only and the crops after quickly move Predators Select a Active at dusk include: of what affects development of harvest – into the lettuce ∙∙ Spiders production and into the ∙∙Nuclear chemicals have Heliothis caterpillars. destroys pupae head. ∙∙ Assassin bugs period that will night. Polyhedrosis been applied to and no other preventing minimise pest Pest pressure ∙∙ Ladybird Caterpillars Virus (NPV) the seedlings caterpillar increases over emergence. Moths will lay beetles pressure. ∙∙Bacillus in the nursery species. eggs in more pupate in the summer. ∙∙ Lacewings Control soil. thuringiensis and how this sheltered areas ∙∙ Predatory (Bt) might affect Resistance to of the plant. important broad spectrum wasps during beneficial ∙∙ Predatory activity in the chemicals has establishment been recorded in shield bugs to hearting. field. ∙∙ Birds corn earworm. Infestation Risk Factors Cultural Practices Chemical Control Conflicts / Issues Increases the Reduces the Monitoring Beneficial Other Pest Lifecycle Chemical IPM Issues risk risk Control Insects Thresholds Vegetable, Use pheromone Consider Plough in crop Bt only works Hearting to Good spray Bt stops corn, traps for both providing residue to a well against harvest is the coverage is caterpillar sunflower, H. armigera and habitat for depth of 10 cm smaller critical period more difficult feeding but cotton or H. punctigera beneficial immediately caterpillars to monitor and to achieve on takes several lucerne crops insects. after harvest to so apply it control. some varieties days to kill. nearby or in Important to destroy pupae. early in pest that tend to rotation. commence lifecycle. Hatching heart early. Apply Bt’s regular caterpillars will or NPV after Historical monitoring NPV (virus quickly tunnel Bt and NPV irrigation not presence of the soon after product) a very into heads do not affect before. Avoid pest. transplanting effective soft and are then beneficials. the heat of the and prior to option in low uncontrollable. day. hearting. to moderate There are new pest pressure If spraying is chemistries Look for situations. required close much less eggs, small to harvest disruptive to larvae, feeding use a product beneficials damage, and with a short than older beneficials withholding broad spectrum period. chemistry.
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Loopers and Cluster Caterpillar Chysodeixis spp. and Spodoptera litura
Effective IPM Rating √ √ √ √ √ Critical Comments: Monitor crops and controls used for Heliothis will generally provide control of these species. Infestation Risk Factors Cultural Practices Chemical Control Conflicts / Issues Increases the Reduces the Monitoring Beneficial Other Pest Lifecycle Chemical IPM Issues risk risk Control Insects Thresholds A nearby crop Good farm and 1 to 2 egg Parasitoids Plant with Control easiest There are Be aware of Apply Bt’s after or a weedy crop hygiene. masses in 10 ∙∙Microplitis spp spacing that at small registered what chemicals irrigation not area could be a plants (wait for ∙∙Netelia spp allows for caterpillar systemic and have been before. Avoid source of insect Plough in all eggs to hatch ∙∙Cotesia spp maximum spray stage. protectant applied to the the heat of the pests. weed and crop before taking ∙∙Trichogramma coverage. insecticides seedlings in day. residue quickly. action). spp Avoid spraying and options the nursery. Warm weather. ∙∙Telenomus spp Rotate crops to at large with good IPM If seedling ∙∙ Prefer outer ∙∙Tachinid fly minimise pest caterpillar Rating. Bt stops drenches Spring though and wrapper pressure. stage. caterpillar have been to autumn. leaves. Predators Bacillus feeding but used these ∙∙ Spiders Select a Hearting to thuringiensis takes several may affect Early season Monitor production harvest is the plantings are ∙∙ Assassin bugs (Bt) only days to kill. beneficial crops prior to ∙∙ Ladybird period that will critical period works well control of this most at risk in hearting. minimise pest to monitor and Bt does QLD and WA. beetles against small pest. ∙∙ Lacewings pressure. control. caterpillars; not affect ∙∙ Predatory apply it beneficials. wasps early in crop ∙∙ Predatory lifecycle. shield bugs ∙∙ Birds Infestation Risk Factors Cultural Practices Chemical Control Conflicts / Issues Increases the Reduces the Monitoring Beneficial Other Pest Lifecycle Chemical IPM Issues risk risk Control Insects Thresholds Consider Encourage If spraying is There are new providing beneficial required close chemistries habitat for insects and to harvest that are less beneficial provide insect use product disruptive insects, lizards, refuge areas with a short than older birds, frogs. where possible. withholding broad spectrum period. chemistry. Plough in crop residue. Beneficials can impact on pest populations if crop managed correctly.
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Sucking pests Thrips spp. (several species Onion thrips - Thrips tabaci, Tomato thrips - Frankliniella schultzei) and Rutherglen bug (RGB)- Nysius vinitor
Effective IPM Rating √ √ √ √ √ Critical Comments: Some chemicals are not suited to IPM. Choose chemicals carefully as not all species are controlled by soft products – RGB has no IPM suitable chemistry.. Infestation Risk Factors Cultural Practices Chemical Control Conflicts / Issues Increases the Reduces the Monitoring Beneficial Other Pest Lifecycle Chemical IPM Issues risk risk Control Insects Thresholds Warm, dry Cool /cold Yellow or blue Predators Ensure good Pests mainly Rotate Year-round Onion thrips, weather. weather. sticky traps ∙∙ Spiders spray coverage. migrate into chemical production and tomato thrips can be used to ∙∙ Ladybird the crop on groups to avoid poor product can spread Some varieties Control weeds. monitor thrips. beetle Select a prevailing resistance. rotation viruses such as may be more production Consider the ∙∙ Lacewing winds. increases Tomato Spotted attractive. Monitor for larvae period that will For thrips range the risk of Wilt Virus use of trap flights of minimise pest RGB moves to of chemicals A nearby crop crops for RGB. ∙∙ Predatory insecticide (TSWV). See migrating thrips pressure. irrigated crops available and resistance. entry for WFT or a weedy Rutherglen in very hot dry some are a area could be a bug. Some predatory Consider using conditions. good IPM Soft option Beneficial source of thrips mites and screening mesh Rating. Choose products habitat may or Rutherglen Not all thrips beetles in nursery area RGB does soft option available for also host bug. are pest if pest pressure not breed in products where some thrips but thrips. species. RGB is not is high. lettuce. available. not all species known to have are controlled. Pest species any predators Control Lifecycle is often move in lettuce. important quicker in warm on prevailing from seedling weather. winds in production to summer. harvest. Infestation Risk Factors Cultural Practices Chemical Control Conflicts / Issues Increases the Reduces the Monitoring Beneficial Other Pest Lifecycle Chemical IPM Issues risk risk Control Insects Thresholds Consider Immediately For RGB control Remove any RGB are very providing after harvest, there are only virus infected mobile and habitat for spray-off broad spectrum plants / weeds if chemical beneficial or cultivate chemicals to minimise control is insects. and plough available at re-infection applied they in lettuce to this time potential. can quickly destroy crop though some re-infest a residue. of the newer crop. systemic products may Need to be effective. consider if control is actually required.
Lettuce Best Practice 21 Farm Services Victoria 22
Western Flower Thrips (WFT) Frankliniella occidentalis
Effective IPM Rating √ √ √ √ √ Critical Comments: Seedling drenches can affect beneficials and affect IPM. WFT is a critical vector for Tomato spotted wilt virus (TSWV) and where both are found, an integrated management approach is critical. Infestation Risk Factors Cultural Practices Chemical Control Conflicts / Issues Increases the Reduces the Monitoring Beneficial Other Pest Lifecycle Chemical IPM Issues risk risk Control Insects Thresholds Consider Nursery fully Yellow or blue Important to Soil predatory Lifecycle is The seedling Difficult to Can spread weather insect-screened sticky traps ensure good mites quicker in warm drench for identify with Tomato Spotted conditions and (thrips-proof should be used spray coverage. weather. Currant lettuce the naked eye Wilt Virus surrounding screen) and in covered ∙∙ Predatory aphid will from other (TSWV). crops and weed double doors systems and Immediately thrips The full control some thrips. hosts. prevent insect can be useful after harvest ∙∙ Some lifecycle can be thrips species Insecticidal entry. in field crops. spray off or predatory completed in but not WFT. WFT has seedling Warm weather cultivate beetles as little as 10 shown itself drenches increases thrips Ensure Visually and plough days at 20°C. Use a range to be quick can affect numbers. transplants are monitor crop in lettuce to Beneficial of chemical to develop beneficial free of pest. for thrips destroy crop predators are Sprays only groups to insecticide insects and numbers residue. commercially effective reduce the resistance. affect an IPM Control weeds and virus available. against certain chance of program. in crop and symptoms. lifecycle resistance Spinosad headlands. stages. Good resistant Virus-infected hygiene in and populations plants should around the exist in some be physically crop minimises production removed and pest pressure. areas. destroyed. Infestation Risk Factors Cultural Practices Chemical Control Conflicts / Issues Increases the Reduces the Monitoring Beneficial Other Pest Lifecycle Chemical IPM Issues risk risk Control Insects Thresholds Surrounding Hygiene and Some new weeds and end of crop chemistry is other crops clean-up claimed to (e.g. tomato critical. be soft on or flowering beneficials. crops) can be a source of WFT and may increase the risk of a resident resistant population. Previous plant virus infection of crops may make control more critical.
Lettuce Best Practice 23 Farm Services Victoria 24
Whiteflies Silverleaf whitefly (SLW)Bemisia tabaci (Biotype b), Glasshouse white- flyTrialeurodes vaporariorum
Effective IPM Rating √ √ √ √ √ Critical Comments: No chemicals registered for control in lettuce but some used for other sucking insects will provide control. Pest does not breed on Lettuce. The two Whitefly species look very similar. Infestation Risk Factors Cultural Practices Chemical Control Conflicts / Issues Increases the Reduces the Monitoring Beneficial Other Pest Lifecycle Chemical IPM Issues risk risk Control Insects Thresholds Hot conditions. Screen nursery Monitor for Wasp Ensure good Whitefly does There are Year-round Crops that host if necessary. presence / parasitoids spray coverage. not breed on limited production and SLW and are Nearby Whitefly damage. Yellow attack SLW Select a lettuce. chemicals poor product sprayed with host crops or Double doors sticky traps nymphs. production available for rotation broad spectrum weeds. on protected can be used Generalist period that will Adult Whiteflies control. increases insecticides cropping to monitor for Predators. minimise pest damage lettuce the risk of will see a large Poor hygiene structures. crops. in protected Whitefly. pressure. insecticide population Consider resistance. increase. cropping Keep crop area 2-4 flies per providing Harvesting structures. weed free. leaf present on habitat for of nearby Some chemical Effective 40% of plants. beneficials. susceptible controls for monitoring. crops may other sucking Correctly cause Whitefly insects on identify the to migrate to lettuce will Whitefly to your crop. provide control. determine its potential Spray oils and impact. even wetters knock-down adults. Infestation Risk Factors Cultural Practices Chemical Control Conflicts / Issues Increases the Reduces the Monitoring Beneficial Other Pest Lifecycle Chemical IPM Issues risk risk Control Insects Thresholds Generally an issue to seedlings and transplants.
Lettuce Best Practice 25 Farm Services Victoria 26
Wireworm / False Wireworm Elateridae spp. / Tenebrionidae spp.
Effective IPM Rating √ √ √ √ √ Critical Comments: Control is best achieved with cultural and management practices, consistent with IPM practices but if chemical control is required it will not fit into an IPM system. Infestation Risk Factors Cultural Practices Chemical Control Conflicts / Issues Increases the Reduces the Monitoring Beneficial Other Pest Lifecycle Chemical IPM Issues risk risk Control Insects Thresholds Stubble If following Monitor newly ∙∙ Common Good soil Soil-borne There are High water Chemical retention and pasture or transplanted brown earwig preparation can insect. registered volumes give control can trash from known problem crop. ∙∙ Predatory significantly insecticides but best results. be difficult to previous crop. paddock ground reduce Control as soon not a suited to achieve as the A nearby crop cultivate Look for beetles numbers. as crop damage IPM. Late afternoon pest hides in or a weedy several weeks damaged detected. control the soil. area could be a before planting (missing, Consider Control Chemical applications wilted) providing important Ground control still tend to give Management source of insect and consider dwelling pests. period of fallow seedlings and habitat for during seedling relies on broad best results. best achieved then search for beneficials. establishment. pest so high spectrum with cultural Consider Normally not damaged roots water volume products, which practices. ground history. an issue in an and wireworms application are not are not Increased risk established in soil around essential a good IPM if coming out crop. the plant. (600L/Ha). Rating. of pasture or lucerne Act quickly to rotation. control pest if it is observed. Lettuce Best Practice 27 Farm Services Victoria 28
Anthracnose Microdochium panattonianum
Effective IPM Rating √ √ √ √ √ Critical Comments: Monitor crops to assess need for control and when conditions suitable for infection start protection program. Rotation Crop Cultural Practices Chemical Control Conflicts / Issues Resistant High Risk Disease Nutrition Irrigation Hygiene Other Chemical IPM Issues varieties Break available If weather Can survive in Well-grown Minimise Only use Rotate with A preventative Infection Monitor conditions soil for up to plants with periods of disease-free non-host monitoring may occur at closely when favour 4 years. a balanced extended leaf seedlings. crops to and fungicidal the seedling conditions disease, nutrition wetness. reduce levels program production favour Anthracnose Host specific program of pathogen (protectants) phase – do infection. can cause to lettuce so are less Use irrigation in soil. should be not over high crop rotate with susceptible. systems that employed to irrigate. losses. any other reduce or Symptoms prevent early non-host eliminate leaf can appear infection if Cool and wet crop. wetting. 4-8 days after a problem is conditions infection. expected. in autumns Avoid Water splash or especially planting in can spread Spray off or Systemic late winter to paddocks the disease. plough in chemicals are early spring. with a harvested available but Optimum history of the areas as soon prevention temperature disease. as possible is more after harvest. 18 ˚C - 20˚C. Control host effective. weeds. Rotation Crop Cultural Practices Chemical Control Conflicts / Issues Resistant High Risk Disease Nutrition Irrigation Hygiene Other Chemical IPM Issues varieties Break available Fields with a Irrigation Need to history of the timing consider disease. important as chemical 2-4 hours of resistance Cos (Romaine) leaf wetness management. lettuce can result cultivars in infection Protective appear to when the copper be more fungus is fungicides susceptible present. will assist than iceberg in disease or loose leaf prevention. varieties. Host weeds such as wild lettuce or prickly lettuce.
Lettuce Best Practice 29 Farm Services Victoria 30
Botrytis (grey mould) Botrytis cinerea
Effective IPM Rating √ √ √ √ √ Critical Comments: Monitor crops to assess need for control.
Rotation Crop Cultural Practices Chemical Control Conflicts / Issues Resistant High Risk Disease Nutrition Irrigation Hygiene Other Chemical IPM Issues varieties Break available Damaged Rotate out Seedlings Free moisture Minimize Spread on air Many Need to seedlings. of lettuce as can be killed is needed for plant debris. currents so fungicides balance the fungus if infected infection. plant up-wind are effective risk and Romaine can survive early in the Avoid of old crops. against gray management types are very in debris, season. Avoid long planting mould. The for tipburn susceptible. soil and on periods of oversize Botrytis does fungicides are with risk alternative Excess leaf wetness. transplants as not infect preventative of Botrytis. High nitrogen leaf damage healthy green humidity. hosts. Irrigate early and should Night (N) and low may occur tissue unless be applied watering is Botrytis has Calcium (Ca) in the day so during the an injury or Botrytis foliage can before preferred is usually a wide host favour the planting dead area is infection for tipburn range. disease. dry as quickly process and present. a minor as possible. occurs. control. problem. this may lead Often to infection. Always Copper In hot follows other Avoid spray-off or overhead applications weather leaf diseases into Botrytis plough in will have wetness a crop. irrigation if infects crop residue possible. some should not be damaged immediately preventative a problem. Maximise tissue. after harvest. effect. ventilation. Rotation Crop Cultural Practices Chemical Control Conflicts / Issues Resistant High Risk Disease Nutrition Irrigation Hygiene Other Chemical IPM Issues varieties Break available If weather Minimise All fungicides If there is a conditions are damage used for conflict in favourable for caused by Sclerotinia disease and the pathogen seedling control are tipburn risk then grey handling also effective irrigate very mould in nursery, against early in the can cause cultural Botrytis. day. substantial practices, crop loss in and other Rotate both green pathogens fungicide house and and pests. groups field lettuce. to avoid resistance.
Lettuce Best Practice 31 Farm Services Victoria 32
Downy Mildew Bremia latucae
Effective IPM Rating √ √ √ √ √ Critical Comments: Use resistant varieties and monitor crops closely and apply protective measures when conditions suitable for infection. Rotation Crop Cultural Practices Chemical Control Conflicts / Issues Resistant High Risk Disease Nutrition Irrigation Hygiene Other Chemical IPM Issues varieties Break available There are Cool, damp Seed should Excessive Avoid Use wider Predictive Apply Choose More difficult many types conditions. be fungicide Nitrogen watering plant spacing models for preventative resistant to control (or races) of treated. may make seedlings to facilitate downy mildew fungicides varieties as the plant this fungus. Free moisture lettuce more from 8.00am better air on lettuce before the where ages and Some lettuce on plant Avoid susceptible. -12.00pm as movement are under disease possible. crop density varieties leaves. planting most spores and leaf evaluation develops increases. near other Avoid high claim High risk are released drying. world-wide. based on resistance to lettuce fields nitrogen during this weather Control may following as airborne levels. Transplants Align plant conflict with some races lettuce crops, period, conditions. spores can irrigation will should be spacing that optimum near globe be dispersed protected allows for Rotate with irrigation artichoke, act to wash from one crop spores out of with maximum curative timing during endive, to the other fungicides to ventilation. fungicides the night chicory and the air and by the wind. provide wet avoid Downy when for tipburn ornamental mildew being Subsequent conditions management. host plants. Crop rotation leaf surfaces plantings for them to introduced are ideal for is important. into the field. should be infection. infect plants. up- wind of current crops. Rotation Crop Cultural Practices Chemical Control Conflicts / Issues Resistant High Risk Disease Nutrition Irrigation Hygiene Other Chemical IPM Issues varieties Break available Wild lettuce Minimise leaf Grow seedlings Rotate the However in is a host wetness outside the appropriate warm weather although it eg. before area of crop registered this will not may not show 8.00 am when production to fungicides. be an issue symptoms. dew may avoid cross as leaves will normally be contamination. Copper is dry quickly. Spores carried on the leaf a general over on crop and avoid protectant debris. watering in fungicide. the evening. Fungicide Trickle resistance irrigated has been crops reported in show less some areas. disease than overhead irrigated crops.
Lettuce Best Practice 33 Farm Services Victoria 34
Rhizoctonia (bottom rot) Rhizoctonia solani
Effective IPM Rating √ √ √ √ √ Critical Comments: Monitor crops to assess the need for control and use good cultural practices. Rotation Crop Cultural Practices Chemical Control Conflicts / Issues Resistant High Risk Disease Nutrition Irrigation Hygiene Other Chemical IPM Issues varieties Break available None. Hotter, humid Soil-borne Plant in well Use a Do not plant Ground with None More common production pathogen drained soils. quality sterile back in a history of available in summer Select areas. that survives seedling mix. fields with Rhizoctonia yet. Consider – hotter varieties that for a long Drip irrigation undecomposed disease may planting on production have upright Once period of will assist residues from need to be small hills to regions. growth habits infection time in disease previous crop. treated with improve air Can be a to reduce is seen in reduction. a fungicide circulation problem in disease an area it Repeated All stages of Avoid over prior to around plant glasshouse- severity. is likely to frequent the crop can transplanting base. grown re-occur cropping irrigation. be infected Over watering in order lettuce. in future with lettuce in conditions to reduce Improve plantings may increase creates wet of high drainage. Direct seeded stems and disease if weather disease levels humidity. incidence. plants may conditions are in the soil. high humidity be severely favourable. around the Greatest risk Apply infected or Avoid fields plant that of infection appropriate killed by with a history can greatly is from heart chemicals to this disease of bottom rot increase formation target the before or problems. disease through to base of young just after severity. harvest. plants. emergence. Rotation Crop Cultural Practices Chemical Control Conflicts / Issues Resistant High Risk Disease Nutrition Irrigation Hygiene Other Chemical IPM Issues varieties Break available Crop residues Spray-off or Preventative Good cultural should plough in action practices and be fully harvested required if management decomposed areas as soon you have provides best (broken as possible a history control. down) before after harvest. of disease planting a occurrence. Rotate new crop. crops with non-hosts to reduce the inoculum but this disease has a wide host range.
Lettuce Best Practice 35 Farm Services Victoria 36
Sclerotinia (lettuce drop) Sclerotinia sclerotiorum and Sclerotinia minor
Effective IPM Rating √ √ √ √ √ Critical Comments: IPM is the most effective control, use of fungicides is not a sustainable long-term measure, management and cultural practices are essential. Identification of the Sclerotinia pest is essential to determine the most effective control methods. Rotation Crop Cultural Practices Chemical Control Conflicts / Issues Resistant High Risk Disease Nutrition Irrigation Hygiene Other Chemical IPM Issues varieties Break available None Cool, humid The pathogen Soil Improve soil Minimise Devise a In fields Use good An IPM available. spring can survive amendments structure to spread of production with history drainage, approach autumn as Sclerotia with high reduce water disease by systems of S. minor cultural is the best weather. in soil for Nitrogen such logging. cleaning that reduces lettuce drop, practices and to manage 5 years or as poultry protectant crop rotation. Sclerotinia. Use raised equipment the risk of Wet soil. more. manure fungicides Chemical beds if after use Sclerotinia can reduce applied The biocontrol control is not Following needed. in infected outbreaks by: Broad survival of paddocks. ∙∙ Using soon after agent sustainable in other host range C. minitans susceptible Sclerotia in Avoid practical transplanting the long-term. including both over can reduce crops. soil. and cost- can reduce Control of some green and under infections effective disease lettuce drop manure or watering to caused by cultural incidence. caused by S. break crops. maintain F. sclerotiorum. practices. Application sclerotiorum consistent ∙∙ Implementing Cereals and must be to is difficult soil moisture a rotation grasses are the base of because levels. program non-host and seedlings airborne spores that thus good Effective and repeated can enter the includes rotation irrigation before plants lettuce fields at non-host crops. scheduling is become too unpredictable crops. essential. large. times. Rotation Crop Cultural Practices Chemical Control Conflicts / Issues Resistant High Risk Disease Nutrition Irrigation Hygiene Other Chemical IPM Issues varieties Break available Cultivars It is Reduce free ∙∙ Improving Fungicides Need to with low important to moisture by overall alone do balance growth habit know which irrigating soil health not provide risk and like Iceberg species is early in the to reduce absolute management lettuce types present for day so that survival of control and for tipburn can be more an effective the crop sclerotia are not a with risk of susceptible control canopy and (eg. add sustainable sclerotinia. than those program. soil surface biological control Night with upright dries quickly. control means. watering is growth like Crop residues agents and preferred some Butter from green Irrigate with increase Important for tipburn head or Cos manure drip irrigation organic to consider control. In types. biofumigant or subsurface matter). water volume hot weather mustard crops drip system to be used as leaf wetness (a brassica) so that the For S. per canopy should not be show soil surface is minor, deep size and a problem. suppressive drier. ploughing Sclerotinia effects soil to bury species. against S. sclerotia minor. below root zone may reduce disease.
Lettuce Best Practice 37 Farm Services Victoria 38
Septoria spot Septoria lactucae
Effective IPM Rating √ √ √ √ √ Critical Comments: Monitor crops to assess need for control and start protection program when conditions are suitable for infection. Rotation Crop Cultural Practices Chemical Control Conflicts / Issues Resistant High Risk Disease Nutrition Irrigation Hygiene Other Chemical IPM Issues varieties Break available Prefers Avoid Crops under Water splash Only use Disease A Hygiene Monitor prolonged planting stress moves disease free normally preventative on farm is closely when periods of lettuce in are more infection seedlings. appears on monitoring important, conditions high humidity fields with susceptible. onto leaves. the older and fungicidal destroy old favour and cool, a history of Keep lower leaves program crop residues. infection. wet windy disease. Minimise seedlings first. (protectants) conditions. periods of disease should be Infected Control host extended leaf free with Rotate with employed if plants are Severe weeds. wetness. protectant non-host conditions are a major infection can fungicides. crops to suitable to source of render crops Use irrigation reduce levels new disease systems that prevent early unmarketable. of pathogen infection. outbreaks. reduce or in soil. Fields with a eliminate leaf Systemic history of the wetting. Spread by chemicals are disease. wet windy available but conditions, prevention older leaves is more affected first. effective. Rotation Crop Cultural Practices Chemical Control Conflicts / Issues Resistant High Risk Disease Nutrition Irrigation Hygiene Other Chemical IPM Issues varieties Break available Host weeds Spray-off or such as plough in wild lettuce harvested or prickly areas as soon lettuce. as possible after harvest.
Lettuce Best Practice 39 Farm Services Victoria 40
Nematodes Meloidogyne spp. and Pratylenchus spp.
Effective IPM Rating √ √ √ √ √ Critical Comments: Effective long-term control will be only be provided by management and cultural practices.. Rotation Crop Cultural Practices Chemical Control Conflicts / Issues Resistant High Risk Disease Break Nutrition and Hygiene Other Chemical IPM Issues varieties Irrigation Avoid planting Crop rotation Nematodes Nematodes are Roots of Nematicides Soil Chemical in fields with with non-hosts “swim” moved on soil stunted plants are registered solarisation control will not ‘high’ RKN or of 1-2 years therefore avoid and machinery should be for use in some using plastic be compatible RLN numbers. is generally wet soil for so hygiene is examined for states. film prior to with IPM sufficient to long periods important for galling caused planting may practices. Sandy soils are reduce RKN to reduce their control. by RKN. General soil be cost- a higher risk numbers to spread. fumigants such effective Note that some for RKN. non-damaging Always work A pre-plant as metham in some biofumigants levels. Avoid over infested soil test should sodium pre- situations. are good hosts overwatering paddocks last be done to planting will of nematodes Some varieties by scheduling and clean determine also provide Growing and (e.g., RKN). of cereals, irrigation machinery nematode control of incorporating grasses and appropriately after working numbers in a nematodes. a biofumigant sorghum are and ensure in infested field if galling crop prior to non-hosts or adequate paddocks. is evident, planting may poor hosts nutrition. a problem also provide for RKN and is suspected control. can be grown or there is prior to the a history of crop to reduce nematodes. nematode numbers. Rotation Crop Cultural Practices Chemical Control Conflicts / Issues Resistant High Risk Disease Break Nutrition and Hygiene Other Chemical IPM Issues varieties Irrigation Chemical Effective options for incorporation nematode and a good control are “kill”, is relatively essential expensive to achieve and toxic. control. Fumigation also kills all Some biological beneficial soil controls and inhabitants soft chemicals – fungi and are available insects. but their effectiveness can be variable.
Several species of plant-parasitic nematodes have been associated with damage to lettuce in Australia. Of these the most important are Root knot nematode (RKN) (Meloidogyne hapla, Meloidogyne javanica and Meloidogyne incognita). RKN causes galling of lettuce roots and stunting of plants, often in distinct patches in the field. Species of Root lesion nematode (RLN) (Pratylenchus spp.) have been reported as parasites of lettuce in Australia.
Control needs to be carried out pre and post-harvest. There is very little that can be done to control nematodes during crop growth.
Lettuce Best Practice 41 Farm Services Victoria 42
Slugs and Snails Mollusca
Effective IPM Rating √ √ √ √ √ Critical Comments: Control is best achieved with cultural and management practices.
Infestation Risk Factors Cultural Practices Chemical Control Conflicts / Issues Increases the Reduces the Monitoring Beneficial Other Pest Lifecycle Chemical IPM Issues risk risk Control Insects Thresholds A nearby crop, A physical Check crop ∙∙ Birds Good soil Cool moist No registered Need to control Totally reliant drain, dam or barrier of canopy and ∙∙ Lizards preparation can environments chemicals in borders and on management a weedy area empty land plant centres in ∙∙ Other small significantly and areas available for headlands and practices. or headlands between crops areas adjacent vertebrates reduce favour pest control within bait those could be a and waterways to drains and ∙∙ Carabid numbers. survival and the crop. areas if a source of slugs and drains wet spots, beetles overwintering. problem is and snails. helps slow pest slugs and snail Fallow periods. Drains, damp likely. Once areas that Long grass in movement to tend to appear Improved drains. the crop. there first. established adjoin the crop Baits or a drainage and pest can can be baited. barrier strip Following a Good crop Larger plants improving soil survive in the around the pasture crop. rotation. are generally quality assists soil between A protective affected crop less affected control. crops unless border can be area. Minimum Keep crop used to prevent but slugs and Drip irrigation the life cycle is tillage. blocks 3m - 4m snails can be a broken. pest movement away from reduces into the crop. Wet weather. contamination occurrence. drains and pest. dams. Plants are vulnerable when small. Infestation Risk Factors Cultural Practices Chemical Control Conflicts / Issues Increases the Reduces the Monitoring Beneficial Other Pest Lifecycle Chemical IPM Issues risk risk Control Insects Thresholds Plough in crop residue. Remove debris that can be used as shelter areas and keep grass short.
Lettuce Best Practice 43 Farm Services Victoria 44
Virus IPM Control - Pre Plant Planning. LBVD
Effective IPM Rating √ √ √ √ √ Critical Comments: Vector and weed control is critical to virus management – the IPM Rating will depend on chemicals used for vector control.. Cucumber mosaic Lettuce mosaic Turnip mosaic virus Lettuce necrotic Tomato spotted Lettuce big vein virus (CMV) virus (LMV) (TuMV) yellows virus wilt virus (TSWV) disease (LBVD). (LNYV) (Mirafiori lettuce virus/lettuce big vein virus) How is it The virus is Seed-borne in The virus is Transmitted by only Spread by several The viruses causing transmitted? transmitted by more lettuce seed and transmitted by more one aphid species, species of thrips: the disease are than 60 species of most outbreaks than 50 species of the Sow thistle ∙∙Thrips tabaci transmitted by the aphid, including: can be traced to aphid, including aphid (Hyperomyzus ∙∙Frankliniella soil-borne fungus ∙∙Acyrthosiphon infected seed lots. Myzus persicae lactucae) in a schultzei Olpidium virulentus. pisum and Brevicoryne persistent* manner. ∙∙F. occidentalis ∙∙Aphis crayccivora Also spread by brassicae, in a (Western Flower The virus survives and aphids (Aphis non-persistent** Thirps) in the fungal resting ∙∙Myzus persicae gosseii, Macrosiphum manner. spore which can in a non- euphorbiae, Myzus remain viable in soil persistent** manner persicae in a for several years. non-persistent** manner). Host plants A very wide host The virus has a wide Wide host range Both the virus and A very wide host The disease is range including: host range including including: aphid have sow range among favoured by cool ∙∙ Lettuce the weeds, thistles ∙∙ Lettuce thistle as their crop, weed and weather and wet ∙∙ Vegetables (Sonchus spp) and ∙∙ Vegetable brassicas major host. ornamental species. soils. ∙∙ Weeds Fat hen. ∙∙ Canola Lettuce often ∙∙ Ornamental ∙∙ Brassica weeds seriously affected. species. ∙∙ other weed species. Cucumber mosaic Lettuce mosaic Turnip mosaic virus Lettuce necrotic Tomato spotted Lettuce big vein virus (CMV) virus (LMV) (TuMV) yellows virus wilt virus (TSWV) disease (LBVD). (LNYV) (Mirafiori lettuce virus/lettuce big vein virus) Host plants An occasional issue continued where lettuce is grown near infected brassica crops or near infected weeds, particularly weedy brassica species. Key control Remove old crops Weed control around Weed control around Weed control, Weed control around As the fungus is information and weed control in and in the crop is and in the crop is particularly for and in the crop is soil-borne the and around the crop essential. essential. Sow thistle, around essential. disease is difficult is essential. and in the crop is to control. It is critical to plant Incidence of TuMV essential. Insecticides may LMV-tested seed. may increase where It is important cause more harm lettuce is grown to plant healthy than good as their near infected seedlings. application may brassica crops or encourage the aphid weeds (particularly Crop rotations can to move from plant brassica species). reduce the disease to plant. incidence. Potentially, CMV will then be transmitted to each plant visited by the aphid. * Persistent – Aphids need to feed for an extended period of time on each host to pick up and then transmit the virus from one host to another. ** Non- persistent – Aphids only need to feed for a very short period of time on each host to pick up and transmit the virus from one host to another. Several of the above viruses produce similar symptoms in lettuce and are difficult to separate in the field. Laboratory tests are often necessary to determine which virus or viruses are present.
Lettuce Best Practice 45 LNYV Farm Services Victoria 46
Virus minimisation strategy
Pre-plant Rotations out of lettuce will help reduce big vein disease incidence. It is essential to control weeds in and around production areas. Collectively, the viruses infecting lettuce have a very wide range of potential hosts so a thorough weed management program is recommended, rather than selecting individual species which may be common hosts. Purchase seed and seedlings from reliable suppliers and ensure that it has been tested for Lettuce mosaic virus (LMV) freedom. Consider LBVD tolerant varieties when growing during cool weather in areas with a history of the disease. If aphid-transmitted viruses are an ongoing issue (CMV, LMV and TuMV) consider the use of permanent wind rows and strategic planting to maximise the distance between lettuce crops. Nursery Ensure nursery area is free of weeds. Control insect vectors-thrips, aphids. Where possible locate nursery in a district remote from production areas. Transplant through to Maintain weed control in and around production areas, especially of virus host plants. vegetative growth Monitor for and maintain good management of insect vectors. Avoid planting new crops near old crops, particularly where virus and other diseases have been prevalent. Remove any virus affected plants from the crop area to minimise virus spread. It is important to control the insect vectors (see control methods for insect vectors) before virus is observed in the field. Transplant through to Once virus is present in a crop, it is too late to eradicate the virus and attempts to control aphid vectors at vegetative growth this point can further spread virus in the crop for diseases such as CMV and LMV, due to the method of virus continued transmission. It is important to reduce virus spread to subsequent crops. Avoid planting near affected crops and plant upwind. Have non-host crops as alternate plantings. Hearting through to harvest Monitor crops closely for insect vectors and symptoms but if the virus is observed in the last stages of crop growth, there will be a minimal affect on yield. Destroy harvested crops promptly. Do not plant new crops close to old crops. Plan to have fallow land or non-susceptible crops as a means of separating plantings. Remove any virus-affected plants from the crop area to minimise virus spread to other plants, particularly younger plantings that are nearby. Plant upwind of affected crops if possible. Have non-host crops as part of your crop rotation.
Lettuce Best Practice 47 Farm Services Victoria 48
Weeds IPM Control
Effective IPM Rating √ √ √ √ √ Critical Comments: Weed control is an essential component of IPM for a range of pest issues. It is essential to consider the range of potential host plants for key diseases and their vectors as well as problem, insect pests. Method of control for a How to do it Negatives Positives weed free seedbed Pre-plant Form beds well before planting and then irrigate Avoid moderate to deep A range of techniques to germinate an initial flush of weeds. cultivations because they can be used to kill off the will cause more weeds to germinating weeds. Kill these weeds by spraying with a knockdown germinate in the crop. herbicide. Alternatively, kill weeds with a very shallow cultivation. For organic farming, flaming, steam or hot water treatments are alternatives to knockdown herbicides. Green manure crops can suppress weed growth. Bed formation before planting Form beds just before planting, with a final Not the preferred option in cultivation to prepare the seedbed and kill any paddocks with substantial emerged weeds. numbers of weeds.
If high weed numbers likely form beds well Reduces weed numbers before before planting and spray-off emerging planting. weeds before planting or pre-plant herbicide application. Method of control for a How to do it Negatives Positives weed free seedbed Fumigation Form beds before planting, then fumigate, Incorrect soil moisture will This is not an IPM friendly (refer to fumigant labels for specific rates). reduce the effectiveness of practice. fumigation. Fumigating or “gassing” can produce variable Fumigation has the additional results depending on a number of factors Expensive and results can be benefit of controlling some including soil type and temperature, moisture variable. diseases, nematodes and content, and exposure time. Contractors with insect pests, depending on specialist application equipment operate in many Fumigation will also kill off pest severity and the rates production areas. beneficial soil organisms. used.
Control using mulch In combination with drip irrigation, lay plastic Cannot be used with May increase soil temperature or paper mulch to control weeds and then overheard irrigation. for an increased planting transplant through this much layer. window. In summer production areas To make the most of the costs associated with excess soil heat generated this system growers usually try and replant these by plastic mulch can cause mulched beds with a second rotation crop. production issues. Plant based plastic type mulches claiming to be Can be expensive and more biodegradable are also now being developed and difficult to manage. sold in some areas. It is too early to know how well these products perform in different environments, how well they break down and whether they are in fact more environmentally friendly than traditional plastic products.
Lettuce Best Practice 49 Farm Services Victoria 50
Weeds IPM Control
Weed management is a significant proportion (about 20%) of pre-harvest variable costs in lettuce production. Poorly managed or ineffective weed control can be even more costly as it impacts on disease severity, harvest weight, heart size and adds to weed potential in following crops.
Weed control is an essential component for IPM for a range of pest and disease issues. Weeds can also act as a reservoir for beneficials so consideration must be given the weeds present and the risks they may be to crop production. Plants or vegetation that are not a host to diseases or pests may help support a beneficial population.
Site selection and preparation It is extremely difficult to grow lettuce in land with large weed seed banks; pre-planting management is the key to success. Land with at least a two-year history of effective weed control achieved by selective crop rotation and cover cropping is best.
Weed management in the lettuce crop starts with planting into a weed-free seedbed. There are a few possible options for achieving this. Broadleaf weeds Grass weeds The most significant weed problem. Particularly the Asteraceae (daisy-type) family (Potato weed and Common Seldom a problem. Most will be controlled sow thistle). by the same cultural practices used to manage broadleaf weeds. Whilst late-emerging weeds may not affect lettuce yields they should still be managed. Species such as potato There are pre-emergence herbicides weed can grow dramatically in the last few weeks before harvest and interfere with cutting and packing to control many grass species before processes. In an integrated weed management program, it is important to minimise the populations of emergence. weeds setting seed. It may make economic sense to selectively hand-weed in the weeks before harvesting, particularly if weed seed development can be prevented. There are registered chemicals for post- emergence grass control in lettuce. There are herbicides registered for broadleaf weed management. They must be applied just before, at, or immediately after planting, before weeds have emerged. They will not kill established weeds. Choosing which herbicide to use will depend on several factors including which weed species is likely to be a problem, what you plan as the following crop in the rotation, and the types of herbicides used in previous crops. To avoid the build-up of resistant weeds, it is important not to continuously use herbicides with the same modes of action. Some chemicals can only be used before transplanting. Some chemicals can be applied directly after seeding or transplanting, and then irrigated in. It is essential to minimise the time between final cultivation (or knockdown herbicide application) and spraying pre-emergent herbicides. The longer the delay (eg. more than 2 to 3 days), the more likely it is that new weeds will germinate and not be controlled by the chemicals. Closer to harvest broadleaf weeds in the lettuce crop can only be killed by cultivation or hand weeding.
Lettuce Best Practice 51 Farm Services Victoria 52
Weeds Post harvest
Rotation Crop Cultural Practices Conflicts / Issues
High Risk Disease Break Nutrition and Hygiene Other Irrigation Areas with a previous A consistent system Some chemicals must Nursery and farm To maintain an effective Take care on sandy history of weeds. of crop rotation and be applied before hygiene are important herbicide blanket, it soils, as the highest weed control between transplanting. factors in both is also important that herbicide rates may Areas planted beside crops will minimise minimising weed cultural operations after cause crop stunting and weedy areas. weed build up prior to population. herbicides are applied, yield reduction. planting. e.g. while transplanting Troublesome weeds Farm-based nursery The Queensland such as nut grass minimise soil surface Because of residual production facilities disturbance. experience found in (Cyperus rotundus) or activity, sensitive crops should be kept weed- some circumstances potato weed (Galinsoga (e.g. beets) should not free and well drained. Whilst late-emerging (high temperatures parviflora), are difficult be sown immediately weeds may not and sandy soils), crop to control. following a lettuce affect lettuce yields damage can occur. crop treated with some they should still be chemicals. Refer to the managed. Species such Growers unfamiliar with label for re-cropping as potato weed can a product are strongly intervals. grow dramatically in the advised to only treat last few weeks before a small area at first, harvest and interfere to determine product with cutting and performance with local packing processes. soils, climate and varieties. Rotation Crop Cultural Practices Conflicts / Issues
High Risk Disease Break Nutrition and Hygiene Other Irrigation In an integrated weed management program, it is important to minimise the populations of weeds setting seed. It may make economic sense to selectively hand- weed in the weeks before harvesting, particularly if weed seed development can be prevented. Within one day of final harvest all weeds and crop residue should be destroyed.
Part of the post-harvest activities are to review the impacts of various control activities on the yield and “pack out” to improve and pest and weed control for subsequent seasons. A key part of the IPM process is to record percentage crop damage and “pack out” rate, crop residue management, migration of beneficial insects and insect pests, rotation – length, break crops and follow on crops.
Lettuce Best Practice 53 Farm Services Victoria 54 References
Disease Managing Soilborne Diseases in Vegetables: Rotation with green manure and Biological Controls for Sclerotinia Diseases, Villalta, Oscar, et al. (2004), Booklet, biofumigant crops shows disease control & yield benefits, Donald, Caroline Information guide, Department of Primary Industries Vic. Available from (2010), Fact sheet, Department of Primary Industries Vic. Available from Horticulture Industry Network website
Lettuce Best Practice 55 Farm Services Victoria 56
Virus Guide to using native plants on the Northern Adelaide Plains to benefit Aphid-transmitted viruses in vegetable crops: Integrated virus disease horticulture (2009), Field guide, South Australian Research and Development management, Persley, D. & Gambley, C. (2009), Queensland, DEEDI Primary Institute. Copies may be downloaded from SARDI website
Lettuce Best Practice 57 www.dpi.vic.gov.au GG/UG-L/1210