Cape Flora Post-harvest Insect Control, including Phytosanitary Compliance, & Post-harvest Physiology

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PROJECT TITLE New tools to Novel technologies for post-harvest treatment of Cape flora flowers for control of phytosanitary insect pests bash bugs PRINCIPAL INVESTIGATOR Dr Shelley Johnson

CONTACT DETAILS Two novel techniques hold great potential for mitigating The European Union receives around 80% +27 (0)21 808 2694 of Cape flora exports, but this does not imply [email protected] the most persistent pests troubling the export of South that the flowers are not in demand elsewhere. However, access to other markets proves more (consisting of 1% oxygen, 15% carbon Methodology and results DURATION Two years African Proteaceae to stricter markets. challenging, due to phytosanitary regulations dioxide in nitrogen) to eliminate pests. Early in 2016, before the start of the peak export that are particularly strict, resulting in the danger • Ethyl formate (EF) is a naturally occurring season, numerous pilot trials were performed. PHI PROGRAMME & IN SOUTH AFRICA, Cape flora cut flowers and harsh reality of consignment rejection. compound that, in high enough doses, Cut stems from the species Protea INDUSTRY CONTRIBUTIONS are grown and harvested in their natural This is particularly true for countries whose prevents oxygen reaching the cells of insects, magnifica (also known as ‘Queen’ or ‘Barbi’) R412 951 & R112 693 1 Dr Shelley environment, which includes the insect climatic conditions are, in places, similar to the ultimately leading to their demise through were subjected to regular atmosphere heat LEAD INSTITUTION Johnson and MSc communities that live there. The insects of the Western Cape’s Mediterranean climate, and asphyxiation. treatments to assess the flowers’ response to Cape Flora SA student Anton Cape flora biome are diverse, even between those that have their own Proteaceae or similar heat stress. These proved far too harsh. The BENEFICIARY growing regions, and are so poorly understood floral families. The risk of South African insects Both these methods are considered flowers lost an average of 13g in water mass Huysamer (right) The Cape flora industry with the laboratory- and understudied that many have not been establishing in overseas crops is too great for environmentally friendly, as CATTS is essentially and yielded unsatisfactory results from an scale controlled identified scientifically. them to accept our flowers without intensive chemical free, and EF breaks down into aesthetic perspective, particularly in terms of FOCUS AREA atmosphere and The complexity and arrangement of phytosanitary inspections and regulations, and naturally occurring, harmless products. leaf damage. Post-harvest insect control, including phytosanitary temperature Proteaceae floral structures, not to mention many have a zero-tolerance approach to living Shelley and Dr Lynn Hoffman, lecturer at With these results in mind, amendments compliance, and post- treatment systems the impressive size of some, provide ample and dead insect pests within consignments. the Department of Horticultural Sciences, were made. The ‘Barbi’s’ were kept at 4°C for harvest physiology (CATTS) unit at hiding places for a massive array of arthropods. The direct and indirect costs of consignment Stellenbosch University, designed a study that no longer than 24 hours after harvesting before Stellenbosch They may inhabit the stem, leaves, receptacle rejection and subsequent damage to the received funding from industry and the PHI treatments commenced. The flowers were HUMAN CAPITAL University. or inflorescence, and can occur in staggering reputation of the Cape flora cut flower industry Programme to achieve two objectives: pulsed using a sucrose solution, and subjected DEVELOPMENT One MSc student 2 Core temperatures numbers. are astronomical. 1. Identify the insect categories that are of to much faster temperature ramps for shorter of ‘Barbi’s’ (Protea Regardless, Cape flora is an internationally Current mitigation techniques for highest concern to the Cape flora cut flower durations. The flowers then underwent 10-day PUBLICATIONS magnifica) are renowned and highly sought after floricultural phytosanitary pests include various pre- and industry. vase life studies, during which they were graded Two product, with more than 20 million stems 2. Establish the efficacy of various CATTS and for both leaf blackening and bract browning of recorded throughout post-harvest protocols. These protocols, PRESENTATIONS the CATTS exported in the 2015/2016 season. although sufficient for flowers intended for EF fumigation treatments on problematic the flower head. Three treatments. some markets, have not yet fully met the high phytosanitary pests, while maintaining post- These brief yet intense treatments, in 3 Protea scarlet 1 standards required for others that have stricter treatment flower quality. combination with controlled atmospheres, butterfly found in phytosanitary requirements. Effective, reliable ‘Barbi’s’ receptacle and preferably greener post-harvest techniques 4 5 was raised from larval are required to ensure that consignments arrive stage to assist in its pest-free, containing only the breathtaking identification. flowers the world has come to expect from the 4 ‘Barbi’ proteas Cape Floral Kingdom. subjected to various Looking further afield for answers, Dr Shelley ethyl formate Johnson, research fellow at the Department (EF) fumigation of Conservation Ecology and Entomology, treatments inside 14 Stellenbosch University, realised that two post- litre desiccators. harvest techniques that have been approved 5 Toxicity with for and are used in other industries have great sugar pulsing in potential for use on Cape flora cut flowers: Leucospermum leaves • Controlled atmosphere and temperature was induced under treatment systems, known as CATTS, use intensive temperature the stresses created by high temperatures ramping protocols. in combination with controlled atmospheres

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1 DID YOU KNOW? According to Tony Rebelo, author of the book A field guide to the Proteas of South Africa, there are currently about 1400 species in more than 60 genera in the Proteaceae family. Virtually all the species occur in the Southern Hemisphere, mostly in Australia which harbours 800 species representing 45 genera. About 400 species occur in Africa, of which more than 330 species When repeated on ‘Barbi’, the same 5 are in the South-Western Cape. Central and South America host about aesthetic challenges were experienced. 90 species, while 80 species occur on the islands east of New Guinea, 45 A diverse range of insects, from stem species in New Caledonia and a few species in Madagascar, Southeast borers and leaf miners to pollen visitors, were Asia, New Guinea and New Zealand. subjected to different treatments to determine their overall tolerance to both heat treatments Taxonomy and fumigation concentrations. Family: Proteaceae Living insects were collected over a period Genus: Proteaceae (The Sugarbushes), Leucadendron (The Conebushes), of two months during official phytosanitary Serruria (The Spiderheads), Orothamnus (The Marsch Rose), Vexatorella inspections at the airport in the peak export (The Vexators), Leucospermum (The Pincushions), Hakea (The season. Adult specimens were identified, and Needlebushes), Diastella (The Silkypuffs), Brabejum (The Wild Almond), larval stages were reared to allow for easier and Grevillea (The Silky Oaks), Aulax (the Featherbushes), Mimetes (The yielded far better results than the standard more accurate identification. Pagodas), Faurea (The Beechwoods), Paranomus (The Sceptres), Spatalla regimes used on fruit overseas, which were A total of 10 species were collected, of which A noteworthy insect was the Protea hister (The Spoons) and Sorocephalus (The Clusterheads) followed in the pilot trials. four occurred regularly. beetle, Platysoma capensis. Although there 1 The Leucospermum ‘Veldfire’ cultivar was The western flower thrip, Frankliniella were never more than two individuals per ‘Barbi’ proteas A ‘protea’ is any member of the Proteaceae family. In order to distinguish subjected to the amended CATTS regimes, occidentalis, was of particular concern due inspection, it has proven to be incredibly hardy subjected to a between a member of the Proteaceae family and a member of the Protea and also yielded more promising results with to the sheer numbers in which it was present, and resistant, with 0% mortality in regular 10-day vase life study genus, the latter is sometimes referred to as a ‘sugarbush’. after EF fumigation regard to leaf damage. However, the controlled resulting in multiple rejections. Living specimens atmosphere treatments and 40% mortality rate treatments. atmosphere protocols did result in significant were collected from commercial plantations and achieved using EF fumigation. 2 Severe leaf damage pin wilting not seen in the same heat treatments subjected to the amended CATTS treatments, Finally, receptacle-boring Lepidopteran insect pests that trouble the Cape flora industry. and pin wilting in performed with regular atmospheres. as well as the lowest concentration of EF caterpillars, such as the Protea scarlet butterfly “To this end, we will include more Protea and ‘Veldfire’ after higher Although these treatments improved fumigation. In both cases 100% mortality was larvae (Capys alpheus) and American bollworm Leucospermum cultivars in our research trials in EF concentrations. the quality of both ‘Barbi’ and ‘Veldfire’ achieved. larvae (Helicoverpa armigera) managed to the last phase of this project. We will continue 3 Typical post- compared to the pilot trials results, they require This was followed closely by the Protea survive all treatments. The CATTS temperature collecting live problematic insects, particularly treatment quality in adjustment to further minimise post-treatment itch mite, Proctolaelaps vandenbergi, which regimes necessary to raise the core of the during peak season, to identify and then subject ‘Veldfire’ subjected to damage and ensure standard vase life quality. too occurred in vast quantities. Both regular flower enough to kill them results in severe and them to different CATTS and EF treatments to regular atmosphere EF fumigation was initially performed on atmosphere treatments and EF fumigation unacceptable damage to the flowers, and EF see which techniques are the most effective heat treatments. ‘Veldfire’, using the same concentrations that resulted in 100% mortality. fumigation does not penetrate deeply enough while still maintaining flower quality. Only 4 Unacceptable leaf were stipulated in an unpublished pilot study in The banded fruit weevil (Phlyctinus callosus) to result in their death. then will rejections of Cape flora be reduced,” damage experienced which Australian wild flowers were fumigated. and Fuller’s rose weevil (Naupactus godmanni) Dr Johnson concludes. due to higher Once again, the treatments were far too were often found, and also in unacceptable Conclusions and future research concentrations of EF. extreme, and considerable damage resulted numbers. These insects will also be subjected to The research results indicate that, in terms 6 5 Vast numbers of from all concentrations but the lowest one. both CATTS and EF treatments. of flower quality, fumigation with EF has the monkey beetles, leaf potential to be developed as a post-harvest beetles and mites 2 3 4 treatment. CATTS has also proven an effective were collected from measure with which to control a vast range of wild-growing flowers insect pests that target Proteaceae. and subjected to However, post-treatment flower quality is varying CATTS and EF still not satisfactory. “We have to fine-tune treatments. different pre- and post-treatment techniques 6 American bollworm by, for instance, introducing forced air cooling caterpillar found directly after CATTS treatments, and optimise boring within the EF fumigation concentrations and durations,” receptacle of a says Shelley. ‘Veldfire’ pincushion She also highlights the need for a greater flower head. understanding of the range and complexity of

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