Natural Cure For Powdery Mildew Big Export Crop

Media Release 21 November 2002

Natural Cure For Powdery Mildew Could Help Big Export Crop
Mildew meets its match

With export squash sales exceeding $80 million last financial year, it is no wonder that there is a need for a safe, natural, easy to use produce to control powdery mildew, one of the most serious disease problems of squash.

HortResearch scientist Kirstin Wurms said she and her team hope to overcome powdery mildew by developing a new fungicidal product based on milk ingredients and other natural compounds.

"Our object is to develop a durable natural control solution that can be commercialised in the shortest time possible through use of products that are already registered as safe for human consumption," she said.

"We expect that this natural fungicide will offer combined protectant and eradicant activity," Dr Wurms said. "There should be fewer resistance problems and shorter withholding periods than synthetic fungicides and the product should be suitable for use by both conventional and organic growers.

Milk products have been used informally as fungicides for many years with varying success, due to problems such as unwanted growth of other non-target organisms such as sooty mould fungus.

Powdery mildew is the common name for a group of fungi with a powdery-white appearance that cause disease on the surface of a wide range of plants such as grapes, roses, cereals and cucurbits. Powdery mildew infections damage leaves, which reduces the quality and quantity of fruit and vegetables produced.

Initial glasshouse trials at HortResearch Ruakura have found that ingredients supplied by Fonterra inhibit the fungus on squash and zucchini plants. Further glasshouse trials on different ingredient combinations have started this month to help identify what compounds are responsible for killing the fungus.

Following this HortResearch will need to establish the compatibility of the mixture with other products and management practices used by growers, for example, compatibility with biological control agents used in Integrated Pest Management. The effect of the fungicide on fruit quality will also need to be assessed. To complete this work HortResearch will be seeking assistance from interested stakeholders.

Squash, one of the cucurbit family that includes pumpkins, zucchini, cucumbers and melons, is New Zealand's second largest vegetable export after onions with 99 percent of the crop sent to Japan.

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For further information please contact Dr Kirstin Wurms, Project leader/Scientist or Lisa Marcroft, Client Manager at HortResearch Ruakura, Tel: 07 858 4650 or Mobile: 021 336 338. Emai:l kwurms@hortresearch.co.nz or lmarcroft@hortresearch.co.nz

Liz Brook Media and Publicity Manager HortResearch Tel: +64 6 356 8080 ext 7749 Fax: +64 6 351 7038 Mobile: +64 21 505 912

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