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Downy mildew on seedlings is the major disease of the nursery industry in Australia. Economic losses from the disease are estimated at 10-12% or $4 million annually. Nurserymen have experienced difficulty in controlling the disease on stocks, pansies and brassicas. One nurseryman had actually stopped growing austral stocks because of the problem. A project, supported by the Nursery Industry Association of Australia, the Horticultural Research and Development Corporation and Agriculture Victoria was developed to control downy mildew on nursery seedlings. The project evaluated fungicides, monitored spore release and reviewed the literature on downy mildews in nurseries, to develop integrated control strategies.
Commercial nurseries in Victoria which have adopted the environmental management strategies and fungicide protocols developed from the research project have markedly reduced the disease on brassica and ornamental seedlings. One nursery reported no disease on their stock seedlings and a 30% increase in sales. The incidence of downy mildew (measured as the number of plants infected divided by the total number of plants counted) was high on Brassica seedlings in one nursery during 1995, prior to adoption of the integrated management strategies, but after adoption of these strategies in 1996 was reduced by up to 100% Acknowledgements : The authors thank the Nursery Industry Association of Australian, the Horticultural Research and Development Corporation and Agriculture Victoria for financially supporting the project. The Nursery Industry Association of NSW, the Nursery and Landscape Industry Association of South Australia, the Nursery Industry Association of Western Australia, the Nursery Industry Association of Tasmania, the Nursery Industry Association of Victoria and the Queensland Nursery Industry Association are thanked for their support of the project. The authors thank the industry development officers Ian Atkinson, Anne Frodsham (SA), Richard Stephens (NSW), Sandy Pate (WA), John McDonald (Qld) and Greg King (Vic), the state secretary Colin Fleming (Tas), the NIAA training officer Greg McPhee, Denis Cook the secretary of the Northern Rivers Branch of NIA of NSW, Chris Douglas president of the Tree and Shrub Growers Association of NSW, Des Leeke of the Tube Growers Association and Domenic Cavallaro Horticultural Consultant for the opportunity to present results of the project to industry and for assistance with organising nursery visits. Nursery management and staff at the various nurseries visited during the project are thanked for making the time available to discuss downy mildew in their nurseries. Also scientists visited during the project are thanked for their helpful discussion. |
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