Control of downy mildew on nursery seedlings
Downy mildews on seedlings (pansies, stocks and brassicas) are a major disease problem for the nursery industry in Australia, with economic losses estimated at 10-12% in production of ornamental and vegetable seedlings or $4 million annually (1997 value). This item contains extracts from the final report of a research project (NY9406) that tested seed for contamination, evaluated fungicides, monitored spore release, recorded weather data, examined the effects of light on disease development and reviewed the literature on downy mildews in nurseries to develop integrated control strategies. These strategies consist of both management practices (irrigation, ventilation, hygiene, nutrition, monitoring) and fungicide spray programs. Fungicides alone will not control downy mildew if disease pressure is high. Adoption of these strategies by commercial nurseries in Victoria has resulted in an 80 – 100% drop in the incidence of downy mildew on Brassica seedlings.