The need for a risk-based approach to botrytis management

摘要

The take-home message of this article is that vineyard managers should not automatically assume that fungicide treatments are the most effective and profitable way of managing botrytis risk in cool climate viticulture. Sometimes disease pressure is too low to warrant the costs of any treatment. Twenty-three field trials were conducted during 2006-08 across six cool climate regions of Australia and New Zealand; only eight of them developed more than 3% botrytis severity at harvest in the untreated plots. The potential for economic losses from botrytis in a given vineyard is determined partly by regional climate and partly by seasonal weather. The best disease management strategy for a particular region is determined by the historical likelihood of botrytis, by the risk imposed by viticultural practices (e.g. the level of bunch exposure) and by the risk of fungicide residues. The tactical decisions about the need for individual sprays or canopy management actions are determined by the way that a season develops. In the future those tactical decisions will be supported by a validated model that summarises all the information relevant to botrytis risk in the current season. A prototype model will be available soon for further development as a user-friendly tool. In the meantime, canopy manipulations such as leaf plucking, which do not use water or disrupt IPM programs used for other pests and diseases, may prove as effective as fungicides.