Management of new fungicides for the control of powdery mildew and other grape diseases

Abstract

This project was undertaken to develop and evaluate management strategies for the efficient use of the new fungicide group, the strobilurins, for the control of powdery mildew, downy mildew and Botrytis bunch rot of grapes. Laboratory, greenhouse and field experiments were carried out to determine the protectant and curative limitation of the strobilurin fungicides Amistar and Flint. These studies showed that they were most effective when applied before infection, and while they were effective against both powdery and downy mildew they were less effective on Botrytis bunch rot.
Field trials over 3 seasons evaluating various sprays regimes were focused mainly on powdery mildew and these showed that excellent control of powdery mildew was obtained when 4 to 6 sprays per season were used and included either wettable sulphur or DMI before and after 2 to 3 applications of a strobilurin around flowering. Where Flint and Amistar were directly compared Flint was the most effective fungicide for controlling powdery mildew whereas Amistar was more effective than Flint in controlling downy mildew.

Summary

Comparing new fungicides and establishing a spray program in conjunction with Sulphur