The SI materials have about 3 days of back action against these diseases. The EBDC fungicides are not allowed by National Grape after bloom begins and Captan is not allowed at all. Phomopsis is a problem especially in Niagara. It causes fruit drop in the late season. The bloom sprays are probably the most important sprays for disease control.
Downy mildew becomes a problem at bloom.
A final EBDC spray is timed for immediately preceding bloom, to control this disease. The SI fungicides do not control downy mildew. Ridomil provides excellent control of downy mildew as an eradicant and was used for that until Ziram was labeled in grapes. A tank mix of Ziram and a SI is used in the post bloom period with about 14 days of control. These materials provide control against all the major grape diseases except Botrytis.