Fixed coppers will not control powdery mildew on highly susceptible varieties. Ziram and Carbamate WDG will provide only moderate management of downy mildew when used for management of black rot. Neither is recommended if downy mildew pressure is high and other alternatives are available. Ridomil is the most effective material to use against downy mildew, but it does not control other diseases. Grape berries remain susceptible to infection by the Phomopsis fungus until pea-sized or later.
Rachises also remain susceptible into the summer.
This has been a particular problem on juice grapes. Thus, it is recommended that an effective Phomopsis fungicide be applied to susceptible varieties if these weather conditions are forecast. Abound and Sovran are only moderately effective against Phomopsis.