black spot on grapes
Here is some information on cultural control for black rot on grapes. You can minimize problems by removing infected fruit, cleaning up mummies, and pruning out leaves that surround fruit clusters.
The soft (organic controls) are not effective. In general lime sulfur gives fair control. However, It can be hard to find and some grape varieties are sensitive to copper or sulfur. Captan is not effective.
The fungicides Immunox (without an insecticide) and Mancozeb offer excellent control.
You will have to view the Va Tech Spray schedule 'Table 3-8' for 'Spray Schedule for Grapes' and
'Table 3.3b' lists the – 'Effectiveness1 of Fungicides for Control of Grape Diseases'