It is probably grape black pox or grape anthracnose.

Medicine prevention and treatment method for grape black pox: 75% chlorothalonil wettable powder + 70% thiophanate methyl 1000~1500 times solution, or 50% application

Bao Gong Wettable powder 1000 times liquid, or 69% Anker manganese zinc + 75% chlorothalonil wettable powder 1000~1500 times liquid, etc. The above medicines can be used interchangeably, spraying once every 10 to 15 days, and spraying 2 to 3 times in a row. Note that medication should be stopped 10 to 15 days before picking fruits.

Grape anthracnose: In addition to the medicines used for black pox, you can also use 15% imidazole wettable powder 1500~2000 times liquid, or 65% polyclonal wettable powder 800 times liquid. , or 50% sterilizing wet powder 500 times, etc. The spraying method is the same as for black pox.