It may be caused by grape anthracnose and grape black pox.

Matters needing attention in growing grapes:

First, after the grapes germinate, the extra branches and buds should be wiped off according to the size of the space. When the branch blooms, that is, when it grows to 10- 12 leaves, 8- 10 leaves are reserved and the top is removed. For branches without ear, 10- 12 leaves can be left for coring, and the top two or three leaves are left in the axils of leaves, and coring can be carried out when the leaves are slightly longer than four or five leaves. This work is carried out about three or four times a year.

Second, disinfection and sterilization to prevent the invasion of germs: Grape trees, like other fruit trees, will have a variety of cortical diseases. If not treated in time, it will affect the growth of trees and the development of fruits. Spray orchards, trunks and branches with 1000 times Guan Shu solution in time to prevent and control airborne diseases and disinfect plants.

Third, pay attention to disease prevention. Grapes are planted in the south, with many diseases. The most serious diseases are black pox, gray mold and anthracnose, followed by brown spot, downy mildew and white rot. Therefore, in addition to selecting European and American hybrids with strong disease resistance, it is necessary to strengthen the prevention and control of diseases, focusing on prevention. All kinds of grape germs are spread by wind and rain. Every time it rains 1 time, it means that the vine is infected 1 time. Therefore, after the rain, it is necessary to spray the medicine in time. Bactericidal drugs include thiram, thiophanate-methyl, chlorothalonil, antiviral alum, carbendazim, carbendazim, mancozeb and so on. The concentration is generally 600 times to 800 times. If the grapes are diseased, the concentration can be higher. The above drugs should be used in rotation to avoid drug resistance.

Fourth, when it begins to grow vines, it should be trimmed properly. Make it grow better, or make its tree look better. When grapes begin to blossom, you should consider pests and diseases. At this time, there are the most bugs, eating buds. In this case, there will be no grapes growing, so you should apply pesticides to the grapes regularly. When small grapes grow, you should give them pesticides regularly, but don't give them pesticides when there are no bugs.