Detailed Explanation of Grape Black Pox (Anthracnose) Control Techniques

Grape black pox, also known as grape scab and grape bird's eye disease, occurs in all production areas and is an important disease in grape production. The disease mainly damages the green, tender parts of the grape; leaves, petioles, fruit stalks, young shoots and young fruit can all be affected, and it can occur from bud break through the late growth stage. So what harmful symptoms does grape black pox have? What are the control techniques?

I. What harmful symptoms does grape black pox have?

1. Canes

On new shoots, the lesions first appear as small round brown spots, which later expand into long oval or irregular lesions, with edges ranging from purplish red to dark brown, grayish brown inside, and sunken and cracked in the center. Several lesions often join together into one patch, and the diseased shoot often dies because the lesions girdle it. The symptoms on tendrils, petioles, flower axes, fruit stalks and cluster stems are similar to those on new shoots. On thick canes, the lesions become larger cankers, lighter in color in the middle and cracked.

2. Leaves

Lesions on leaves first appear as blackish brown spots the size of a pinhead, surrounded by a yellowish brown halo; after expanding, the lesions are round or irregular, 1-4mm in diameter, with edges from purplish brown to blackish brown and a grayish white center, and they crack and perforate when dry. Sometimes lesions occur in strings along the veins; lesions on the veins are spindle-shaped and slightly sunken, and after the veins are damaged, the young leaves stop growing and become shrunken, twisted and deformed.

3. Fruit

On young fruit, small reddish brown to blackish brown round spots appear, and in the later stage the diseased parts often crack; affected berries mostly wither and turn black, then dry up and drop off. On grown berries, the lesions are round, 3-8mm in diameter, with edges from purplish brown to purplish red, brown inside and grayish white in the center, slightly sunken, resembling a bird's eye, and the surface becomes hardened and sometimes cracks. Multiple lesions can join into large patches; the lesions are limited to the fruit surface and do not penetrate into the fruit, but the fruit tastes sour and loses its edible value.

II. Control techniques for grape black pox

1. Use resistant varieties

Different varieties differ markedly in resistance to black pox. Before planting a vineyard, local production conditions should be considered, and varieties should be selected that are suitable for local planting, have relatively high market value and are comparatively resistant to the disease. For example, the Kyoho variety is moderately resistant to black pox; others such as Campbell Early, Delaware, Jifeng 14, White Banana, Baco, Seibel 2003, Seibel 2007, Italian Riesling, Crystal, Golden Queen, Lan Francais, Carignan and Jimsha are also relatively resistant to black pox, and can be chosen according to local conditions.

2. Winter orchard cleanup

Because the primary infection of black pox mainly comes from mycelium overwintering on diseased plant residues, doing a good job of winter orchard cleanup is of great significance for reducing the amount of primary inoculum and slowing the development of the disease. When pruning in winter, cut off diseased shoots and remaining diseased fruit, scrape off diseased and old bark, thoroughly remove dead branches, fallen leaves and rotten fruit from the orchard, and then burn them in a centralized manner. During the growing season, remove diseased shoots, diseased leaves and diseased fruit at any time and destroy them in a centralized manner.

3. Timely pruning

In the western Henan region, management is carried out using methods such as north-south oriented small trellises, single dragon trunk, short-spur or very short-shoot pruning, single-cane renewal, and bow-shaped vine tying. During the growing season, work such as bud removal, shoot thinning, branch training, pinching and leaf removal must also be done in time to prevent branches, vines and leaves from becoming too densely crowded, so that shoots, leaves and fruit maintain an appropriate ratio, thereby ensuring good ventilation and light penetration, healthy tree growth and enhanced disease resistance.

4. Bag the fruit clusters in time

Bagging the fruit clusters in time to isolate pathogens and protect young fruit is also an important measure for controlling black pox and producing pollution-free fruit.

5. Apply more organic fertilizer

Apply more decomposed organic fertilizer to ensure comprehensive nutrition and healthy growth of the tree. Pay attention to the amount of nitrogen used to prevent excessive late-season vegetative growth.