There are more than 30 known grape diseases. Among them, sour rot, anthrax and powdery mildew are the most common diseases. If we know more about grape diseases, we can improve grape growing environment, promote grape yield and improve economic benefits.
Grape Sour Rot
Sour rot is usually caused by the mixture of acetic acid bacteria, yeasts, fungi, Drosophila larvae, and other microorganisms. It is a serious disease that can reduce grape yield by 30%-80%.
Symptom: There are rotten grapes, if it is bagged grapes, under the bags there is a dark moist, while there are vinegar flies around the rotten ears, emitting acetic acid taste. White maggots can be seen in the rotten fruit. As the rotten juice flows out, the place where the juice flows will rot.
Site of Occurrence：fruit
Occurrence Stage：After grape sealing→When grapes are colored
Best Prevention Time：Staining to Maturity
Grape Powdery Mildew
Powdery mildew is a common disease of many plant species and belongs to the fungal disease of the genus Leptospira of ascomycetes. Mycelium overwinters in the injured tissue or between buds and scales.
In the second year, when the conditions are suitable, spores are produced and transmitted by wind and insects, which infect young tissues such as leaves, fruits and vines. In severe cases, white powders are covered with leaves, branches and fruits, resulting in leaf curling, withering, small and sour fruits.
Grape Anthracnose
Grape Anthracnose is a fungal disease of the genus Anthracnose. The pathogen overwinters by mycelium in the surface tissues of annual branches and diseased fruits or in leaf scars, panicle stalks and joints. It usually occurs in colored or nearly ripe fruits. In the grape field, anthrax is known as bird’s eye rot disease. It is a fungal disease. Fruit grains are soft rotten and easy to fall off. In hot and rainy years, it is easy to spread in vineyards. Grapes infected with anthrax are ugly and have low commercial value.
Symptom: Brown lesions on leaves and stems may be the first symptom of grapevine anthracnose, a disease similar to hail damage that produces necrotic, irregular spots with dark halos. The infected part cracks, causing the grapevine to become brittle. Over time, these spots accumulate into more significant depressions and may have reddish-brown raised margins. These ridges distinguish fungi from hail damage and may occur on either side of stems and leaves. In fruits, the center is light gray, with thick dark edges around it.
Grape Grey Mold
Grape gray mold damages the inflorescence and fruit, and sometimes also damages the leaves and new branches. The inflorescence seems to be scalded by hot water at the initial stage. Fall off.
The fruit is susceptible in the near-maturity period, and the light brown sunken spots appear first, which quickly spread to the whole fruit and make the fruit rot.
When the disease is severe, the new shoot leaves can also be infected, producing irregular brown spots, and sometimes irregular ring patterns appear in the spots.
During storage, if infected by pathogens, the berries will change color and rot, sometimes producing black sclerotia on the surface of the fruit stem.
Grape Brown Spot
Grape brown spot is caused by the infection of Pseudocercerospora vulgaris, which mainly damages the leaves. The infection point shows light brown, irregular horn-like spots at the initial stage of onset. It is clear, the periphery of the back of the leaf is fuzzy, the diseased part dies in the later stage, and the gray-brown mold appears when it is rainy or humid.
Small brown spot disease is caused by the parasitism of Cercospora sylvestris, and small yellow-green round spots appear at the infection point and gradually expand into 2 to 3 mm round spots. The diseased spots gradually withered, and a black mold layer appeared on the back of the diseased spots.
The conidia of the brown spot disease fungus have a long lifespan and can adhere to the surface of branches and vines for overwintering, spread by wind and rain, and germinate under high humidity conditions.
Grape Black Rot
Grape black rot mainly occurs on fruits, leaves, petioles, and new shoots. After the fruit is injured, small purple-brown spots appear at the initial stage of the disease. After gradually expanding, the edge is brown, the center is gray-white and slightly sunken. The diseased fruit is soft and rotten and then becomes a dry shrunken fruit. When the leaves are onset, small reddish-brown spots are produced at the initial stage, which gradually expands into nearly circular lesions.
The center is gray-white, the outer edge is brown, and the edge is dark-brown. There are many small black protrusions on it, which are discharged into a ring. The damaged part of the new shoots has brown oval lesions with a depression in the center and small black granular protrusions on it.