What are the common grape diseases and how should they be prevented and controlled?
Grape is one of the common fruits. It is not only delicious but also highly nutritious, and it is widely planted in our country. During its growth, it may encounter diseases, and if prevention and control are not timely, its yield and quality will be affected. So, what are the common grape diseases? How should they be prevented and controlled?
1. What are the common grape diseases?
Anthracnose, downy mildew, powdery mildew, and brown spot disease are common grape diseases.
2. How should the common grape diseases be prevented and controlled?
1. Grape anthracnose
Symptoms: Small brown round spots appear at the infected sites, gradually expand and become sunken. On the lesions, concentric ring-like nearly circular lines form, and neatly arranged small black dots appear. They can spread to the entire berry surface. The diseased berries gradually shrink and dry into mummified fruit, and sometimes an entire cluster shrinks and dries into a mummified cluster.
Prevention and control methods:
(1) Thoroughly remove diseased clusters, diseased vines, and diseased leaves to reduce inoculum sources. In areas south of the Yangtze River, bagging can be done immediately after petal fall.
(2) Strengthen cultivation management, promptly prune, tie vines, and pinch tips so that the trellis surface is well ventilated. Increase the application of phosphorus and potassium fertilizers and control the amount of nitrogen fertilizer.
(3) At the budbreak stage when buds form a fluffy ball, spray once with 0.3% sodium pentachlorophenate plus 4 degrees Baumé lime sulfur mixture, or 150 times thiram arsenic, or 100 times thiram as an eradicant.
(4) In the south from late April and in the north from late May, carry out chemical spraying for prevention and control. You can spray 80% anthracnose thiram at 700-800 times dilution, 50% chlorothalonil at 600-700 times dilution, or 50% thiram or mancozeb at 800 times dilution.
2. Grape downy mildew
Symptoms: On the leaf surface, small oily-looking spots appear at the damaged sites. After the small spots slowly expand, pale yellow angular spots appear, then further turn brown, causing the leaves to wither. If the growing environment is relatively humid, a layer of white downy mildew will also appear on the affected spots on the leaf surface, and then they gradually turn brown and dry up.
Prevention and control methods:
(1) Strengthen cultivation management, apply more organic fertilizer, strengthen tree vigor, and improve disease resistance; promptly pinch tips, thin out overly dense branches and leaves, and tie vines to maintain good ventilation and light transmission, which can reduce disease occurrence.
(2) Pay attention to orchard sanitation, remove diseased residues, and burn them in a centralized manner or bury them deeply to reduce inoculum sources.
(3) Before budbreak, spray once with 3-5 degrees Baumé lime sulfur mixture; after budbreak, spray 0.2-0.5 degrees Baumé lime sulfur mixture, or 50% thiophanate at 500 times dilution, or 70% thiophanate-methyl at 1000 times dilution, or 25% triadimefon wettable powder at 1000 times dilution.
3. Grape powdery mildew
Symptoms: Damage to the fruit causes the greatest loss. First, a layer of grayish-white powdery mildew forms on the surface of the berries. When the white powder is wiped off, the epidermis shows brown patterns, and finally the epidermal cells turn dark brown.
Prevention and control methods:
(1) Strengthen cultivation management, apply more organic fertilizer, strengthen tree vigor, and improve disease resistance; promptly pinch tips, thin out overly dense branches and leaves, and tie vines to maintain good ventilation and light transmission, which can reduce disease occurrence.
(2) Pay attention to orchard sanitation, remove diseased residues, and burn them in a centralized manner or bury them deeply to reduce inoculum sources.
(3) Before budbreak, spray once with 3-5 degrees Baumé lime sulfur mixture; after budbreak, spray 0.2-0.5 degrees Baumé lime sulfur mixture, or 50% thiophanate at 500 times dilution, or 70% thiophanate-methyl at 1000 times dilution, or 25% triadimefon wettable powder at 1000 times dilution.
4. Grape brown spot disease
Symptoms: It mainly damages leaves. At the initial stage of infection, the infected spots appear light brown, irregular angular spots. The lesions gradually expand, with a diameter of up to 1 cm. The lesions change from light brown to brown, and then to reddish brown, with a yellow-green margin. In severe cases, several spots connect into large spots with clear edges, while the margins on the underside of the leaf are blurred. In the later stage, the diseased parts die, and grayish-brown mold-like matter appears during rainy periods or when humidity is high.
Prevention and control methods:
(1) Thoroughly remove dead branches and fallen leaves to reduce disease sources, apply fertilizer reasonably, and prune scientifically.
(2) Before budbreak, spray 3-5 degrees lime sulfur mixture.
(3) Chemical control. You can spray 50% carbendazim at 500 times dilution, chlorothalonil at 600-800 times dilution, or 70% thiophanate at 800-1000 times dilution in alternation, spraying once every 10-15 days.
In general, “prevention first, integrated control” is the basic principle for grape disease and pest control. During production, it is necessary to observe the dynamics of disease occurrence at all times and achieve early prevention.