How to prevent and control grape pests and diseases? Latest technical method tutorial

Grapes are woody vines of the genus Vitis in the family Vitaceae, native to western Asia, and are now cultivated all over the world, but about 95% of the world's grapes are concentrated in the Northern Hemisphere. During grape cultivation, the main common diseases include black spot disease, powdery mildew, downy mildew, white scale insects and aphids, among others. Let's take a look at grape pest and disease control techniques together below!

Grape anthracnose

1. Symptoms: Grape anthracnose can infect fruits, canes, leaves and tendrils. Brown small round spots appear at the infected sites, gradually expand and become sunken, and concentric ring-like nearly circular lines form on the lesions, along with neatly arranged small black dots. These black dots are acervuli, and in humid weather the acervuli exude pink gelatinous masses of conidia. The lesions can expand to the entire fruit surface, and the diseased fruit gradually shrinks and dries into a mummy berry; sometimes an entire cluster shrinks and dries into a whole-cluster mummy.

2. Disease pattern: Infection generally begins in June, with the peak period from July to August, and the disease gradually worsens as the fruit approaches maturity. According to observations in Suzhou, diseased fruits appear half a month after flowering (about June 10-15), becoming the first disease peak of the year. Around August 10, because a large number of fruits mature, whenever there is muggy thundery rain, the disease enters its peak period, which is the most severe damage of the year.

3. Control methods

① Thoroughly remove diseased clusters, diseased canes and diseased leaves to reduce the source of inoculum. In areas south of the Yangtze River, bagging can be done immediately after flowering.

② Strengthen cultivation management, promptly train shoots, tie canes and pinch tips so that the trellis surface is well ventilated. Increase phosphorus and potassium fertilizer and control the amount of nitrogen fertilizer.

③ At the bud-burst cotton-ball stage, spray once with 0.3% sodium pentachlorophenate plus 4-degree lime sulfur mixture, or 150 times Bordeaux mixture of asomate, or 100 times thiram as an eradicant.

④ In the south from late April, and in the north from late May, begin spraying for control, then generally spray once every 10-15 days, using 80% anthracnose thiram 700-800 times solution, 50% chlorothalonil 600-700 times solution, 50% thiram or mancozeb 800 times solution. In the south where there is more rain, add “6501” at 1500 times or 0.03-0.05% skin glue and other adhesives to the spray solution.

Grape white rot

1. Symptoms: On fruit stalks and cluster stems, the diseased sites first produce light brown water-soaked nearly circular lesions; later, grayish-white small granular pycnidia appear on the surface of diseased berries and diseased parts of the cluster stem. When humidity is high, grayish-white masses of conidia overflow from the pycnidia. Diseased fruits tend to drop, and when dried and shrunk they become brown or grayish-white mummy berries. On canes, the initial disease shows water-soaked light brown lesions of variable shape; the lesions mostly extend longitudinally into large brown sunken spots, with grayish-white granular pycnidia on the epidermis. Later, the epidermis of the diseased part splits longitudinally and separates from the woody part, the epidermis falls off, and the vascular bundles appear brown and tangled like hemp. When a lesion extends around the entire circumference of a cane's epidermis, the cane above it dies. Leaf disease mostly occurs at the leaf margins, initially as brown water-soaked irregular lesions that gradually enlarge and become slightly circular with brown concentric rings.

2. Disease pattern: It occurs favorably at 28-30°C and atmospheric humidity above 95%. The disease is severe in hot, humid and rainy seasons, with a disease peak after rain. In the north, it can occur from June to the harvest period, increases during fruit coloring, and peaks after storms. The disease is severe near the ground and under conditions of heavy clay soil, low-lying terrain and poor drainage; it is prone to occur when weeds are overgrown, branches and leaves are dense, or humidity is high; and vigorously growing and leggy plants are susceptible.

3. Control methods

① Thoroughly remove diseased canes, diseased clusters and diseased leaves.

② Prune promptly, raise the fruiting position, weed promptly, pay attention to drainage, and strictly prohibit applying nitrogen fertilizer before flowering to leggy plants.

③ In the north, after grapes are uncovered from the soil, spray 5-degree lime sulfur mixture or 100 times chlorothalonil; from the young fruit stage (early June), spray once about every 15 days for preventive control until harvest. In the south, focus on control during the inflorescence separation stage (late April to early May), 7 days after flowering, and half a month before maturity. The main agents include half-strength, equal-strength or double-strength Bordeaux mixture, 75% chlorothalonil 800 times solution, 50% carbendazim wettable powder 700 times solution, 70% thiophanate 700 times solution or 50% thiram 800 times solution.

④ White rot occurs relatively lightly on Kyoho grapes. In the south, develop varieties with a maturity period earlier than Kyoho as much as possible, or use forcing cultivation to avoid the peak period of white rot.

Grape downy mildew

1. Symptoms: Grape downy mildew mainly damages leaves, new shoots and young fruits. On affected leaves, small light yellowish-brown water-soaked spots with indistinct edges first appear, and the lesions gradually expand into irregular or slightly circular large yellowish-brown spots. The lesions become reddish-brown or yellowish-brown; in severe cases the lesions and the leaf tissue outside them dry up, or the entire leaf dries up and drops. On affected new shoots, water-soaked brown spots appear; in severe cases the new shoots become distorted, stop growing and even die, and in high humidity a frosty mold layer forms on the lesions. Tendrils, petioles and cluster stems can also be affected. After young fruits are affected, water-soaked light brown spots appear; in high humidity a grayish-white mold layer forms on the young fruits and fruit stalks, and second-crop fruits in autumn suffer more severely. After the fruit colors, damage is relatively light.

2. Disease pattern: This disease is prone to major outbreaks in autumn with much rain, much dew and low temperatures. Poor ventilation in the vineyard, high humidity and excessive nitrogen fertilizer favor the disease. In the north it can generally occur in June, with the peak period from August to September. In areas south of the Yangtze River, there are 2-3 disease peaks throughout the year: the first during the plum rain season, and the second in mid-to-late August. In some years, another peak also appears from mid-September to early October.

3. Control methods

① Remove fallen leaves and diseased branches, bury or burn them. Promptly pinch tips, prune, drain and weed, and increase phosphorus and potassium fertilizer.

② Spraying should begin at the early stage of disease; in the north it generally starts in early to mid-June, spraying once every 15 days. 25% metalaxyl or domestic metalaxyl 600 times solution has the best control effect; 40% fosetyl-aluminum 300 times solution, 90% fosetyl-aluminum 500 times solution or 1:0.5:200 Bordeaux mixture also have relatively good control effects. In areas south of the Yangtze River, before early autumn spraying can in principle be combined with control of black spot disease; before disease occurs, Bordeaux mixture has the best control effect, and if downy mildew occurs, spray 25% metalaxyl 700 times solution or 90% fosetyl-aluminum 500 times solution in time.

Grape black spot disease

1. Symptoms: The disease damages young fruits, new shoots, leaves, tendrils and other green young parts of grapes. On affected young fruits, brown small round spots first appear on the fruit surface, then gradually expand, and later the center of the lesion becomes grayish-white. On affected new shoots, tendrils, petioles and fruit stalks, brown circular or irregular small spots first appear, then expand into nearly oval shapes. On canes, canker spots form, and diseased shoots stop growing, wither, dry and turn black. On affected young leaves, brown or black small spots the size of a needle head first appear.

2. Disease pattern: The pathogen overwinters as mycelium in canker spots on diseased shoots and can also overwinter in diseased fruits and diseased scars. In May of the following year it produces conidia, which spread by wind and rain to cause primary infection. Long-distance spread is mainly through nursery stock and cuttings. After grape buds break in spring until September, the disease can occur.

3. Control methods

① In combination with summer pruning or throughout the entire growing season, thoroughly cut off diseased shoots and remove diseased fruits and diseased leaves; after autumn pruning, thoroughly clean up dead branches and fallen leaves, burn them in a centralized manner and bury them deeply, so as to reduce the source of inoculum to the greatest extent.

② Reasonably increase potassium fertilizer to prevent leggy growth of the plants, strengthen tree vigor and improve disease resistance; the trellis surface should be reasonable to maintain good ventilation and light conditions.

③ In spring, before the plants are uncovered from the soil and sprout, spray 200 times sodium pentachlorophenate solution, or 3-5 Baume lime sulfur mixture. During the growing period, spray 1:0.5:200-240 Bordeaux mixture once each before and after flowering. Other agents include 75% chlorothalonil 500 times solution, or 50% carbendazim 1000 times solution.