What are the small black spots on grape leaves?

Grape blight is also known as grape blight. It is distributed in Liaoning, Hebei, Henan, Shandong, Anhui, Jiangsu, Zhejiang and other provinces. The disease is not serious in normal years, but it is severe in high temperature and high humidity environmental conditions, if the orchard is poorly managed and the tree is weak.

1) Symptoms. It mainly harms the fruit and cob, and can also harm the leaves in severe cases. At the beginning of the disease, the base of the small fruit stalk is dark yellow, the edge has a brown to dark brown halo, the lesion gradually expands, the color becomes brown, when the lesion around the fruit peduncle for a week, the small fruit stalk is dried up, and the fungus often spreads from the small fruit stalk to the cob.

The disease of the fruit grains, initially from the fruit pedicle part of the water loss wilting, the appearance of irregular brown lesions, gradually expand to the whole fruit, so that the fruit turns purple and black, after the loss of water and shrinks, it becomes a stiff fruit, and on the surface of the fruit grows sparse small black spots, that is, the conidia of the pathogen. After the cob dries up, all the fruit spikes below the diseased part turn into black stiff fruits, which are not easy to fall off when hung on the vine. When the leaves are diseased, small round spots appear, and after gradually expanding, the edges of the lesions are brown, the middle part is gray-white, and the later lesions are scattered with small black spots.

Generally, the color of the diseased fruits of grape house blight and grape white rot is similar, and it is difficult to distinguish them, but the diseased fruits of grape house blight grow small black spots after shrinking, and the distribution is sparse, and the small black spots are larger, and the diseased fruits are not easy to fall off. The diseased fruit of grape white rot has gray-white small grain spots before drying out, which is densely distributed, the particles are small, and the diseased fruit is easy to fall off.

2) Onset conditions. The grape blight overwinters on diseased fruits and leaves with conidia and ascomycetes, and radiates conidia and ascospores in March and July of the following year. Conidia and cystspores are transmitted to the host by wind and rain, which is the first infection of the fungus.

The conidia germinate at 24 28 and can germinate after 4 hours. Ascospores germinate at 25 hours and take 5 hours. The temperature is between 9 and 40, and the pathogen can grow and develop, but 35 is the most suitable.

Although the growth and development of the pathogen itself requires a higher temperature, the temperature at which the pathogen invades the host is often lower than the temperature of normal growth and development. Therefore, in July and September, the temperature can be in the range of 13 35, but 24 28 is the most suitable for the occurrence of blight.

3) Prevention and control methods.

Clean up the countryside. After the autumn defoliation, it is necessary to pay attention to collecting and cleaning up the remains of diseased plants and sweeping away the fallen leaves in the field, and burning them intensively or burying them deeply to reduce the initial pathogen in the second year**.

Spray protection. Generally, spray the first time after the grapes fall into flowering, and then spray 1 time every half month, a total of 3 5 sprays, and pay attention to making the fruit ears evenly sprayed. The commonly used agent is 1::200 Bordeaux liquid.

Strengthen cultivation management. The orchard drains water in time and increases fertilizer to promote the growth of the tree and improve the disease resistance of the tree. In areas with severe disease, disease-resistant varieties can be cultivated.

In terms of disease resistance of grape varieties, grapes in the Eurasian system are generally more susceptible to this disease; The Grape Disease in the Americas system is milder. The disease occurs severely in the conditions of damp, poorly managed, and weakened orchards.

Cockscomb leaf spot (also known as brown spot) infects leaves, petioles and stems. The lesions on the leaves are rounded and enlarged later.

It is irregular and large, and produces ring lines, and the lesions change from reddish-brown to black-brown, **gray-brown. on the stem and petioles.

The lesions are brown and elongated.

Fishtail sunflower leaf spot (also known as black spot). Small round black-brown spots are produced on the leaves, and then enlarged or diseased spots appear as irregular large patches, with slightly raised edges and small black spots scattered on both sides of the leaves.

In general, leaf spot is common.

Prevention and control methods]:

Remove the diseased tissue in time and burn it intensively.

Crop rotation (soil can be changed in greenhouses).

Plants should not be sprayed.

Spraying starts at the early stage of the disease to prevent the spread of the disease. Commonly used agents are 300-600 times of 25% carbendazim wettable powder (1000 times of 50%, 600-800 times of 40% suspension), 1000 times of 50% tobuzin, 500 times of 70% mancozeb, 400-600 times of 80% mancozeb, 500 times of 50% cloxindan, etc. It is necessary to pay attention to the alternate use of pesticides to avoid the development of antimicrobial resistance by germs.

I look at the fourth method

Black spots on grapes are small spots left by the invasion of germs.

Black spots on grapes are caused by grape anthracnose. It mainly harms the fruit close to maturity, so it is also called "late rot" pathogen, which damages the stem and shaft of the fruit, and the top of the panicle near the ground is the first to disease.

After the fruit is damaged, small brown round spots the size of needles appear on the surface of the fruit, and then the lesions gradually expand and depression, and many small black spots arranged in a wheel-like arrangement appear on the surface, that is, the umbilicus of the pathogenic bacteria. In wet weather, the most noticeable feature is the appearance of pink colloidal conidia. In severe cases, the lesions can spread to the entire surface of the fruit.

In the later stages of infection, the fruit will rot and fall off, or it will gradually lose water and shrink into a frozen fruit. The stem and shaft of the fruit are diseased, producing black-brown rectangular dimples, and in severe cases, the entire spike will dry up or fall off.

Precautions against grape anthracnose:

1. Seedling disinfection:

Grape anthracnose is transmitted mainly through seedlings. Therefore, the vineyard should select disease-free seedlings and regularly disinfect the seedlings to prevent the seedlings from being infected with diseases. Use ammonium sulfate solution, copper sulfate solution and other seedling disinfectants, soak the seedlings in the disinfectant for three to five minutes, take them out, and then plant the seedlings.

2.Clearing the orchard:

The first infect of grape anthracnose comes mainly from the mycelium of overwintering organisms. Clean well in winter and kill diseases directly in swaddling clothes, so as to reduce the number of plants infected by diseases. When pruning in winter, cut off diseased branches and fruits, remove dead branches and leaves, and then concentrate on treatment.

Agents such as limestone-sulfur mixtures are sprayed on the land surrounding the fruit trees.

3.Disease-resistant varieties:

Different grape varieties have different resistance to grape anthracnose. For example, varieties such as Combare and Rose Dew are very resistant to black pox. Choosing disease-resistant varieties that are suitable for local growing conditions can reduce the occurrence of black pox and play a key role in improving the quality and yield of grapes, thereby increasing farmers' economic income and avoiding greater economic losses.

4.Fertilizer and water management:

Strengthening fertilizer and water management plays an important role in reducing the occurrence of grape anthracnose. Trenches should be made before and after the grapes are planted to effectively play the role of organic fertilizer, which is conducive to maintaining the vigorous growth of the trees. When topdressing, the use of compound fertilizers containing nitrogen, phosphorus and potassium helps to replenish the nutrients required by plants in time.

Black spots on grapes can be insect infestation or pesticide infestation.

Grapes are highly susceptible to disease, especially grapes grown in the open air, so it is best not to eat them.

If you want to eat grapes, you can buy one that is grown in a greenhouse or in a rain shelter, which is a little safer.

Grape Coal Point Disease:

When the fruit grows and begins to soften, small black dots with a diameter of millimeters appear in the chaotic wheel of the fruit shed, scattering like fly droppings.

It does not harm the pulp, and the diseased fruit does not rot. However, the green fruit surface has obvious black spots. The diseased spores are scattered on the fruit surface, and the mycelium secretes decomposition enzymes to decompose the chain letter fruit powder after germination, and the mycelium covers the fruit surface, and when the fruit powder disappears, the appearance of the fruit is damaged.

The onset of new shoots is also accompanied by small black spots.

It may be that the grapes are rotten, they may be too ripe or they have gone bad in the area that has been touched by insects, so it is best not to eat those spoiled grapes.

<> small black spots on the grapes may be caused by black pox or anthrax. Symptoms of black pox: small reddish-brown to black-brown spots of pin-eye size appear on the leaves in the early stage of the disease, and will spread to the berries in the middle and late stages, and the berries will appear nearly round light brown spots after damage, and the spots will gradually turn black.

Symptoms of anthrax: Berries are damaged with small brown spots that are watery and develop into dark brown spots.

If there are black spots on the grapes, you can use chemicals such as difenoconazole to prevent and control black pox, and spray them continuously for two days in a row for two days, so that the occurrence of the disease can be controlled, and then the disease can be completely solved by using a preventive plan.

Preventive measures for black pox.

1. Seedling disinfection:

Black pox is transmitted mainly through diseased seedlings. Therefore, the vineyard should choose disease-free seedlings and disinfect the seedlings regularly, so as to prevent the seedlings from being infected with diseases. Use Bisong seedling disinfectant such as ammonium sulfate solution, copper sulfate solution, etc., soak the seedlings in the disinfectant for three to five minutes and then take them out, and then plant the seedlings.

2. Clean up the orchard.

The primary infection of the disease mainly comes from the mycelium on the diseased remnants that have overwintered. Do a good job of cleaning up in winter to directly strangle the disease in the swaddling clothes, so as to reduce the number of infected plants. When pruning in winter, prune off diseased branches and fruits, remove dead branches and leaves, and then concentrate on treatment.

Use an eradicator such as a mespar sulfur mixture to spray on the land around the fruit trees.

3. Disease-resistant varieties.

Different varieties of grapes have different resistance to black pox. For example, if there is a lack of a number of beats, Combar, rose dew and other varieties have strong resistance to black pox. Choosing disease-resistant varieties suitable for local planting conditions can reduce the incidence of black pox and play a key role in improving grape quality and yield, thereby increasing farmers' economic income and avoiding large economic losses.

4. Fertilizer and water management.

Strengthening fertilizer and water management plays a vital role in reducing the incidence of black pox. Before planting and after harvesting, the grapes should be effectively used as organic fertilizer by ditching, which is conducive to maintaining the growth of the tree, and when topdressing, the use of compound fertilizer containing nitrogen, phosphorus and potassium is conducive to timely replenishment of the nutrients required by the plants.