Powdery mildew: preparations, control measures on cucumbers and onions
Powdery mildew, or peronosporosis is one of the most common diseases that affects various plants. This disease is fungal, and it causes its lower fungus Peronospora. The causative agent of this disease is preserved both in the seed material and in plant debris, and its activation is observed with a strong increase in air humidity, for example, during prolonged rains or in wet weather.
Features of the disease
In plants affected by downy mildew on the front surface of leaf plates, oily, round or angular spots of greenish-yellow color are formed, which are limited by veins. Later, a faint purple-gray tinge appears on the underside of the foliage. Over time, the spots become more and more connected with each other. As a result, the affected foliage becomes shriveled, wilts and dries, after which it crumbles into fragments that can transfer pathogens to plants located in the neighborhood. Due to the fact that the leaves of a diseased bush begin to die actively, the fruits set and develop more slowly than usual, while they become faded and lose their taste.
If the plant is severely affected by peronosporosis, then because of this it can die very quickly. All cultivated plants are affected by this disease: both vegetables, fruit shrubs and trees, as well as indoor and garden flowers. During one growing season, the disease can form up to 20 generations and spray more than one million zoospores. Various pests, such as aphids, whiteflies, etc., “help” peronosporosis.
Downy mildew control measures
To cure a plant affected by downy mildew, use a solution of sulfur (1 bucket of water from 50 to 80 grams). It is used to spray the plant itself, as well as the surface of the soil around it. The following fungicidal agents are also used to combat peronosporosis. preparations: Gamair, Alirin-B, Fitosporin-M, Planriz or Gliokladin. A garden or a garden plot with a solution of these funds is sprayed with an interval of 15 days. When about four weeks remain before harvesting, all spraying with fungicidal preparations will need to be stopped, and if necessary, treatment is continued with less toxic and safer folk remedies.
Please note that getting rid of this disease only by treating plants with fungicides will not succeed. You will also need to strictly adhere to the agrotechnical rules of various cultures, and also do not forget about measures for the prevention of the disease.
In order to prevent the appearance of plants affected by peronosporosis in their area, it is necessary to carry out preventive measures. For example, in autumn, when the entire crop will be harvested, the site is cleaned of plant debris, and the soil is dug up to a depth of 25 to 30 centimeters.
If last season on your site there were plants affected by peronosporosis, then in early spring it is recommended to treat the soil on the site with a solution of copper sulfate (2-3%) or manganese potassium (1%). After processing, compulsory digging of the soil is carried out. The following biological agents can also be used to disinfect the soil: Gamair, Fitosporin-M or Alirin-B.
In order to prevent downy mildew at the beginning of the spring before the buds bloom, the plants are treated with a solution of urea (7%), ammonium sulfate (15%) or ammonium nitrate (10%). Further, the trees are treated with a solution of Bordeaux mixture (1%): the first time - in the phase of the green cone, the second - at the end of flowering and the third - during the formation of the ovaries.Even after the plant fades, it can be processed with such biological products as: Haupsin, Gamair, Planriz, Integral or Mikosan. Also, Planriz biological product is used for processing, unlike other means, they can process plants even when only 1 day is left before harvesting.
In order to reduce the risk of crop damage by peronosporosis, they are not grown annually in the same area. For example, if cucumbers grow on a certain site this season, then it will be possible to grow the same crop on it again only after 3-5 years (no less). Otherwise, pathogens will accumulate in the soil, due to which the bushes will grow weak and painful.
Sowing material must be pre-sowed, for this it is kept in a solution of potassium permanganate (1%) or sprinkled in a thermos filled with warm (from 45 to 50 degrees) water for 15 minutes. Before planting seedlings in a greenhouse or in open ground, their root system is immersed for 2-3 hours in a solution of Trichodermin, which must be done according to the instructions (see packaging).
For cultivation, it is recommended to choose those types and varieties of crops that are resistant to fungal diseases. Plantings should not be too dense, and the crowns of shrubs and trees should be systematically thinned, because fungi grow and develop best in crowded conditions. Be sure to adhere to the agrotechnical rules of the crops and provide the plants with proper and timely care. Those plants that are very affected by peronosporosis are dug up and destroyed by fire.
Downy mildew on vegetables
Peronosporosis of cucumbers
Powdery mildew develops on cucumbers most often in August, since it is at this time that the air temperature decreases at night, as a result of which condensation appears on their foliage, which is considered an excellent medium for the propagation of fungal spores. Peronosporosis can develop on cucumbers due to the fact that there is too much nitrogen in the soil, or when plants lack phosphorus or potassium. Most often, peronosporosis develops on bushes of cucumbers growing in a greenhouse, since there are favorable conditions for the appearance of dew.
If the first symptoms of downy mildew are detected, the bushes growing in the greenhouse are sprayed with a solution of a fungicidal preparation, for example, Gold, copper oxychloride, Ridomil or Efal. Those bushes that grow in the open ground, it is recommended to process with such means as Kvadris, Strobi or Acrobat MTs. But remember that you need to process the cucumbers in a timely manner, if you are at least 2 days late, then you will not be able to save the plants. That is why special attention should be paid to preventive measures. If you do not forget about preventive measures, then cucumbers will be reliably protected both from downy mildew and from most fungal diseases.
- For cultivation, you need to choose those varieties that are resistant to peronosporosis, for example: Katyusha, Idol, Photon, Zodiac, Rodnichok, Debut or Golubchik.
- Seed material must be pre-sowed, for this it is immersed in warm (about 50 degrees) water for a quarter of an hour.
- Immediately before planting, the soil must be treated, for this use Gamair or Fitosporin-M. Then spend his deep digging.
- In the greenhouse you need to carefully monitor the level of humidity. Immediately after the detection of stained leaf plates, they should be cut with the petioles.
- To make plants less susceptible to pathogens, they are fed phosphorus and potassium. Remember that the soil should not contain too much nitrogen.
- Spray the bushes on a green leaf with a solution of the biological product Planriz, which is made on the basis of an extract of herbs.
How to save cucumbers from the disease. Peronosporosis.
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Peronosporosis of onion
As soon as the first symptoms of the disease are found on the onion, it is immediately stopped being fed with organics and fertilizers containing nitrogen. At the same time, onions should continue to be fed with potassium and phosphorus. Pause watering the beds for a while, this will help lower the moisture level.
To cure onions affected by peronosporosis, it should be treated with a solution of Bordeaux mixture (1%), a suspension of Polycarbacin or Arbamide. In order to prepare a suspension, combine 30 to 40 grams of Polycarbacin or Arbamide and a bucket of water. Re-treatment is carried out after 7-15 days. When 20 days remain before harvesting, treatments with the Bordeaux mixture are stopped. Remember that if the onion is treated with pesticides, then its greens are not used for food.
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Downy mildew on sunflower
If the sunflower is struck by downy mildew, then it has a growth lag, its stems do not thicken, and the root system does not develop. Chlorotic spots form on the front surface of the leaf plates, and a whitish tinge on the underside. Only a small part of the affected bushes reaches the flowering phase, while inflorescences on them form small ones with undeveloped small seeds. Experts have 6 forms of sunflower damage by peronosporosis. To cure the affected bushes, they are sprayed with such means as: Ridomil Gold, Amistar Extra, Pictor, Abacus and others of similar action.
In order to prevent sunflower damage by peronosporosis, it is necessary to adhere to the rules of crop rotation and crop farming.
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Downy mildew on shrubs
Grapes are also affected by peronosporosis, but in this case it is called mildew. For European grape varieties, this disease poses a very great danger. Mildew was introduced to the southern part of France in 1878 from North America. If you do not treat the affected grapes, then the damage from this for the vineyard can be significant.
The disease affects the upper parts of the stems, foliage, antennae, inflorescences, young fruits and ridges. To preserve the grapes, it will be necessary to carry out preventive treatment of the bushes in a timely manner, for this they use such means as: Cabrio TOP, Poliram, Acrobat TOP or Delan. The bushes are treated before flowering, and then in rains, plentiful and frequent dew, and with high humidity spraying is carried out 1 time in 7 days. If the weather is dry, then the treatment is carried out 1 time in 15-20 days. Throughout the season, grapes for prevention are sprayed 2-8 times.
Peronosporosis in garden flowers
Powdery mildew on roses
Unlike powdery mildew, which in roses first affects leaf plates located very close to the soil surface, peronosporosis initially affects the upper part of the plant. Roses fall ill when their buds are about the size of a pea. The disease develops very quickly, for example, even in the evening the bushes were absolutely healthy, and in the morning foliage was flying around them, and the flowering wave was disturbed. Brown spots are formed on the foliage of the affected plant on the foliage, and then a yellow border appears around them. Foliage from a rose flies almost immediately after the appearance of spots. However, this disease cannot destroy the rose.
If the bushes are grown in a greenhouse, then try to lower the level of humidity, for this, do not forget to turn on the heating every night. If bushes located in open ground are affected by peronosporosis, then air humidity cannot be reduced; in this case, the bushes can be sprayed with the following means: Ordan, Thanos, Ridomil, Previkur, Acrobat, Consento or Revus.
Downy mildew. How to fight and extend the harvest of cucumbers
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Downy mildew on indoor plants
Indoor plants are also affected by peronosporosis. On the front surface of the foliage, yellow spots are formed in an irregular shape, with time they become darker and become necrotic. A gray coating appears on the underside of the sheet plates, which eventually turns black. Yellowing and dying of foliage are also observed. The disease develops very actively in heavy and acidic soil mixtures, and the plant suffers especially severely in crowded areas and with insufficient ventilation on shelves or window sills.
They struggle with downy mildew on indoor plants in the same ways as in garden crops, for example:
- Obligatory pre-sowing preparation of seeds. To do this, they are immersed in very warm (about 50 degrees) water for a quarter of an hour.
- Cut off all diseased leaf plates from the bush.
- The flower must be sprayed with a pesticide 5 times with an interval of 7 days, for this they use a solution of Bordeaux mixture (1%), Kuproksat, Bravo, Oksikhoma, Ordana or Kvdris.
Means of downy mildew (preparations)
From peronosporosis, both folk remedies and chemical preparations are used, and more precisely, fungicides. The following pesticides are most popular among gardeners and gardeners:
- Acrobat MC. This drug is a contact and systemic local action, which is very toxic to humans.
- Alirin-B. Such a biological agent suppresses fungal diseases both in the soil and on plants. Its action is very similar to Fitosporin-M.
- Bordeaux fluid. Contact drug of a wide spectrum of action, very toxic to humans.
- Gamair. It is a biological bactericide that is used to combat bacterial and fungal diseases both on crops and in the ground.
- Glyocladin. This biological product actively fights pathogens of fungal diseases. It is an analogue of Trichodermin.
- Oksihom. Systemic-contact preparation of a wide spectrum of action, is highly toxic to humans.
- Polycarbacin. This is a systemic drug of therapeutic and prophylactic action. It is used for processing vegetables and fruit crops.
- Bravo. Contact protective agent. The duration of its action is from 1.5 to 2 weeks.
- Previkur. The systemic preparation has a wide spectrum of action and is used in the fight against downy mildew and root rot.
- The order. Such a contact-systemic drug for humans is moderately dangerous.
- Ridomil Gold. Contact system tool. Very toxic to humans.
- Trichodermin. This biological agent is used to protect and treat root diseases. They process both indoor and decorative plants.
- Fitosporin-M. Contact microbiological preparation used to protect crops from various fungal diseases.
- Quadris. Systemic preparation of protective and therapeutic action. It has one unusual property - prolonging the fruiting of plants for 15–20 days.
- Revus TOP. This tool is used both for treatment and for the prevention of fungal diseases.
After the ripening of fruits on trees, as well as vegetables and berries, all spraying of crops with pesticides that are dangerous to human health is stopped. However, the processing of crops must be continued, but for this they are already using folk remedies that are also capable of combating downy mildew.
There are several very effective folk remedies that are used by many gardeners and gardeners in the fight against peronosporosis:
- Mix a liter of skim milk and 9 liters of water. In the resulting mixture, pour 10 drops of iodine (5%). This solution is used to treat any crops.
- Pour a couple of glasses of wood ash into the container and fill them with 2-3 liters of freshly boiled water.The cooled mixture, filtered through a napkin, folded 3-4 times, is poured into 10 liters of water.
- A solution of manganese potassium fights very well against downy mildew; for its preparation, a bucket of water with 1–2 g of substance is combined.
- When the disease is at the initial stage of development, then you can try to cope with it with infusion prepared from onion husks. Combine 10 liters of water with 0.2-0.3 kg of onion husks, put the mixture on fire and let it boil. Remove it from the stove and leave for 2 days to insist. Strained broth is used to treat plants.
- Useful microflora develops in manure, which is able to destroy pathogens, which is why it is often used to prepare funds for downy mildew. Combine water with mullein in a ratio of 3: 1. The infusion will be ready after 3 or 4 days. The filtered product is diluted with such an amount of water so that the final solution volume is 7–8 liters. The composition is sprayed with foliage of crops in the evening or on a cloudy day.
Here it is PERNOSPOROZ cucumber and vegetable marrow. Why do cucumber leaves turn yellow.
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