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Of fungal infections, powdery mildew is common on onions, every vegetable grower should know how to deal with it. Otherwise, the disease will begin to progress, spreading to neighboring plants. Zucchini, cucumbers, pumpkin suffer the most from pathology. You can save the crop by applying measures to combat pathogenic microorganisms. They use treatment with both chemical and folk remedies. You need to know the symptoms of the disease, why it appears and how to avoid infection.
Description of the disease
As soon as they do not call powdery mildew, and ash, and linen. Of the fungal diseases that affect both vegetable and berry crops, powdery mildew is the most common. The fungus parasitizes vegetation, multiplying by spores, similar to miniature brown balls. The name of the disease reflects the main symptom of infection.
In addition to the true disease, downy mildew, or peronosporosis, is also found on vegetables. The types of pathology differ in the location of the white plaque. In powdery mildew, infection of the plant begins from the outside of the leaf, in the false - from the inside.
But the mechanism of the effect of spores on the plant organism is the same. Absorbing the pulp of the green parts, which is rapidly necessary for vital activity, the fungus develops.
Parasitizing onions, mycelium depletes the plant. With raindrops, wind blows, spores pass to other plants... They are carried by the gardeners themselves, not observing the rules of care. From the moment of infection, it lasts from 5 days, as the first symptoms appear. Among the signs of the disease is not only the appearance of white plaque. The leaves, as if doused with lime, turn yellow. Necrotic brown spots appear on the stems, which indicates the neglect of the pathological process.
Conidia keep well in the harvested crop. In rooms with temperatures above 15 degrees Celsius and humidity of 85–90 percent, the infection spreads instantly. Therefore, protecting onions from powdery mildew is an important stage in the cultivation of vegetable crops.
Why does powdery mildew appear?
Fungal spores are spread when:
- Water the plants. If the onion is affected by powdery mildew, the microorganisms are blown into the healthy crops by splashing water.
- The weather is hot, accompanied by high humidity. The infection develops rapidly in rainy weather. The air is saturated with moisture vapor, which is favorable for the spread of powdery mildew. Conidia are formed 5–10 days after entering the plant. 15 degrees Celsius is enough for them to develop activity. Moreover, plant cells are weakened under such conditions.
- The plants are planted densely. By touching each other, the onion stalks take on the fruiting body of the fungus. This is how new lesions are formed. This happens in the beds where there is no access to fresh air, there is no wind movement.
- The earth contains a large amount of nitrogen.
- The vegetable garden has not been cleaned after digging up vegetables. Spores hibernate in plant debris, covered with snow, and retain their viability.
- Pests attack onion plantings. The carriers of the fungus are onion flies, nematodes, and aphids. By damaging plants, pests make them vulnerable to fungal infections.
- Seed material is infected. Spores remain on the seed, in order to then develop on the stems and leaves of the vegetable.
Whatever cause is causing the disease, you must get rid of it when the first signs appear.
What can you pour onions with?
The main task in a situation of how to deal with powdery mildew on onions is to reduce the lesion focus. Therefore, all parts of the plants, sprinkled with white bloom, are cut out, followed by burning. Diseased plants are removed from the garden, eliminating entirely.
At the initial stages of the development of powdery mildew, a spray preparation is prepared for plants. Potassium permanganate is diluted in warm water. The high concentration solution kills the spores of microorganisms. Destroys powdery mildew fungus and soda ash, a spoonful of which is dissolved in a bucket of water.
Another way to stop the spread of the disease is spraying with a solution of copper sulfate. Dissolving ten grams of the substance in half a liter of hot water, pour it into a bucket of warm water. So that the solutions used are better retained on the plants, add one hundred grams of laundry soap to a bucket of liquid. Use the processing of beds with onions 3-4 times a month.
Two weeks before harvesting onions, Bordeaux liquid is used, although many leave the remedy unattended. Vegetable growers believe that Bordeaux mixture is only suitable for disease prevention. Although a 1% drug copes well with powdery mildew at the beginning of the development of the disease.
How else can you save the bow?
When the first signs of a disease are detected, the plant:
- moistened with iodine tincture (10 ml), dissolved in ten liters of water;
- processed by Fitosporin for powdery mildew in a ratio of one gram per liter of liquid;
- sprayed with a mixture of copper sulfate (10 grams), soda ash (50 grams), laundry soap (200 grams) and two liters of water diluted in a bucket of water.
Chemicals and fungicides are more effective: Agrolekar, Chistoflor, Ridomil, Skor. Use the funds in accordance with the instructions. The drugs act against the fungus on the plant, on the bulbs. Fungicides are used to fight other fungal infections.
It is necessary to spray with chemicals three times during the growing season. You can repeat the procedure after one and a half to two weeks. But onion planting is processed twenty days before harvest. Processing of onions against powdery mildew is also carried out using folk remedies.
Folk remedies for powdery mildew
Vegetable growers have developed their own methods of how to deal with powdery mildew, use folk remedies to eliminate the disease.
To combat infection, weeds are pulled out, placed in a bucket and poured with boiling water. The infusion is prepared for several days, fermenting. After filtering, the onion feathers are sprayed with the finished medicine.
Another product is prepared from separated fermented milk whey, it is diluted with cold water in a ratio of 1:10. To enhance the effectiveness of the solution, add a teaspoon of copper sulfate.
An infusion of fresh mullein, diluted in water, is prepared for three days. After stirring, filter and add a liter to a bucket of water. Onions are treated with a folk remedy in the evening.
Infusions of tobacco or onion husks, which are made the day before processing, will help to cope with peronosporosis. Many gardeners advise saving bulbs infected with powdery mildew in a simple way. It is necessary to warm up the collected onion heads well in the sun, dry. Then the pathogenic fungi will die.
In order not to use chemical agents to combat powdery mildew, to make it easier for yourself, you need to think in advance about measures to prevent fungal infection.
Measures to prevent the appearance of powdery mildew on onions include:
- observance of the rules of crop rotation, without planting onions where the baton, shallots, garlic grew;
- preliminary soaking of seeds and seeding before planting in a solution of potassium permanganate;
- ensure air circulation in the beds, avoiding thickening of the plantings;
- disinfection of tools, devices for carrying out garden work without fear of infecting vegetables with powdery mildew;
- watering in the morning to allow the plants to dry out;
- the introduction of less nitrogenous fertilizers, and more mineral complexes with potassium and phosphorus.
As a preventive measure, the vegetable beds are sprayed with a solution of serum, an infusion of wood ash. During the season, any garden weeds are also used, sprinkling with infusion of planting a vegetable plant.
After digging up the ripe onions, dry stems and leaves are raked and destroyed. After all, pathogenic organisms are preserved in plant waste, which are activated in spring.
It is mandatory to carry out preventive treatments of the bulbs collected from the garden with fungicidal preparations.