Powdery mildew is a common fungal infection on onions; every vegetable grower should know how to fight it. Otherwise, the disease will begin to progress, spreading to neighboring plants. Zucchini, cucumbers, and pumpkin suffer the most from pathology. You can save the crop by taking measures to combat pathogenic microorganisms. They use both chemical and folk treatments. You need to know the symptoms of the disease, why it appears and how to avoid infection.
Description of the disease
Powdery mildew is called as well as ash and white.Of the fungal diseases that affect both vegetable and berry crops, powdery mildew is the most common. The fungus parasitizes vegetation, reproducing by spores that look like miniature brown balls. The name of the disease reflects the main symptom of infection.
In addition to the true disease, downy mildew, or downy mildew, or downy mildew, is also found on vegetables. The types of pathology differ in the location of the white plaque. In true powdery mildew, infection of the plant begins from the outside of the leaf, while in downy mildew, from the inside.
But the mechanism of action of spores on the plant body is the same. Absorbing the pulp of the green parts, which is rapidly necessary for life, the fungus develops.
By parasitizing onions, the mycelium depletes the plant. With raindrops and wind, spores spread to other plants. They are carried by gardeners themselves, without following the rules of care. From the moment of infection it lasts from 5 days until the first symptoms appear. Among the signs of the disease is not only the appearance of white plaque. The leaves, as if covered in limescale, turn yellow. Necrotic brown spots appear on the stems, which indicates the neglect of the pathological process.
Conidia are well preserved in the harvested crop. In rooms with temperatures above 15 degrees Celsius and a humidity of 85–90 percent, the infection spreads instantly. Therefore, protecting onions from powdery mildew is an important stage in vegetable cultivation.
Why does powdery mildew appear?
Fungal spores spread when:
- Water the plants. If onions are affected by powdery mildew, along with splashes of water and wind, microorganisms fall on healthy crops.
- The weather is hot, accompanied by high humidity. The infection develops quickly in rainy weather.The air becomes saturated with moisture vapor, which is favorable for the spread of powdery mildew. Conidia are formed 5–10 days after contact with the plant. 15 degrees of heat is enough for them to develop activity. Moreover, plant cells are weakened in such conditions.
- Plants are planted densely. In contact with each other, the onion stems accept the fruiting body of the fungus. This is how new lesions are formed. This happens in beds where there is no access to fresh air and there is no wind movement.
- The soil contains large amounts of nitrogen.
- The garden was not cleaned after digging up the vegetables. The spores overwinter in plant debris, covered with snow, and retain their viability.
- Pests attack onion plantings. The fungus is carried by onion fly, nematodes, aphids. By damaging plants, pests make them vulnerable to fungal infections.
- The seed material is infected. Spores remain on the set to then develop on the stems and leaves of the vegetable.
Whatever the cause of the disease, it must be gotten rid of when the first signs appear.
What can you water onions with?
The main task in the situation of how to deal with powdery mildew on onions is to reduce the lesion. Therefore, all parts of plants covered with white coating are cut out and then burned. Remove diseased plants from the garden, eliminating them entirely.
At the initial stages of development of powdery mildew, a preparation for spraying is prepared for plants. Potassium permanganate is diluted in warm water. A high concentration solution kills microorganism spores. 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 by spraying with a solution of copper sulfate.Having dissolved ten grams of the substance in half a liter of hot water, pour it into a bucket of warm water. To ensure that the solutions used are better retained on the plants, add one hundred grams of laundry soap to a bucket of liquid. Treat beds with onions 3-4 times a month.
Two weeks before harvesting onions, Bordeaux mixture is used, although many people ignore the product. Vegetable growers believe that Bordeaux mixture is only suitable for disease prevention. Although the one percent drug copes well with powdery mildew at the beginning of the development of the disease.
How else can you save onions?
When the first signs of disease are detected, the plant:
- moisturized with tincture of iodine (10 ml) dissolved in ten liters of water;
- treated with Fitosporin against 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.
Chemical preparations and fungicides are more effective: Agrolekar, Chistoflor, Ridomil, Skor. Use the products in accordance with the instructions. The drugs act against fungus on the plant, on the bulbs. Fungicides are used to combat 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 plantings are processed twenty days before harvest. Treatment of onions against powdery mildew is also carried out using folk remedies.
Folk remedies for powdery mildew
Vegetable growers have developed their own methods to combat powdery mildew and use folk remedies to eliminate the disease.
To fight infection, weeds are pulled out, placed in a bucket and poured with boiling water. The infusion is prepared for several days, fermenting. After straining, spray the onion feathers with the prepared 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 mixing, filter and add a liter to a bucket of water. Treat onions with a folk remedy in the evening.
Infusions of tobacco or onion peels, which are made the day before treatment, will help cope with peronosporosis. Many gardeners advise saving bulbs infected with powdery mildew in a simple way. It is necessary to warm the collected onion heads well in the sun and dry them. Then the pathogenic fungi will die.
Preventive measures
In order not to use chemicals to combat powdery mildew, and to make your work easier, you need to think in advance about measures to prevent fungal infection.
Measures to prevent the appearance of powdery mildew on onions include:
- compliance with the rules of crop rotation, not planting onions where trumpet, shallots, and garlic grew;
- preliminary soaking of seeds and sets before planting in a solution of potassium permanganate;
- ensure air circulation in the beds, avoiding dense plantings;
- disinfection of tools and devices to carry out gardening work without fear of infecting vegetables with powdery mildew;
- watering in the morning to allow the plants to dry out;
- applying less nitrogenous fertilizers, and more mineral complexes with potassium and phosphorus.
As a preventative measure, vegetable beds are sprayed with a solution of whey and an infusion of wood ash.During the season, any garden weeds are used by spraying the vegetable plant with infusion.
After digging out the ripe onions, the dry stems and leaves are raked and destroyed. After all, plant waste contains pathogenic organisms that become active in the spring.
It is mandatory to carry out preventive treatments of bulbs collected from the garden beds with fungicidal preparations.
