Onion downy mildew (downy mildew): control measures and treatment with photo

Onion peronosporosis is a fungal disease that often affects a plant at any stage of its maturation. Onions can become infected with a fungus every year, as spores overwinter either in the soil or on the bulb without causing it to rot. This disease is widespread and becomes a big problem for many farmers, so you need to know what to do if the onion is affected by downy mildew.

Description of the disease

Downy mildew (peronosporosis in onions) has such a name because of the gray-purple bloom on the "feathers" of the plant.

Peronosporosis on onions, the photo of which makes it possible to see the possible manifestations of the fungus, does not appear before planting. This makes it unrealistic to select unsuitable planting material. The disease develops rapidly, and the stronger the lesion, the more additional symptoms can be noticed.

The following signs and stages of the development of the disease are distinguished:

1. The earliest manifestations of false dew can be seen in the second half of April - early May, when small yellow spots appear on the leaves and peduncles. And after a while, gray-purple spores of the fungus appear on the infected plants.
2. Powdery coating is best seen in the morning when the beds are covered with dew.
3. As the disease progresses, the spots on the leaves increase. Onion feathers become brittle. Over time, they sink to the ground and wither. The plant looks sick.
4. Due to the penetration of the infection deep into the bulb, the culture cannot develop normally. If flower stalks are infected, the seeds often do not ripen.

Fungal disease can destroy up to 50% of the onion crop, so you need to know not only how peronosporosis manifests itself, but also the main conditions under which the disease occurs.

Peronosporosis infection

The main conditions for the development of false dew are a sharp change in temperature and high humidity in the morning, that is, dew delay. In dry summer periods, the fungus is less common. Peronosporosis on onions develops if the temperature drops to +16 ° C, and the humidity rises to 90-100%.

Such weather conditions are observed at night, in spring and early summer. At this time, the spores awaken, and when the sun rises and the air temperature becomes higher (but the dew has not yet evaporated), they begin to develop intensively.

The incubation period of peronosporosis lasts from 3 to 15 days, and during the season, mushrooms develop up to 6 generations.

Favorable conditions for onions to become ill with downy mildew are the lack of fresh air and sunlight. Therefore, it is necessary to choose the right place for the beds and not plant the plant too densely.

For planting onions, agronomists recommend choosing those parts of the garden where sunlight enters freely. The beds are best placed away from moisture and shade, since constant dampness and lack of sunlight are excellent conditions for the spread of the fungus. The spores are carried by air currents and water droplets during rain or heavy watering.

The fungus often remains in the soil along with the remains of onions from last year's infected crop. To prevent a new infection, it is recommended to change the place for planting a vegetable.

Treatments

If signs of fungus are found on the plant, it is necessary to abandon organic fertilizers and switch to phosphorus-potassium fertilizers. Since onion downy mildew thrives in high humidity, it is recommended to reduce watering if symptoms are detected.

In the fight against the disease, chemical and folk remedies are used to treat the affected areas. During the growing season, onions can be sprayed with fungicides, but after treatment, green feathers should not be eaten.

Bulbs can be eaten after reading the instructions for using the chemical, as the vegetable will be unfit for food for some time. In the future, to consolidate the result, gardeners recommend spraying with soapy water.

Pesticide treatment is quite effective, but there are other, safer options for dealing with downy mildew. Effectively and without harm to human he alth, various home methods and methods are used, folk remedies are fighting the infection.

One of the effective solutions is whey. It contains bacteria that are harmless to the plant, but harmful to the fungus. The serum is diluted in a ratio of 1:10 with water. Then the diseased onion is sprayed with the resulting solution.

Prevention methods

It is much easier to prevent disease than to save an infected crop. Therefore, experienced gardeners are advised to regularly prevent the disease using the following measures:

1. Carefully remove crop residues from the top layers of the soil.
2. For the winter, it is imperative to dig up the soil where the infected vegetable grew.
3. Do not use the same plot of garden for planting.
4. Sow only he althy seeds.
5. Before planting onions, warm up the planting material at a temperature of +40 °C for at least 8 hours.
6. Check plants periodically for signs of disease.
7. Carry out appropriate outdoor care: weeding, watering in the morning.

Advice from an experienced gardener

Experienced gardeners have been facing this problem for many years, so tips and rules have been formed, following which you can effectively deal with downy mildew and prevent its occurrence:

1. After the crop has been harvested, the bulbs must be thoroughly dried until dry flakes form.
2. When you see the first signs of onion downy mildew, it is recommended to remove the infected specimens and treat the rest of the plants with wood ash at the rate of 50 g per 1 m².
3. Onions should only be planted on the sunny side of the garden and not placed too densely.

A good method for the prevention and treatment of many plant diseases, including downy mildew, is fertilizing with herbal infusion.

To prepare the remedy, you will need chopped grass. Weeds will do. Grass is poured with boiling water and insisted for 4 days. During this time, the greens should ferment. Then the infusion is filtered and sprinkled with onions.

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