Powdery mildew: symptoms and treatment options

Powdery mildew is one of the most common plant diseases. If the lesions are not treated, the plantations will die. The reasons for the development of a fungal disease, effective methods of treatment and prevention will be considered in the article.

What is powdery mildew and what plants does it affect?

Powdery mildew is a disease caused by biotrophic fungi that feed on plant cells. Their spores are airborne, travel in rainwater, and germinate on leaf surfaces.

External signs of powdery mildew

What does powdery mildew look like? Powdery mildew appears as a white coating on the leaves and shoots of plants. Mycelium of mushrooms reproduces, grows, drops of liquid similar to dew appear on it. Outwardly, fungal spores resemble loose flour, which is why the disease has such a name.

Most often, the disease affects the following plantations:

• in the garden - vines, apple and pear trees, gooseberries, currants of various kinds, garden strawberries;
• in the garden - tomatoes, sweet pepper, cabbage, cucumbers, pumpkin crops, carrots;
• in the flower garden - delphinium, roses, peonies, petunias, chrysanthemums, phloxes.

Each type of plant has its own powdery mildew. It does not move, for example, from roses to cucumbers, on the other hand, in monoplants, the fungal disease spreads quickly. There is a technology of planting as many different plants as possible on one bed to strengthen their immunity. In such beds, saprophytic microbes and fungi actively multiply in the soil, which prevent the development of powdery mildew.

You can detect a disease on a plant by the following external signs:

• powdery mildew appears on the lower leaf and gradually creeps up;
• after erasing the plaque, it is renewed within a few hours;
• gradually the white spots turn brown and spread throughout the plant;
• plaque acquires the structure of felt or cotton wool;
• the infected parts of the plant (leaves, shoots, flowers, ovary) bend with a shuttle and die.

Small black dots on the affected areas are new powdery mildew spores. They are formed at the end of the growing season, fall on the ground and hibernate in the soil until the next season.

Causes of powdery mildew

Fungal mycelium, which causes plant disease with powdery mildew, settles for the winter in plant buds and vegetation remnants under shrubs and trees. In the spring, fungal spores are fixed on young shoots and leaves, and with the onset of heat, they actively develop, affecting plants in the garden, vineyard and vegetable garden.

Here are favorable factors for the rapid development of the fungus:

• unpicked leaves, carrion, withered grass, in which fungal spores overwinter;
  thickened plantings in the garden and vegetable garden, which leads to the transfer of fungal spores by air and mechanical means (hands, tools, watering hose) to healthy plants;
• violation of the humidity regime (excess or lack of moisture);
• non-compliance with the feeding schedule, which leads to a lack of calcium and an excess of nitrogen in the soil;
• rejuvenating pruning of more than 1/3 of the bush, which causes a weakening of the plant's immunity;
• lack of sufficient illumination of plantings by the sun, poor ventilation of the crown of trees and shrubs;
• sharp fluctuations in the temperature regime, increased humidity on hot days;
  infection by insect pests that reduce plant resistance to diseases and carry fungal spores (whiteflies, aphids, spider mites).

In closed soil (greenhouses, greenhouses, greenhouses), where there is high humidity and temperature, plants are affected by powdery mildew more often than in an open area.

How to fight powdery mildew on plants

The fight against powdery mildew on the site should be carried out systematically. If the development of fungal spores is not stopped in time, diseased plants will infect healthy ones. This will lead to the fact that the crop and ornamental plants on the site will die.

Preventive measures

To prevent the development of a dangerous disease, plan simple measures in the garden area:

• carry out sanitary cleaning of the area from fallen leaves and plant residues in autumn and early spring;
• loosen the circles around the trunk and the soil under the bushes in autumn;
• feed the plants with phosphorus-potassium fertilizers according to the schedule and during the outbreak of powdery mildew;
• treat plants with copper-containing preparations;
• choose stable varieties of vegetable crops, flowers and fruit trees for planting, observe crop rotation;
• during the period of planting and active plant vegetation, disinfect seeds, thin seedlings, crowns, remove weeds, follow the regime of watering and fertilizing, disinfect tools.

To fight the disease, use the following agrotechnical measures:

• treat the seeds of vegetable and flower crops before sowing in a solution of potassium permanganate or in disinfecting preparations, for example, Sporomax B biofungicide;
• thin out dense stairs, crowns, opening the access of air and light;
• weed and mow grass on lawns;
• adjust the mode of watering cultivated plants, do not allow stagnation of water in the rows;
• reduce the amount of nitrogen fertilizers by mid-summer;
• clean and treat garden tools after each use.

At the first sign of powdery mildew, remove the affected parts of the plant and burn them outside the site.

Methods of combating powdery mildew

You can use chemical means, especially if the disease has already developed.

In the spring, before the leaves bloom, treat the plants with Bordeaux mixture or iron sulfate. To prevent the development of powdery mildew or at the initial stage of the development of the disease, biological fungicides Sporomax™ B and Sporomax™ T, in a dosage of 10 g/10 l of water, are suitable.

Sporomax™ B (10 g/ha) + Microstim™ PS (30-40 ml/ha) are recommended for fruit crops with signs of powdery mildew.

During the growing season, it is advisable to add the adjuvant Izomax™ 2ml/10l to the tank solution, which increases the efficiency of processing plants, especially those with thick leaves, wax coating (cabbage) and light pubescence.

Preventive measures and implementation of agrotechnical rules for planting and caring for plants will help protect the garden area from the spread of powdery mildew. The main task of gardeners and gardeners is to notice a suspicious white coating on the leaves of plants in time and take effective measures to get rid of the dangerous disease.