Mealy dew - an infectious disease of plants. It is dangerous, as it is able to spread rapidly, seizing new landings. If you do not take action, plantings may die.
What powdery mildew looks like
Mealy dew (MR) is caused by different types of microorganisms belonging to the same family. The symptoms of the infection are always the same: white scurf appears on the upper surface of the leaves, due to which the sheet looks as if powdered or sprinkled with flour. At this stage, many are mistaken, taking the symptom for ordinary dust, and try to brush away the bloom with your finger. But the next day, he reappears and moves to neighboring leaves.
In addition to the leaves, whitewash young shoots, flower stalks, fruits. The raid can go on the lower side of the sheet. Spots grow, become brownish or grayish, compacted and take the form of felt or brown film.
Already for 2-3 days the plates, which suffered first, turn yellow and dry. New leaves grow deformed, weak.
Even a small defeat of the plant with powdery mildew reduces the hardiness of shoots and buds, as a result they freeze out in winter.
Plaque is the mycelium of microorganisms of the family Erizifovogo or Farinaceous fungi. All members of the family, and there are more than 700 species, parasitize on flowering plants.
Erisyphic - parasites of plants. The mycelium grows into host cells by side branches and sucks fluid from the cytoplasm and vacuoles of plant cells. As a result, the plant's tissues are dehydrated and it dries out. Looking through the microscope, you can see that under the bloom the leaf is covered with ulcers, that is, the mycelium almost "eats" living cells.
After a spore has matured, droplets appear on the surface of the plaque - hence the name powdery mildew. Plants, having lost a significant part of leaf plates, lack nutrients, because a leaf is an organ in which the process of photosynthesis takes place.
One must be able to distinguish between MR and peronosporosis or downy mildew. In the latter case, the spots on the leaves are not white, but yellowish-brown, gray mold develops on the underside of the plates.
What planting powdery mildew damages
The disease is found on garden and indoor plants. The overwhelming majority of erisyphic parasites on dicotyledons. But among them there are dangerous pathogens of cereals, for example, Blumeria graminis.
In the garden the fungus strikes gooseberries and currants. Sugar beet, pumpkin, especially cucumbers, roses, grapes, peach, strawberries are unstable to the disease. At risk are woody plants:
- hazel nut,
- dog rose,
From houseplants, Erisyphus attack roses, begonias, violets, rubber plants, hydrangeas. The disease can be found on cissus, gerbera, Kalanchoe.
There are species that parasitize only on one plant. For example, the mushroom Oidium prefers grapes, so the powdery mildew on the grapes is called Oidium.
Powdery mildew on currants and gooseberries is caused by Spheroteca, a species of mushrooms from the Muscovidae family, native to North America. The disease is often referred to as American powdery mildew. The pathogen penetrated into Russia at the beginning of the 20th century and spread throughout the country. In the homeland of the infection, only spherocute-resistant currants and gooseberries are grown.
Protection scheme of black currant and gooseberry from powdery mildew
Powdery mildew shrubs spray four times per season:
- in the spring,
- before and after flowering,
- after harvest.
For spraying use 1% suspension of colloidal sulfur or a three-day infusion of manure 1: 3, diluted 3 times before use. In addition, to protect against other fungal diseases, before blooming buds and after the leaves are falling, planting currants is sprayed with a compound prepared from 100 g of copper sulfate + 100 grams of quicklime, diluted in 20 liters of water.
Infected bushes are cleaned from diseased leaves and shoots. In autumn, fallen leaves are raked and burned.
There are varieties of currants that are resistant to powdery mildew. Such are Dovinka, Katyusha, Bagheera, Karelian, Black Pearl, Green Haze. The Biryulevskaya, Leningradsky giant varieties are strongly affected. Resistant to most diseases and pests currant varieties Dense.
Folk remedies for powdery mildew
Than to treat plants when powdery mildew appears - use traditional control measures by spraying the affected plantings with one of the following home-made products:
- pink solution of potassium permanganate;
- soda ash - dilute 5 g of soda in a liter of water and spray it once a week, trying to get on the upper and lower sides of the plates;
- water infusion of garlic;
- a mixture of antibiotics - penicillin + streptomycin 1: 1.
For better adhesion of the solution to each liter of water add one teaspoon of liquid soap or soap chips.
Before treatment, remove diseased leaves and cut off the affected shoots. Trimments cannot be laid in the compost pile. After cleaning and spraying, feed the plants with potassium phosphate fertilizer.
Powdery Mildew Drugs
Powdery mildew will help to cope with the problem:
- Copper Cupros,
In greenhouses use colloidal sulfur fumigation. The result is copper oxychloride treatment - 0.5%, copper-soap emulsion - copper sulphate + soap to stick.
The most popular powder for powdery mildew is Topaz: the active ingredient is penconazole. Means protects berry, pome, vegetable, ornamental crops and grapes. When processing houseplants with Topaz, there are no stains on the leaves, which is convenient when treating Saint baroque violets.
In the middle lane, black currants, gooseberries, cucumbers, raspberries and cherries are treated with Topaz. In addition to powdery mildew, penconazole inhibits the development of spotting, gray rot and rust.
The virtue of Topaz is consistency. The tool is absorbed into the tissue of the plant and is not washed off by rain. The drug circulates through the plant, protecting the disease for 2 weeks. Already after 2 hours from the time of treatment, the growth of the mycelium on the plant stops.
The waiting time after spraying with Topaz is 20 days, that is, for almost 3 weeks after treatment, the fruits of the sprayed plant should not be eaten. When processing flowers intended for cutting, the waiting period is 3 days.
Prevention of powdery mildew
Spores of the fungus persist throughout the winter on plant debris. Infection occurs when airborne spores are transported. To prevent this from happening, in the fall the leaves are raked and burned. In the room, the florist can contribute to the spread of pathology by touching the leaf with a bloom and then touching a healthy flower.
The development of the disease is promoted by a high temperature and overfeeding with nitrogen fertilizers with a lack of calcium. Another common cause of MR infection is water deficiency in the soil. Drought leads to the loss of turgor by the plant, which helps to reduce the resistance of powdery mildew. With an air temperature of around 20 ° C and a relative humidity of 80%, we can talk about the threat of an outbreak of the disease.
As a preventive measure, it is necessary to prevent excess nitrogen in the initial period of plant growth. Phosphate-potassium supplementation increases the plant's immunity to the disease. Prevention of MR are nezaguschennost plantings, and timely cutting of currants and gooseberries old branches, thickening the bush. Stagnation of humid air significantly accelerates the development of the pathogen and can lead to an outbreak of infection.
Fitosporin, which is a concentrate of Bacillus subtilis bacteria - hay bacillus, is popular among gardeners. The drug is safe for harvest, and is able to displace pathogenic fungi and bacteria from the soil and from the surface of plants. As a cure for the already developed MR, Fitosprin is useless, but it is excellent for prophylaxis.
For the prevention of MR, the aerial part of the plant is sprayed with Phytosporin. During the outbreak of the disease, the procedure is repeated once a week. In rainy weather, the drug is used after each rain.
One of the advantages of Fitosporin is that it is safe for humans, animals and insects. Already on the day of spraying, the fruits collected from the plant can be eaten, therefore Fitosporin can be used even for greenhouse cucumber treatments.
It is easier to engage in prevention than to treat plants that are already ill, especially if the disease is in an advanced form. To avoid the fight against powdery mildew, pay attention to preventing the disease: do not try to plant maximum seedlings per square meter, thin out old trees and shrubs and spray plants during the growing season with herbal infusions or systemic fungicides - these measures will preserve the crop.