In confusion, there is a novice gardener in the country in front of his beloved garden. Just yesterday, cucumbers, zucchini, tomatoes, onions and other vegetable crops “shone” with health under the gentle sun. The long-awaited spring warm rain passed at night and here is the result. The leaves of the plants lost turgor, became stained. This means that there will be no home-made organic cucumbers and other vegetables. Plants were damaged by powdery mildew, the most dangerous pathogenic fungus.
The defeat of plants is caused by several lower fungi of the peronospore family, which parasitize on living plants. Powdery mildew is divided into 2 groups: real and false powdery mildew. Routes of infection and external manifestations of the disease have distinctive features. In the article, we consider in more detail the features of downy mildew and measures of protection against infection.
- Ways to infect plants with downy mildew
- Methods of protection against downy mildew
- Folk remedies for the control of downy mildew
Ways to infect plants with downy mildew
A prerequisite for the spread of downy mildew is a humid environment, so the disease most quickly manifests itself after rains and subsequent wet weather. In the fungal life cycle, a spore formation phase is necessarily present, forming a special type of spore. They are called zoospores. These are single coated cells.
On the outer side of the zoospore are 2 flagella. In a humid environment, thanks to flagella, zoospores quickly move and penetrate into the internal organs of the host plant through stomata, cracks and wounds on young stems and bark.
The internal environment of plant mildew infected with downy mildew is ideal for the life of zoospores that form a vegetative organ - mycelium or mycelium. The mycelium grows with tremendous speed and already on day 2-3 its hyphae literally clog the entire inside of the affected organ and through the stomata, tissue breaks, wounds come out.
They are in the form of a whitish or gray-violet gun and the discouraged host sees on the underside of the affected leaves. This is the last stage of the development of an obligate pathogen, when the plant can no longer be cured.
Affected leaves, initially still green, droop and wrinkle. Separate yellowish spots appear on the upper side, spreading over the entire surface of the sheet. Dechlorinated, they acquire a brown-brown color. The leaves dry and crumble into separate pieces, which remain able to infect a healthy plant.
The overgrown mycelium of downy mildew forms reproductive organs, which through a magnifying glass on the underside of the leaves are visible as dark dots. These are fruit bodies in which zoospores (zoospores) are located, ready to capture and defeat a new healthy host.
False powdery mildew affects all groups of cultivated plants (vegetable, fruit trees, shrubs, indoor and garden flowers). The pathogen forms up to 20 generations per vegetation, spreading millions of zoospores. Zoospores hibernate in fallen leaves, affected organs of plants and with the onset of heat (+11 ° C) by the wind, raindrops, spray of irrigation water are carried, settling on healthy plants.
In warm and damp weather, the incubation period of the pathogen is greatly reduced. Epiphytotic lesions can cover large areas of plants in literally 2-7 days. With the onset of hot, dry weather, the disease fades, but the pathogen remains alive, therefore (without being seduced by the false conclusion that the disease has disappeared), it is necessary to continue protecting plants from a new wave of lesions.
The wide spread of downy mildew is greatly facilitated by insect pests such as aphids, whiteflies and others. They carry zoospores over long distances, increasing the area of infection. In addition, the spread of the disease can also occur through the seeds, which probably happened during the spread of powdery mildew from the Far East to the middle and warm regions of the USSR in the 80s of the last century.
Powdery Mildew Protection Methods
Methods of protecting plants from downy mildew are preventative (agrotechnical measures) and active (use of drugs). The protection of plants from any diseases, including fungal diseases, must begin with preventive measures, the lion's share of which falls on agricultural technology of garden crops. This is all the more important because at home, every owner of a summer cottage or house adjoins trying to grow environmentally friendly products, that is, without the use of chemicals.
Vegetable Soil Care
Annual thorough cleaning of the site from the affected plants and their burning. This is necessary, since with composting the viability of the pathogen zoospores is preserved.
Annual digging and disinfection of soil intended for garden crops. Digging the site is carried out to a depth of 25-30 cm. In case of strong infection of plants in the previous year, it is advisable to repeat the digging in the spring and disinfect the site with a 2-3% solution of copper sulfate or 1% solution of potassium permanganate followed by a shallow seal of 5-10 cm.
It is advisable not to get involved in disinfection with copper sulfate. It is poisonous not only for pathogenic, but also beneficial microflora. With annual soil disinfection, it is better to use biological preparations or alternative methods for its improvement.
From the permitted list of drugs for disinfecting the soil from downy mildew, biofungicides can be used: Fitosporin, Alirin-B, Gamair. Processing is mandatory according to the recommendations accompanying the drug.
Excellent results from downy mildew are shown by the long-term use of the Baikal EM-1 preparation, which also acts as a fertilizer and inhibits the development of pathogens of many diseases, including downy mildew.
It is imperative to observe cultural turnover in the garden and to return the cultures to their former place no earlier than 3-5 years. With long-term use of the site with the same culture, an accumulation of infection occurs, which sharply increases the incidence of plants.
Be sure to sow the seeds and plant seedlings of vegetable crops in the optimal time by zoned varieties or hybrids. Seeds before sowing must be decontaminated using a thermal method (15 minutes at a temperature of +40 ° C) or a 0.1% potassium permanganate solution. Dip the roots of seedlings for 2-3 hours in a solution of trichodermin or another disinfecting drug.
Follow all agrotechnical requirements for sowing and planting. To withstand the density of sowing and planting garden crops.
During the growing season, the area under the plants should be kept clean from weeds. Ill with downy mildew, not amenable to garden crops to remove from the site and burn.
Protection of vegetable crops from downy mildew during the growing season
Vegetables (cucumbers, zucchini, pumpkins, beans, tomatoes, cabbage, onions, garlic, peppers and others) in the phase of mass emergence, and seedlings 2 weeks after planting for the purpose of prevention, it is necessary to spray 0.5-1% solution of Bordeaux liquids.
If the beginning is missed and there is a massive defeat of plants with downy mildew, then vegetable crops (especially pumpkin) can be sprayed with a solution of sulfur at the rate of 50-80 g / 10 l of water.
It is very important to systematically feed the plants with organic and mineral fertilizers, according to the recommendations for the culture, which will help increase resistance to various diseases, including fungal ones.
Since vegetables are mainly used fresh during the season, it is better not to use chemicals, but to limit oneself to biological preparations, which, if used correctly, do not harm the human and animal organisms.
If the summer is cool and humid, then approximately every 2-3 weeks, plants of vegetable crops are treated with the following biological products: Fitosporin-M, Gliokladin, Alirin, Gamair, Planriz.
With prolonged dry and hot weather, plants are treated less often, about 1 time per month. Doses, methods and timing of the introduction of drugs are indicated on the package or in the accompanying recommendations.
Protection of fruit trees and bushes from powdery mildew
After harvesting, clean the soil under the crowns of trees from fallen leaves and fruits. After trimming wood and shrubberies, remove the remaining branches and other garbage from the site and burn them. In the garden, shtamb and skeletal branches should be whitened several times a year with a mixture of freshly slaked lime, clay, copper sulphate and fungicidal preparations.
In autumn, after the leaves fall completely, the crowns of the trees must be treated with a 2-3% solution of copper sulfate.
In the spring, before buds open (swelling phase), for prophylaxis, treat the shtamb, the crown of trees and tree trunks with a solution of mineral fertilizers. For crown, 5% is used, and for soil, a 7% solution of urea or 10% solution of ammonium nitrate, which can be alternated with a 15% solution of ammonium sulfate. Dig up the treated stem trunks after 3-4 days by 10-15 cm.
With mass budding of the buds (phase of the green cone), the crown of trees and shrubs are sprayed with a 1% solution of Bordeaux fluid. Treatments are repeated before and after flowering and at the beginning of fruit setting.
Some gardeners-summer residents use chemicals that protect fruit crops from infection with fungal diseases, considering 1-2 times a sufficient treatment in the initial period of vegetation to be sufficient. But such a scheme for the use of chemicals does not guarantee against infection at a later date in the development of crops and, moreover, does not provide an environmentally friendly crop.
Therefore, if necessary, further protection of fruit crops from damage by fungal diseases, including downy mildew, it is necessary to switch to the use of biological products.
Before flowering (pink bud phase) and almost before harvesting, trees and shrubs are treated every 3 weeks (in wet weather more often) with the following biological products: Fitosporin-M, Gamair, Integral, Mikosan, Gaupsin Agat 25 "," Planriz ". Moreover, planaris can be processed crops a day before picking the fruit. This measure promotes better storage of products.
When processing crops, a change of drugs is necessary so as not to become addictive. Systematic treatment of plants with biological products according to the recommendations will help to maintain a healthy crop with high quality and will be good protection against epiphytotic damage by powdery mildew.
In order to reduce the number of crop treatments during the growing season, spraying with tank mixtures can be carried out. To do this, separately for each drug, prepare the appropriate solution, check for compatibility, drain into one container, mix thoroughly and process the trees. In tank mixtures, you can use 3-5 drugs from various diseases and pests at the same time.
Folk remedies for the control of downy mildew
It will destroy downy mildew of 10 drops of 5% iodine dissolved in 1 liter of milk and mixed with 9 liters of water. Milk must be skimmed. The solution is sprayed with plants.
2 cups of ash are brewed (like tea) with 2-3 liters of boiling water, filtered through a 2-3 layer gauze napkin. “Tea leaves” are mixed with 10 l of water and plants are sprayed.
Against powdery mildew, the treatment of plants with a weak solution of potassium permanganate is effective. It is enough to dissolve 1.0-1.5 g of potassium permanganate in 10 l of water and sprinkle the plants.
It removes the infection with powdery mildew in the initial stage of the infusion of husks of onions. 200-300 g of ripe husk pour 10 liters of water, bring to a boil, leave for 1-2 days to infuse and use the solution for spraying. The solution must be filtered.
It is known that a huge amount of beneficial microflora develops in manure, which destroys pathogenic fungi mycelium. To prepare the drug, 1 part of the mullein is diluted with 3 parts of water, insisted for 3-4 days, carefully filtered, water is added up to 7-8 l and in the evening or in cloudy weather the leaves are sprayed after 7-9 days.