The main trouble of any gardener or gardener has always been, is and will be pests and plant diseases. After all, it is not enough to plant a site with different cultures - it is necessary to ensure that they give a plentiful and high-quality crop, and for this it is necessary to protect your plantings from uninvited guests and sudden ailments. One of the most common problems is powdery mildew - it was met in zucchini and other gourds and almost every gardener struggled with it. Let's try to summarize the experience of all predecessors.
What it is
This plant disease is of two types: powdery mildew itself (it is most often found on zucchini, pumpkins and other relatives) and false, to which cucumbers are most susceptible. Both species are of fungal origin, although they are caused by different representatives of the mushroom family. The difference can be noted only in external manifestations: the "real" type of disease appears on the outer surface of the leaves, and downy mildew (with the scientific name peronosporosis) - on the inside, and only then spots appear on the top - are no longer white.
External signs of the disease
The most obvious of these is distinct white stains on the surface of foliage and flowers. In principle, they really look like flour powder. If urgent measures are not taken, the disease spreads to the stems. And after some time, white (or grayish) spots turn brown - this indicates that the process has gone far enough, and the disease already threatens all your landings.
However, with the general similarity of the onset of the disease, additional symptoms in different plants will differ. So, powdery mildew in zucchini gives itself out as a sharp wilting of leaves, which are covered with a white coating, resembling a thin layer of flour. If the leaf does not have enough time to grow strong, then it dies very quickly. The same applies to the stem: young shoots die before they have time to develop.
Things are a little different with such a culture as blackcurrant. Powdery mildew, hitting the bushes, bends the young branches and shoots of this year and causes twisting of the leaves. As a result, the foliage dries and falls. If the berries have begun to set, they are completely covered with a white coating.
Powdery mildew manifests itself mainly in the same white spots. When flowering, it is worth paying close attention to flowers - if they are brightly colored, you can notice the first manifestations of the disease on them earlier than on foliage.
What contributes to the development of the disease
Powdery mildew in zucchini and other garden plants is especially active in conditions of intense heat and high humidity. Sudden significant temperature drops also favor the spread of the fungus. In greenhouse conditions, airing is too rare, and stagnation of moist and warm air can also cause a surge and rapid spread of the disease.
However, not only the weather can be a stimulant of powdery mildew. Errors of the owner of the site can also contribute to the defeat of plants. The first of them is too dense landings. The second, no less frequent, is the contamination of the soil. Fungi and spores safely overwinter on harvested weeds, and in spring they move to cherished crops. The third is illiterate plant nutrition, which includes an excess of nitrogen and a lack of calcium. And finally, a careless attitude to planting, insufficient treatment from pests. But some of them, for example, scabbard, aphid or mealybug, leave behind a sweet sticky mark on which malicious spores develop rapidly.
How to prevent the onset of the disease
Preventing ailment is always cheaper and easier than then treating your pets for a long time and hard. In addition, do not forget: preparations from powdery mildew are mostly chemistry, which, of course, relieves plants of the disease, but is neither useful for the soil, nor for the gardener who comes into contact with it. So first of all, carefully examine your plantings. If they are too thick - mercilessly thin out, do not create tropics on the site in which the fungus feels so comfortable.
Pay attention to how you water the plants. If in the process you get water on the leaves - change the tactics. Pour it under the root: so moisture will reach it faster, and the disease will have less chance of multiplying, and save water.
Carefully monitor the dose of fertilizer applied. Do not “overcharge” with nitrogen, it is better to increase the dose of phosphorus and potassium, which increase the ability of plants to resist diseases. But in moderation, in moderation! Busting is often as bad as shortage.
Ventilate the greenhouses as often as possible. The greenhouse effect, we repeat, is only useful for spores of a harmful fungus, and your crops need fresh air and hardening. And constantly collect fallen leaves or broken off stems - in them the infection miraculously multiplies.
Pay close attention to the cleanliness of your garden tools and pots if you are preparing seedlings or planting indoor plants. Powdery mildew is often found at home.
What to do first
No matter how much your "plantation" is struck, you need to start with the most important thing - reducing the focus of the disease. To do this, all parts of the plant infected with the fungus are cut with the capture of healthy areas. In order not to become the very source of the spread of infection, the tool - whether it be a pruner or a knife - must be disinfected. If the disease has affected a large part of the plant, it is better to eliminate it entirely so that it does not infect nearby growing ones. Whatever means you use in the next stages of the rescue operation, this part of the work must be done.
How can plants be helped in the early stages of the disease?
While things have not gone very far, and most of your plantations are healthy, good results are obtained by spraying them with a solution of ordinary potassium permanganate after medical circumcision. In a bucket of warm water, it will be enough to dilute approximately a kilogram of potassium permanganate. Processing should not be the only one: it will have to be repeated two to three times with an interval of a week or two. Every time before the procedure, you need to inspect the plants and cut out the diseased parts. Soda ash in the amount of two tablespoons per ten-liter bucket of water also works well. But if the spread of powdery mildew is large, you will have to resort to more serious methods.
Disadvantages of the most popular “drugs”
Most gardeners are convinced that colloidal sulfur and Bordeaux fluid are a panacea in the fight against powdery mildew. However, it must be admitted that this is not entirely true. The fungus that causes this disease produces a kind of addiction, resistance to sulfur and copper. A kind of mutated strain appears, whose “descendants” are simply not susceptible to them. So both funds are suitable only if they were used at most once in this particular area. True, pollination of plantings with colloidal sulfur as a preventive measure is still approved by most gardeners. But not as a treatment, especially if many plants are affected by the fungus.
Features of powdery mildew onions
Unfortunately, this culture is also susceptible to the disease in question. False powdery mildew on the onion is manifested by light green spots on young leaves. They spread on the surface in a violet-grayish bloom, then the leaves turn yellow and dry, and the fungus “leaves” into the bulbs, stopping their growth. Flat-feather varieties — shallots, chives, turnip, batun, etc., are susceptible. Flat-leaved — leek, allspice, slime (and garlic for company) —are not amenable to it. "Onions" are usually treated with copper-containing preparations ("Polycarbacin", the same Bordeaux mixture or copper chloride), mixed with a solution of laundry soap for better adhesion.
Folk ways of struggle
One of the most reliable methods recommended by the wise villagers is the “milkshake”. For three liters of regular serum, seven liters of water and a teaspoon of copper sulfate are taken. Here is a combination of folk experience and chemical achievements. Onion tincture is no less popular: 200 g of husk is poured with boiling water in a volume of 10 l and infused for a couple of days. Do not forget to strain! A soap chip solution or tobacco infusion is also recommended, and some highly praise pollination with ash or its infusion in warm water.
Chemistry to the rescue
In complex and neglected cases, it is necessary to use potent modern chemical preparations from powdery mildew. Their main advantage is that they do not cause an addictive effect and equally destructively affect all generations of the fungus. Most of these products are “embedded” in the tissues of protected plants, making their juice deadly for parasites. At the same time, they do not act on a person; they do not accumulate in fruits and leaves. The most popular and effective now are Fitosporin and Topaz. However, note that different plants require an individual approach. So, powdery mildew on tomatoes is better treated with a solution of cineb, which is used to spray diseased plants for seven to ten days. They say other methods are more time-consuming and less effective.
But powdery mildew on grapes is easier to natural methods of struggle. Among them, the most effective is manure infusion, which is diluted with water in a ratio of 1: 2. After straining, the product is used to spray grape bushes, but only before the buds bloom.
Another popular method is recognized, how to get rid of powdery mildew (and not only on grapes - it suits almost all plants). For this, plantings are treated with diluted serum in a ratio of 1: 3. Lactic acid is the enemy of the fungus, it dies from it. By the way, it is also suitable for prevention: in the fall, you can simply water the soil with such a solution.
There is still powdery mildew on the cucumbers. Initial treatment is standard: the same Bordeaux liquid or a solution of powdered copper sulfate. But if the fungus is already used to copper, you will have to resort to a diluted karatana. For 10 l, they take up to 10 g and spray the affected plantings for two weeks.
Do not give up! Even if such a misfortune befell you, it is quite possible to fight it.