How to deal with powder mildew on grapes
If earlier fungal diseases of the grapes have not been reminded of themselves too often, this problem is now becoming increasingly urgent. One of the most common was the disease of the Oidium grapes, which affects an increasing number of plants in all regions of the country and delivers great difficulties for the vineyards.
What is Oidium?
Oidium is the most common fungal disease that has other names – an ashtray or a real mildew. His pathogen lives exclusively from living and green tissues. Pulling Dew makes grapes unsuitable for use and the production of wine.
The largest epidemics of the Oidium occur after winter frost (the temperature should not drop belo w-30 ° C). The spores of the disease are preserved under the trenches, and with a temperature rise to +18 ° C … +25 ° C they germinate. Promotes the development of the mushroom and the increased humidity. However, the rains can slow down and in some cases stop the distribution.
In order to reduce the likelihood of the occurrence of infections in grapes, varieties must be selected that have a high resistance to illness, remove excess drives, cut the sick parts of the plants and burn them. Do not use fertilizers with an excess of nitrogen.
Signs of the disease
The symptoms of Oidium, which manifest themselves in different seasons, differ.
The following characters manifest themselves in spring:
- The yellowed young shoots and leaves that are covered with dirty white robbery, similar to flour.
- The edges on the leaves dry and bend.
- Brown spots appear under a white attack in green shoots. If you try to delete the plaque, the smell of lazy fishing appears.
- The growth of drives is disturbed with a serious defeat and their fabrics begin to die.
In summer these signs are a little different:
- The flowers and young piles dry out and the coat of arms of the leaves become fragile.
- When it grows, young berries are covered with dark spots, and later a mesh pattern manifests itself on them and is tested.
- Berries begin to crack and rot. The development of the disease can continue until harvest.
Prevention and fight against the disease
When a mildew has been discovered on grapes, it becomes a very urgent problem. There are various ways to get rid of this fungal disease.
With sulfur and sulfur medication
In a dispersed form, the sulfur is very effectively absorbed by a fungus, where it turns into a hydrogen sulfide that puts it. It is best to process gray in the morning or evening, as the leaves and fruits can occur with heavy heat. The processing is repeated every 10-20 days. For prevention, it is necessary to dissolve 25-40 grams of sulfur in 10 liters of water and treat 80-100 grams.
Before spraying grapes, it should be noted that the treatment of sulfur is only effective at air temperatures of more than +20 ° C at lower temperatures. If the temperature has dropped below, the colloidal gray or one of the sulfur medication should be treated.
Contact and systemic medication
Chemicals should not be used during the ripening of berries. Therefore, a solution of potassium permanganate is used to delay the development of the disease. Complex preparations, which are allowed to be used during maturation, are best suited for treatment.
Biological methods against Oidium
The most accessible of all methods is the preparation of concentrated saprophytic microflora from humus in the spring. It is made like this: a third of a hundred-liter barrel is covered with hummus and filled with water heated to 25 ° C, then covered with burlap and left in heat for 6 days with regular stirring.
Strain the resulting substance through cheesecloth and pour into a sprayer. For prophylaxis, it is sprayed on freshly blossomed vine leaves. The effect is based on the penetration of microflora under the kidney scales and their contact with fungal spores, which are the nutrient for them. Processing is carried out on a cloudy day or in the evening.
Re-treatment should be done after seven days and again before flowering. With a strong development of infection, by the end of flowering, the plant must be treated several times with an interval of a week.
How to save grapes from powdery mildew or oidium: advice from an experienced grower Olena Nepomnyashchaya
Unfortunately, the time of the vineyards completely free of disease is over, fungal diseases have reached the northern countries. And the most common disease is oidium, or powdery mildew.
This year is very difficult for our plants and diseases have already attacked the vines in June, powdery mildew in particular is very active this year! We learn how to deal with the disease from real professionals: from Olena Nepomnyashchaya, the owner of her own vineyard in Tver.
Background information on oidium or powdery mildew:
Oidium (synonyms – powdery mildew, ashtray) is the most common grape disease.
The pathogen affects all green parts of the plant and lives only on living tissue, making the berries unsuitable for winemaking.
It causes the greatest damage in hot summers, especially after winters with temperatures not belo w-30 °C. The spores of the fungus hibernate under the eye scales and on infected shoots, and germinate at a temperature of +18. +25°C.
It actively develops at high humidity on a dry tissue surface. Oidium does not require drip liquid to germinate spores, so rain can stop the spread of the disease.
Choose vine varieties with high resistance to oidium, break off excess shoots, remove diseased parts and burn plant debris. Apply a balanced fertilizer without excess nitrogen.
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Signs of infection with Oidium grapes
Spring: young leaves and shoots of clusters of buds infected since last year turn yellow, covered with an off-white powdery coating, mainly on the top. Separate spots merge, the edges of the leaves are bent up and dry up. A plaque also appears on the green shoots, and brown spots below it. If you try to put it out, you can feel the specific smell of spoiled fish. With a severe defeat, the tissues of the shoots darken and die, growth is disrupted.
Summer: young grapes, grape blossoms dry up, ridges become brittle. Young berries, the sugar content of which does not exceed 8%, become covered with dark spots when stuffing, then with the coloring of the berries, a mesh pattern appears on the surface of the skin and its corking. The berries crack, rot, and the bones “peep” out. The development of the fungus on berries can continue until harvest.
Use sulfur medication to combat Oidium on grapes
In thinly dispersed form, the sulfur is absorbed by the cells of the fungus and affects the spores of the mushroom as a toxin in the hydrogen sulfide. In the south, the processing continues during the time of the names of the kidneys, which prevents the appearance of an Oidium in green shoots. The pollination of the sulfur is only effective at air temperatures above +20 ° C, and in cold weather there is no effect. Perform the processing of bushes in morning or evening hours – burns on the leaves and berries of grapes can occur in hot weather. Consumption for prevention 25–40 g/10 liters during treatment 80–100 g/10 l, waiting period 5-6 days. If the air temperature is below +20 ° C, it is better to spray the vineyard with colloidal sulfur or sulfur preparations, Tiovit beam or Kumulus DF. The processing is repeated after 10-20 days, 3-6 processing is carried out during the season. It is useful to use the complex fertilizer PlantaFol 5:15:45, which already contains 12% sulfur.
System and contact drugs to combat Oidium
Do not use chemicals during the ripening period. The conspiracy (5 g per 10 l water) stops the Oidium.
Topaz, Horus, scorer – the most famous drugs against Oidium. If you have had an Oidium since last year, spray on vine and young green horus in spring. This is one of the few systemic drugs that “function” in cold weather. If these products do not help, use the Strobi drug. There are reviews that a mixture of strobi and tiovit beam can also be used for berries, but Strobi no more than three times a season. Good for the prevention of Oidium Talendo and Karatan, the latter – only after flowering. According to the Oidium with passing putrefaction, a combined fungicide sweatshirt is effective, a new complex medication (from Oidium, mild and anthracnosis).
Biological methods to combat the Oidium in the vineyard
The most affordable and interesting technology is tested by Professor Gunvaldis Vesminsha from Latvia. In spring, a concentrate of saprophytic microflora from humus is made: a barrel of 100 l is filled with a third with sifted humus, cast with warm (+20 ° C) water, covered with a sack linen and 5-6 days in the warmth, Mix constantly. After 5-6 days, the competition with the microflora multiplication around food begins. The concentrate is filtered by gauze and poured into a spray. Only flowering leaves and vines of grapes are processed for prevention. The kidney scales are open, saprophytic microflora falls directly on the myzel of the mushroom myzel. This is a nutritious substrate for our microflora. They are only treated on cloudy days or in the evening. The second processing takes place after one week, another – before flowering. Often, the Vesminsha team only carried out the first processing in blooming and prevented the Oidium of the “flower”. But if you have a lot of infections, especially if autumn was without rain, you have to do a few more workmanship with an interval after flowering. So in Latvia they have been fighting successfully against the Oidium for more than 15 years.
Peter Cripus from the University of Adelaids discovered that milk fat and possibly serum protein serve as food for microorganisms that live on the skin of berries that compete with mildews in competing in order to vacate and eat its disputes. With a 10%aqueous solution of milk or milk serum once a week you can control the spread of mildew.
I hope that you now, colleagues, have enough information to overcome this disease. Well, I personally “put” the Vesminsha method. Good luck for all of us.
People’s funds for protection against Oidium am Weinberg
1. Daily infusion: half a bucket ashes for 7 liters of water. Before spraying with water, dilute 1: 1 and add 100 g of green soap as a stick as a stick. The ashes cannot be passed, but cooked for 20 minutes.
2. Pour fresh manure or straw dust with water 1: 3, insist on neat for three days. Process the evening in the evening at any time, stam and dilute three times.
Olena Nepomnya, an experienced vineyard, the lover of the vineyard in the Tver region and the constant expert of the Supersadovnik.ru website for growing grapes. Site: traffic lights north.ru