Oidium grapes, photo and how to treat

The most terrible harm to the crop can be caused by the real causative agent of powdery mildew - grape powdery. (OIDIUM TUCKERI BERK or UNCINULA NECATOR). It causes serious damage, worse than the pathogen of downy mildew.

Grape powdery disease was first discovered in 1845 by Tucker. The disease was first noticed in England after she moved there from the United States of America. Already in 1850, oidium began to damage grape bushes in European countries.

In France, colossal damage was already noticeable in 1852-1854. Through trial and error, it was possible to find out an effective way to protect against grape powdery - the use of sulfur.

Signs of manifestation of oidium grapes

Oidium grapes: photo of the disease

When the vineyard enters the active growth phase, gray-white dust can be seen on some of the leaves. The leaf itself looks curly, small and weak. In the first month of summer, a white-grayish bloom is visible at the top or bottom of the leaf. It seems that the fruits and flowers of the vineyard are sprinkled with some kind of incomprehensible pollen or ash. Unfortunately, after such an ailment, the flowers gradually die. Fruits that are infected early dry up. Large berries the size of a pea decompose and burst under the influence of the fungus. And also they can simply dry out from lack of enough moisture in the air.

Oidium grapes are very harmful to the bunches of the vineyard. Bunches that have suffered significant damage are moved and thrown out. Because if such berries are used in winemaking and juice making, the drinks will acquire a moldy taste.

Powdery sundew fungus can damage not only vineyards. And also gooseberries, apple trees, crops, roses. But this pathogen is not one of its kind capable of causing such harm to plants.

The greyish-white bloom is attached to the plant with the help of suckers (suction cups). It itself does not lie down in a thick layer, but only covers the surface of the leaves insignificantly. Oidium inserts haustoria into the epidermis layer of the plant with "suction cups" in order to continue its vital activity.

Soon the main cell dies and forms a maroon pigment. As a result, the grapes of the vineyard burst from the arising severity, the seeds are shown outside.

Oidium grapes: photo of the disease

The incubation period for oidium grapes is 1-2 weeks, depending on the temperature regime. This time interval is characterized by the settling of conidia with the transition to the appearance of a grayish-white bloom. They grow actively at 20 degrees, but the minimum temperature for growth is 5 degrees.

Oidium on grapes is easier and faster to reproduce in damp and warm weather, but the possibility of development in hot weather should not be ruled out. Oidium affects especially dense bushes from the inside, shrubs that irregularly receive a sufficient amount of oxygen are also affected.

In winter frosts, the fungus is underground in the form of mycelium. Also, scientists have found that the causative agent of powdery mildew forms a large number of perithecia, which help to endure frosts, but it has not yet been proven that ascopors, which come from club-shaped sacs, infect the vineyard with the disease in spring. All European grape varieties succumb to the negative effects of powdery mildew.

Oidium grapes: how to fight?

Oidium grapes: photo of the disease

If the grapes receive sufficient air circulation and are not very dense, then the powder will not appear on the grapes. The use of copper and organic fungicides is not effective in controlling the pest.The best way to kill milad is the use of sulfur. The substance reacts with the causative agent of the disease in the course of which it forms hydrogen sulfide, after which the fungus gradually loses its vitality.

For the reaction, sulfur is not used in solid form, but converted into a vaporous form, to obtain steam, you need to use a temperature above 20 degrees.

Important: Pollination of grapes from powdery mildew is carried out in warm weather, so that the sulfur goes into the form of steam!

The greatest effect is obtained after the sulfur, which has very small particles. Therefore, the substance is usually highly crushed and sieved through fine strainers. In order for sulfur to keep its striking effect permanently, it is necessary to store it indoors always dry. The sulfur layer should cover all the greened parts of the shrub, it should penetrate straight into its depths. On leaves and fruits in dry weather, the sun can burn the plant. If pollination is planned to be carried out in the heat, then it is best to do this in the morning or in the evening, when the heat is not so strong. Gray can be pollinated on dry soil or on the side of the grapes that is in the shade.

The fight against powdery mildew on grapes can be immediately carried out with the destruction of mildew, you can use powders for lubrication or paste-like creams, in which there is a small amount of sulfur, only shrubs are sprayed with these preparations, and not pollinated. You can add other organic fungicides to the solution and fight against caterpillars and larvae.

Also, against the false and real oidium of grapes, combined complexes act, to the composition of which copper and other organic compounds are added. If you use a solution instead of a solid, then you can be 100% sure that precipitation will not affect the preservation of sulfur on the leaves in any way.

How and when to pollinate grapes from oidium?

Oidium grapes: photo of the disease

To understand when is the best time to take control measures against mildew on grapes, you need to look at the damage to the plant in the past year. If the fungus has hit the shrub very strongly, then the affected areas are treated in the spring, as soon as the plant has sprouted. Experienced gardeners are immediately treated with other drugs for other fungi and diseases. If last year the degree of damage is not very high, then the grapes are processed from mildew when the first treatment is carried out against mildew. Re-processing is carried out at a time when the plant is treated from other pests.

In dry and warm weather, when powdery mildew occurs on unripe fruits, pollination should be carried out with sulfur. But if the weather is damp and cool, then they are sprayed with organic poisons or, as an option, with a solution of 0.2 percent colloidal sulfur, after the procedure, after a while, the clusters need to be washed.

It is necessary to withstand a certain waiting time, that is, the time interval between processing and collection of fruits, which is thought out in advance. This is 55-56 days for fungicides and sulfur.

Shrubs that are damaged by grape powdery should be pollinated or irrigated two weeks before the fruits are soft. In order not to lose the vineyard, it is necessary to carry out mandatory measures to combat the disease.