Oïdium

Favorable grounds

Contrary to other groups of mushrooms (tavelure, Mildew, rust S, etc), it proliferates in relatively dry weather, subject to a water content from 70 to 80%. It is often in May that it begins its devastations, favoured by the moisture still quite present and the arrival of heat. The important variations in temperature between the night and the day constitute factors supporting the appearance of this mushroom which threatens great number of cultures, as well with the garden of ornament as to the Verger or with the Potager… Danslecasde attacks important, fruit-bearing harvest is reduced.

Description

Its attack starts with the appearance of a felting (powder), white with white-grisâtre, of farinaceous aspect on the surface of the sheets, stems and sometimes of the flowers, from where its local nickname of “miller”. The oïdium can cause a deformation of the sheets, which are gondolent and rise. The mushroom multiplies preferentially on the young bodies (sheets), which it invades and deforms, from where the name of “flag”, given to the attacked sheets.

Principal oïdiums

Oïdium of the vine ( Erysiphe necator )
Oïdium of the cereals ( Erysiphe graminis )
Oïdium of the apple tree ( Podosphaera leucotricha )
Oïdium of cucurbitaceous the ( Sphaerotheca fuliginea )
Oïdium of the chestnut tree ( Uncinula flexuosa )
Oïdium of the strawberry plant ( Podosphaera aphanis )

Means of fight

Preventive action

sufficient Spacing of the seedlings.
regular Cleanings around the plantations (to release the center of the rose trees not to support the maintenance of moisture).
fast Suppression of the parts or subjects reached in order to avoid or to slow down the propagation.
not to sprinkle the foliages when the weather is hot.
To cover the sensitive topics on suspicion.

Treatment milk

A study of 1999 indicates that a regular vaporization of the foliage with a mixture of water and Lait (9 per 1 or 2) allows éradiquer the oïdium. Moreover, this vaporization would reinforce immunizing defenses of the plant. To use preferably a skimmed milk or partially skimmed to avoid the odors of decomposition of greases of milk. Not surdoser milk if not other types of mushrooms would develop. The action of milk on the oïdium would be explained by its natural anti-fungic properties.

Curative action

Suppression when that is possible sheets and branches reached (and to burn them).
Subject treating as of the whole beginning of the appearance of the primary symptoms : Treatment (pulverization or powdering) of products Fungicidal S standard Myclobutanil (Triazole)

Bicarbonate of soda treatment

The pulverization of Bicarbonate of soda is rather effective. Its basic pH prevents the Spore S of Champignon from germinating. To dissolve 5 G (1 spoon with coffee) of bicarbonate of soda per liter of water and to add 1 spoon to coffee of Household soap liquid.
Pulvériser this solution under and on the sheets and to renew after all large rain.

Potassium permanganate treatment

To dilute 1,5 G of Permanganate of potassium (available in pharmacy) in 1 liter of water. To pulverize the tree or to whitewash with a brush. To renew under 15 days. One will be able to assemble the amount to 15 g/l in the difficult cases while taking care to protect the mound before usage.il is however advised to supplement this treatment later 48 hours with a sublimated sulfur or mouillable.

Treatment sulfur

The Sulfur, commodity basic, employee for a very long time against the oïdium (towards 1850 on the vine), always gives good performances in preventive fight (end of autumn and beginning of spring) or semi-curative. It is authorized in organic farming and can be employed very close to harvest because it is completely biodegradable. Its secondary actions are also interesting on a certain number of others Champignon S and Insecte S or Acarien S.

It acts by vapor (it is said that it sublimates). On the other hand, it can be aggressive in calm and hot weather, on the plants, if it badly were distributed or too concentrated. It is advised to apply it by temperatures ranging between 10 and 20°C and preferably except sun (like any treatment to be pulverized on the sheets), the evening for example, to avoid the burns of the foliage. Generally applied in pulverization, it forms a white deposit on the sheets. For a tree out of pot, one can put a small container with a sulfur solution at the foot of the tree and the vapors of sulfur prevent the development of the oïdium.

Sulfur is bought in the form of “powder to wet” which one thus dilutes in water according to the amounts indicated on packing; to increase the effectiveness does not improve of the treatment. In the absence of preventive medication, when the disease is declared, it is advisable to treat as of the appearance of the primary symptoms. The effectiveness very strongly drops beyond 10 to 15% of surface reached.

Namely that each treatment affects the close environment more or less (ground, insects, birds…) it is necessary to respect proportionings strictly. A beginning of epidemic can be slowed down or stopped thanks to the pulp of Bordeaux, definitely less toxic than suffers it with great amount.

Bleach treatment

Preventive action or curative. In pulverization at the beginning of winter to prevent. 25 ml of Bleach for two liters of water, even dilution in curative but to avoid the sun. The result is guaranteed even with a strong infection. Advantages: the cost, little of environmental impact - the Chlore is destroyed very quickly -, not spots and disinfection of the ground in premium. It is an average radical of care for the Rosier S sensitive to this mushroom.

In more concentrated solution, this process is also particularly effective for the “ink of the trees” of the Noyer S in particular. The cure and the cicatrization intervene quickly even at the very old specimens.

External bond

Oïdium of fishing and the apple tree

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