🔎 Powdery Mildew - Definition and Explanations

Introduction

The term Oidium is the vernacular name given to the asexual form of certain fungi belonging to the Erysiphaceae family. Powdery mildew is a cryptogamic disease (The disease is an alteration of the functions or health of a living organism, animal, etc.) , Anglo-Saxon mildeaw ...) and other fungal parasites). well known to gardeners and farmers, powdery mildew mainly attacks certain tree species such as oak (Oak is the common name for many species of trees and shrubs belonging ...), maple, quince (The genus Cydonia is composed of a single species called quince (Cydonia oblonga...), apple (Apple trees are a genus (Scientific name: Malus) of the family of Rosaceae. This...) or hawthorn (L' hawthorn (Crataegus) is a genus of thorny trees or shrubs of...) which are particularly sensitive to it.

Main species called “oidium”

Description

Its attack begins with the appearance of a felting (powder), white to white-greyish, floury appearance on the surface (A surface generally designates the superficial layer of an object. The term a...) of the leaves , stems and sometimes flowers or fruits, hence its local nickname "miller". Powdery mildew can cause leaves to become distorted, curling and blistering. The fungus multiplies preferentially on young organs (leaves), which it invades and deforms. Note however that on peas, for example, it is the old leaves that are first affected. In this specific case (In the life sciences, the species (from the Latin species, "type"...), the culture (Culture is a pan-galactic civilization invented by Iain M. Banks through his ...) late is highly threatened.Its winter conservation can be done in the form of mycelium in the buds which will then give totally infected shoots called "flag" shoots.

Favorable grounds

Unlike other groups of fungi (scab, mildew, rusts, etc.), it proliferates in relatively dry weather, subject to a humidity level (Humidity is the presence of water or water vapor in the air or in a substance...) from 70 to 80%. It is often in May that it begins its ravages, favored by the still very present humidity and the arrival of heat (In everyday language, the words heat and temperature often have an equivalent meaning:...). The significant temperature differences (The temperature is a physical quantity measured using a thermometer and...) between night and day (The day or day is the interval between sunrise and sunset ; c'est la...) constitute factors favoring the appearance of this fungus which threatens large numbers (The notion of number in linguistics is dealt with in the article "Number...) of crops, both in the garden of ornament than in the orchard or in the vegetable garden... In the event of a major attack, the fruit harvest is reduced.

Means of struggle

Bleach treatment (Bleach (also called Javel) is a liquid solution that frequently oxidizes...)

Preventive or curative action. By spraying (The term spraying was introduced in 1975 by JM Steele in his...) at the beginning of winter (Winter is one of the four seasons in temperate zones.) to prevent. 25 ml of water (Water is a ubiquitous chemical compound on Earth, essential for all...) of bleach for two liters of water, same dilution (Dilution is a process consisting in obtaining a final solution of concentration...) in healing but avoid the sun (The Sun (Sol in Latin, Helios or Ήλιος in Greek) is the star...). The result is conclusive even with a strong infection. Advantages: cost, environmental impact (The environmental impact is all the modifications to the environment, whether they are...) limited — chlorine (Chlorine is a chemical element of the halogen family, of symbol Cl, and of...) evaporates fairly quickly — no stains. It is a radical means of care for roses sensitive to this fungus. Disadvantages: it kills the fauna and flora (Flora is the set of plant species present in a space...) of the soil, which reduces fertility (For common sense, fertility designates at the end of the 20th century la...) in the medium term. Prefer therefore as a curative as soon as the first symptoms appear.

In a more concentrated solution, this process is also particularly effective for the "ink of trees" of walnut trees in particular. Healing (Healing is a biological process by which cells in the body ...) and cicatrization occur rapidly even in very old specimens.

Natural treatments

The use of horsetail manure, containing silica (Silica is made up of silicon dioxide, a chemical compound that enters the ...), or an infusion of garlic with added milk (sulphur compounds for garlic , milk serving as an adjuvant (An adjuvant is something or someone who helps accomplish a process.) adherence and also an antifungal: see below), can suppress powdery mildew while (The whole understood as all that exists is often interpreted as the world or...) while preserving the environment (The environment is everything that surrounds us. It is the set of natural elements and... ) and soil fertility. To be used as soon as the first symptoms appear.

Powdery mildew is hydrophilic... so it is not enough to spray it with water to prevent its development. However, the use of several infusions of sulfur (Sulphur is a chemical element of the chalcogen family, symbol S and ...) in the greenhouse (A greenhouse is a generally closed structure intended for the production...) remains very effective in the fight against powdery mildew.

Preventive action

milk treatment

Regular spraying of the foliage with a mixture (A mixture is a combination of two or more solid, liquid or gaseous substances...) of water and skimmed milk, or better, whey (10 to 1) allows eradicate powdery mildew. In addition, this vaporization would strengthen the immune defenses of the plant (Plants (Plantae Haeckel, 1866) are multicellular beings at the base of the...). Preferably use skimmed or semi-skimmed milk to avoid odors of decomposition (In biology, decomposition is the process by which organized bodies, they...) of milk fats. Do not overdose the milk otherwise other types of fungus will grow. The action of milk on powdery mildew is explained by its natural anti-fungal properties.

Curative action

Baking soda treatment

The baking soda spray is quite effective. Its basic pH prevents fungus spores from germinating. Dissolve 5 g (1 teaspoon) of baking soda per liter (The liter (from the Greek λίτρα lítra, old measure of capacity...) of water and add 1 teaspoon of Marseille soap (The Marseille soap is a type of soap that is particularly effective in its power...) liquid (The liquid phase is a state of matter. In this form, matter is...) or milk so that the solution clings to the leaves.

Spray this solution under and on the leaves and renew after any heavy rain (Rain generally designates a precipitation of water in the state...).

Potassium permanganate treatment (Potassium permanganate is an inorganic salt with the chemical formula KMnO4. It is composed of...)

Dilute 1.5 g of potassium permanganate (Potassium is a chemical element, symbol K (Latin: kalium, de...) (available in pharmacies) in 1 liter of water. Spray the tree or brush with a brush. Repeat within 15 days. The dose can be increased to 15 g/l in difficult cases, taking care to protect the root ball before use (Usage is the action of using something.). to complete this treatment 48 hours (The hour is a unit of measurement:) later with a sublimated or wettable sulphur.

Sulfur treatment

Sulfur, a basic product, used for a very long time against powdery mildew (developed (Graphie) by Henri Marès around 1850 on the vine), always gives good results in preventive control (late autumn (Autumn is one of the four seasons of the temperate zones. It is placed between summer and...) and beginning of spring) or semi-curative. It is authorized in organic farming (Organic farming is based on the rational management of the fraction of the soil, in the...) and can be used very close to the harvest because it is completely biodegradable. Its secondary actions are also interesting on a number of other fungi and insects (Insectes is a French-language journal of ecology and entomology intended for a wide audience...) or mites.

It acts by vapor () (it is said to sublimate). On the other hand, if it has been poorly distributed or too concentrated, it can be aggressive on plants in calm and hot weather (above 25°C). It is advisable to apply it at temperatures between 10 and 20°C and preferably out of the sun (like any treatment to be sprayed on the leaves), in the evening for example, to avoid burning the foliage. Generally applied as a spray, it forms a white deposit on the leaves. For a tree (A tree is a terrestrial plant capable of developing itself in height, in...) in a pot, one can put a small container with a solution of sulfur at the foot of the tree and the vapors of sulfur prevent the development of powdery mildew.

Sulfur is purchased in the form of “wetting powder” which is therefore diluted in water according to the doses indicated on the packaging; increasing them does not improve the effectiveness of the treatment. However, this "water-based sulfur" is much less effective than powdered sulfur (Powder is a split state of matter. It is a solid present...).

In the absence of preventive treatment, when the disease breaks out, it is advisable to treat as soon as the first symptoms appear. The efficiency drops very sharply beyond 10 to 15% of the surface area reached.

To know that each treatment affects more or less the close environment (soil, insects, birds...) it is necessary to strictly respect the dosages. The beginning of an epidemic can be slowed down or stopped thanks to Bordeaux mixture (Bordeaux mixture is a pesticide (algicide and fungicide) made by neutralization...), much less toxic than sulfur in large doses.

Treatment with Bordeaux mixture (Bordelaise is a French cattle breed.)

Bordeaux mixture, a powerful fungicide can also be used.

Biological treatments

The decoction of nettle or sorrel roots (Sorrel (Rumex L.) is a genus of herbaceous plants of the Polygonaceae family,...) has a spectacular effect: soak in a liter of water, 100 g of roots for 24 hours. Simmer 30 minutes (Primary form of a document: Straight: one minute is the original of a...) and use pure.