How to treat currants if white bloom appears on the leaves

Sometimes gardeners have to deal with such a phenomenon as white bloom on currant leaves. It is clear that this is not a variant of the norm, but a sign of a disease. The so-called powdery mildew affects many crops, including fruit bushes. It is her symptoms that appear in the form of a white cannon bloom that affects leaves and shoots. The disease must be treated immediately so as not to be left without a crop.

Powdery Mildew Harm

This disease belongs to the group of fungal infections. Under favorable conditions, the fungus multiplies rapidly, covering all new parts of the plant.

1. The first signs of infection are easy to miss, as the symptoms first appear on the underside of the leaves.
2. By the middle of summer, the disease enters the active stage - the white bloom is growing rapidly. If untreated, powdery mildew can affect the entire currant bush.
3. As the spores mature, the plaque acquires a compacted structure and begins to resemble felt in appearance. Sick plants stop developing, and young shoots die off.
4. The leaves become smaller, begin to curl, and then fall off. Together with them, the plant also loses the set fruits. The yield of black currant is sharply reduced.

Weakened bushes do not tolerate wintering well and can freeze out in the cold season. Even if currant growth resumes in spring, the plant will not be able to develop normally. The overwintered fungus attacks it with a vengeance, which will ultimately lead to the death of the bush.

The causes of the disease

The fungus that causes powdery mildew can reproduce sexually and asexually. In the first case, the fruiting bodies of the fungus produce ascospores, which, with the arrival of spring heat, begin to attack the plant. In the summer, during asexual reproduction, conidia are formed, which again and again infect the plant, easily spreading from one leaf to another.

The causative agents of the disease belonging to the genus of ascomycete fungi are distinguished by their incredible vitality and resistance to external influences. The following factors contribute to their active reproduction:

• Moderately warm weather. Spores of the fungus are active at temperatures from + 5 ° C to + 28 ° C, but the most rapid development and reproduction of the mycelium occurs at + 20 ° C. The incubation period of the disease can last for 5-10 days, which is also determined by temperature indicators.
• High humidity. Most often, an outbreak of the disease occurs when the air humidity is 60–80%. The fungus begins to actively multiply not during the rain, but after it, when there is strong evaporation of moisture. Red and black currant bushes often get sick with powdery mildew with alternating rainy and clear days.
• Failure to comply with the landing pattern. The minimum distance between currant bushes should be 1.5-1.8 m. The spacing between rows should be slightly larger. If you break this rule, there is an excessive planting density. Bushes shade each other and are poorly ventilated, which favors the growth of the fungus. In addition, in close proximity, spores are more easily transferred from one plant to another.
• Excess nitrogen. Many already know that the excessive content of nitrogenous fertilizers in the soil contributes to the active reproduction of fungal diseases. Young shoots begin to suffer especially quickly.It takes a little less than 2 weeks from the moment the spores hit - and lesions already appear on the leaves.

Sucking harmful insects often contribute to the spread of the fungus. They puncture the leaves, making it easier for the spores to enter the plant tissue.

Powdery mildew symptoms

The symptoms of the disease are quite specific. Powdery mildew is difficult to confuse with other fungal infections.

The development of the lesion is accompanied by the following symptoms:

1. Young shoots are the first to be infected, which in a short time become covered with a whitish bloom.
2. The lesion can then be seen on the underside of the leaves. It can be described as a thin film with a cobweb-like pattern.
3. Soon a gray-brown bloom appears on the berries.
4. The infection is increasing. Light bloom darkens, individual black specks appear on it.
5. The leaves lose their natural color, curl. Affected berries become inedible.

The sooner powdery mildew treatment is started, the more chances are to save the crop and the plants themselves. If signs of damage are visible only on individual branches, these shoots should be removed immediately and burned outside the site. The same is done with shrubs that could not be saved. It is dug up and disposed of, and the earth in this place is disinfected by pouring boiling water or a solution of potassium permanganate.

How to deal with the disease?

Controlling powdery mildew requires an integrated approach. As for agrotechnical measures, first you need to:

• exclude nitrogen fertilizing;
• stop spraying the bush;
• reduce watering;
• make thinning pruning if necessary.

If these rules are ignored, the disease will come back again.

For the treatment of currants, chemical fungicides and folk remedies can be used.

Use of drugs

With a strong degree of damage, modern chemical preparations will help to fight powdery mildew. Bushes must be treated with one of the following fungicides:

• "Agrolekar". The main active ingredient of the drug is propiconazole. The tool can be used to treat and prevent powdery mildew during the growing season. For maximum protection, treatment will need to be done 3 times. Before use, the fungicide is diluted in a proportion of 7-10 ml per 10 liters of water.
• "Speed". The fungicide is developed on the basis of difenoconazole. You can spray currant bushes up to 4 times per season. The drug is diluted at the rate of 2 ml per 10 liters of water. The last spraying is carried out no later than 3 weeks before picking the berries.
• "Vectra". The product is based on bromuconazole. The peculiarity of the drug is that it is used only after flowering. The working solution is prepared from 3 ml of fungicide per 10 l of water. Suitable for the prevention and treatment of powdery mildew. If necessary, the bushes can be sprayed again after 1.5–2 weeks.
• "Topaz". The main active ingredient is penconazole. 4 treatments are allowed per season. Provides shrub protection for up to 3 weeks. The working solution is prepared from 2 ml of the product per 10 liters of water.

You can also treat currants from powdery mildew with the help of drugs: Fitosporin-M, Chistoflor, Forecast, Chistotsvet, Raek, Tiovit Jet.

The use of folk remedies

Some formulations prepared according to folk recipes have a depressing effect on the development of powdery mildew spores.

The proportions are indicated based on 10 liters of water:

• Soda. In order to prepare the solution, 2 tbsp is used. tablespoons of soda ash, 40 g of shavings of laundry soap are added to enhance the effectiveness. The composition is infused for 1 hour. The bush and the ground under it are abundantly watered with a solution from a watering can.
• Potassium permanganate. This old proven antiseptic effectively destroys various pathogenic microorganisms, including fungal spores. To prepare the solution, use 5 g of crystals and a bucket of water. The composition must be thoroughly mixed until the substance is completely dissolved.
• Nettle. The infusion is prepared from 2 kg of a burning plant, when it comes to fresh grass. Dried raw materials are consumed in the amount of 200 g. The infusion should be prepared for 3 weeks. It needs to be stirred from time to time. After the specified time, plant residues are consumed for compost, and the concentrated infusion is used for spraying in the evening, diluted with water in a ratio of 1:10.
• Copper sulfate. This compound is known for its antifungal properties. The substance is consumed in an amount of 5 g per bucket of water. The powder is preliminarily dissolved in a small volume of hot water, and then brought to the desired concentration.

Treatment of the disease can also be carried out with the help of infusions of mullein, ash, whey, iodine. In the piggy bank of folk recipes, there are quite a few tools that help in the fight against fungal diseases. Spraying is carried out in dry, calm weather, repeating the treatment several times with an interval of 7-10 days. You can alternate the compositions with each other.

Prevention of the appearance of white plaque

Breeders have bred many varieties of currants that are resistant to powdery mildew, and when buying seedlings, you should pay attention to them.

Before planting young bushes, they are soaked in a solution of copper-containing preparations. For disinfection, it is enough to hold the seedlings in the solution for no more than 10 minutes.

It is necessary to deal with weeds and pests on the site, since it is they who often contribute to the outbreak of powdery mildew. In autumn and spring, the earth around the bushes is dug up, pre-raking and burning fallen leaves.

Water the currants sparingly, avoiding waterlogging. The most favorable time for such procedures is morning. The soil should have time to dry out slightly before nightfall.

Before pruning bushes, garden tools must be treated with a disinfectant.

Whatever terrible consequences powdery mildew may bring with it, you can cope with it - you should not give up. With proper care of the shrub, the risk of infection will be minimized. When signs of illness appear, it is important to take immediate action, preventing him from going into an advanced stage.