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This disease is well known to all plant breeders. Powdery mildew affects indoor plants, penetrating into apartments.
- The causes of powdery mildew
- Signs of powdery mildew
- One of the popular ways to fight the disease
- The choice of planting material - as a measure of control
- Conditions for the development of the disease
The causes of powdery mildew
The disease is caused by a parasitic fungus. Young leaves and shoots acquire a silvery coating and sparkle in the sun with the smallest droplets of moisture. Without proper treatment, the disease spreads throughout the plant. The leaves curl, the ovaries wither, and the fruits fall off. By the end of the growing season, the plant weakens and does not tolerate the winter period.
With all the similarity of the external signs of the onset of the disease, powdery mildew is caused by various types of fungus. This suggests that powdery mildew that has settled on a cucumber crop is not able to infect gooseberries or currants.
Powdery mildew appears on plants, in particular on currant bushes, at the very beginning of the growing season. Spores of the fungus, carried by the wind, settle on young foliage. With the onset of stable heat, closer to the beginning of summer, spores burst and mycelium penetrates into the plant body. From this moment, the destructive effect of the fungal infection occurs.
Signs of powdery mildew
Powdery mildew was introduced in the middle of the 19th century from the American continent. The parasitic fungus received good conditions for its life. Until now, this disease is considered intractable.
An affected plant can always be distinguished from a healthy currant. The leaves and branches of the currant bush are covered with a powdery bloom, like felt. Under mechanical stress (for example, manually wiping off such a coating), the plaque does not go away. Bushes that have been infected stop their development and stop bearing fruit.
If not taken appropriate measures, powdery mildew on currants, as a rule, leads to permanent death of the plant.
The appearance of powdery mildew is associated not only with poor plant care. An excess of nitrogen fertilizers can also lead to parasite damage to currant bushes. Not all currants are susceptible to disease, but the risk of powdery mildew contamination applies to all varieties.
One of the popular ways to fight the disease
If powdery mildew is found on currants, how to deal with it can be suggested by one of the popular methods of combating this disease. As protection of the currant bush from damage by powdery mildew, the following measures can be applied:
- Before flowering, 1 kg of sifted ash is diluted in 10 liters of water (bucket). Exposed in a sunny place with direct sunlight for 3-4 days.
- 1 bar of laundry soap is dissolved on a grater and added to the mixture, ensuring the stickiness of the solution.
- After the end of flowering, the bush is sprayed with a solution of soda ash, at the rate of: 25 g of soda per 5 liters of water.
This event is recommended to be carried out before signs of disease appear.
Proceeding from the fact that powdery mildew spores are carried by air currents, that is, by the wind, spring spraying with the "old-fashioned method" is a preventive measure to combat the disease. It is aimed at preventing the spores of the fungus parasite, brought by the wind, from developing on the treated plants.
The choice of planting material - as a measure of control
Buying healthy planting material can be seen as one way to prevent powdery mildew from entering the grower's area. It is advisable to purchase young currant bushes in plant nurseries. Being located directly on the territory where the seedlings are grown, you can see the growing conditions, as well as get qualified advice from specialists.
Specialized nurseries will provide advice on varieties, the choice of a site for planting currant bushes, soil composition, fertilizer complexes, and, of course, protection against diseases and parasites.
Conditions for the development of the disease
The best conditions for the development of powdery mildew spores are warm and humid days in early spring. Fungal spores begin to develop when the air temperature rises to + 17C, and the relative humidity is 90%.
The disease starts from the center of a poorly cut bush, in the most shaded part of it, or on those bushes where there is no direct sunlight.
The intensity of development of powdery mildew spores falls on the period of violent development of the vegetative mass. This period is associated with large-scale rejuvenating pruning of the bushes. Often, an unbalanced application of fertilizers leads to an intensive development of the disease: a large amount of nitrogen fertilizers prevails over phosphorus and potash fertilizers.
In conclusion, I would like to remind you that pathogens overwinter on fallen leaves, berries and affected shoot tips of the past growing season, causing summer secondary infection of plants. The viability of summer spores does not exceed two to three days. But this period is also reduced at daytime air temperatures of + 30 + 32C, especially when dripping moisture gets into it.
Cleaning of fallen leaves and timely spring pruning of currant bushes will help to avoid secondary infection of plants with powdery mildew.