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Video: Diseases Of Strawberries: White, Leathery, Black, Gray Rot
How to save the strawberry harvest
On each garden plot, you can find even rows of bushes of well-known and beloved strawberries with delicate, juicy berries, with which they usually please us for 2-3 weeks. But, unfortunately, both the plants themselves and their aromatic fruits are affected by numerous pathogens.
In total, more than thirty fungal, bacterial and viral diseases have been registered, which annually cause significant crop losses on this crop. Because of these diseases, the bushes weaken, begin to bear fruit poorly, the taste of the fruits deteriorates. Every gardener, if he wants to constantly be with a good harvest, must be able to recognize the symptoms of the main fungal diseases of berries, and also know the measures to combat them.
According to experts, the most common and harmful mycoses of strawberry fruits are gray, white, black and late blight (leathery) rot.
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In addition to ripe fruits, the ubiquitous gray rot pathogen also affects leaves, buds, flowers, stalks and ovaries of plants, especially in lowland and poorly ventilated plantings. In cool seasons with repeated precipitation, the loss of berries from this mycosis often exceeds half of the harvest. On the leaves, the causative agent of the disease causes the appearance of large blurry spots of a brown hue with a weak gray down. On the stalks, the disease manifests itself in the form of brown spots, which can quickly ring them, which causes complete drying and death of the still green ovaries.
Diseased ovaries and green berries turn brown, stop developing and dry out, and those that begin to blush become watery and tasteless. On ripe fruits, separate softened brown (sometimes yellowish) spots initially appear, which quickly grow in a day or two, as a result of which the fruits completely rot, lose their aroma and taste and are completely unsuitable for consumption. On diseased berries, a plentiful gray fungal mycelium appears, which is an accumulation of pathogen spores. Over time, such fruits mummify and, turning into small gray lumps, continue to hang on the stalks for a long time. They "dust" with spores, even with a light touch. As a result, the pathogen spreads throughout the site.
Rainfall and wind also contribute to this. The causative agent of mycosis overwinters in the form of sclerotia and mycelium on affected leaves, petioles, on plant debris in the soil and on its surface. Infection of bushes occurs, as a rule, during the flowering period of the culture and at the time of fruit ripening, when the most intense years of spores in the air are noted. Ripening fruits can also become infected by contact with infected berries.
Gray rot develops intensively on berries during their transportation and storage (especially in closed containers), and in positive temperatures it quickly spreads to neighboring healthy fruits.
Each strawberry variety is good in its own way, but, unfortunately, all strawberry varieties are affected by gray mold, although among them there are varieties characterized by a reduced susceptibility to this mycosis. It was found that fruits of a denser consistency, containing a lot of dry substances, suffer less. The most dangerous disease is for varieties in which the fruits are located close to the ground; fewer lesions in those varieties in which the vertically arranged peduncles are higher than the leaves, since the berries of such varieties do not come into contact with the soil.
According to experts, the strawberries of the varieties Leningradskaya Early, Early Makheraukha, Sudarushka, Divnaya, Tsarskoselskaya, Druzhba are slightly affected, the varieties Zenga Zengana, Zarya, Talisman, Scarlet Dawn, Cinderella, Krasavitsa, Nadezhda, Festivalnaya, Volshebnitsa are more susceptible.
In addition, it must be remembered that the causative agent of gray rot affects not only strawberries, but also a wide range of other fruit and berry and vegetable crops.
In humid weather, on ripening fruits, a thick, dense coating of the fungus (with water droplets on the surface), the causative agent of white rot, may appear. Sick berries rot very quickly. The pathogen also infects the leaves, roots and rosette of the bush, causing wet decay of plant tissue. As a rule, damaged, contaminated and in contact with the ground berries are more likely to suffer.
Cold weather, thickened plantings, weeds in the beds and excessive watering contribute to the infection of berries.
It is celebrated only on berries. With this disease, the affected fruits turn brown, quickly become covered with abundant tomentose gray (later blackening) powdery mycelium. Mechanical damage to the berries by insects and slugs, their overripening and high temperatures (28 … 32 ° C) during ripening are favorable. The coming cold snap only temporarily restrains the rotting of berries from this disease.
Black rot is especially dangerous for overripe berries, especially after picking them up during storage. A characteristic sign of a developing disease is the release of juice by berries. In addition to strawberries, mycosis affects the fruits of raspberries, blackberries and some other fruit crops.
Late blight (leathery) rot
It is much less common than previous mycoses. This rot manifests itself at the beginning of the ripening of the berries: their color turns brown, a characteristic bitter taste appears. On the surface of such fruits, the appearance of an abundant white bloom is noted. In diseased fetuses, the affected tissue does not separate from healthy tissue. They shrink, and their surface takes on a leathery character.
In humid weather, the pathogen also infects leaves, which develop vague, dark green oily patches. These spots quickly increase in size, turn brown, then the leaves begin to wilt. With the onset of dry weather, the leaves become brittle and brittle. The causative agent of this rot can affect the leaves of the petiole and sheath, as well as the peduncles and the root collar of plants.
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Crop protection methods
In household and garden plots, the main role in protecting strawberries from these diseases should be assigned to a complex of agrotechnical methods. It is advisable to plant strawberries in one place for no more than four years, and it is possible to return it to its original place no earlier than after five years. The best predecessors for her in crop rotation, in order to avoid the spread of these diseases, are legumes, dill, celery, parsley, garlic, onions; it is not recommended to arrange her plantations after tomato, cabbage, potatoes, carrots and pumpkin crops.
Strawberries should be placed on an open, well-lit and ventilated area with fertile, well-drained (air and moisture permeable) soil. Only healthy seedlings are taken for planting.
As soon as the snow melts and the average daily air temperature rises above 5 ° C, on the beds with strawberries, it is necessary to shovel and destroy the dried and diseased green leaves. When planting strawberries, the plant density is calculated taking into account the characteristics of each variety; for ordinary varieties, the optimal pattern is 70x25 cm.
Excessive doses of organic and nitrogen mineral fertilizers cannot be applied to strawberries. During the growing season, you should regularly loosen the soil in the beds, remove weeds, and fight berry pests.
At the beginning of fruit ripening, you can use temporary soil mulching with clean straw. Some gardeners, in order to avoid being affected by diseases, advise to lay the peduncles to support the berries (especially in wet years) on ropes stretched along the rows, on special stands or flyers sold in the retail network. This prevents the berries from touching the ground.
Ripe fruits must be collected immediately, at the same time removing from the bushes and deeply burying diseased berries.
As a preventive measure against mycoses of strawberries, experts recommend in the spring (before the leaves grow back) to treat the bushes with a solution of 3% Bordeaux liquid. If this moment of its application is missed, then during the period of exposing the buds, the plants are sprayed with a 1% solution of this drug. An increase in plant resistance and a significant decrease in the stock of infection of fungal pathogens is facilitated by repeated processing of strawberries with the same copper-containing preparation immediately after harvesting the berries.
Some gardeners use a slightly pink solution of potassium permanganate to limit the infection of flowers with the pathogen of gray rot. This technique is also a foliar feeding of plants with several nutrients at the same time. To reduce the harmfulness of this disease, other amateurs treat plants with a settled solution of potassium chloride (100 g) or ash (two glasses) per bucket of water).
Diseases and pests of strawberries