IF POTATO COVERED WITH NARROW LEAVES - WHAT IT IS AND HOW TO FIGHT
This year, underdeveloped - narrow and elongated - leaves appeared on some potato bushes, as can be seen in the picture (they are located in the middle). Harvest from such plants was lower than on others. If this is a disease, is it dangerous?
© Author: Stanislav Grigoryevich PARFENOVICH
This question is rather complicated, and it is difficult to answer it unequivocally. It is necessary to determine the cause of this phenomenon on the spot, although there may be several of them, and they can act simultaneously. This is an undesirable phenomenon, and it leads to a significant decrease in yield. In this article, we list the main causes of such a physiological disorder and try to show ways to minimize the harmful effects of these factors on the productivity of a potato plant.
Mosaic leaf curl
Mosaic leaf twisting is caused by a virus. It is transmitted mechanically, by aphids, bedbugs and a potato cow. With a severe defeat, crop losses can reach from 15 to 70%, and with a mixed infection, more. Symptoms of the disease
on potatoes are very different and depend on the variety, the conditions of its cultivation, the strain of the pathogen, the type of infection, the time of its manifestation. It is worth noting that this disease does not cover the lower physiologically old leaves.
The most typical signs are observed on young plants in the form of a more or less pronounced mosaic pattern and twisting upwards of the edges of the lobes of the upper leaves. At the same time, they are always flexible and soft; they are never fragile. Sometimes there is an undulation of the edge of the lobes, a slight reddish staining of the leaves or their yellowing.
On some varieties of potatoes, the disease manifests itself in the form of curls, streaks of petioles, stems, necrosis of the veins or is asymptomatic. In the second half of the potato plant vegetation, the external signs of the disease are almost indistinguishable.
Curling potato leaves
Twisting the leaves of potato plants is also caused by a virus that is carried by aphids and field bugs. Crop is reduced by 30-80%, starch content in tubers - by 2-5%. The virus infects the cells of the phloem (conductive tissue) of plants, dramatically reduces the outflow of nutrients from the leaves and thereby disrupts photosynthesis and other physiological processes.
Plants have a pale green, chlorotic color, often lag behind in growth. The main symptom of the disease is the twisting of the shares of the leaves of the lower tier along the middle vein. They become stiff, rustling when touched. Anthocyanin staining may appear on the underside of the leaves, and net pulp necrosis may appear on the tubers. Flowering in some varieties is absent.
Signs of damage on plants intensify at high temperatures of air and soil, lack of moisture. The infection persists in the tubers.
This disease is very harmful, affecting sprouts in the soil, which causes decay and premature death of plants, reduces the germination of potatoes. Crop losses range from 7-15 to 30%. All organs of the plant are affected. Dense dark brown or black plexuses of mycelium are formed on the tubers - sclerotia (black scab), resembling lumps of soil that adheres to the skin, but, unlike the latter, they are not washed off by water.
After planting tubers from sclerotia, the mycelium of the pathogen develops, affecting the potato sprouts in the form of brown or almost black ulcers of various sizes and shapes. Sick bushes lag behind in growth. In summer, rhizoctoniosis manifests itself in the form of dry rot of the underground part of the stem, on which brown ulcers of various sizes form. Fabrics die off, resembling rotten wood; the surface of the stem becomes rough. Stolons and tubers are affected, especially young ones. The apical leaves are twisted in a boat around the central vein, the plants become similar to patients with the leaf curl virus, which makes it difficult to identify the disease.
How to prevent the development of the above diseases? To obtain high potato yields in individual farms, both private and general protective measures should be constantly carried out.
First of all, you need to take care of the seed material. For 10-12 days before harvesting, you should dig up the bushes intended for seed purposes, select the medium-sized and weight (50-80 g) tubers and plant them in diffused light for several days. Plants for this purpose must be healthy and have a good look. It is necessary to exclude from practice such a case when the tubers are dug up completely on the ridge, and then the seed fraction is selected.
In preparation for planting, it is necessary to carefully discard diseased specimens in the seed material. This can be achieved by bulkhead and pre-planting germination. Tubers should be laid out in 2-3 layers in a bright, warm room with temperatures above 12 degrees or in an open sunny area.
At a temperature of 12-17 degrees, potatoes for germination in the light are laid out 35-40 days before planting, in warmer conditions - 30 days. During this time, the inferiority of tubers (disease, non-awakening of the eyes, threadlike sprouts) becomes clearly visible, and such specimens are subject to rejection.
And, of course, during the growing season should carry out the whole range of protective measures against pests and diseases.
To avoid the spread of viral and bacterial infections, cutting tubers before planting is not recommended.
Unacceptable planting of non-sorted seed material and small tubers, which are often the offspring of plants affected by a black leg, ring rot or viruses. Most of these tubers do not have external signs of damage, however, diseases can occur during the growing season of potatoes.
Often, towards the end of the growing season, a pale, gradually browning border appears on the leaves of potatoes of middle and late varieties. This means that plants lack potassium. It will help to cope with this problem by feeding potatoes with ash (a glass per meter) or potassium sulfate (25-30 g).
POTATO DISEASES AND COMBATING THEM - VIDEO
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