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The vast majority of gardeners take potato cultivation very seriously, because for many villagers, a crop grown on their own is a serious help in storing supplies for the winter. Many also grow potatoes for sale, and this is part of their annual income. Therefore, gardeners, of course, cannot calmly walk past withering or drying leaves and stalks of potatoes. It is one thing when the tops of potatoes wither at the end of summer - it is this sign that indicates that the tubers are beginning to ripen and after a couple of weeks they need to be dug out. But when it is still far from harvesting, and the leaves begin to wither, dry or turn yellow, then something is wrong with the potatoes. It is necessary to understand the main reasons for this phenomenon, since they are very diverse.
The reasons why potato tops wither, dry and turn yellow
Potato diseases
Sadly, but most often the wilting and drying of potato leaves is associated with the spread of fungal, bacterial or viral diseases.
Fungal and bacterial diseases
One of the most common fungal diseases on potatoes is late blight. The leaves underneath become lethargic, lifeless, then extensive dark and brown areas appear on them and they quickly turn black and dry. Over time, tubers also begin to be affected, and more than half of the crop may be lost.
The safest thing to do is to take the following preventive measures to combat this problem:
- Do not plant potato tubers too thick;
- Do not plant potatoes in a place where symptoms of late blight have already shown. Moreover, since this disease is characteristic of the entire family of nightshades, it is worth paying attention also to the proximity of tomatoes and peppers;
- Choose potato varieties resistant to late blight;
- Weeding, loosening and hilling potato bushes to enhance air exchange in the ridges;
- Process potatoes with copper preparations during the flowering period or phytosporin at a later date;
- If the tubers are germinated in the light before planting, then the infected tubers from this procedure begin to rot and they are quite easy to reject.
If you notice small necrotic spots with a yellow rim on the leaves of a potato, then most likely the potato has been affected. alternaria... If the spots on the leaves are large - this macrosporiosis... In any case, the potato dries up and you can try to save the crop by treating the bushes with phytosporin - after all, it does not contain harmful chemical substances and can be used at any stage of the growing season.
Another dangerous fungal disease begins with the wilting of the upper leaves - fusarium.
Most often, the most effective way to combat this disease is dressing the tubers before planting with one of the antibacterial drugs (Baktofit, Fitosporin).
A very unpleasant disease of potatoes is ring rot, the first signs of which can be seen even during flowering. Some stems turn very yellow, while the top twists with leaves, and the bush begins to wither and decay. The most unpleasant thing is that the tubers are quickly affected. With these signs, diseased bushes are subject to mandatory destruction along with the tubers. And all potato plantings are immediately processed with medicinal preparations.
Known to experienced gardeners is bacterial disease blackleg... It manifests itself immediately after germination and is expressed in the fact that the bases of the stems rot, and young seedlings turn yellow, curl and wither. To combat this scourge, sprinkling the potato area with a mixture of ash and copper sulfate can help (for 1 kg of wood ash, 2 tablespoons of copper sulfate are taken).
Viral diseases
Viral potato diseases pose a particular danger to the gardener, since there are no means yet that can protect plants from them. The variety of viruses is great, it is enough to name such as: mosaic alfalfa, mottling, haulm haulm virus, gothic other. Symptoms of diseases are also varied, but most often they manifest themselves in yellowing and dryness of leaves, tubers acquire ugly shapes, stems die off prematurely, and the yield as a result of all this is sharply reduced.
Therefore, it is very important to completely destroy the virus-infected potato bushes together with all the tubers. Preparations such as epin and zircon increase the immune system of plants, so they can be used to further protect potatoes from viruses.
The best prevention of viral diseases is planting healthy tubers.
Parasites on potatoes
A kind of worms called nematodes can exist in the soil for decades. This species is a parasite on many plants. In particular, on potatoes, they settle in the root system, and their larvae actively suck out all the juices from the leaves. From the presence of nematodes, the tops turn yellow and dry, many black dots are clearly visible on it. Tubers practically do not develop. Future harvest can easily be minimized.
There are special chemicals that effectively combat the presence of nematodes in the soil.
The gardeners themselves have to subject all tools to thorough disinfection before each planting season and use seed material that is resistant to nematode damage. In addition, you can try to change the potato planting site every 2-3 years and plant corn, rye, oats, marigolds, lupines, peas, and beets in the infected areas. The root system of these plants is quite successful in combating the dominance of nematodes.
Insects
Among insects, there are also many who like to feast on juicy leaves, stems and tubers of potatoes. This is both a potato flea and a wireworm, but the most vicious enemy is, of course, the Colorado potato beetle. This insect of yellow color with black stripes can breed up to 3-4 generations in one season. The beetles themselves fly well, but the most dangerous for potatoes are their larvae, which are able to quickly destroy almost all potato leaves and stems. There are many ways to combat harmful insects, but not all of them are equally effective.
- Quite often they are collected by hand in a jar with a strong solution of sodium chloride;
- To scare off the beetle, calendula, nasturtium, beans, marigolds and dill are planted between potato rows;
- Sometimes the bushes are sprayed with herbal remedies, such as an infusion of elecampane or celandine;
- Biological agents cope well with them - boverin or bitoxibacillin;
- If the invasion of beetles has acquired a large scale, then there are many chemical means of fighting the pest.
Weather
Speaking about the reasons why potato bushes wither and dry, one cannot but mention unfavorable weather conditions. This is especially typical for the southern regions, but in the middle lane, in conditions of hot and dry summers, potatoes can begin to wilt without additional watering.
Therefore, even on large planting areas, it is important to provide for watering the potato field at least once a season during the phase of flower formation.
Of course, it also happens that even in June unexpected return frosts will come, and the tops of the bushes may dry out. But in this case, spraying with immunostimulants (Epin, Zircon, HB-101) can help and after a while the potato bushes will come to their senses and the crop can still grow very good.
Top dressing of potatoes
Oddly enough, but potato bushes may well turn yellow and even wither from a lack or excess of nutrients.
- The lack of iron and magnesium is manifested in potatoes precisely in the yellowing of the leaves. Only with a lack of iron, as a rule, the upper leaves turn yellow. A lack of magnesium is manifested primarily in the yellowing of the lower leaves;
- If the plants do not have enough potassium, then the potato stalks acquire a bronze tint, curl and dry;
- Due to a lack of nitrogen, all potato growth stops, the stems come out thin, and the leaves gradually become lighter and lighter;
- If your potato bushes do not grow up at all and remain weak, squat, then the plants may lack phosphorus. You can check this by cutting the tuber in half. In the case of a lack of phosphorus on the cut of the tuber, it will be possible to clearly distinguish a purple tint.
In addition, feeding potatoes with many microelements, especially in a chelated form, when they are well absorbed by plants, can reduce susceptibility to various diseases. Spraying potato bushes with boron is especially important.
Of course, the reasons for withering and yellowing of potato tops there are many, but it is important to diagnose and cope with this problem in time in order to have time to get a full and healthy crop of potato tubers.
