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The vast majority of gardeners take the cultivation of potatoes very seriously, because for many villagers a crop grown on their own is a serious help in preparing supplies for the winter. Many also grow potatoes for sale as part of their annual income. Therefore, gardeners, of course, cannot calmly pass by withering or drying leaves and stalks of potatoes. It is one thing when the tops of the potatoes wither at the end of summer – it is this sign that indicates that the tubers begin to ripen and after a couple of weeks they need to be dug up. But when the harvest is still far away, and the leaves begin to wither, dry or turn yellow, then something is wrong with the potatoes. It is necessary to understand the main causes of this phenomenon, since they are very diverse.
Reasons why potato tops wither, dry and turn yellow
Diseases of potatoes
Sad as it may seem, 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 below become lethargic, lifeless, then extensive dark and brown areas appear on them and they quickly blacken and dry out. Tubers also begin to be affected over time, and more than half of the crop may be lost.
It is most reliable to take the following preventive measures to combat this problem:
- Do not plant potato tubers too densely;
- Do not plant potatoes in a place where signs of late blight have already appeared. Moreover, since this disease is characteristic of the entire nightshade family, it is also worth paying attention to the proximity of tomatoes and peppers;
- Choose potato varieties resistant to phytophthora;
- Carry out weeding, loosening and hilling of potato bushes to enhance the air exchange of the ridges;
- Treat potatoes with copper-containing preparations during the flowering period or with 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 are quite easy to discard.
If you notice small necrotic spots with a yellow rim on potato leaves, then most likely the potato has been affected. Alternariosis. If the spots on the leaves of large sizes are 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 chemical harmful substances and can be used at any stage of the growing season.
With the withering of the upper leaves, another dangerous fungal disease begins – fuzarioz.
Most often, the most effective way to combat this disease is to treat the tubers before planting with one of the antibacterial drugs (Baktofit, Fitosporin).
A very unpleasant potato disease is ring rot, the first signs of which can be seen even during flowering. Some stems turn very yellow, while the top with leaves twists, and the bush begins to wither and fall apart. The most unpleasant thing is that the tubers are quickly affected. With these signs, diseased bushes are subject to mandatory destruction along with tubers. And all potato plantings are immediately treated with copper-containing preparations.
Known to experienced gardeners is a bacterial disease blackleg. It manifests itself immediately after germination and is expressed in the fact that the bases of the stems rot, and young shoots turn yellow, curl and wither. To combat this scourge, sprinkling a potato patch with a mixture of ash and copper sulfate can help (1 tablespoons of copper sulfate are taken per 2 kg of wood ash).
Viral diseases
Viral diseases of potatoes are of 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 curl virus, gothic and others. The symptoms of diseases are also varied, but most often they manifest themselves in yellowing and dryness of the leaves, the tubers become ugly, the stems die off ahead of schedule, and the yield, as a result of all this, is sharply reduced.
Therefore, it is very important to completely destroy the potato bushes affected by the virus, along with all tubers. Preparations such as epin and zircon increase the immune system of plants, so they can be used to additionally protect potatoes from viruses.
The best prevention of viral diseases is the planting of healthy tubers.
parasites on potatoes
Peculiar worms called nematodes can exist in the soil for decades. This species parasitizes 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 be easily minimized.
There are special chemicals that effectively fight the presence of nematodes in the soil.
It remains for the gardeners themselves 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 place of planting potatoes every 2-3 years and plant corn, rye, oats, marigolds, lupins, peas, and beets on infected areas. The root system of these plants quite successfully fights against the dominance of nematodes.
Insects
Among insects, there are also many lovers of juicy leaves, stems and tubers of potatoes. This is both a potato flea and a wireworm, but the most malicious enemy is, of course, the Colorado potato beetle. This yellow insect 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 can quite quickly destroy almost all potato leaves and stems. There are many ways to deal with 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 table salt;
- To scare away 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 become large-scale, then there are many chemical means of pest control.
Weather
Speaking about the reasons why potato bushes wither and dry out, one cannot fail to mention adverse weather conditions. This is especially true for the southern regions, but even in the middle lane, in hot and dry summers, potatoes can begin to wither 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 flower formation phase.
Of course, it also happens that even in June unexpected return frosts come, and the tops of the bushes can 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 well.
Potato feeding
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 manifests itself in potatoes precisely in the yellowing of the leaves. Only with a lack of iron, as a rule, the upper leaves turn yellow. And the lack of magnesium is manifested, first of all, in the yellowing of the lower leaves;
- If the plants do not have enough potassium, then the potato stalks acquire a bronze hue, curl and dry;
- Due to the lack of nitrogen, the entire growth of the potato 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 not have enough phosphorus. You can check this by cutting the tuber in half. In the event of a lack of phosphorus, a purple hue can be clearly distinguished on the cut of the tuber.
In addition, feeding potatoes with many trace elements, especially in the 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, there are many reasons for wilting and yellowing of potato tops, but it is important to diagnose and deal with this problem in time in order to have time to get a full and healthy crop of potato tubers.
