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The vast majority of gardeners take growing potatoes very seriously, because for many villagers, a crop grown on their own is a serious help in stocking up on 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 potato stems. It’s 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 need to be dug up in a couple of weeks. But when the harvest is still far away, and the leaves begin to wither, dry out 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.
Reasons why potato tops wither, dry out and turn yellow
Potato diseases
As sad as it may be, 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 limp, lifeless, then large dark and brown areas appear on them and they quickly turn black and dry out. Over time, tubers also begin to be affected, and more than half of the harvest may be lost.
It is best to take the following preventive measures to combat this problem:
- Do not plant potato tubers too thickly;
- 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 late blight;
- Carry out weeding, loosening and hilling of potato bushes to enhance air exchange in the ridges;
- Treat potatoes with copper-containing preparations during the flowering period or with phytosporin at a later date;
- If you germinate tubers 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 the leaves of the potato, then most likely the potato has been damaged Alternaria blight. If the spots on the leaves are large, this is macrosporiosis. In any case, the potatoes dry out and you can try to save the crop by treating the bushes with phytosporin - after all, it does not contain harmful chemicals and can be used at any stage of the growing season.
Another dangerous fungal disease begins with the withering of the upper leaves - fusarium.
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 noticed even during flowering. Some stems turn very yellow, while the top and leaves curl, and the bush begins to wither and fall apart. The most unpleasant thing is that the tubers are affected quite quickly. With these signs, diseased bushes must be destroyed along with the tubers. And all potato plantings are immediately treated with copper-containing preparations.
A bacterial disease known to experienced gardeners blackleg. It appears 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 plot with a mixture of ash and copper sulfate can help (2 tablespoons of copper sulfate are taken per 1 kg of wood ash).
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, top roll virus, gothic and others.Symptoms of diseases are also varied, but most often they manifest themselves in yellowing and dryness of leaves, tubers take on ugly shapes, stems die off ahead of schedule, and the yield as a result of all this is sharply reduced.
It is therefore very important to completely destroy 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 to plant 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. Due to the presence of nematodes, the tops turn yellow and dry out; many black dots are clearly visible on them. The tubers practically do not develop. Future harvests can easily be minimized.
There are special chemicals that effectively combat the presence of nematodes in the soil.
The gardeners themselves just have to thoroughly disinfect all their tools before each planting season and use seed material that is resistant to nematode damage.In addition, you can try to change the location of planting potatoes every 2-3 years and plant corn, rye, oats, marigolds, lupine, peas, and beets in infected areas. The root system of these plants quite successfully fights the dominance of nematodes.
Insects
Among insects, there are also many who like to feast on the succulent leaves, stems and tubers of potatoes. This includes the potato flea beetle and the wireworm, but the worst enemy is, of course, the Colorado potato beetle. This yellow insect with black stripes can produce 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 combat harmful insects, but not all of them are equally effective.
- Quite often they are collected by hand into a jar with a strong solution of table salt;
- To repel the beetle, calendula, nasturtium, beans, marigolds and dill are planted between potato rows;
- Sometimes the bushes are sprayed with herbal remedies, such as infusion of elecampane or celandine;
- Biological agents - Boverine or bitoxybacillin - cope well with them;
- If the beetle infestation has become widespread, then there are many chemical means of pest control.
Weather
When talking about the reasons why potato bushes wither and dry out, we cannot fail to mention unfavorable weather conditions. This is especially typical for the southern regions, but even in the middle zone, under hot and dry summer conditions, 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 there will be unexpected return frosts, 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 harvest can still grow very well.
Potato feeding
Oddly enough, 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 do the upper leaves, as a rule, turn yellow. A lack of magnesium manifests itself, first of all, in yellowing of the lower leaves;
- If the plants do not have enough potassium, the potato stems acquire a bronze tint, curl and dry out;
- Due to a lack of nitrogen, all potato growth stops, the stems emerge thin, and the leaves gradually become lighter and lighter;
- If your potato bushes do not grow upward at all and remain weak and squat, then perhaps the plants do not have enough phosphorus. You can check this by cutting the tuber in half. If there is a lack of phosphorus, a purple tint can be clearly distinguished on the cut of the tuber.
In addition, feeding potatoes with many microelements, especially in 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 harvest of potato tubers.
