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Today, not a single Russian family can present its diet without potato dishes. This important food product is in demand all over the world not only because of its cheapness, but also due to its useful taste qualities. Growing potatoes is one of the main occupations of many farmlands. However, in order to get a good harvest of the tuberous plant, you need scrupulous care for each bush. This will help in time to identify and eliminate many diseases of potatoes caused by fungi, bacteria, viruses, parasitic insects and worms.
Unfortunately, there is no universal instruction for the prevention of potato disease. Each type of disease provides its own precautions. But there is something in them and something in common - you need to carefully select the tubers for planting and remove the infected plants on time.
The main factors affecting yields
The most frequently asked question for many beginners is why do potatoes have yellow leaves? The right answer is known to experienced farmers. They are ready to suggest what to do in this case and what are the main causes of the unpleasant phenomenon.
Monitor the condition of the soil. The lack of moisture and air in the surface layer of the soil can lead to yellowing of the lower leaves. The plant is forced to take from them all the nutrients to maintain its normal life.
Hot dry weather strongly affects any plant, and potatoes are no exception to this rule. The first reaction to a drought is the yellowed lower leaves. However, intensive watering is not worth pursuing too. The resulting crust on the soil can cause the plant to suffocate. For the same reason, the appearance of yellow leaves can be affected by heavy rains, after which caring truck farmers loosen the soil.
In some potato varieties, the lower leaves turn yellow in June. If an unfamiliar variety was planted earlier, then one should not be very surprised at this phenomenon.
Varieties of viral diseases of potatoes
The most dangerous diseases of potatoes are viral. The thing is that they are completely untreatable. The main symptoms of the disease are the twisting of the leaves of the potato, its yellowing and wilting. But they may differ depending on the conditions of growth, the type of virus and the variety of potatoes. Infection occurs by contact of an infected and healthy plant or with the help of insects.
The most effective method of combating the disease is the timely removal of diseased plants. It is advisable to do this before the leaves of neighboring plants begin to touch. Also, you need to ensure that only healthy tubers are planted and that insects that can become carriers of the disease are planted. If you follow all the precautions, then the harvest will be much richer than with a frivolous attitude.
The most common are two types of viral potato disease:
- Leaf twisting virus. It strongly affects the quality and quantity of tubers and provokes a very serious disease. Infection with this virus is primary and secondary. At the primary leaves of the upper part of the plant blush around the edges, twist and become stiff. In the secondary - the same symptoms are manifested, but with the lower leaves. Tubers are affected by network necrosis. Controlled by planting healthy tubers, removing infected plants and destroying harmful insects.
- Alfalfa mosaic virus. This virus is not as dangerous as the previous one, but it is also very unpleasant for potatoes. It is the reason why the potato tops are turning yellow. This, in turn, reduces the chlorophyll content in the leaves of the plant and leads to a poor crop of this plant. The virus can be stored in tubers, so when planting it is necessary to carefully select them to minimize the number of diseased plants
Parasites are represented mainly by three species of nematodes:
- The stem cell.
A golden nematode is very dangerous for potatoes. When infected with this parasite, the amount of harvested crop can fall by half. Basically, it affects the root system of the plant. Accordingly, the tops begin to turn yellow and wilted, which prevents the tubers from forming fully and reduces their number. But the visible symptoms can only appear if there is a strong infection. If it manifests itself in a weak form, then it can only be found by digging a bush and examining the roots and tubers.
To avoid infection with this parasite, it is better to use varieties resistant to it. But every 3-4 years they should alternate with an unstable variety. This is done so that the parasite does not adapt. You can also use the cultivation of legumes or corn on this area.
The stem nematode penetrates into the tuber from the side of the stem. After this, the tuber starts to deteriorate - it cracked, rot appears. Accordingly, this fruit already loses its edible properties and it remains to be thrown away.
The root nematode also settles in tubers, roots and in the underground part of the stem. The plants affected by them stop growing and gradually fade. In the lesions are formed thickening, which increase and merge with each other. This leads to damage to the protective cover of the root or tuber and the penetration of microorganisms there, after which the affected area begins to decay.
Fungal diseases are also one of the reasons why the bottom leaves turn yellow. One of these diseases is late blight. Below is a photo of this disease of potato leaves, on which all the signs of the fungus are clearly visible.
1- affected leaf: 2 - affected sprouts; 3 - affected eyes; 4 - on the left the affected tuber, on the right it is in a section
The main sources of the disease are infected planting tubers and the remains of infected plants that remain in the ground. Biofluorosis can reduce the yield by half and even more. In order to prevent the tops sprayed with fungicides when buds begin to appear.
To reduce the likelihood of infection with this fungus, you can sprinkle the tops with a solution of potassium permanganate and garlic. To do this, take a half cup of pulp of garlic and insist 24 hours in a bucket of water. Then this infusion is filtered and added to it, gram of potassium permanganate. The treatment should be carried out in the evening. The first time it is held 14 days after disembarkation and is repeated after 10 days.
Fighting potato diseases - video