Wilting potato tops is a natural process that occurs during harvest. If the foliage turns yellow before this time, then this indicates a violation of the vegetation process of plants.
The reasons why the tops of potatoes turn yellow are very diverse. These include elevated air temperature, lack of nitrogen, phosphorus and other fertilizers. Yellow leaves often indicate the spread of diseases or pests.
Causes of yellowing of potato tops
Temperature and humidity
The main cause of wilting potato tops before harvesting is the violation of the temperature regime. In a drought, the potato leaves begin to turn yellow from the bottom, gradually this negative phenomenon spreads to the whole bush.
Permanent rain or excessive moisture will not fix the situation. Then, a crust forms on the ground surface, which prevents air from entering the root system.Important! Potato prefers a temperate climate and low temperature, uniform moisture, high humidity.
If the temperature reaches 30 degrees, then the metabolism is disturbed in the plant. As a result, the yield of potatoes is reduced.
During the growing season, soil moisture indicators should remain at 70%. In arid regions, planting necessarily requires irrigation. The need for additional moisture increases with flowering potatoes.
During the period of tuber formation, it is necessary to provide oxygen to the soil. To do this, periodically loosening the soil.
Potatoes turn yellow with insufficient intake of nutrients. Most often, plants lack the following substances;
- Nitrogen. If there is not enough nitrogen in the soil, the potato leaves turn pale green, then turn yellow and fall off. When nitrogen enters the plant increases the green mass and forms new tubers. 10 kg of root vegetables require up to 50 g of nitrogen-containing substances. Mineral compounds are applied to top dressing, which are introduced into the soil before planting tubers.
- Phosphorus. Phosphate fertilizer helps root development, speeds up the formation of tubers and increases their starch content. With a lack of phosphorus plants suffer worse than hot weather. As a result, the potato does not grow to the required height, and its leaves turn yellow. One hundred square meters require up to 0.9 kg of superphosphate. It is better to apply fertilizer in the fall so that easily absorbable forms of phosphorus are formed in the spring.
- Potassium. Due to potassium, the immunity of plants is increased, the taste and duration of storage of tubers are improved. With a lack of potassium, the photosynthesis process is disturbed, and the plants are less likely to tolerate drought. Potassium sulphate is used to fertilize potatoes, which is applied in the fall or spring before planting. The rate of fertilizer is 1 kg per hundred.
- Iron and manganese. With a lack of iron and manganese, wilting of potatoes occurs. Correct the situation will help fertilizing planting potassium sulphate. A bucket of water requires 5 g of fertilizer, after which the bushes are watered under the root. A solution of copper sulfate (50 g per bucket of water) is prepared for spraying the potatoes. The procedure is carried out every 5 days.
Early yellowing of the tops is often associated with the development of diseases:
If the potatoes turn yellow and the leaves dry, this is a sign of viral damage. Verticillary wilt spreads at a temperature of 17 to 22 degrees. On a cut of a stalk of a potato dark spots are formed. With the development of the disease bush must be removed from the site. For the prevention of wilting, the planting is treated with copper oxychloride solution.
If yellowness spreads from the top of the potato, this is a sign of fusarium. The disease develops with high humidity in a cool climate. Save planting in this case is impossible, so you need to eliminate the affected plants.
To prevent fusarium, you must follow the rules of crop rotation. Planting material is processed for disinfection.
If yellowed tops in the lower part of the bush - this is the first symptom of phytophthora. At the same time, dark spots are formed along the edges of the leaf plate, gradually spreading over the entire bush.
What to do when distributing phytophthora? Be sure to process potatoes with fungicides: copper oxychloride, Kuproksat, Ditamin.
The disease appears on the leaves of potatoes two weeks before flowering. First, on the leaves of the potato, rounded brown spots appear, which gradually grow. Dry blotch is determined by the presence of yellowed tops.
The causative agent of the disease is a fungus. To combat it, chemicals are used: "Kvadris", "Oksikhom", "Ridomil".
Potatoes are susceptible to various pests, under the influence of which the tops take on a yellow color:
The potato nematode lives in the soil and feeds on the sap of the plant root system. As a result, the stem and leaves of the potato turn yellow. Nematode leads to the death of the crop, which can be up to 80%.
To fight the nematode, fescue, lupine, marigold, rye, oat or pea are planted next to the potato. Before planting the tubers, urea is introduced into the ground (1 kg per each hundredth).
One of the most common pests in the garden is the Colorado potato beetle. This insect eats potato tops, which leads to its withering.
To cope with the Colorado potato beetle allows the use of special drugs: "Iskra", "Bankol", "Commander" and others. For processing you need to make a solution. The procedure is carried out during the growing season of the plants prior to harvesting.
Next to the potatoes, you can plant calendula, beans, marigolds, tansy. These plants have a strong odor that repels pests.
To get rid of the Colorado potato beetle, traditional methods are used: an infusion is prepared on the basis of dandelion, celandine or garlic.
When the potato leaves have yellow leaves, it is necessary to analyze the conditions in which the plants grow. Be sure to adjust the scheme of irrigation and fertilizer. Upon detection of diseases or pests, plantings are treated with chemicals. For the prevention of tubers treated before planting, and next to the plantations planted marigolds, calendula and other useful plants.