In the greenhouse greenhouse in Tengzhou, Shandong, a few days ago, many bell pepper leaves were not normal in color. Some leaf margins are charred, some are yellow-green around the leaves, some have large yellow spots in the middle of the leaves, and some small leaves near the growing point have many yellow spots. Many leaf leaves do not have flat surfaces and there are protruding bubbles. Some people think that it is a viral disease, and they have sprayed various drugs for preventing and treating viral diseases. They have a certain effect within 7 days after spraying, but they do not work for a few days. After checking, the reasons for the abnormal color of the leaves are as follows:
1. The temperature in the months of March and February of this year has been lower than in previous years. The growth of plants is also slow, and the color of leaves is not as good as in previous years.
2. In the greenhouse cultivation, most of the continuous cropping seasons are 7-8 years. The results of heavy cropping cause serious root rot and blight. The diseased plant leaves have different degrees of yellowing and charring symptoms. When planting, the application of compound fertilizer per acre was more than 100 kilograms, and some of them were unevenly applied. There was excessive burning of roots resulting in dry tips.
3. The cultivation shed is arched and covered with grass rakes. The insulation performance is poor, so the night temperature in the shed is below 10°C for a long time and the ground temperature is lower. Low ground temperature for a long time, combined with excessive nitrogen fertilizer application, excessive accumulation of ammonium nitrogen in the soil, inhibits the absorption of nutrient elements such as nitrate nitrogen, phosphorus, and potassium in melon roots, resulting in lack of fertilizer in leaves. Yellow. At the same time, it also inhibited the absorption of zinc, magnesium, calcium, iron and other fertilizer elements in the root system, resulting in the lack of symptoms of the above elements: calcium deficiency, leaf margin scorch; potassium deficiency, yellow leaves around the leaves, yellow ring; magnesium deficiency, Yellow spots in the middle of the leaves; zinc deficiency, the top leaflets become smaller, clustered, curled or shrunken, yellow spots, virus-like illness.
4. Because of the low temperature, the plants have not dared to ventilate after planting. The air humidity in the shed has been saturated, and the humidity is very high, which makes the transpiration of the leaves nearly stagnate, which seriously reduces the water absorption of the roots, and brings nitrogen to the leaves through the water. Trace elements such as phosphorus, potassium, and zinc, boron, and calcium are also greatly reduced, and thus the symptoms of deficiency, such as yellowing, scorching, and chlorosis, clearly occur.
5. In the current situation where the temperature is very low, it is not suitable for the occurrence of viral diseases, and the symptoms are not contagious, so it is not a viral disease. The current drugs for the prevention and treatment of viral diseases are mostly stimulants that promote growth and development. After spraying, they have the effect of promoting growth and development. Therefore, the above symptoms are relieved for a short time, but they cannot be cured.
Measures to prevent abnormal color of sweet pepper leaves: In the future, the deep-turning soil to 30 cm or more before planting will have two advantages: First, the depth of the soil is loose, the roots develop strongly, the absorption capacity is enhanced, and the abnormality of the leaves due to lack of fertilizer elements is reduced. Second, loose soil, strong water storage, reducing the number of watering, to prevent excessive watering to reduce the ground temperature. In order to solve the difficulties of greenhouse inverting land, it is possible to use 200 grams of soil conditioner without deep plowing, add 100 kg of water, and spray an acre of ground. After spraying, it can loosen and loose the 50-80 cm deep soil. The application of organic fertilizer is mainly to reduce the amount of nitrogen fertilizer, 25 kg of compound fertilizer can be applied per acre when planting. Appropriate application of calcium, magnesium, zinc fertilizer. In the lower temperature season, extra-root fertilizer is applied every 3-5 days, 0.2% potassium dihydrogen phosphate is sprayed, and organic calcium, zinc, magnesium and other foliar fertilizers are applied once to supplement the potassium, calcium, zinc, and magnesium of the plant. Supply, solve the root absorption disorder, prevent the plant from the lack of the above-mentioned fertilizer elements caused by the symptoms. The application of the above fertilizer can also increase the concentration of the cell fluid and enhance the cold resistance of the plant. Spraying 10,000 times of apigenin 481 once every 20 days to promote photosynthesis and enhance plant resistance to disease. Under the premise of temperature conditions, pay attention to ventilation and dehumidification, reduce air humidity in the greenhouse, promote leaf transpiration, and increase the capacity of roots to absorb water and fertilizer elements. The use of high-temperature stuffy shed, application of carbendazim, methyltobacillus and other measures to prevent root rot and blight.
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