Recently, the author went to field technical guidance and found that the tomato fern leaf phenomenon was more serious. The main reasons are as follows:
First, pesticides, hormone poisoning
Excessive application of pesticides, hormones or pesticides will often cause phytotoxicity. In order to prevent tomato seedlings from becoming long, growers often spray some growth inhibitors on their seedlings, such as chlormequat, dwarf, etc. If the concentration is not well controlled, hormone poisoning can easily occur. In addition, the excessive concentration of silkworm cultivars, the excessive amount of wolfberry, the excessive temperature during repeated flowering and flowering, the temperature of the shed after the flowering, or the accidental spraying of the medicine on the leaves can cause the edges of the plant leaves to rise. Rolled up, the upper young leaves are slender and linear. The symptoms of fern leaves are similar to those of tomato fern leaf viral disease.
The phytotoxicity and hormonal intoxication generally occurred in large areas and in large areas, and the number of affected plants was high. After hormonal intoxication, the top part of the plant generally shows that the leaves are slender, do not spread out, curl up and stiff, the leaves thicken, the texture is thick, the branches twist, the color of the leaves does not change or become greener. Symptoms of hormonal intoxication generally appear progressive.
Control measures: Strictly control the use concentration of hormones and pesticides, and the use concentration should decrease with increasing temperature. Strictly grasp the use of time and use of time, flowers are generally 810 hours in the sunny morning, avoid strong sunlight at noon in order to avoid the occurrence of phytotoxicity. When the first flower head of the tomato plant has 23 flowers open, it is a suitable period for the pod flower, and the pod must be treated with flowers that are open on the same day. Too early or late will affect the pod flower effect and cause phytotoxicity. Each flower can only be picked up once, avoiding repeated flowering, and must pay attention to can't drop the medicine to tender branch, young leaf and growing point when the flower is decorating. In addition, the concentration of the medicine should be adjusted accordingly according to the growing situation of the plant during flowering. The concentration of the weaker growing plants should be reduced accordingly, otherwise it is easy to produce phytotoxicity. Add a certain amount of coloring agent when formulating the drug so as to leave a mark on the spent flower to avoid repeated flowering. The drug should be used as soon as possible. If slight phytotoxicity occurs, spray the whole plant with 0.3% brown sugar solution and strengthen ventilation to relieve humidity. Strengthen the management of fertilizer and water, spray and other leaf fertilizer.
Second, fern leaf virus disease hazards
Facilities Tomato fern leaf virus disease is mainly caused by the infection of cucumber mosaic virus. It is spread and spread by sucking pests such as aphids and whitefly. Tomato fern leaf virus disease does not generally occur in large fields in the field like hormone poisoning, but occurs sporadically and occurs most frequently during tomato seedling to anthesis. Once a plant is infected with a virus disease, the symptoms will appear immediately instead of progressively. The diseased plants showed different degrees of dwarfing. The color of the apical leaves was generally yellow, and the leaves were curled in a tube and uneven. When severe, the leaves are slender and twisted linearly.
Control measures: The old greenhouse must be strictly disinfected; the seed poisoning is an important source of tomato fern leaf virus disease in the facility, so the virus can be killed by soaking seeds in the warm soup before sowing, and the seeds are generally soaked in warm water at 55°C for 15 minutes. The seeds can also be soaked in clean water for 34 hours, soaked in 10% trisodium phosphate solution for 30 minutes, then rinsed with water, and germinated; so as to prevent and control aphids and fly hoppers, through the vents in the greenhouse. A series of measures such as covering pest nets and trapping yellow planks to reduce the density of locusts and planthoppers in sheds and reduce the spread of disease transmission; strengthen cultivation and management, and promptly remove field litter and crop stalks before planting, especially some Sick plants and weeds around the shed to reduce the source of the disease. Avoid the high incidence of locusts. Spray 20% of virus A wettable powder 500 times or 1.5% of diseased sorrow emulsion 1000 times at seedling stage. Foliar spray can also be used to enhance plant disease resistance and alleviate disease symptoms.
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