The symptoms are: the infected tomato plants are dwarfed, the growth is slow or stagnant, the top leaves are often slightly green, yellow and small, the edges of the leaves are rolled up, the leaves are thickened, the leaves are hardened, and the veins on the back of the leaves are often purple. In the early stage of growth and development, the infected plants were seriously dwarfed and could not blossom and bear fruit normally; In the later stage of growth and development, only the upper leaves and new buds of infected plants show symptoms, the number of fruits decreases, the fruits become smaller, and the fruits are uneven in color (red and opaque) when they mature, which basically loses commercial value.
Main route of transmission: under natural conditions, it can only be transmitted by Bemisia tabaci for a long time.
Prevention and control methods:
At present, the control measures of tomato yellow leaf curl virus are generally to cultivate TY antiviral vaccine and control the spread of Bemisia tabaci. Because TY virus-resistant seedlings also have viruses after colonization, once infected with tomato yellow leaf curl virus disease, the pesticides currently used have poor control effects and residues, which are unsafe for people, livestock, crops and the natural environment, and viruses and Bemisia tabaci are also prone to drug resistance. Do a good job in virus prevention and control mainly from two aspects:
(1) agricultural control
1. Cultivating disease-free and insect-free seedlings is the key. The earlier the disease harms tomato plants, the higher the incidence rate, so the prevention and control should start from the seedling stage, achieve early prevention and early control, and strive to have fewer or no diseases. Weeds around the seedbed should be removed and the soil of the seedbed should be disinfected to reduce the source of the disease.
2. Agricultural measures: Fertilize more and water more, so as to avoid drought and waterlogging, release the wind in time, avoid high temperature in the shed, adjust the temperature and humidity in the field, apply more organic fertilizer, promote the healthy growth of plants, improve the disease resistance of plants, remove weeds and fallen leaves in the field in time, and reduce the source of insects. The air outlet of greenhouse is isolated with 40 ~ 60 mesh insect net, and the yellow hanging board is used to control Bemisia tabaci in the field.
(2) Drug control
Plant-derived Chinese herbal medicine virus inhibitors of "TY virus type I" and "TY virus type II" can be used, which can effectively control the harm of virus diseases. In general, 450-fold solution of "Taivirus No.2" or "Cui Jie" antiviral foliar fertilizer is used for seedling control and spraying. If you are infected with this disease, you can control it with "TY virus I". Generally 1-2 courses of treatment can control the disease.