If the pesticide is sprayed excessively or the concentration is too high, clean water can be sprayed to the damaged watermelon field for 2 ~ 3 times continuously to reduce the pesticide concentration and reduce the pesticide residue on the leaves. Because of weakness, the function of watermelon leaves decreases and photosynthesis is inhibited. Watermelon may have symptoms of insufficient fertilizer, so it needs to be supplemented with quick-acting fertilizer or foliar fertilizer in time. According to the characteristics of watermelon growing season, timely harvest ether or ternary compound fertilizer. To promote the rapid growth of watermelon and improve the weak resistance of plants themselves. Chongqing autumn fertilizer combined with water and fertilizer can increase soil permeability and ground temperature, promote root development and improve plant stress resistance.
Acute symptoms appear within a few hours to 3 ~ 4 days after administration and develop rapidly. Like burns, dead leaves, fallen flowers, loneliness and so on. Chronic phytotoxicity only causes obvious reaction in a long time after drug distribution, and physiological activities are inhibited, resulting in poor growth, abnormal leaves, delayed maturity, bad flavor and dissatisfaction with seeds and eggs. After spraying pesticides on the leaves, it will permeate from pores, water holes and wounds in large quantities, and some will permeate from branches, leaves, flowers and fruits and root epidermis. When the drug is injected, the particles in the drug directly prevent the stomata, artificial or tissue from entering, prevent the intercellular space, and inhibit the normal respiration, transpiration and assimilation of crops. After entering plant tissues or cells, some inclusions and chemical reactions will occur, which will destroy normal physiological functions and lead to abnormal symptoms and physiological metamorphosis.
Washing most chemicals with clean water is not easy to penetrate. When the concentration of the injection is too high and phytotoxicity occurs, it can be immediately filled with clear water (within 6 hours after medication) and sprayed repeatedly on the stems and leaves to clean the residual drugs on the plant surface and reduce phytotoxicity. When washing, the air pressure of the sprayer should be sufficient and the water content of the roots should be large. Try to avoid using drugs during the period of weak crop resistance. Generally, fatigue is most likely to occur during stunts and flowering and fruit-setting periods, which requires special attention. Accurately master the reagent technology, prepare drugs according to the prescribed concentration and dosage, and make them scientifically and reasonably mixed. Avoid taking medicine at hot noon. This is because under strong light and high temperature, the drug resistance of crops is weakened, and the activity of chemicals is improved, which is easy to weaken.