Cotton injury symptoms and prevention methods

Because of the improper use of pesticides in cotton, such as excessive concentration, spraying at high temperature, spraying at flowering time, and using herbicides sensitive to cotton, all can form phytotoxicity. Symptoms Contact poisons can produce acute injury, usually in a few hours to a few days to appear phytotoxicity, the performance of the leaves scald, was water-like, or there are spots, stripes, discoloration, curling, scorch and so on. Suction-type medicaments produce chronic phytotoxicity. After application for a long time, they show dwarfing, malformation, thickening of the mesophyll, thick green leaves, leaf-shaped shrinkage, etc., and severe branching and growth point necrosis. Herbicides and growth regulators inhibit growth, show abnormalities, and even die at high concentrations. For example, if the cotton is damaged by 2,4-dibutyl benzoate, the leaves become narrower and narrower, showing a "chicken claw shape"; excessive use of trifluralin can cause the cotton root to form a tumor, affecting the growth of secondary roots. Prevention measures 1. Select high-quality pharmaceuticals. Emulsifiable concentrates must not contain flocculent precipitates. The agents must be dispersed in water to form a white emulsion. There should be no emulsifiable concentrates on them. Powdered medicines should not be agglomerated, otherwise they are particularly prone to phytotoxicity. Wettable powders and powders should be evenly dispersed. In water, it can also cause phytotoxicity. 2, the number of application should be appropriate. The number of pesticides used should be determined based on the frequency of the pests and the duration of the pesticides. The number of pesticide application is less, and the control effect is not achieved. The number of pesticides is more likely to cause injury. 3, a reasonable preparation of liquid concentration. The concentration of the drug solution should not be too high. According to the instructions, it is reasonable to formulate it. Some peasants treat the disease with eagerness to treat the disease. They fear that the pesticide is diluted and no matter what. Therefore, if the concentration is increased, it will often be counterproductive, resulting in phytotoxicity. 4. Rationally mix pesticides. In the formulation of pesticides, the following pesticides should not be mixed: organophosphorus insecticides and alkaline Bordeaux mixture, lime sulfur, emulsifiable concentrates and certain water-soluble chemicals, Bordeaux mixture and lime sulfur. 5, the liquid to be used with the match. After the liquid medicine is properly prepared, it must be used in a timely manner. The effect of long-term control of pesticides will be reduced, and sometimes precipitation will occur. Spraying this kind of pesticide can easily cause damage to cotton. 6, to avoid the application of cotton in the sensitive period. In general, mature tissues of cotton are more resistant to drugs, younger organizations are less resistant to drugs, and are very sensitive to pesticides. Therefore, when selecting the type of drug, determining the concentration and frequency of spraying, consider the “phase of cotton growth”. Factors, especially in the flowering period of cotton, minimize the application of pesticides. In addition, spraying at high temperatures is also prone to phytotoxicity. Therefore, try not to administer it at noon in the summer. Remedial measures The following “five laws” remedies can be taken in light of the nature of pesticides and the degree of severity of injury. 1, spray water medicine. If the leaves and plants spray liquid medicine caused by the damage, and found early, the liquid did not completely penetrated or absorbed into the plant body, can be quickly sprayed with a lot of water damage the cotton plant, repeated spraying 3 to 4 times washing. 2, irrigation detoxification. For some of the poisonous soil and some herbicides caused by the phytotoxicity, can be appropriate irrigation or drainage rinsing drugs to reduce toxicity, which can reduce the degree of injury. 3. Remove the damaged foliage. After the leaves have suffered phytotoxicity, the discolored foliage should be removed in time to control the penetration of the pharmaceutical agent in the plants. 4, top dressing promote seedlings. For the phytotoxicity produced by the contact-killing agent, and the leaves have produced symptoms such as patchy spots and leaf scorch, the water-spray irrigation is not effective at all, and it can be used as top-dressing cultivator, and the urea can be applied in an amount of 5-6 kilograms to promote the growth of the cotton plant and reduce the growth. Damage degree. 5, hormone remission. For regulators and herbicides that inhibit and interfere with crop growth, gibberellin-like plant growth regulators can be sprayed to reduce the extent of injury when the phytotoxicity occurs. Such as 2,4-D-butyl ester harm, can shoot deformed branches, and spray gibberellin to promote collateral growth.

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