How to "confirm" the crop phytotoxicity
The widespread application of insecticides, fungicides, herbicides and various plant hormones in the production of pesticides will inevitably cause crop injury. Therefore, it is safe to use pesticides in order to grasp the types and symptoms of crop injury and take timely preventive and control measures. Problems that cannot be ignored. Crop injury, generally divided into the following three types. 1. Residual phytotoxicity This phytotoxicity is characterized by no phytotoxicity occurring in the current season crop after pesticide application, whereas the pesticide residues in the soil cause phytotoxicity to crops that are more sensitive to diarrhea. For example, the use of Simazine herbicide in corn fields often causes phytotoxicity to crops such as sorghum and beans. This kind of phytotoxicity occurs mostly in the germination stage of the seed crops of the lower pods, lighter root tips, bud tops and other parts become brown or rot, affecting normal growth; severe rot and poor shoots, reduce the emergence rate or no seedling emergence. This kind of phytotoxicity is difficult to diagnose, and it is easy to be confused with fertilizers. Can be used to understand the cultivation and management of the previous crop, pesticide use history, soil testing and other measures to prevent misdiagnosis. 2. Chronic-type drug injury This kind of drug injury, the symptoms do not appear immediately after application, has a certain degree of latent, so that crop growth is blocked, the fruit flavor deterioration and so on. This phytotoxicity is often difficult to diagnose and is easily confused with other physiological diseases. When the diagnosis is made, diagnosis can be made by understanding the occurrence of pests and diseases, the type, amount, area of ​​application, and method of plant control. 3. Acute-type phytotoxicity This phytotoxicity has the characteristics of rapid occurrence and obvious symptoms. Generally, symptoms can appear within a few hours to several days after the application, and the general appearance is that the crop leaves have spots, perforation, burning, curling, and deformity. , withering, yellowing, chlorosis, or bleaching. The roots suffer from short and thick roots, few root hairs, yellow or thick roots, brittleness, and rot. Seed victims are unable to germinate or germinate slowly. Plants suffer from falling flowers, falling buds, malformed, smaller, spotted, brown fruit, rust, and fruit drop. This kind of phytotoxicity is mostly caused by improper use of pesticides or improper use of pesticides for seed treatment.