If the pesticide method is not used properly, the technical requirements are not strictly controlled. Not only can it not receive insecticide, disease prevention, weeding, and regulation of crop growth, but also cause abnormal growth and physiological symptoms of tobacco, such as yellowing of leaves and serious Leaf spot, wilting, burning, dwarfing, slow growth, deformity or even withered or death of tobacco plants. The occurrence of such symptoms is called phytotoxicity. Crops affected by phytotoxicity are classified into acute phytotoxicity, chronic phytotoxicity and residual phytotoxicity according to different symptoms. (1) Symptoms of acute phytotoxicity: The symptoms of acute phytotoxicity occur very quickly. Generally, it will appear 2 to 5 days after application. The symptoms are also obvious. It is characterized by burns, wilting, defoliation, rolling leaves, deformity, tenderness. Tissue is scorched, chlorotic, yellow or yellow, dwarf, etc. (2) Symptoms of chronic phytotoxicity: After the pesticide is used, the phytotoxicity does not appear immediately, and the symptoms are not obvious, mainly affecting the physiological activities such as the growth of tobacco. Most of them are characterized by weak photosynthesis, slow growth and development, and small deformity of the leaves. , the output is reduced or the quality is deteriorated, the color is deteriorated, and the like. Identification of chronic phytotoxicity, generally compared to healthy tobacco. (3) Symptoms of residual phytotoxicity: caused by pesticides or their decomposition products remaining in the soil (actually, they should also be chronic toxicity). This type of phytotoxicity is mainly caused by the long residual period of some pesticides, which affects the growth of crops, and the symptoms are not obvious in the short term. China Low Speed Centrifuge,Low Speed Centrifuge Rpm supplier & manufacturer, offer low price, high quality Tabletop Low Speed Centrifuge,Centrifuge Low Speed, etc. Low Speed Centrifuge,Low Speed Centrifuge Rpm,Tabletop Low Speed Centrifuge,Centrifuge Low Speed Zenith Lab (Jiangsu) Co.,Ltd , https://www.zenithlabo.com