Symptoms of drug injury: emergency type. The emergency type has the characteristics of rapid onset and obvious symptoms. The symptoms of drug damage appear within hours or days after application, such as leaf injury and root injury, and the leaves appear spots, perforations, anxiety, curl, deformity, withering, yellowing, chlorosis and albinism. The root is short-term hypertrophy, the root hair is scarce, the root bark turns yellow, becomes thick and brittle, decays and so on.
Chronic type. Chronic type has a certain incubation period, which hinders the growth and development of crops, reduces the yield and quality, and makes the flavor of products worse.
Remaining types. Residual type has the characteristics that crops do not suffer from phytotoxicity in the current season, but the chemical substances remaining in the soil do harm to the next crop, resulting in the next crop not sprouting or sprouting late, affecting normal growth, and even worse, rotten seeds and buds.
Causes of herbicide damage:
First, there are quality problems in pesticide products. If the herbicide dichloroquinic acid is added with low price and high activity, it will have potential safety hazards to the following crops, and it will be safe for rice in the current season when it is used for weeding rice fields, but it will lead to phytotoxicity to the following vegetable crops such as tomatoes and Chinese cabbage, and even lead to crop failure in severe cases. At the peak of drug use, illegal traders sell fake drugs, which will lead to drug harm.
Second, improper use of herbicides. For example, a sprayer sprays a variety of herbicides, mistakenly uses herbicides as pesticides, uses herbicides in the wrong target, uses too many herbicides, and sprays them repeatedly, causing herbicides to hurt people.
The third is the impact of drug abuse on the environment. Environmental factors such as temperature, weather and soil moisture affect the formation of phytotoxicity. For example, in windy weather, spraying will cause phytotoxicity to sensitive crops nearby.
Remedial measures after phytotoxicity: analyze the causes of phytotoxicity and take scientific preventive measures to reduce the harm of herbicide phytotoxicity.
First, when herbicide damage has occurred or will occur, measures should be taken to detoxify as soon as possible. Combined with watering, toxic plants can be washed with clear water to reduce phytotoxicity. For some herbicides that are easy to decompose and fail when alkaline substances are encountered, crops can be sprayed with 0.2% quicklime or 0.2% sodium carbonate diluent, and the effect is good.
The second is to strengthen on-site management. The management of crop fields with phytotoxicity should be strengthened, and measures such as increasing chemical fertilizer, scientific irrigation, fine pruning or removing damaged parts should be taken to restore the physiological functions of the affected crops, promote the healthy growth of crops and reduce the harm of herbicide phytotoxicity to crops.
The third is to promote crop growth. Plant growth regulators can stimulate the growth and development of crops, such as gibberellin and growth-promoting factors. In addition, foliar spraying 1% ~ 2% urea or 0.3% potassium dihydrogen phosphate solution also has a significant effect on promoting crop growth and improving crop resistance to phytotoxicity.