How to identify the harm of different kinds of herbicides?

How to identify the phytotoxicity of different types of herbicides? Herbicides can effectively and quickly control weeds in farmland. In recent years, the application amount and application area have been continuously expanded, and the effect is remarkable. However, when it is used, it often causes various phytotoxicity to crops due to improper application, resulting in serious losses. In order to prevent and overcome phytotoxicity, attention should be paid to the diagnosis and application of herbicides. 1. Symptoms of poisoning. The phytotoxicity symptoms caused by herbicides are variable and diverse, similar to those of some diseases, and often cause cognitive errors in diagnosis. Generally, phytotoxicity was faster than disease symptoms, and no pathogen appeared. The identification of herbicide toxicity should be strengthened in production. (1) Phenoxycarboxylic acids: commonly used agents are 2,4-drops, dimethyltetrachloro, 2,4-drops butyl ester, etc. Symptoms are leaf, flower and ear deformity. Leaves thick, dark green, curly, claw-shaped or onion tubular; stem brittle, easy to break, stem base swelling; roots short and thick, no root hair, plant short; serious when stop growing, cortex dehiscence, drop flowers, fruit, and finally death. (2) Aroxyphenoxy propionic acids: commonly used agents are stable, clopramide, clopramide, Weiba, Puma, etc. The main symptoms are abnormal plants, yellowish-brown growth points, purple or yellow heart leaves. (III) Diphenyl ether: Commonly used agents are grass cumin, weed burning, tiger Wei and so on. The symptoms are brown necrotic spots on the leaves, severe leaf deformity, scorch and no new leaves. (4) Amides: Commonly used agents include lasso, duryl, propanil, butachlor, etc. Symptoms are yellow leaves in light, spots in heavy leaves, curling and shrinking, and finally death. (5) Carbamates: Commonly used agents include benthamate, methomyl, oatmeal, etc. Symptoms are curly leaves, more tillers, short stem base and new roots, and short plants. (6) Substituted ureas and trichlorobenzene: mainly chlorotoluron, prometryne, simazine, etc. Mainly chlorosis, heart leaf and leaf tip start, yellow like fire, plant short, slow growth. (7) Heterocycles: mainly paraquat, glyphosate, leguminous carb, bentazone, etc. The symptoms are leaf discoloration, yellowing, and finally plant death. 2. Prevention of phytotoxicity. In order to prevent harm caused by improper use of herbicides, it is necessary to strictly follow the use of technology and standard operation. (i) Pay attention to herbicides and sensitive crops. Different crops have different sensitivities to different herbicides. Grass crops are sensitive to broadleaf weed control herbicides, while broadleaf crops are sensitive to grass weed control herbicides. For example, 2,4-D and dimethyltetrachlorine are sensitive to cotton, melons, beans, fruit trees, etc.; Gai Cao Neng and Wensha De are sensitive to wheat, rice and corn. Therefore, when using, you should look at the instructions, recognize the characteristics and properties of herbicides, pay attention to sensitive crops, and guard against misuse or chemical drift. (b) Pay attention to the sensitive period of crops. Under normal circumstances, crops are particularly sensitive to herbicides during germination, pre-trifoliation and flowering and filling stages, and are prone to phytotoxicity. (3) Strictly control the dosage and concentration of herbicides. In order to prevent local phytotoxicity caused by excessive herbicide dosage and concentration, when using herbicides, the liquid medicine should be sprayed evenly, the walking speed, the width and speed of manual control spray should be uniform, and the working time should not be too long. (4) Master the technical operation points of herbicide use 1."Yiping": the ground should be flat. The field for pesticide application should be carefully cultivated to ensure that the ground is flat, without large soil blocks and potholes. 2,"two uniform": medicine on the carrier to mix evenly, spray or sprinkle poison soil to be uniform. 3,"three accurate": application time accurate, application amount accurate, application plot area accurate. For example, 40% oats are used to control wild oats, 3 kg/ha before sowing. 4,"four look": look at seedlings, grass, weather, soil. It is not easy to apply pesticides to unrooted or thin seedlings: according to the species and growth of weeds; when the temperature is lower, the application amount is at the upper limit of the application; the application amount is higher in sticky soil and less in sandy soil; the soil is dry. 5."Five noes": no application for weak seedlings; no application for shallow paddy field less than 3 cm or water depth exceeding the heart leaf; no application for dry paddy field; no application for heavy rain or dew on leaves; no application for leaky paddy field. (5) Master the performance of the medicine. Master whether the agent is easy to volatilize, photolysis, and whether it is easy to occur physical or chemical reactions in soil. (6) Clarify the "main attack position". The "main attack position" of herbicide in general soil treatment is the position of weeds just sprouting, young stems and leaves, that is, before 3 leaves. Sulfochlor was absorbed by stems and leaves and then transferred to other tissues. (7) Reasonable time for medication. For example, propanil in the 2-leaf stage, butachlor in 2-3 days before sowing, gramoxone, glyphosate with weed leaf area increase and improve the effect. (8) Play the role of water. After application, the water layer is kept at 4-6 cm, and the efficacy can be exerted without phytotoxicity; however, benthamate and benthamate are easy to produce phytotoxicity when the field is accumulated. (9) It is prohibited to use it in disorder. Herbicide mixture can improve efficacy and enlarge herbicide control spectrum, but blind mixture is easy to cause phytotoxicity. Such as propanil can not be mixed with organophosphorus or carbamate; dimethyl tetrachloromethane can not be mixed with acidic pesticides. (10) Cleaning spray equipment. Spray machine that used herbicide should be cleaned, rinse with clean water first, then wash repeatedly with soapy water or 2-3% alkaline water several times, and finally rinse with clean water. 3. Overcoming phytotoxicity. Once the herbicide is used, effective measures should be actively taken to remedy the damage and minimize the possible losses. (1) Detoxification: (1) When the application is maximum, the irrigation water in the field should be drained immediately, irrigated with new water several times, and neutralized acid herbicides such as lime should be applied. (2) If there is a lot of herbicide on the plant, it can be rinsed with sprinkler water to reduce the poison stuck on the leaves. (3) When phytotoxicity occurs locally in the field, water washing and ploughing shall be carried out first, then seedlings shall be supplemented, and quick-acting chemical fertilizer shall be added. (4) If the field is seriously poisoned, the plot should be exposed to the sun, deep ploughed after leaching, and replanted after no influence, otherwise re-irrigated. Or plant a small number of sensitive crops and observe for 10-15 days. (2) Strengthen field management. When the phytotoxicity is light, top or remove the damaged part in time, apply quick-acting fertilizer and irrigate reasonably; when it is serious, plough the land, replant or replant; when the tubular leaves of Gramineae are found, apply more tillering fertilizer and organic fertilizer, and spray dilute ammonia water or 1% lime water, and spray hormone pesticides. (3) Application of plant growth regulators. Spraying 4% gibberellin EC promotes crop growth. (4) Application of safety agents. Safeners, also known as antidotes, protect crops and detoxify a variety of herbicides. If the seeds are coated with activated carbon or dipped in roots and stems, or evenly sprinkled on the soil surface, simazine can be prevented from causing phytotoxicity to soybeans and wheat; tea dimethyl anhydride can prevent the phytotoxicity of sulfurized carbamates such as propan to corn. Click for mass herbicide application technology Click for mass pesticide application technology