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In recent years, with the increasing variety of herbicides, the use range and use area of ​​herbicides have been expanding, and the problem of phytotoxicity has become more and more serious. It has become a top priority to popularize the knowledge of herbicides, improve the use of herbicides, and prevent the occurrence of phytotoxicity.
First, the type of herbicide phytotoxicity
1. Classification 1 direct phytotoxicity according to the period of occurrence of phytotoxicity. The phytotoxicity caused by improper use of herbicides to the current and seasonal crops. For example, medicinal damage caused by dicamba to wheat before or after the 3rd leaf stage of wheat. 9
Indirect phytotoxicity. The phytotoxicity caused by the improper use of herbicides to the sorghum or the next season crops; or the herbicide residues used in the former sputum, causing phytotoxicity of the squat crops. For example, the wheat field uses the phytotoxicity of chloroplast on the sorghum rice, and the corn field uses atrazine to cause phytotoxicity to the sorghum wheat.
2. Classification according to the time of occurrence of phytotoxicity 1 Acute phytotoxicity. Symptoms of symptoms appear within hours or days after application. Such as 2,4-butyl butyl ester on the phytotoxicity of grapes. 2 chronic phytotoxicity. Two weeks or more after application, the symptoms of the drug are manifested even when the product is harvested. For example, apple orchard uses atrazine to cause damage to apple trees.
3. Classification according to the nature of the symptoms of the phytotoxicity 1 trapped phytotoxicity. The phytotoxicity did not manifest itself in the form, and it was difficult to visually measure it, but eventually caused a decline in yield and quality. For example, the effect of butachlor on the roots of rice decreased the number of grains per panicle and 1000-grain weight. 2 visible phytotoxicity. Abnormal representation of the morphology of different parts of the crop that can be distinguished by the naked eye. Such phytotoxics can also be classified into hormonal phytotoxics and contact phytotoxics. Hormone-type phytotoxicity is mainly caused by abnormal green or yellow leaves, stagnant growth, dwarfing, twisted stems and leaves, and deformation of lobes until death. Such as 2,4-butyl butyl ester, 2 methyl 4-chloro, paraquat, chlorpyrifos, dichloromorphic acid, causing it to cause phytotoxicity. Contact-type phytotoxicity is mainly caused by yellow, brown and white necrotic spots in the tissues until the stems, sheaths, leaves and tissues die. Herbicides such as paraquat and diuron cause red, yellow, gray and white symptoms in plant leaves.
Second, the main factors inducing herbicide damage
1. Excessive use or misuse of arbitrarily increase the dosage per unit area to cause phytotoxicity. If some farmers increase the amount of 667 square meters per 2,4-butyl butyl ester in the corn field to 100 ml, the result is serious phytotoxicity of corn. There are more examples of misuse of herbicides. The wheat field herbicide chloromeron is misused in rice Honda, leading to the death of rice seedlings. Because the label of the medicine bottle fell off, 2,4-dibutyl acrylate was mistakenly used as a dimethoate to control cucumber aphids. As a result, the insect did not kill the cucumber but died.
2. If the agricultural treatment is improperly used, whether it is paddy field or dry land, the drug layer should not be destroyed, otherwise it may cause phytotoxicity. If the paddy field is used, it will soon be plucked or fertilized, so that the agent can be exposed to the roots of rice to cause phytotoxicity. After the transplanting of rice, the use of Nongsi, the water layer submerged the heart caused the leaves of the rice to be yellow.
3. Improper adjustment of the equipment In the field, the lack of precise adjustment of the spray equipment before the field operation, the uneven flow of the nozzle and the overlapping spray, the uneven application of the granules and the powder can cause phytotoxicity to the crop. For example, amphetsulfuron-methyl is used for weeding in rape fields, and repeated application of pesticides may cause residual phytotoxicity to rice, corn, cotton, etc. The summer corn field is not evenly sprayed, and the winter wheat in the sprayed area will be tainted, which can cause serious death.
4. When the medication is improperly used, it will cause the herbicide to coincide with the sensitive period of the crop and cause phytotoxicity. For example, the use of chlorpyrifos and butachlor in the germination stage of rice seeds can easily cause seedlings to sprout, and the leaves are dark green and yellow. In severe cases, the seedlings die. 2.4-D-butyl ester, herbaceous enemies, etc. before the 3rd leaf stage of wheat and after spraying from the jointing stage to the flowering stage, phytotoxicity will occur, causing the ears and leaves to curl and affecting heading. Fluorine spray will quickly evaporate at high temperatures at noon. Lead to phytotoxicity in sensitive crops.
5. Poor application method The depth of the oats mixed soil is in the same position as the wheat sowing depth, resulting in wheat phytotoxicity. The herbicide treated by the stem and leaf is added with a surfactant and sprayed with a large amount of water. The accumulation of the liquid in the leaf margin of the broadleaf crop is apt to cause phytotoxicity.
6. When the application interval is not the same as when the same crop uses two kinds of medicines, the application period is too close to cause phytotoxicity. Shortly after the use of propanil, the use of organophosphorus or carbamate insecticides (1605, malathion, phosphorus amine, trichlorfon, carbaryl, etc.), the rice lost its ability to detoxify the enemy A phytotoxicity occurred. In addition, the soybean field is used before the sowing, and the soybeans are used again. After treating the soil with nematicides, the dinitroaniline herbicide such as trifluralin is used to cause damage to the soybean. Sekinz is used in conjunction with malathion or carbaryl for 3 days, which can increase the phytotoxicity of Secchin on tomatoes. The recent use of Baocheng and organophosphorus pesticides can increase the phytotoxicity of Baocheng on corn.
7. Improper mixing of herbicides with another herbicide or insecticide or fungicide may cause phytotoxicity. For example, the combination of bentazon and grass, chlorpyrifos and organophosphorus pesticides can cause the phytotoxicity of bentazon on soybeans. The combination of gram music and catching nets will increase the phytotoxicity of Ke Kuole on soybeans. Mixing dicamba with organophosphate insecticides can cause medicinal damage to wheat by dicamba. Mixtures of pesticides of different dosage forms, such as emulsifiable concentrates and wettable powders, may cause phytotoxicity by changes in the physicochemical properties of the medicament.
8. Volatilization of the agent and the drift of the mist When the herbicide is applied, the liquid or powder will be dispersed to the adjacent field, which may cause phytotoxicity to sensitive crops. When the rice field uses He Da Zhuang, 2 A 4 chlorine, and Xicaojing, the volatilization will cause phytotoxicity to the adjacent cucumber. When paraquat or Roundup is used to weed the rice fields, the mist drifts to the rice and can cause phytotoxicity. Wheat, stems and leaves are treated with 2,4-butyl butyrate or chlorpyrifos, and small droplets drift with the wind to nearby sensitive crops such as sunflower, tobacco, cotton, tomato, cucumber, lettuce, potato, alfalfa, grapes, peanuts, peas. Carrots, watermelons and fruit trees produce phytotoxicity. Spraying 2,4-dibutyl acrylate on the aircraft allows the agent to evaporate in the air, causing sensitive crops and trees to be damaged in the distance. Quick killing, 2 A 4 chlorine, trifluralin, He Da Zhuang, grass grass, quick harvest, Mori grass net, etc. can cause phytotoxicity due to drift.
9. There are many examples of temperature-induced abnormal temperature-induced herbicide phytotoxicity. High temperature can induce phytotoxicity, and low temperature can also induce phytotoxicity, especially when the temperature changes drastically, it is more likely to cause disease. For example, the application of oxacillin at low temperatures can cause slight damage to rice seedlings. Before and after the cold current, the wheat field was treated with green meron, which caused the damage of the crop due to freezing damage. After applying dur or cable, soil moisture and low temperature can cause phytotoxicity of soybean seedlings. When using high temperature, it is easy to cause phytotoxicity. This is mainly because the high temperature makes the plant's contact and absorption of the agent faster, and the crop can not degrade in time. Huwei will produce dead spots on soybean leaves during high temperature and drought, and will temporarily languish in severe cases.
10. The effect of temperature is the use of Xicaojing at high temperature, and the low atmospheric humidity is harmful, because low humidity can promote the absorption of Xicaojing by rice roots. For high-humidity herbicides in the dry field, it is beneficial to the efficacy of the drug; it is also easy to cause phytotoxicity. Dry field herbicides can cause phytotoxicity under drought conditions. For example, the use of bentazone in extreme drought can cause phytotoxicity. Soybean is used in soybean fields and can cause soybean damage when the climate is dry.
11. Light affects the symptoms of paraquat in low light, and the symptoms of phytotoxicity are not obvious. After the emergence of the tomato, the squid is sprayed. If the light is weak before application, the glare after application will significantly decrease the fresh weight and dry weight of the plant.
12. The water layer affects the crop tissue and is immersed in the herbicide solution for a long time. Although the drug effect is better, it is also prone to phytotoxicity. For example, Wo Da Zhuang has a water layer to exert its efficacy, but in the case of flooding in the bud stage of rice, the phytotoxicity is serious, and herbicides such as herbicide ether, Nongsi, and butachlor have similar problems.
13. Soil effects For soil treatment of herbicides, soil texture, organic matter content and salinity are closely related to phytotoxicity. In general, the greater the soil's adsorption power to herbicides, the less likely it is to cause phytotoxicity, while the soil with high adsorption capacity is generally soil with higher organic matter content and more clay components. For example, Secchin prevents soybeans and potato field weeds from being used when the soil organic matter content is less than 2%, otherwise it will cause phytotoxicity. Ligulong produces phytotoxicity by leaching the agent into the deep layers of the soil due to heavy rain in light soil. For herbicides with long-lasting effects, such as atrazine, simazine, trifluralin, chlorsulfuron, chlorpyrifos, and chlorhexidine, they can be adsorbed in a large amount of soil with high organic matter content, resulting in phytotoxicity of squat crops. . Excessive salt in the soil will also cause some herbicides to cause phytotoxicity. For example, green mellon can achieve good results in soil treatment before sowing in soybean fields, but it can cause phytotoxicity in saline soil.
14. Herbicide quality herbicides contain toxic impurities or fake pesticides for crops, which are also susceptible to phytotoxicity after use. If alachlor contains alachlor, the inhibition of rice will be greatly increased. The herbicides in the herbicides are mixed with the adjacent herbicides, and the phytotoxicity to the rice buds is 17 times larger than that of the paraquats.
Herbicide phytotoxicity occurs and prevents
Herbicides can achieve herbicidal purposes through plant morphology, time difference, dislocation, physiology, biochemistry and other selections. However, these effects are closely related to environmental factors, plant characteristics, herbicide characteristics, and use techniques. Under certain conditions, the efficacy and phytotoxicity can be transformed into each other. Even the same selective herbicide, even in the same amount, may cause damage to crops under different conditions of use. This damage is called herbicide phytotoxicity.
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