With the increase in labor costs and the acceleration of land transfer, the application of herbicides has become very common, and herbicides are frequently used. According to statistics, nearly 50% of the country’s crop fields have produced different degrees of phytotoxicity and have been increasing year by year. This has seriously affected the benefits of agricultural production and the adjustment of planting structure, and has become a chronic disease in agricultural production and herbicide application. .
The specific performance is as follows: Traditional long-lasting herbicides such as chlorimuron-methyl and chlorsulfuron are used. Since the dosage is reduced year by year, the phytotoxicity of sensitive crops of postharvest crops has a tendency to decline; new long-lasting herbicides such as fomesafen , mesotrione, metoxime, quinclorac, and so on, the phytotoxicity caused by the crops after the crop has increased year by year; due to continuous sowing of soy in individual areas, commonly used pharmaceuticals applied year after year and a variety of pharmaceuticals mixed The compound residual pesticide damage is caused; the use of herbicides is generally too high, which makes the occurrence of crop phytotoxicity worse year by year; the phytotoxicity caused by poor safety of some herbicides is also very serious.
How did herbicide harm occur?
To sum up, there are generally several reasons for herbicide poisoning: First, the nature of the herbicide itself, such as poor safety, containing impurities or unqualified formulations, the formula is unreasonable, the content is too high, adding illegal hidden ingredients.
The second is the impact of environmental conditions. It is easy to cause phytotoxicity when it is cold, rainy, windy, or during the period of application. For example, in rainy weather, low-lying plots of soybeans and corn fields are leached and dissolved.
The third is the application of technology. Long-lived herbicides such as imidazoyl niacin and chlorimuron-ethyl for the production of phytotoxicity to sensitive crops at low residual concentrations; excessive application of herbicides, misuse, misuse, and improper selection of additives to produce phytotoxicity; incorrect application period, application of pesticides The method is wrong, the performance of the spraying equipment is poor, the spraying technology is backward, the sprayer cleaning is not thorough, and the quality of the field preparation is poor.
The fourth is crop factors. The tolerance of herbicides to the herbicides (for example, the resistance of different rice varieties to Shafen Phosphorus), the sensitivity of crops at different stages of development, and the differences in crop seedling quality and growth.
Fifth, we do not understand the history of medication in the fields. With the large-scale land transfer, land contractors do not know about the history of drug use of contracted land, and they often cause residual pesticide damage due to the use of long-lasting residual herbicides.
According to the survey, herbicides accounted for more than 70% of the damage caused by pesticide application technology.
What are the types of herbicides?
The first is the seasonal injury. Such as soybean field application of fomesafen, acetochlor, and oxathione herbicide phytotoxicity; corn field after the application of nicosulfuron, 2,4-D butyl phytotoxicity (mainly for corn malformation, heart The leaves are whip-like, and the tassels cannot be extracted normally, which seriously affects the yield;) The rice seedbeds are treated with ding pukiolecose to varying degrees; the black bean, cowpea and other mung bean fields blindly apply unregistered herbicides; Herbicides used to control phytotoxicity caused by peanuts, mungbean fields, etc., and 2,4-D butyl esters were used to cause phytotoxicity before or after the third leaf stage of wheat.
The second is residual drug damage. Mainly in the soybean field application of chlorimuron-ethyl, fomesafen, imidazoyl niacin, clomazone and other herbicides, resulting in post-planting sensitive crops such as corn, melons, potatoes, rice, sugar beet and other phytotoxicity. In addition, low temperature and high humidity in spring, crops such as onions, melons, and watermelons often appear as residual phytotoxicity after transplanting.
The third is drift hazards. Liquid droplets evaporate and drift with the wind, causing damage to nearby sensitive crops, such as the application of 2,4-D butyl ester and clomazone to the phytotoxicity of adjacent broad-leaved crops and trees.
In general, conductive herbicides appear to have late symptoms of injury and often suffer from damage to the entire plant. Severe ones result in permanent production and are difficult to recover. Symptoms of contact-type herbicides appear to be rapid and urgent, and symptoms often appear locally in crops. Without victimization, it can be alleviated.
Preventing the correct application of herbicides is the key
Before applying the herbicide, read the label carefully to clarify the applicable crop of the herbicide, the appropriate application period and method, the control object, the safe drug dosage and precautions for medication, and avoid using the wrong drug or over-range drug to avoid safety. Dosing period and external medication. Especially in the application of new herbicides, we must be more careful, first small-scale test demonstration, and then a large area of ​​application.
Different herbicides targeted different crops such as butachlor and acetochlor, bensulfuron-methyl and chlorimuron-methyl. Although they were all inferior, one was applied in paddy fields and one in dry fields. Even with the same crop, the herbicide applied is not the same at different growth stages or in different crops. If we choose post-emergence herbicides, some corn varieties are more sensitive to nicosulfuron and prone to phytotoxicity, such as Zhengdan 958 and Yuyu 22. Some products indicate that they are prohibited from being used in corn inbred lines, sweet corn, waxy corn and other varieties.
The herbicide liquid should be evenly mixed and sprayed evenly. Before the application of the herbicide, in particular, the herbicide must be fully dissolved before the herbicide is mixed, and the herbicide is mixed evenly by using the method of secondary dilution. When spraying in the field, be sure to walk evenly and spray evenly. Application of advanced herbicide spray equipment, add spray additives. After applying the herbicide, the sprayer should be thoroughly cleaned.
The long residual period of some herbicides will result in long seedlings, rotten roots, or dead seedlings in susceptible (seasonal) crops. Therefore, in the selection of herbicides, we must consider what kinds of crops should be planted in the next season (season). For the following crops: beets, potatoes, melons, sorghum, rice, cotton, vegetables, etc., atrazine and chlorine should not be used. Sulfosulfuron, chlorsulfuron and other herbicides for the previous crop;
In the case of soybeans and wheat, the use of atrazine in the upper crop should be reduced by half. The sensitivity of different crops to different herbicides is different. When selecting herbicides, it is necessary to pay attention to the influence of the lower crop and the next crop.
Acetochlor was sprayed on the soybean fields. Pre-emergence application was safe for soybeans. However, after application, it encountered low temperature and rainy conditions. Especially in the fields where the fields were low and easily accumulated water, acetochlor could easily cause damage to soybeans. Therefore, spraying acetochlor in soybean fields requires consideration of environmental weather factors. Spraying atrazine in the corn field generally does not cause phytotoxicity, but when the dose is too large, it will cause slight damage to the corn, so it is necessary to strictly control the dosage.
Field plots must be intensively cultivated, land is leveled, and there are no potholes. In addition, excessive land gaps cause the liquid to leach into the roots of the crops and cause leaching.
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