Strategies and measures to deal with herbicide injury
When controlling weeds in various farmlands, the use of herbicides is usually preferred to control weeds; coupled with the current structural shortage of young and middle-aged labor in rural areas, farmers can reduce manpower input and alleviate labor shortages by using efficient mechanical spraying to carry out chemical weeding Therefore, the area of chemical weeding is increasing year by year. But at the same time, it is not uncommon for crops to grow abnormally due to improper use of herbicides, that is, phytotoxicity, which has brought varying degrees of losses to agricultural production. Phytotoxicity limits the promotion and use of herbicides, causing environmental pollution risks and threatening Grain and food safety have become issues that cannot be ignored in agricultural production. Starting from the practice of plant protection work, and referring to medical theory, according to the three main points of phytotoxicity, hazard risk, and occurrence situation, the strategies and measures to deal with herbicide phytotoxicity are divided into three types: prevention, mitigation and remedy, one by one. Analysis and discussion to ensure the safe production of crops.
Three strategies
prevention strategy
In medicine, if the etiology is known and can be avoided, the preventive strategy of "preventing the disease" can be adopted to prevent the disease from forming. For example, long-term alcohol abuse can easily lead to alcoholic liver disease, which can be prevented by abstaining from alcohol, and the need for treatment will naturally be eliminated if you don’t get sick. This situation corresponds to the field of plant protection, that is, phytotoxicity has not yet occurred on crops, but there is a risk of phytotoxicity caused by pesticide application. If no changes or changes are adopted, phytotoxicity will inevitably occur in the future. For example, if 24-Disooctyl, 2-methyl-4-chlor, clopyralid, fluroxypyr and other herbicides are used in the corn field, and there are watermelon fields around, and the watermelon is sprayed in the weather with wind force above level 4, then the watermelon The phytotoxicity of rice seedlings has basically become a foregone conclusion. In this case, it is necessary to switch to other herbicides that are not sensitive to melon seedlings or to adopt artificial weeding to prevent pesticide damage.
mitigation strategy
In medicine, when the etiology is known and the pathogen already exists in the body, it is difficult to detect it without medical means (for example, early cancer). A medical method to prolong the life of patients. There are similar situations in agricultural production: for example, when soybeans are planted on a certain land, imazethapyr and other long-lasting herbicides are used for weeding, and there are pesticide residues in the soil. For maize sensitive to imazethapyr, it is expected that phytotoxicity will occur on corn. In this case, although it is impossible to completely remove herbicide residues from the last stubble, some measures can be taken to delay or alleviate the severity of phytotoxicity and reduce Effects of Chemical Residues on Maize.
remedial strategy
In medicine, when a patient develops a disease, it is necessary to scientifically detect it, clarify the cause, and treat it symptomatically. This is an illness-treatment process that most people have experienced. Similar situations of phytotoxicity in agricultural production are also the most common. Many farmers only seek medical advice from plant protection technicians when they find obvious symptoms such as crop leaf curling, chlorosis, underdeveloped root system, shortened tap root, and growth stagnation. "Plant doctors also need to make an analysis first to determine the cause and severity of the phytotoxicity, and then propose targeted remedial measures to help farmers recover their losses. However, the change in plant growth timing is irreversible. When obvious external symptoms such as dead spots have appeared on the plants, unlike some sore spots on human skin, they can still be eliminated after a period of treatment. Therefore, this medicine for crops The relief of harm is called remedy, not cure.
Measures corresponding to the strategy
Precaution
Select products with complete "three certificates". Go to regular agricultural material stores to purchase herbicides with complete "three certificates" (pesticide registration certificate, pesticide production license, product quality standard certificate) and within the shelf life, and check with the local pesticide management department if necessary.
Select herbicide varieties according to the crop rotation plan. Herbicides are not universal for all crop fields. After replanting crops in the same field, the previous herbicides cannot be used completely. Before implementing crop rotation and stubble reversal, you should inquire about the sensitivity of the next crop to herbicides Or consult plant protection technicians, plan the use of corresponding herbicides in advance, make reasonable arrangements for crop rotation and stubble rotation, and avoid long-residual herbicides from causing phytotoxicity to the next crop.
Select herbicide varieties according to adjacent crops. If different types of crops are planted around the spraying field and they are sensitive to the herbicide planned to be used, you need to inquire or consult, choose other herbicide varieties or spraying methods, and pay attention to improving the quality of spraying to avoid contact with crops Sensitive parts or drift to adjacent sensitive crops.
Use herbicides according to the plot conditions. Sandy soil, saline-alkali soil or plots with low organic matter content and paddy fields with water leakage are prone to phytotoxicity, and the amount of herbicides should be appropriately reduced when applying pesticides; while low-lying plots are prone to enrich the medicinal solution during rainfall, and it is also easy to cause pesticide damage. Harm, the land should be leveled before spraying.
Spray according to the weather. Low temperature and high humidity can easily cause phytotoxicity. Try not to use herbicides in such an environment, and reduce the amount of herbicides when necessary. If the wind is strong when applying pesticides, the herbicide mist will drift downwind with the wind, causing damage to adjacent sensitive crops. Therefore, do not apply pesticides when the wind is greater than level 3 to prevent drift damage, and be careful not to Applying medicine against the wind. During the high temperature period in summer, the pesticide should be applied before 10:00 am or after 3:00 pm, and the pesticide should not be applied at noon.
Do not blindly mix herbicides. Indiscriminate use of herbicides not only has no synergistic effect, but may reduce the efficacy of the herbicide and even cause phytotoxicity. Experiments should be carried out before mixing pesticides to investigate the efficacy of the mixture and the safety of the crops. The common herbicides that are prone to phytotoxicity when used in combination include: propanil and organophosphorus or carbamate pesticides, nicosulfuron and organophosphorus pesticides, clodinafop-propargyl and mefentrazone or fluorfen, chlorofluoro Pyridyl esters and propannil or malathion; common species that are prone to antagonism when mixed are: diclofop and 2,4-D isooctyl ester or 2-methyl-4-chloride, bentazone and quizalofop-ethyl or pyridoxop-ethyl Fluazofop-p-p, acifluorfen and quizalofop-p-ethyl.
Carefully read the herbicide instructions. Read the instructions before applying pesticides, carefully check the name, content, applicable crops, control objects, sensitive crops, etc., and select safe, efficient, and low-risk herbicide varieties for the types of weeds in the field. Strictly follow the scope of use, time, dosage and concentration on the label. Follow the usage techniques and precautions, accurately calculate the dosage based on crop growth, do not increase the dosage at will, and do not expand the scope of use.
Add safener. Safeners can be added to the herbicide liquid before spraying to improve the safety of pesticides and avoid or reduce the occurrence of phytotoxicity. Cyprosulfonamide or isoxadifen, add isoxadifen to the rimsulfuron-methyl solution.
Thoroughly clean the spray equipment. After the sprayer is sprayed with 2-methyl-4-chloro or 2,4-D isooctyl ester, if it is not cleaned properly, it will be used to spray dicotyledonous crops, which will easily cause phytotoxicity. Therefore, it is necessary to clean the spraying equipment that has been sprayed with herbicides, first rinse with clean water, then repeatedly wash with soapy water or 2%~3% alkaline water several times, and finally rinse with clean water to prevent the remaining liquid medicine from causing drug treasure.
Check and adjust the spray equipment before spraying. The uneven spraying of medicines and equipment may easily cause excessive liquid medicine in the working area. Therefore, it is necessary to adjust the spraying equipment to the standard state required by the agronomic technology before operation to prevent "running, dripping and leaking". The walking route of the operator spraying the herbicide should be Consistent with the sowing time, if there is a problem with the medicine equipment, immediately close the medicine application valve, and leave the field for inspection and maintenance.
Mitigation
Increase the number of cultivating. When it is necessary to apply long-residual herbicides, pay attention to applying them in front, and do not use them after the crops emerge in the current year; and after the crops have basically been sealed, combine shoveling with manual or mechanical intertillage to loosen the soil surface and increase the ventilation of soil particles. light to accelerate the natural degradation of long residual herbicides.
Plow the land deeply. The long-residual herbicides applied to the crops of the current season are mainly left in the topsoil layer. After harvesting in autumn, the soil can be deep-ploughed by using locomotives to pull the deep-plowing agricultural implements, turning the surface soil into the deep layer, and turning the deep soil to the surface. It is recommended that the depth of plowing be more than 30 cm, which can loosen the hard plow bottom soil, and then make the soil in the plow layer scattered and loose through agricultural operations such as turning the ground and removing stubble. In addition to alleviating phytotoxicity, it can also create better soil aggregates. Structure, improve soil air permeability and heat permeability, improve soil moisture and nutrient supply capacity, improve the physical environment of crop rhizosphere, activate and play the role of soil microorganisms, and maximize the growth potential of crops.
Apply decomposed farmyard manure or organic fertilizer. Applying decomposed farmyard manure or organic fertilizer during soil preparation can not only ensure sufficient nutrient supply for crops, but also increase the types and quantities of beneficial microorganisms in the soil, cultivate robust plants through the growth-promoting effect of microorganisms, and increase the stress resistance of crops Ability to alleviate the severity of phytotoxicity. It is also necessary to pay attention not to apply undecomposed livestock manure directly to the farmland, otherwise it will cause problems such as "burning roots and seedlings" and breeding diseases and insect pests.
Irrigate. Before planting the next crop of sensitive crops, the water requirements for crop growth are met by irrigation and moisture creation to ensure the germination and growth of seeds, and avoid the failure of seeds to germinate due to insufficient water, the inability to dig into the soil after germination, or the inability to take root and grow into strong seedlings. At the same time, irrigation is also conducive to the penetration of herbicides remaining in the surface soil to the deep layer, reducing the herbicide content in the surface soil.
Use safety protective agent for seed dressing. The safety protection agent includes naphthalene anhydride, dichloroacetate amine, dichloropropenylamine, chlorhexamide, oxanitrile, and oxamoxime, etc. The safety protection agent is added to the seed coating agent as an auxiliary agent, and then coated. It can reduce the degree of herbicide residual phytotoxicity of the following crops and weaken part of the toxicity of the residual herbicide in the soil.
Remedy
Rinse with water spray. If it is detected that the herbicide has been sprayed too much in the early stage after spraying, and it is predicted that the plants in the spraying area will be damaged or the adjacent crops will be damaged by drifting pesticides, you can quickly spray the stems and leaves of the affected crops with a large amount of water, and repeat 2 to 3 times. Try to wash away or reduce the pesticides on the surface of the plants.
Paddy field drainage and irrigation remediation. When phytotoxicity occurs in the paddy field, the water in the field should be discharged first, and then new water should be poured in, and the drainage and irrigation should be repeated several times to wash away some residual pesticides.
Water the dry land. For plots that still have drought when phytotoxicity occurs, water first to meet the crop's demand for water, promote crop growth, accelerate the metabolism and excretion of pesticides in crops, and reduce the content of pesticides in crops.
Application of growth regulators. Composite growth regulators such as red-inb-brassica can activate multiple activities of plants through systemic induction and significantly improve plant stress resistance. They can be used in various field crops such as corn and soybeans, as well as fruits and vegetables. Gibberellin can be sprayed after rice is injured by pesticides, and brassinolide can be sprayed after corn is injured by pesticides.
Apply foliar fertilizer. Spray 0.3% urea solution + 0.2% potassium dihydrogen phosphate solution on the leaves, spray once every 7-10 days, and spray 2-3 times in a row. You can also spray humic acid or amino acid foliar fertilizers.
Use neutralizing substances. For phytotoxicity caused by acidic pesticides, some quicklime or plant ash can be sprinkled, or 0.5%~1% lime water can be sprayed; for phytotoxicity caused by alkaline pesticides, acidic fertilizers such as ammonium sulfate can be sprinkled.
Remove the parts with severe phytotoxicity. For example, after 2,4-D-butyl ester damage occurs on corn, the typical "horse whip-shaped" damaged leaves can be manually identified and removed; after fruit trees are damaged by pesticides, the severely damaged branches should be pruned in time to stop the spread of the damage as soon as possible. , followed by other measures to aid crop recovery.
Apply quick-acting fertilizers. Apply an appropriate amount of quick-acting nitrogen fertilizer to supplement crop nutrition, promote plant meristemity and development, and restore the physiological functions of damaged crops.
Cultivation loose soil. Intertillage can enhance the permeability of the soil, increase the ground temperature, promote the activities of beneficial microorganisms, accelerate the decomposition of soil nutrients, promote the growth and development of crop roots, and restore the crops to normal growth status as soon as possible.
Problems needing attention in response to drug damage
Correct diagnosis. Only a correct diagnosis can better remedy and reduce crop losses. It is necessary to conduct field investigations on the plots where the phytotoxicity occurred, check the appearance symptoms and internal tissue changes of the affected plants, and record them truthfully and accurately through observation and inquiry. Crop varieties, fertilizer application rates, environmental conditions, weather conditions, herbicide use, previous crop types and application conditions, crops planted in adjacent fields and application conditions, etc. On this basis, analyze the possible causes of the injury, and if necessary,
Supplementary tests for weak links are verified by high-performance liquid chromatography and other instruments. After inferring the main (or most likely) cause of the phytotoxicity of the crop and the subsequent impact of the phytotoxicity on the growth and development of the crop, the mitigation plan and remedial measures are put forward in a targeted manner.
Prevention is the best measure to avoid drug injury. Prevention is the real cure for a disease. It can not only ensure the safety of the crops in the current season, but also the safety of the sensitive crops in the next stubble, and avoid herbicide damage from the source. However, successful prevention of pesticide damage also requires long-term and scientific research. The planning and firm, down-to-earth implementation.
Mitigation measures cannot completely avoid drug injury. Mitigation measures can only alleviate the phytotoxicity of the next sensitive crops, but cannot completely avoid the phytotoxicity. This is a method that must be used when replanting is necessary, and the hope of avoiding the residual phytotoxicity of long-lasting herbicides cannot be put to rest. It is all based on these measures, and it is still necessary to be psychologically prepared for the loss of sensitive crops in the next stubble due to phytotoxicity.
It will take time for remedies to work. Remedial measures can only improve the ability of crops to resume growth and promote the absorption of water and nutrients by crops. After implementation, there will be no immediate effect, and it will take some time to take effect.
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