In recent years, China's pesticide industry is developing rapidly, and the types and dosage forms of pesticides are constantly being removed from the old ones. Therefore, the requirements for its application technology level have also increased accordingly, and it has become more specialized. In the process of using pesticides, if it is not prudent, it will easily cause phytotoxicity, affecting the growth of crops, causing large-scale production reduction, and even if there are serious particles.

1. From the perspective of the occurrence of pesticide phytotoxicity, the reasons are various, generally as follows:

(1) There is a problem with the quality of the drug itself.

(2) climatic conditions

Low temperature spraying causes phytotoxicity. High-temperature spraying in summer is easy to cause pesticide damage. Under normal circumstances, the number of phytotoxics in summer spray accounts for more than 80% of the annual phytotoxicity, or after the rain, the humidity is high at night, there are water drops at night, and it is easy to produce phytotoxicity after spraying.

(3) uneven spraying, problematic operation

(4) The selected application device is wrong or it is not clean enough

It is not appropriate to use some large-scale high-pressure equipment that sprays pesticides on fruit trees to spray pesticides on corn, wheat and other crops to control pests and diseases. The application of herbicides can no longer apply to sensitive crops.

(5) Too many pesticides can cause phytotoxicity

Some farmers use several kinds of drugs at the same time in the process of application, and they are prone to phytotoxicity after spraying.

Excessive drug use causes phytotoxicity

2. Identification of phytotoxicity:

(1) Acute phytotoxicity

Symptoms usually appear after a few hours after 2-5 days of spraying. For example, the germination ability of the seeds is reduced, and the leaves of the cotyledons have burns, yellowing, leaf spots, wilting, and deformity. Such plants grow with fewer leaves, flowers, and fruits.

Sometimes the brown spotted, young or even withered death of young tissues is caused by improper application of pesticides or by spraying pesticides on adjacent fields. Spraying 24-D butyl or dimethyl tetrachlorine herbicides in wheat fields can cause dystrophic symptoms in broad-leaved crops in adjacent fields.

From the point of view of the victim plant, the damage occurred obviously in the faster growing parts of young leaves, flowers and fruits. Generally, the upper leaves were heavier than the lower leaves and the old leaves were heavier than the old leaves.

(2) Chronic phytotoxicity

The phenomenon of phytotoxicity not immediately indicated after the plant is damaged mainly affects the physiological activities of the plant. For example, photosynthesis weakens growth and slows down the flower, and the result is small, and the maturity delays the graininess and the flavor, the color deterioration, and the poor quality of the product.

Most of these phytotoxics are caused by overdose or high concentration of the drug, especially when applying organophosphorus pesticides or when applying ripening to the melon and fruit crops.

(3) Residual phytotoxicity

Caused by pesticides or their decomposition products that remain in the soil (actually chronic toxicity). This type of phytotoxicity is mainly caused by the high residual amount of some pesticides in the soil and the long residual time.

For example, before the cotton planting, the soil was treated with trifluralin to reduce the yellowing and dwarf tillers of the waxy corn and the wheat; the metsulfuron-methyl was used for weeding in the wheat field, so that the low-low leaves of the later waxy corn plants became smaller and thinner, purple, and non-realistic. Higher than these are caused by residual phytotoxicity.

3. Preventive measures for phytotoxicity:

The reasons for pesticides causing phytotoxicity to crops are many, except that some pesticides are sensitive to crops and some special pesticides are used improperly. When pesticides are used, they are not strictly used according to the prescribed methods of use and techniques, or because of weather conditions. The key to the occurrence of phytotoxicity and therefore the prevention of phytotoxicity lies in the scientific and correct mastery of the use of pesticides.

(1) Strictly prevent pesticides from being used indiscriminately

Symptomatic administration of pesticides and proper mixing can improve the control effect of diseases, insects and grasses, and save drugs and costs. However, indiscriminate use and blind mixed use not only fail to achieve the purpose but will reduce the efficacy of the drug. Such as: Amethyst vinegar can not control leaf mites; canopy can not be used to control weeds in wheat fields.

Common varieties of herbicides that can reduce the efficacy and cause phytotoxicity are: 24-D butyl ester and chlorpyrifos cannot be mixed; grass gram and bentazon can not be mixed; net can not be mixed with bentazon, miscellaneous Grass burning and mixing; stable killing and bentazon can not be mixed; diuron and phorate can not be mixed and so on.

(2) Correctly grasp the concentration and application rate

In particular, some super-efficient pesticides and plant growth regulators, such as superstars (sulfonylureas) and paclobutrazol (endogenous gibberellin synthesis inhibitors), are rarely taken in a small amount per hectare to cause phytotoxicity. For such agents, a small amount of water should be used to prepare the mother liquor, and then the remaining amount of water should be added to the required concentration as required to make the liquid uniform and not cause phytotoxicity.

(3) A comprehensive understanding of the sensitivity of different crops to pharmaceuticals

Such as: sorghum, cruciferous vegetables sensitive to phoxim; Xiuzhijin is easy to produce phytotoxicity to bean crops; sorghum is particularly sensitive to trichlorfon and dichlorvos; use of herbaceous enemies after wheat jointing is particularly cautious.

(4) Properly master the application time and climatic conditions according to the characteristics of the drug to improve the efficacy and prevent phytotoxicity

The application time is generally from 7:00 am to 11:00 pm and from 3:00 pm to 7:00 pm (both in Beijing time). At noon, due to high temperatures and strong sunlight, most crops are vulnerable to phytotoxicity. For example: take net, chlorpyrifos (herbicides) should be used with caution when the temperature is above 30 °C;

However, some pesticide varieties require spraying under higher temperature conditions to improve the efficacy and avoid the occurrence of phytotoxicity. For example, the activity of phenbutyltin ( acaricide ) is lower than 22 °C, and the activity is poor; the amitraz (acaricide) is poorly applied when the temperature is lower than 25 °C.

4. Countermeasures after the occurrence of phytotoxicity:

(1) Spray with water or alkaline water

When the pesticide is sprayed on the lighter and earlier phytotoxicity caused by the foliage of the plant, the leaf surface of the victim crop should be sprayed with a large amount of water as much as possible, and the pesticide concentration can be repeated 2-3 times until the pesticide concentration is lower than the victim concentration. These clean water not only wash away the medicine on the surface of the plant, but also allow the crop to absorb more water and increase the water content of the crop cells.

The reduced effect of the phytotoxicity is due to the dilution of the concentration of the agent in the crop. For fields that are over-applied, irrigation should be carried out to wash the fields, and the residual drug concentration is diluted and eliminated with water. This can effectively reduce the degree of phytotoxicity of crops.

Also consider the pH of some pesticides, such as organophosphorus drugs, fungicides, etc., which are acidic or slightly acidic. If chemically reacted with alkaline substances, the efficacy will be much lower. Therefore, when the pesticide causing the phytotoxicity is acidic, a large area of ​​0.2% baking soda aqueous solution is added to accelerate the decomposition of the medicament.

(2) removing or trimming the affected organs and replanting the seeds

After the occurrence of phytotoxicity, the leaves of the affected fruit can be trimmed and removed in time to prevent the dead part from being infected by the pathogen. For example, in the fruit trees, the methods of perfusion, injection, dressing, etc., when the branches are relatively strong, should be removed immediately to prevent the liquid from continuing to conduct and penetrate, and immediately irrigate the water to prevent the spread of the disease.

When applying a highly systemic insecticide , if the phytotoxicity occurs due to excessive application concentration, the more harmful branches should be removed immediately. For fields with more serious damage to seeds or seedlings, the crops should be destroyed or replanted or interplanted according to the degree of damage. In the event of serious misapplication of the drug, it is impossible to recover, and it should be completely destroyed in time.

For the plots where the field management seeds or seedlings are less damaged, in order to promote the early emergence of seedlings, it is necessary to strengthen the management of fertilizer and water in the field, and it is necessary to supplement the nitrogen fertilizer. If the soil is damaged in the middle of plant growth, the soil permeability should be improved in time, and artificial soil or cultivating loose soil should be carried out.

At the same time, appropriate application of phosphate fertilizer and potassium fertilizer to promote the development of plant roots. For example, after chloromeron has caused phytotoxicity to wheat seedlings, it can promote the recovery and growth of plants by adding human excrement or external fertilization.

(3) Spray appropriate safety adjuvants to reduce phytotoxicity

When crop phytotoxicity caused by liquid pesticide spray occurs, the symptoms of phytotoxicity appear early. At this time, spraying a certain amount of suitable safe adjuvant can reduce the phytotoxicity of the pesticide on the crop, thereby playing a role in detoxification protection.

If the phytotoxicity caused by omethoate is applied, spraying 0.2% borax solution can alleviate; the phytotoxicity caused by copper sulphate or Bordeaux mixture can be alleviated by spraying 0.5% calcium hydroxide solution;

Spraying crops with pesticides caused by herbicides such as glyphosate, 24-D butyl ester, ethametsulfuron, agrochemical, butachlor, etc., spraying 0.15% with Huangjia natural saponin 5000-10000 times solution It can alleviate the phytotoxicity; 0.2% of the soap liquid can alleviate the phytotoxicity caused by organophosphorus pesticides.

Choosing the right proper safe adjuvant not only detoxifies, but also acts outside the roots to promote plant growth and development.

(4) Chasing quick-acting fertilizer or spraying hormone remedy

Rapidly topdressing urea and other fertilizers on medicinal crops to increase nutrients, enhance the growth of crops, promote early crop growth and accelerate crop recovery. For herbicides and plant growth regulators that inhibit or interfere with the synthesis of gibberellin in plants, spraying gibberellin and detoxification after the drug can effectively alleviate the occurrence of phytotoxicity.

Brass Nut

Copper nuts made of all kinds of embossed wire (usually lead brass, such as H59, 3604, 3602). Our daily contact with the embedded knurled copper nuts are processed by precision automatic lathes. The reference standard of embedded knurled copper nut comes from GB/T809, but the technical parameters of all kinds of embedded nuts produced by our company exceed the relevant indexes required by the national standard.

Knurling copper nut is mainly used for hardware Spring, shaped spring, craft gift spring, battery spring, spring antenna,key ring, phosphorus copper spring CNC automatic lathe turning parts (copper car parts, iron, aluminum car parts), metal stamping parts, electronic parts, iron shaft, single Rachel,Rachel, iron pin, non-standard Screw nut,fittings,fasteners, wire forming (wire card holder, Model aircraft landing gear, S hook, R latch, triangle buckle, D buckle) and other hardware products, belonging to the copper nut series.

Brass Nut,insert nut,knurled nut,injection nut,hex nut

Shenzhen Lanejoy Technology Co.,LTD , https://www.bbq-grillgrate.com