Pesticide application should pay attention to details to avoid phytotoxicity
If the details are not paid attention to during the application, the plant will often cause phytotoxicity, affecting its normal growth and development, such as affecting respiratory photosynthesis or transpiration.
Classification of phytotoxicity
1. Symptoms appear in the short-term after acute drug application, such as spots, perforations, coke formation, chlorosis, malformation, and fallen leaves in the leaves; fruit spots, rust, and even fruit can be produced on the fruit; the seed germination rate is low. Or no bud, root development is not normal; plant growth retardation, dwarf, stalk distortion. Serious phytotoxicity can even lead to the death of the entire plant.
2. Chronic phytotoxicity occurs only after a long time of application, such as malnutrition, inhibition of growth, short planting, it is likely to delay the flower bud formation time or reduce the seed setting rate.
3. Residual phytotoxicity The phytotoxicity caused by pesticides or their decomposition products left in the soil, such as slow-dissolving organochlorine pesticides and metal ion-containing pesticides.
Incidence factor
1. Pharmacy factors Oil agents and emulsions are more likely to cause phytotoxicity, followed by wettable powders, and granules are safer. In addition, poor quality pesticide products may also cause phytotoxicity. In recent years, due to the development of pest resistance, the concentration of pesticides has been continuously increased and the number of times has increased. This is one of the important reasons for the current phytotoxicity.
2. Plant factors The sensitivity of different plants to pesticides varies widely. Plants are generally sensitive to medicinal agents during germination, seedling, and flowering, and are prone to phytotoxicity. In addition, plants with small stomata are less susceptible to phytotoxicity, and plants with thick foliar wax and thick cell walls are highly resistant.
3. Environmental factors High temperature will enhance the chemical activity of pesticides and the metabolism of plants. Drugs are more likely to invade plant tissues and cause phytotoxicity. For example, the higher the temperature, the more gaseous sulfur is volatilized by the stone sulphur mixture, although the disease prevention effect is better, but the possibility of phytotoxicity is also large. Humidity is greatly beneficial to the dissolution of the drug, and intrusion into the plant to cause phytotoxicity. For example, the Bordeaux mixture is prone to phytotoxicity when applied under the conditions of high humidity such as fog or rain. In addition, soils containing less organic matter or strong sand are prone to phytotoxicity, followed by loam and clay.
Prevention method
1. Rational use of pesticides must fully understand the performance of pesticides, such as dosage form, active ingredients, and prevention principles. Considering the biological characteristics and growth of plants, avoiding the germination and flowering period of plants sensitive to the drug. Investigate the type, quantity and developmental stage of pests in detail and use them in a timely manner.
2. Check the quality of pesticides Before applying pesticides, it is necessary to identify whether the pesticides have failed, such as whether the emulsifiable pesticides are stratified, precipitated or flocculated. If the upper layer of oil and the lower layer of sediment appear, shake the bottle to allow the pesticide to stand evenly for one hour; if it is still layered, it proves that the pesticide has failed and can no longer be used. The wettable powder is gently sprinkled on the water surface. If the pesticide is not dissolved in the water after one minute, it indicates that the deterioration has failed.
3. The concentration of the pesticide is diluted to achieve a reasonable concentration, which can achieve good control effect without causing phytotoxicity. Usually there is a range of dilution ratios for each pesticide, and it is desirable to choose an intermediate concentration between the lowest dilution factor and the highest dilution factor.
4. Consider the sensitivity of plants to chemicals. Avoid using sensitive plants when applying pesticides.
5. Meteorological factors should be applied in sunny and windless weather to avoid high temperature application at noon. If there is no special requirement for pesticides, the best application time is from 8:00 to 10:00 in the morning and from 4 to 00 to 6:00 in the afternoon.
6. The application technique spray must be even and thoughtful to avoid excessive spraying of local leaves. Choose the right spray device. Need to strictly calculate the amount of injection, it is best not to use the original solution. After the granules are applied, they should be diluted with water.
7. Increasing soil moisture When the weather is dry and the plants are deficient in water, it is an effective measure to prevent the occurrence of phytotoxicity by watering the soil before application.
Classification of phytotoxicity
1. Symptoms appear in the short-term after acute drug application, such as spots, perforations, coke formation, chlorosis, malformation, and fallen leaves in the leaves; fruit spots, rust, and even fruit can be produced on the fruit; the seed germination rate is low. Or no bud, root development is not normal; plant growth retardation, dwarf, stalk distortion. Serious phytotoxicity can even lead to the death of the entire plant.
2. Chronic phytotoxicity occurs only after a long time of application, such as malnutrition, inhibition of growth, short planting, it is likely to delay the flower bud formation time or reduce the seed setting rate.
3. Residual phytotoxicity The phytotoxicity caused by pesticides or their decomposition products left in the soil, such as slow-dissolving organochlorine pesticides and metal ion-containing pesticides.
Incidence factor
1. Pharmacy factors Oil agents and emulsions are more likely to cause phytotoxicity, followed by wettable powders, and granules are safer. In addition, poor quality pesticide products may also cause phytotoxicity. In recent years, due to the development of pest resistance, the concentration of pesticides has been continuously increased and the number of times has increased. This is one of the important reasons for the current phytotoxicity.
2. Plant factors The sensitivity of different plants to pesticides varies widely. Plants are generally sensitive to medicinal agents during germination, seedling, and flowering, and are prone to phytotoxicity. In addition, plants with small stomata are less susceptible to phytotoxicity, and plants with thick foliar wax and thick cell walls are highly resistant.
3. Environmental factors High temperature will enhance the chemical activity of pesticides and the metabolism of plants. Drugs are more likely to invade plant tissues and cause phytotoxicity. For example, the higher the temperature, the more gaseous sulfur is volatilized by the stone sulphur mixture, although the disease prevention effect is better, but the possibility of phytotoxicity is also large. Humidity is greatly beneficial to the dissolution of the drug, and intrusion into the plant to cause phytotoxicity. For example, the Bordeaux mixture is prone to phytotoxicity when applied under the conditions of high humidity such as fog or rain. In addition, soils containing less organic matter or strong sand are prone to phytotoxicity, followed by loam and clay.
Prevention method
1. Rational use of pesticides must fully understand the performance of pesticides, such as dosage form, active ingredients, and prevention principles. Considering the biological characteristics and growth of plants, avoiding the germination and flowering period of plants sensitive to the drug. Investigate the type, quantity and developmental stage of pests in detail and use them in a timely manner.
2. Check the quality of pesticides Before applying pesticides, it is necessary to identify whether the pesticides have failed, such as whether the emulsifiable pesticides are stratified, precipitated or flocculated. If the upper layer of oil and the lower layer of sediment appear, shake the bottle to allow the pesticide to stand evenly for one hour; if it is still layered, it proves that the pesticide has failed and can no longer be used. The wettable powder is gently sprinkled on the water surface. If the pesticide is not dissolved in the water after one minute, it indicates that the deterioration has failed.
3. The concentration of the pesticide is diluted to achieve a reasonable concentration, which can achieve good control effect without causing phytotoxicity. Usually there is a range of dilution ratios for each pesticide, and it is desirable to choose an intermediate concentration between the lowest dilution factor and the highest dilution factor.
4. Consider the sensitivity of plants to chemicals. Avoid using sensitive plants when applying pesticides.
5. Meteorological factors should be applied in sunny and windless weather to avoid high temperature application at noon. If there is no special requirement for pesticides, the best application time is from 8:00 to 10:00 in the morning and from 4 to 00 to 6:00 in the afternoon.
6. The application technique spray must be even and thoughtful to avoid excessive spraying of local leaves. Choose the right spray device. Need to strictly calculate the amount of injection, it is best not to use the original solution. After the granules are applied, they should be diluted with water.
7. Increasing soil moisture When the weather is dry and the plants are deficient in water, it is an effective measure to prevent the occurrence of phytotoxicity by watering the soil before application.
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