Fungicide's considerations

The general pesticide instruction manual has recommended concentration, which can be used according to the instructions, but it is best to apply according to the concentration used by the local plant protection technical department based on the efficacy test. In dry or hot summers, the concentration should be reduced to avoid phytotoxicity. Secondly, when using fungicides, pay attention to the period of use and the number of uses. The key to mastering the spraying period is to master the law of disease occurrence and development, to predict and predict the occurrence of diseases, or to predict crop diseases according to local plant protection departments. The preparation for spraying the fungicide is forecast. Under normal circumstances, the spraying of fungicides is carried out at the beginning of the disease, such as rice blast, especially in high temperature weather, rice blast develops rapidly, and should be sprayed immediately. Peanut leaf spot disease development is relatively slow, do not spray easily when the disease occurs, but can not spray before the onset of disease, but start to spray when the formation of a certain development trend after the onset. The climatic conditions are conducive to the rapid development of the disease, and should be sprayed immediately. Sometimes, in order to control the disease, it is necessary to spray the medicine when it is drizzling. The spraying period is determined by the law of disease development, and the growth period of the crop is also taken into consideration. Many diseases occur in connection with a certain stage of growth of the crop.

In addition, attention should be paid to the tolerance of the fungicides during the growth period of the crops to prevent phytotoxicity. The occurrence and development of plant diseases often takes a while, and it is difficult to solve the problem once by spraying the fungicide. It often needs to be sprayed several times. The number of sprays is mainly determined by the reinfection of the bacteria, the residual period of the fungicide, as well as climatic conditions, light, temperature and rainfall. Seedling disinfection. Soaking seeds should use emulsions and solutions, and suspensions should not be used. Wet powders should not be used for soaking seeds. The key to soaking seeds is the concentration of the liquid and the time of soaking. Improper handling can result in poor sterilization or phytotoxicity. Other factors such as temperature, seed type, and the location of the pathogen also affect the soaking effect. Under normal circumstances, after the seed type, temperature, and drug type are determined, the concentration of the drug and the soaking time can be coordinated. The high concentration can appropriately prolong the soaking time. If the pathogen is deep or the seed coat is hard, the soaking time can be extended appropriately. The high temperature can shorten the soaking time. Seed dressing and powder must be dry when seed dressing, otherwise it will cause uneven seed dressing, produce phytotoxicity, and affect the germination rate of seeds. The dosage of the powder generally accounts for 0.2%~0.5% of the weight of the seed. When seed dressing, the medicine and the seed should be divided into 3~4 batches, and then the seed dressing container is properly rotated to make it evenly mixed. After the emergence of systemic fungicides, a new method of seed dressing--wet mixing method appeared.

That is, the powder is wetted with a small amount of water, and then seeded, or the dried powder is mixed on the wet seeds, so that the powder adheres to the surface of the seed. After being sown, the medicament is slowly dissolved and absorbed into the plant to conduct upward. Soil-borne diseases such as cotton wilt and cucumber wilt may be controlled by soil disinfection, in addition to being controlled by soaking or seed dressing. Soil disinfection should first select the appropriate fungicide according to the type of disease, and then select the appropriate soil treatment method according to the physical and chemical properties of the drug and the soil structure and properties. The watering method is suitable for the water-soluble bactericide. After adjusting the agent to the appropriate concentration, watering about 5~10 kg of liquid per square meter of ground can be used. When the soil is dry, a lower concentration of the liquid can be used, and the watering volume is appropriately increased. High-concentration small-volume irrigation can be used when the soil is wet. The bactericide with higher vapor pressure can be applied by plowing or furrow, that is, the powder or liquid is evenly sprinkled into the bottom of the first plough, and the soil is covered by the soil of the second plough. This method is not suitable. For heavy soil, the powder or liquid can be applied to the surface of the soil, and then the soil is buried in the soil.