How high is the temperature at which tomatoes use fungicides to cause phytotoxicity?

The temperature at which fungicides are used in tomatoes will cause phytotoxicity, and the optimum temperature for applying fungicides in greenhouse is 25 ~ 35℃.

1. Water and wettable powder drugs need to be diluted with water before spraying. Different concentrations of fungicides have requirements, which need to be mixed in strict accordance with the instructions. Reasonable configuration concentration is more conducive to the effectiveness of fungicides. If mixed at will, too high concentration will cause phytotoxicity to crops; The concentration is too low to meet the control requirements.

2. The spraying time of fungicides is directly related to the control effect. Spraying fungicides too early will waste fungicides and reduce the control effect. Too late pathogens have done harm to crops. Therefore, it is necessary to use drugs in time according to the occurrence law, prediction and specific conditions of different diseases. Generally speaking, the application time of fungicides can be selected before or at the early stage of onset.

3. The quality of bactericide includes quantity, frequency and spraying quality. The dosage should be appropriate, too much medication will increase the cost and cause phytotoxicity, and too little medication will not achieve the prevention and control effect, and it should be increased or decreased according to the specific situation. The application frequency depends on the residual period and weather conditions. Generally, it is sprayed once every 10- 15 days and 2-3 times. If it rains after application, it needs to be sprayed again. The way to improve the quality of medicine is to spray the medicine evenly and carefully, and spray it all over the stems and leaves of plants.

4. There are many reasons why fungicides cause phytotoxicity. Pesticide itself, different crop sensitivities, crop growth stages and climatic conditions will all affect it. Generally speaking, drugs and crops with strong water solubility are more likely to cause phytotoxicity at seedling stage, booting stage and flowering stage, such as high temperature, drought, fog and high humidity, which need to be handled carefully.