Detailed Explanation of Pesticide Application Techniques for Pollution-Free Vegetables

1. Target the specific problem. On the basis of fully understanding the properties and methods of use of pesticides, select the appropriate pesticide type or formulation and the appropriate concentration according to the type of pest or disease to be controlled; do not artificially increase the concentration used.

2. Apply pesticides at the appropriate time. According to the occurrence patterns of pests and diseases, strictly grasp the optimal control period and apply pesticides at the right time. For diseases, control should be carried out at the early stage of onset, controlling the center of infection and preventing its spread and development; once a disease breaks out and spreads extensively, it becomes very difficult to control. Biological pesticides act more slowly, so they should be applied 2-3 days earlier than chemical pesticides.

3. Use pesticides scientifically. Pay attention to alternating and rotating pesticides with different mechanisms of action; do not use a single pesticide over the long term, so as to prevent pathogens or pests from developing resistance and to help maintain the control effect and service life of the pesticide. In the early stage of vegetable growth, high-efficiency, low-toxicity chemical pesticides and biological pesticides should mainly be mixed or used alternately; in the later stage of growth, biological pesticides should be the main choice. For pesticide application, the low-volume spray method should be promoted, and attention should be paid to even spraying.

4. Choose the correct spraying point or part. When applying pesticides, determine the target parts of the plant according to the occurrence characteristics of different pests and diseases at different stages, and carry out targeted application. This achieves the purpose of timely controlling the occurrence of pests and diseases, reducing pathogens and lowering insect population density, thereby reducing pesticide use. For example, downy mildew starts from the lower leaves and develops upward; the focus of early control of downy mildew is on the lower leaves, which can reduce infection of the upper leaves.

5. Mix pesticides rationally. Use mixed pesticide application methods to achieve the purpose of controlling multiple pests and diseases with a single application. However, pesticide mixing must be premised on maintaining the original active ingredients or having a synergistic effect, not increasing toxicity to humans and livestock, and having good physical compatibility. Generally, neutral pesticides can be mixed with each other; neutral pesticides can be mixed with acidic pesticides; acidic pesticides can be mixed with each other; alkaline pesticides must not be mixed arbitrarily with other pesticides; microbial insecticides (such as Bt) must not be mixed with fungicides or pesticides with strong systemic activity; mixed pesticides should be prepared and used immediately.

6. Strictly follow the pesticide pre-harvest interval. The pre-harvest interval for pyrethroid pesticides is 5-7 days, for organophosphorus pesticides 7-14 days, and among fungicides, chlorothalonil, zineb and carbendazim require more than 14 days, while the rest require 7-10 days. For mixed pesticide formulations, follow the pre-harvest interval of the active ingredient with the greatest persistence.