How can pest resistance to pesticides be prevented?
In recent years, due to the heavy use of chemical pesticides, combined with the fact that many flower growers lack basic knowledge of pesticide use, improper application has led to an increasing number of pest species with pesticide resistance on flowers and trees, and the degree of resistance is also growing higher. To address this, the following methods can be used to prevent flower and tree pests from developing pesticide resistance.
1. Rotating pesticides
Do not use a single pesticide to control a certain pest over the long term, as this can cut off the process by which resistant pest populations form. For rotation, choose pesticides with different mechanisms of action whenever possible, such as organophosphorus pesticides, pyrethroid pesticides, carbamate pesticides, and biological pesticide formulations. If their insecticidal principles differ, they can be used alternately. Rotating pesticide varieties within the same class should be done with caution, because pests easily acquire cross-resistance, meaning that after developing resistance to one pesticide, they also develop resistance to other varieties in the same class as that pesticide. For example, chrysanthemum aphids resistant to dimethoate will likewise develop resistance to dichlorvos, trichlorfon, and others.
2. Mixing pesticides
Mixing two pesticides with different modes and mechanisms of action can slow the development of pest resistance, and even if resistance has already formed, mixed pesticide use can suppress resistance. At present, the more successful mixed-pesticide schemes include: trichlorfon, dichlorvos mixed with malathion; pyrethroid insecticides mixed with organophosphorus insecticides; trichlorfon mixed with phoxim; and machine oil emulsion mixed with organophosphorus insecticides, etc. Note: mixed pesticides also cannot be used alone over the long term; pesticides must be rotated, otherwise resistance will likewise be caused and may even trigger pests to develop multiple resistance.