Damage characteristics of aphids
Aphids commonly known as greasy worms, sweat, honey, etc. , adults and nymphs can be harmful, adults and nymphs gathered in the leaves, growing points, flowers, young fruit, etc. . Adults are divided into winged and wingless aphids. Winged aphids have strong migratory ability. They do this by constantly migrating, looking for host plants, and repeatedly moving to taste food.
Aphids reproduce very well. One year may reproduce 20 ~ 30 many generations, especially in the high temperature dry season, reproduces the speed to be quicker. The generation overlap of aphids is serious, and the aphids can reproduce both sexually and parthenogenetically. In winter, the adults and fertilized eggs overwintered in the soil of weeds, tree crevices and the base of seedling stems. In spring, they hatched into dry females and parthenogenetically reproduced for 2-3 generations.
The reason why aphids are difficult to control
Migration ability: aphids are a kind of piercing-sucking pest, to piercing-sucking plant juices to live. Spray control is the most commonly used method of prevention and control, quick effect, high efficiency. However, the duration of the general agent is only 7 to 15 days. After the validity period, the adults from other places rapidly reproduce parthenogenetically under suitable environmental conditions, and the number of aphids increases geometrically.
Large number of aphids: because of the high reproduction speed and large number of aphids, it is impossible to spray every leaf, flower and fruit evenly. There are always places that are missed, and individual aphids become the fish that escape the net, continue to breed in large numbers, in the appropriate temperature conditions, only 4 ~ 5 days will be re-outbreak.
Prevention measures
(1) soil treatment: soil treatment has the characteristics of high efficiency, long duration and good effect. Can be transplanted before sowing crops, combined with the application of base fertilizer. 2% imidacloprid granules 500 ~ 1000 g/mu, or 2% thiamethoxam granules 300 ~ 500 g/mu, mixed with organic fertilizer, broadcast application, furrow application, hole application. Because imidacloprid and thiamethoxam have strong conductivity, they can be quickly transmitted to the stems, leaves, fruits and other parts after being absorbed by the roots, which can better protect the stems, leaves and fruits from aphids.
(2) seed treatment: seed dressing has the characteristics of low cost, simple operation, long duration and good effect. Before sowing, the seeds could be dressed with 60% imidacloprid suspension seed coating agent in the ratio of 1:200-300, or with 30% thiamethoxam suspension seed coating agent in the ratio of 1:400-500. The pesticide forms a protective zone around the seed and is delivered to various parts of the plant to kill the pests in each part through imbibition.
(3) topdressing application: in the middle and late stages of crop growth, watering can be combined with topdressing, mixing chemicals and fertilizer after topdressing, or adding drip irrigation liquid to irrigate roots. The roots absorb the pesticide nutrients and water together and transport them to the aerial parts, killing the aphids.