Detailed Explanation of Key Soybean Aphid Control Techniques
The soybean aphid belongs to the order Homoptera, family Aphididae, and is a major pest in the soybean-producing areas of Huachuan County. In the past two years, its occurrence period has advanced, and the damage has also worsened. The soybean aphid is tender-growth-tropic; adults and nymphs gather on the terminal leaves, tender leaves and tender stems of plants to pierce and suck sap, and in severe cases they cover the stems and leaves, and can also attack tender pods. When plants are severely damaged, the leaves curl, the root system develops poorly and turns yellow, the plants are stunted, branching and pod setting decrease, and the 1000-grain weight drops. If an outbreak at the seedling stage is not controlled in time, the yield is reduced by 20%-30% in mild cases, and by more than 50% in severe cases. The soybean aphid can also transmit soybean mosaic virus disease. This pest begins to appear in soybean fields in mid-to-late June, and causes severe damage during periods of high temperature and drought.
Morphological characteristics
The winged parthenogenetic female aphid is oval, yellow or yellowish brown. The wingless parthenogenetic female aphid is long oval, yellow or yellow-green, with antennae shorter than the body.
Life habits: In Huachuan County, the soybean aphid produces about 10 generations a year, overwintering as eggs on the branches of Rhamnus davurica. In the following spring: when the average temperature is above 10 degrees, winged parthenogenetic females begin to migrate to soybean fields to harm seedlings; from late June to mid-July they enter the peak damage period; in late July, light yellow small soybean aphids appear, and the aphid population begins to decline; from late August to early September, as the temperature drops, the soybean aphid enters the late-stage reproduction phase. From late June to early July, when the average temperature reaches 25°C and the relative humidity is below 70%, it is favorable for a major aphid outbreak.
Control measures
When the soybean aphid occurs in spots and patches, 5%-10% of plants in the field have curled leaves, or the rate of aphid-infested plants exceeds 50%, and the number of aphids per 100 plants is more than 1500, spraying can be carried out for control.
1. Select highly effective, low-toxicity insecticides. In the past, when controlling aphids, farmers habitually used organophosphorus insecticides such as omethoate and dimethoate, or pyrethroid insecticides such as cypermethrin and cyhalothrin. In view of the high toxicity of organophosphorus pesticides and the relatively high resistance that has developed, it is recommended that each township (town), when guiding farmers in soybean aphid control work, selects the following pesticides:
(1) 3% acetamiprid (Mobilan, Jin Shiji, Adake, etc.) emulsifiable concentrate, at 15-20 milliliters per mu. According to trials and demonstrations in the past two years, 3% acetamiprid emulsifiable concentrate has the advantages of good control effect, long residual activity, high safety and simultaneous control of red spiders, and can be used as the current first-choice pesticide for aphid control.
(2) 10% imidacloprid at 30 milliliters per mu.
(3) 25% Huifeng Kuaike emulsifiable concentrate or 25% Kuaishaling emulsifiable concentrate, at 30 milliliters per mu.
(4) In plots where red spiders also occur, the above pesticides can also be mixed with 1.8% avermectin (Chongmanke, Qimansu, Aifuding, at 20 milliliters per mu) to simultaneously control red spiders.
2. Do not use highly toxic and high-residue pesticides, such as omethoate, phorate, methamidophos and other pesticides.
3. In soybean fields that have already closed their rows, it is recommended to use a mist sprayer for spraying.