I. Morphological characteristics: The bean stalk fly is small, the adult body is 2.5 mm long, the larval body is 3-4 mm long, and the pupae are long and cylindrical, 2.5-2.8 mm long. Pupae overwinter in soybean straw , petioles and other hosts in the winter , and feather in the following spring.
Second, the symptoms of harm: bean stalk fly commonly known as bean stalk heart piercing, common bean stalk black diving fly, bean shoot black diving fly, bean root skin snake diving fly and bean root snake diving fly, etc., mainly for a variety of legume plants, the most serious harm in our county is summer soybeans and some late-sown spring soybeans. Bean stalk flies generally start to harm from the seedling stage, the hatching larvae moth into the main stem, side branches and petioles of the beans moth and xylem, forming a tunnel, affecting the transport of nutrients and water, so that the affected crops leaves yellowing, like lack of fertilizer and water, the diseased plant is significantly dwarfed, the heavy stem hollow, leaf shedding, resulting in death, resulting in lack of plants. At the adult plant stage, the flowers, pods and leaves fall off prematurely, resulting in a decrease in pods, an increase in grains, and a decrease in the weight of 1,000 grains, which greatly affects the yield and quality of bean crops. The old mature larvae bite a feather hole in the stem wall and pupate in the stem near the feather hole.
III. Prevention and Control Measures:
1. Agricultural control: the diseased plants are found to be pulled out in time, the residual branches and leaves in the field are cleaned up in time after the soybean harvest and burned in a concentrated manner, and the deep sunding before winter suppresses the pupa base of overwintering insects. Increase base fertilizer, sow early, seedlings at the right time, and rotate crops to change stubble.
2, pharmaceutical control: pharmaceutical control should be carried out in the adult period to the larval moth before eating better (once the moth into the inside of the stem, the prevention and control is more difficult), can be used 40% of the fruit or oxy fruit, 50% octyl thiophosphate emulsion, 10% imidacloprid wettable powder and other 1000 times liquid, or 75% of the fly amine wettable powder 1500 times liquid uniform spray. On the basis of adult control, the control of larvae is better every 6 to 7 days. Once the larvae have entered the inside of the stem, they can be irrigated with the above agents and sprayed foliar with foliar fertilizer or nutrient regulators to enhance the plant's disease resistance.