Plutella xylostella is a common pest in vegetable production. In recent years, due to the influence of warm winter and little rain and dry weather, the base number of the winter moth of Plutella xylostella is large, and the natural mortality rate is low, leading to aggravation of vegetable cultivation areas. Occurrence of law. Plutella xylostella occurred in the Yangtze-Huaihe region in the 1st year of 6-8 generations, and overlapped by generations. It became the source of insects in the following year as adults and cockroaches overwintered on vegetables and stubble leaves and weeds, and in soil seams. Overwintering and eclosion occurred in mid-April, and adult eggs were spawned or several eggs were produced on the back of leaves and near the leaf veins. The growth and development temperature of Plutella xylostella larvae was in the range of 20-30 °C. In the spring of April and June, crops such as potato, rapeseed and cabbage are mainly harmed; in the fall of August and early November, crops such as Chinese cabbage, radish, loofah and vinegrass are mainly damaged. In the middle and late November, the larvae larvae winter. Harmful symptoms. The newly hatched larvae of Plutella xylostella plunged between the upper and lower epidermis of the leaves of the plant and ate the mesophyll and the lower epidermis, leaving only the epidermis showing a clear white spot. After the third instar, the larvae fed a large increase, and they bite into the leaves to form holes, which are not serrated. In severe cases, the entire leaf is eaten cleanly, leaving only reticular veins. The larvae particularly like to damage the young parts of the plant and the heart and leaves of the seedlings, making them unable to grow normally, resulting in a decline in yield and quality. The extent of damage to autumn vegetables is greater than that of spring, and drought can promote the occurrence of pests. Prevention strategies. Plutella xylostella is a kind of pest with high resistance to insecticide. It is difficult to prevent and control. In prevention and control, it should be mainly controlled by agriculture, which will cause adverse environment for the diamondback moth. Chemical control should strengthen pest prediction and use pesticides in appropriate period. The preference for biological pesticides, the scientific and rational use of pesticides, and the alternative use of different types of pesticides and biopesticides can effectively improve the effectiveness of pesticides. 1, agricultural control. After the harvest of vegetables in spring and autumn, the defoliation and weeds of the stubs shall be promptly removed, and the stacking or selective burial shall be centralized to reduce the number of pest habitats and the base number of overwintering insects. Heavy land masses occur throughout the year, and it is necessary to rationally arrange spurs and try to avoid continuous production of small-scale crucifer crops. Careful management of nursery beds during nursery, higher temperatures to cover shade nets, can effectively prevent adults from invading spawning. Black light can also be used to trap adult insects. 2, biological control. At the beginning of the moth, synthetic moths can be used to form strands of wire and place them on a water basin. Ten centimeters from the surface of the water can be trapped and trapped. The radius of the pot attracts up to 100 meters, and the effective moth period is more than 30 days. Incubation period of larvae can be selected from Bacillus thuringiensis BT preparation or compound BT emulsion and acaricidal bacillus, containing about 10 billion viable spores per g, diluted 600 times, 50-60 kilograms of mu plus 18% of insecticidal double water per mu 100 In milliliters, when the temperature is above 20°C, spray at 5pm, once for 7 days, 2-3 times in succession. 3, chemical control. The beginning of the larvae damage, use 5%% Sodium thiocide suspension diluted 1000-1500 times, 50 kilograms of acres plus avermectin 20 ml; can also be used to dilute 90% of trichlorfon crystals 800 times liquid, 50 kg per mu Add 48% of 75ml of Le Siben EC, stem and leaf spray, once a day for 7 days, 2-3 times in succession. 15 days before the harvest of vegetables, pesticides should be banned to prevent excessive pesticides and affect safety. The National Meat Quality Supervision and Inspection Center has verified that the “microecological preparation†pork complies fully with the national meat quality standards, all kinds of antibiotics have not been detected, and the amino acid content is higher than 30% of ordinary pork.
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