Silver-striped noctuidae, Lepidoptera noctuidae. It is harmful to cruciferous vegetables such as kale, cauliflower, cabbage, radish, etc., crops such as soybeans and peas, vegetables such as lettuce, eggplant, carrots, and paulownia and tung oil. The country is spread throughout all provinces and regions, of which the Huanghuai Yangtze River Basin is more seriously affected.
symptoms
The larvae feed on the leaves, eat the leaves into holes or gaps, and excrete feces to contaminate the vegetable plants. 1 ~ 2 instar larvae have clusters, often dozens of secluded leaf back nibbling on leaf flesh, dispersed after 3 years of age, for the damage is aggravated, often climb to the upper part of the plant, the leaves, tender tips, buds, young pods all eaten, sometimes drilled into the pods to harm the grains, there is a pseudo-death.
prevention and cure
(1) Agricultural control. Remove leaves from the field in time to eliminate pupae. Using the suspended death of the larvae, the plant can be shaken, so that the insect falls underground and is destroyed intensively.
(2) Biological control. In the 1st to 2nd instar stages of larval development, spray with Bacillus thuringiensis or B?t emulsion containing more than 10 billion live spores per gram. Add 800 to 1 000 times the water to prevent and control, and the prevention and control effect is good when the temperature is 20 ° C or more.
(3) Physical prevention and control. The use of black light can kill a large number of adult silver-streaked moths, so that the rate of insect infestation is reduced.
(4) Chemical control. The larvae are sprayed before the 3rd instar stage for control. Pollution-free pesticides such as 25% urea no. 3 suspension 500 to 1000 times liquid, or 5% anti-Taibao emulsion 3 000 to 4 000 times liquid are preferred. It is also possible to choose 10% imidacloprid emulsion 1 500 times liquid, or 2.5% cypermethrin emulsion 3 000 to 4 000 times liquid, or 10% bifenthrin emulsion 6 000 to 8000 times liquid, or 21% synergistic cyanide? Horse emulsion 3 000 to 4 000 times liquid, or 40% juma emulsion 2 000 to 3 000 times liquid. Spray once every 10 to 15 days for 1 to 2 consecutive sprays.
Pathogenesis
(1) Generations occur. There are 2 to 5 generations in Northeast China, Hebei and Shandong every year, and about 4 generations in Shanghai, Hangzhou and Hefei. 6 to 8 generations in northern Fujian. (2) Overwintering. Pupae overwinter in various places on dead leaves, soil surfaces, etc. (3) Occurrence period. Larvae appear between April and May. (4) Environmental factors. In the planting method, pure crop occurs heavily, while intercropping and co-nesting occur lightly. Increased micro-fertilization occurs lightly. Late broadcasting occurs heavily. Potassium is more often mild. Phosphorus is more often light. Nitrogen is more likely to occur heavily. Mulching cultivation is conducive to occurrence. (5) Natural enemies. White zombie fungus, green zombie fungus, as well as predatory ladybugs, spiders, dragonflies, frogs and rice bracts melanoma wasps.