It is predicted that the rice leaf roller will tend to occur in the second half of the year. It uses larvae to injure rice leaves, hides the leaves in longitudinal folds, and eats leafy meat. After rice suffers, the empty-heading rate increases, and the grain weight decreases. Generally, the yield can be reduced by 2 to 30%. When the rice grows up, the rice fields are white and even the grains are not harvested. . The rice leaffolder adults are 8-9 mm in length and 18 mm in wingspan. The body is tan-brown. There are dark brown broad edges on the outer edges of the front and rear wings. The forewings have three dark brown stripes. The middle one is short and the hind wings are black. Brown stripes. The mature larvae are red-brown and 12 to 15 mm long. The conditions of occurrence of rice leaffolders are closely related to climatic conditions, farming systems, species distribution, seedling growth, and natural enemies. 1. When the rice leaf roller is 22-28 degrees Celsius and relative humidity is more than 90%, it is favorable for ovarian development, mating and spawning, large amount of eggs laid, high hatching rate and survival rate of larvae. Early rice early sowing and early sowing are beneficial to the first generation of rice leaffolders, increase the amount of second generation, and the damage is obviously aggravated. In the early and middle stages of rice breeding, partial application of nitrogen fertilizer or too late fertilization, leaves too long and tender are easy to attract moths to lay eggs, favoring larvae scab; early rice varieties broad leaves, egg-laying density will be large. There are many kinds of natural enemies in rice leaffolders, especially parasitic natural enemies, which have a great inhibitory effect on their occurrence. Prevention and control of rice leaf roller should be based on agricultural control, rational use of pesticides, protection and use of natural enemies, in order to achieve economic and effective control effect. One is to check the amount of moths and predict the period of occurrence. The investigation method was to use a bamboo raft about 1.5 meters long, and toggle 5 rows of seedlings, 200 bundles per row. When the seedlings were toggled, they carefully counted the number of total moths that were flying and calculated the amount of mu and the average type of moth. . The peak period of the moth is the most, and the moth is the beginning and end of the moth when the moth amount decreases. The second is the amount of eggs investigated and the progress of hatching to predict the larval stage. The method is to select 1 to 2 plots for each type of field, use 5 sampling points for each plot, and use 2 clusters of rice at each point for a total of 10 clusters. Check the number of eggs, eggs hatched, the number of unhatched eggs, and the number of parasitized eggs by leaf. Then calculate the parasitic rate and the hatching rate of the eggs. When the hatching rate reached 16% to 20%, it reached the beginning of the egg hatching, reaching a peak period of 45% to 50%. This time is an important period of spraying, and the best effect of the application of this time. The main reason is that a large number of larvae in the incubating stage feed on the base of the heart, and the amount of the drug is the largest in this area, and it is easy to contact the body. Second, the newly hatched larvae have the lowest resistance. At the same time, since the emergence of parasitic bees is often 3 to 7 days later than the hatching of rice leaf roller, it is beneficial to protect parasitic natural enemies. If you miss this opportunity, you can apply it before 1 inch. Pharmacy and use of methods: 1. Each mu with 18% of insecticidal double water 200 to 300 grams of water 50 to 60 kg spray. 2. Each acre with 40% acephate 100 grams plus 50 to 60 kg of water spray. Biological control can be considered to release Trichogramma or the application of bacterial pesticides can also achieve a certain effect.
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