Control efficiency of Cnaphalocrocis medinalis by rice seed treatment with chlorantraniliprole and its safety evaluation

In order to reduce the operation times of pesticide, avoid damage to natural enemies and release human labor, a series of seed treatment methods was conducted. Safety for germination and emergence were determined in lab with rice seeds dressed with chlorantraniliprole. According to field experiments in different cultivation model, the effective period and leaf protection effect were confirmed. The safety on natural enemies and the final residue of seed dressing were determined. The results showed that germination and seedling rate were not influenced when the rice seeds were dressed with 30-120 g(a.i.)/hm² chlorantraniliprole. When the dressed seeds were used directly in seeding rice filed with the effective concentration 60 g(a.i.)/hm², the leaf keeping rate was 97.13% in the 110^th day. When drily raised rice seedling techniques were used with the concentration of 90 g(a.i.)/hm², the leaf keeping rate were over 82%. In mechanical transplanting rice seedling model with concentration 90-120 g/hm², the leaf keeping rate was over 95%. The control efficiency and effective period of chlorantraniliprole seed treatment were better than that of the leaf spray treatment in three different cultivation modes. It can control the rice leaf roller in the middle and early stages of rice development and reduce the number of pests in the late rice growth. The killing of natural enemies risk in the field were not observed when rice seed was dressed with chlorantraniliprole, and chlorantraniliprole residues in harvested rice was lower than limit of quantity (0.000 8 mg/kg). By using the seed treatment, it was not necessary to prevent and control the rice leaf roller until the heading stage in japonica rice in the hilly area of Jiangsu, and the number of the rice leaf roller in late rice growth was reduced, which make it a simple prevention and control method of the rice leaf roller.