Document Type : Research Article
In order to managing rice striped stem borer (Chilo suppressalisWalker) on Hybrid rice, a field study was conducted at the Rice Research Institute of Iran, Rasht during 2006-2007. The treatments were early planting, late planting, releasing of Trichogramma wasp, spray of Dazinon granular (10%), mixed of Trichogramma releasing with spray of Dazinon granular and control. Indexes of evaluation were number of larvae, percentage infection of Dead hearts (D.h), White heads (W.h) and yield in various treatments. The results showed that highest of infection D. was 1.78 to 0.77 percentage in control and early planting in vegetative stage receptively. Also, The highest W. h infection observed in control treatment and late-planted was from 3.32and 2.49 percentage receptively. The highest of larvae average in vegetative stage observed in treatments of control and early planting The most of larvae mean in reproductive stage showed in control. The highest of yield showed in releasing of Trichogramama wasp with apply of granular Diazinon(10%) about 7512.5 kg/ha during two years. At least of yield observed in checked and late-planed treatments with4368.80 and 4580.90 kg/ha at this time receptively. This research showed the more suitable of method is mixed releasing of Trichogramma wasps with spray of Dazinon granular. By the way, average of crop loss due to in early planting in comparison with late planting was remarkable.