development of striped stem borer (chilo suppressalis) management strategies in hybrid rice in mazandaran province

rice is among the most important food crops throughout the world. hybrid rice benefits from about a 30 percent yield advantage over the conventional pure line varieties and this phenomenon can play an important role in fighting world hunger. to diminish the damage of rice pests, development of insect pest management strategies in hybrid rice is necessary. this study was aimed at evaluating the grain yield and stem borer infestation of hybrid rice (daylam) grown in two planting times and when different control methods employed. the study is expected to provide the suitable needed information for implementing ipm in mazandaran province. a randomized complete block design, involving four treatments (biological, biological-mechanical, chemical vs. control) and of three replications was adopted. to estimate the pest damage, dead hearts and whiteheads were respectively taken from central parts in each plot at the vegetative and reproductive stages respectively. analysis were made using duncan's multiple range test to separate means. results indicated the least average contamination occurring in biological- mechanical control method at either one of the vegetative or reproductive stages. the least overall average contamination occurred in chemical and biological-mechanical control method. in a second trial, percentage of contamination in early planting time treatment was reported as lower than that in late planting time. therefore, early planting is an effective measure to be taken for decreasing the damage of striped stem borer in daylam rice in mazandaran province.