Abstract

Use of fertilizer within plant protection system can prove a key factor for pest management strategy. The effects of Zinc sulfate (33% - Zn) fertilizer on the incidence of rice stem borers (Scirpophaga species) (Lepidoptera: Pyralidae) in rice crop were investigated. The Zn was applied using broadcast method at three levels (20, 25 and 30 kg/ha) in the vicinity of the roots, 30 days after crop transplantation. The results of field experiment on rice cultivars Shadab and Mehak showed that Zn had significant influences on the stem borers population and paddy yield over the unfertilized control. Average yield per hectare was increased at all doses of Zn and by applying it at the rates of 20, 25 and 30 kg/ha, the differences in grain yield were not significant, but production increased significantly over the untreated crop due to varying pest prevalence. With respect to borers incidence, higher dose 30 kg Zn/ha markedly decreased infestation, while, applications at 20 and 25 kg permitted slightly more deadhearts and whiteheads incidence, but differed significantly from unfertilized control. The present study implies that due to suppressive effects of Zn fertilizer on the incidence of the rice stem borers at crop maturity stage increased grain yield, and the use of soil amendments strategy can create an unfavorable environment for pest inducing resistance through anti biosis or feeding inhibition.

Key words: Rice, Oryza sativa, Scirpophaga, insect control, rice stem borer, Zinc.