ASSESSMENT OF SELECTIVE HERBICIDES ON Orseolia oryzivora INFESTATION ON GROWTH AND YIELD OF RICE (Oryza sativa L.)

Abstract

Rice (Oryza sativa L.) is an important cereal crop with high nutritional value to human beings worldwide. The low yield of rice has been partly, attributed to insect pest damage. Orseolia oryzivora is a serious insect pest of rice for which use of selective herbicides in controlling weeds has been assumed to predispose rice plant to infestation by O. oryzivora. This experiment was conducted in 2020 and 2021 cropping seasons at Edozhigi Niger State, Nigeria (Latitude 90  041Longitude 60  071  E), to assess the influence of selective herbicides on O. oryzivora infestation, growth and yield of rice. The experiment was laid out in Randomized Complete Block Design, replicated three times. The treatments were application of Vestermine (2,4 D isobutyl ester), Ricepro (propanil and 2,4 D isobutyl ester), Bracerplus (cyhalofop-butyl 12 % + bspyrbac-sodium 4 %) and hand weeding (without any application of selective herbicide) as control. Data were taken on tiller count, plant height, number of days to 50 % flowering, O. oryzivora incidence and severity, panicle count, panicle length and grain yield. Data were subjected to analyses of variance and significant means were separated using Fisher’s Least Significant Difference. The results showed that there were no significant differences (P<0.05) in plant height and tiller count among the four treatments in both 2020 and 2021 cropping seasons. The control plot and plots treated with Vestermine and Bracerplus had significantly (P <0.05) higher panicles/m2, and higher grain yield compared to plots treated with Ricepro. Also, plots treated with Ricepro had significantly (P<0.05) higher incidence and severity of O. oryzivora compared with other treatments. From the results, it is concluded that the use of Ricepro to control weeds in rice field predisposes rice to infestation and damage by O. oryzivora.