Abstract

Weed is the major limitation to the adoption of aerobic rice system, the most potential water saving rice production technology. Herbicide is the appropriate tool to address this problem but suitable herbicide or their combination in controlling the predominant weed flora in this system is not established. The present study was conducted to evaluate the response of weed flora in the aerobic rice field to the sequential application of a single, proprietary or tank mixed herbicides in dry season 2008 and wet season 2008 to 2009. Results revealed that different weed species responded variably to herbicides tested. In the present study, the most dominant weeds were: Eleusine indica, Digitaria ascendense, Echinochloa colonum andCyperus iria. The most effective control of weed flora was obtained by Pretilachlor fb Bentazon/MCPA, Cyhalofob-butyl + Bensulfuron fb Bentazon/MCPA, Pendimethalin fb Bentazon/MCPA, Propanil/Benthiocarb fb Bentazon/MCPA, and Pretilachlor / Pendimethalin fb Bentazon/MCPA. The study concludes that the  combinations of herbicides dryer broader spectrum of weed control and the herbicide selection should be based on the target weed species in addition to their broader category of  grass, sedge and broadleaf  for planning an effective weed control program for aerobic rice.

Key words: Herbicide combination, weed abundance, weed control, sedge, grass, broadleaf weeds, dry seeded rice.