Comparative performance of low and high volume herbicide sprays for weed control in lowland rainfed rice (Oryza satica L)

Abstract

Pre- and post emergence herbicides, were evaluated for weed control in lowland rice -(Oryza sativa L)) in field trials during 1998 and 1999 cropping seasons. Herbicides; were applied at high volume (416 1/ha) using a knapsack sprayer (CP 15), or at low volume (30 l/ha) using a controlled droplet application (c.da.) equipment. the Herbi-4 sprayer. The herbicides tested at varying dosage rates were saturnvalor. Ronstar and Basagran PL 2. In both seasons. Cyperus rotundus L (purple nutsedge) was the most dominant weep spp. A variety of broad leaf and grass weeds were also observed. All herbicides used stunted the growth of purple nutsedge but none was able to control the weed completely. Hand-weeding was most effective in reducing weed growth and resulted in the highest 2-season average yields in rice (2. Z t/ha). Rice yields  were reduced to their lowest levels averaging 1.1 1.1 t/ha where no weeding was done. All the herbicide treatments resulted in similar (p>0.05) but relativeiy lower yields  to handweeding in both years. These results suggest that the high volume formulations of Satumvalor and Basagran PL 2 and Ronstar can be succesfully used for weed control in rice using a c.d.a equipment.

Keywords: Herbicides; rice, spray volume, weed control

Tanzania J.Agric.Sc.(2002) Vol, 5 No. 2, 89-94