COMPETITION EFFECTS OF WILD OAT AND ANNUAL POA IN FIRST YEAR PERENNIAL RYEGRASS SEED CROPS

M. P. Rolston and W. Archie

AgResearch, PO Box 60, Lincoln, New Zealand

Wild oat (Avena fatua) and annual poa (Poa annua) densities were manipulated with herbicide treatments in ryegrass (Lolium perenne) seed crops.  Ryegrass seed yields were very sensitive to competition from wild oats, with seed yields declining from 2620 kg/ha (nil wild oat) to 650 kg/ha in the untreated control.  Seed yield decline was more strongly associated with wild oat mass (r²=0.86), than to wild oat head density (r²=0.57). Annual poa reduced seed yields from 1160 kg/ha (nil annual poa) to 650 kg/ha in the untreated control.

Keywords: competition; seed yield; Avena fatua; Poa annua; Lolium perenne; herbicides; ethofumesate; fenoxaprop.