Chemical, mechanical and integrated weed management under two phosphorous fertilizer application methods in rapeseed

A two-year field experiment was conducted in 2011 and 2012 at the College of Agriculture and Natural Resources, Shiraz University, Iran to determine the effect of the herbicide trifluralin, mechanical and integrated weed control under different application methods of P fertilizer (midrow banded and surface broadcast) on weed biomass and yield of rapeseed, cultivar Talayeh. Plants grown in unweeded plots at midrow banded and surface broadcast P fertilization methods produced the greatest rapeseed yield (3217 and 1034kgha(-1), respectively). The increasing effect of P fertilizer on rapeseed yield was less consistent when rapeseed was competing with weeds. It showed that weeds were able to prevent rapeseed from capturing the full benefit of P fertilizer. Trifluralin at 1400gha(-1)+rotary cultivator+sweep cultivator consistently provided the highest rapeseed grain (2953.5 and 2912kgha(-)(1), respectively) and oil yield (1363 and 1320kgha(-)(1), respectively). Additionally, trifluralin alone did not provide acceptable full season weed control in rapeseed. Since mechanical weed control implements such as rotary and sweep cultivators are available and inexpensive to Iranian farmers, trifluralin at 1400gha(-)(1)+rotary cultivator+sweep cultivator is recommended to improve weed control in rapeseed.