Effect of narrow row-spacing and weed crop competition duration on cotton productivity

Amongst all biotic factors, weeds pose the most serious threat to successful cotton production. Adoption of conservation agriculture, the evolution of herbicide-resistant weed populations, and the absence of any new herbicide chemistry are allowing weeds to become more destructive and uncontrollable. It is important now to investigate cultural practices (non-chemical) to reduce the pressure on herbicides. Trials were conducted at the Gatton Research Farm of University of Queensland during 2015/16 and 2016/17 to assess the implications of narrow row-spacing (50 cm) in managing weeds in glyphosate-tolerant cotton at different weed-infestation intervals [0, 21, 42, 63, 84 and 154 days after planting (DAP)]. Results revealed that narrow (50 cm) row-spacing (at the same density of planting) was not only beneficial in suppressing weed growth (55% lower) and achieving greater lint yield (26% more) but also made the cotton plants more competitive in the early weed-crop interference compared with wide (100 cm) row-spacing. Consequently, the weed-crop competition period (CWIP) was shorter (42 days after emergence) in narrow row-spaced cotton when compared with wide row-spaced cotton (154 days after emergence). The use of this technology will reduce the reliance on herbicides, which in turn will decrease the development of future herbicide-resistant weed populations.