Weed Interference with Cotton (Gossypium Birsutum). II. Tumble Pigweed (Amaranthus Albus)

Abstract

Relationships between production of cotton (Gossypium birsutumL. ‘Westburn M’) and full-season interference from tumble pigweed (Amaranthus albusL. ♯ AMAAL) at densities ranging from 0 to 64 plants/10 m of row were measured in three replicated experiments in the field. Dry weight of harvested tumble pigweed increased by 0.149 to 0.402 kg/plot for each additional weed/10 m of row. Intraspecific competition among tumble pigweed plants was observed at the higher weed densities. Cotton plant height was reduced in all three experiments at the 32 or 64 weed densities, but harvesting difficulties were not encountered in these studies. The threshold density where initial lint yield reductions occurred ranged from 4 to 16 tumble pigweed plants/10 m of row in the three experiments. Lint yields were reduced from 8 to 11 kg/ha for each additional tumble pigweed plant/10 m of row. Interference from tumble pigweed did not significantly affect cotton fiber length, uniformity, strength, or micronaire of hand-harvested bolls.