Farmer experience with weed resistance to herbicides in cotton production

A mail survey of 2,500 potential cotton farmers in 13 southern cotton-producing states was conducted in 2012 to assess the temporal and geographic extent of weed resistance to herbicides in cotton production, appraise changes in production practices after the emergence of herbicide-resistant weeds, evaluate the effectiveness of those changes in managing resistant weeds, and ascertain the influence of herbicide-resistant weeds on cotton weed-control costs. Over two-thirds of the farmers surveyed reported herbicide-resistant weeds on their farms. Pigweed and horseweed were the dominant resistant weed problems, accounting for 61% and 25% of the responses, respectively. Newly observed infestations of pigweed and horseweed peaked in 2008-2009 and have declined thereafter. Farmers relied extensively on labor-intensive and mechanical/ chemical practices to control resistant weeds. The proportion of farmers in the sample who indicated they had total weed control costs of $50 or more per acre nearly doubled with the emergence of herbicide-resistant weeds on their farm.