Using a Grower Survey to Assess the Benefits and Challenges of Glyphosate-Resistant Cropping Systems for Weed Management in U.S. Corn, Cotton, and Soybean

Abstract

Over 175 growers in each of six states (Illinois, Indiana, Iowa, Mississippi, Nebraska, and North Carolina) were surveyed by telephone to assess their perceptions of the benefits of utilizing the glyphosate-resistant (GR) crop trait in corn, cotton, and soybean. The survey was also used to determine the weed management challenges growers were facing after using this trait for a minimum of 4 yr. This survey allowed the development of baseline information on how weed management and crop production practices have changed since the introduction of the trait. It provided useful information on common weed management issues that should be addressed through applied research and extension efforts. The survey also allowed an assessment of the perceived levels of concern among growers about glyphosate resistance in weeds and whether they believed they had experienced glyphosate resistance on their farms. Across the six states surveyed, producers reported 38, 97, and 96% of their corn, cotton, and soybean hectarage planted in a GR cultivar. The most widely adopted GR cropping system was a GR soybean/non-GR crop rotation system; second most common was a GR soybean/GR corn crop rotation system. The non-GR crop component varied widely, with the most common crops being non-GR corn or rice. A large range in farm size for the respondents was observed, with North Carolina having the smallest farms in all three crops. A large majority of corn and soybean growers reported using some type of crop rotation system, whereas very few cotton growers rotated out of cotton. Overall, rotations were much more common in Midwestern states than in Southern states. This is important information as weed scientists assist growers in developing and using best management practices to minimize the development of glyphosate resistance.

Reduction in common milkweed (Asclepias syriaca) occurrence in Iowa cropland from 1999 to 2009

“…Although adoption of GR corn was much slower than that of soybean, approximately 35% of the US corn acres were planted with GR corn hybrids in 2006. Seventyl five percent of farmers reported planting continuous GR crops in a 2006 survey (Shaw et al, 2009). Due to the systemic characteristics of glyphosate, repeated use of glyphosate in GR crops could reduce infestations of perennial weeds such as common milkweed (Duke and Powles, 2008).…”

Integrated weed management systems with herbicide-tolerant crops in the European Union: lessons learnt from home and abroad

“…A survey across six states in the US has highlighted that crop rotation is likely to be adopted as a mitigation practice to address problems with GR weeds by growers in the Midwest US, although the response was not the same across the Southeast US. [31] Encouraging results are reported also from Australian grower surveys; these highlighted growers' awareness of HR weeds and associated cost, thereby promoting the adoption of integrated solutions for the mitigation of the risk related to the evolution of HR weeds. [112] However, these studies also highlighted that growers prefer alternative herbicides to non-chemical means to obtain the highest economic return on investment.…”

“…[26][27][28] This, in turn, may induce modifications of growers' weed management practices through intensification of herbicide use and use of herbicides with less benign environmental profiles, with consequent adverse environmental effects. [29][30][31][32] In regions where GR weeds exist, growers have exacerbated this phenomenon by increasing glyphosate rates and application frequency which further increases the selection pressure on weeds populations leading to more cases of evolved glyphosate resistance. [27,33,34] Diversification in crop systems and weed management tactics reduces the risk of weeds evolving herbicide resistance(s) and promotes biodiversity.…”

Weed management in cotton (Gossypium hirsutum L.) through weed-crop competition: A review

“…Many of the weeds have already developed glyphosate resistance wherever herbicides are used without diversity Shaw et al, 2009;Sosnoskie and Culpepper, 2014). Many A. palmeri populations have rapidly evolved resistance to glyphosate in North America (Culpepper, 2006;Norsworthy et al, 2007;Sosnoskie and Culpepper, 2014;Webster and Sosnoskie, 2010) and it is an issue that many weeds from Amaranthacea family are predominant weeds in the cotton producing zones (Table 1).…”