Giant Ragweed (Ambrosia trifida) Competition in Cotton

Abstract

Glyphosate-resistant (GR) weeds, including giant ragweed, are among the most challenging weeds for growers to control in cotton. A field study was conducted in 2011 and 2012 to determine the competitiveness of giant ragweed with densities of 0, 0.1, 0.2, 0.4, 0.8, or 1.6 plants m−1of row. Early in the growing season, giant ragweed competition with densities of at least 0.8 plants m−1row reduced cotton height compared with the weed-free control. Based on node above white flower (NAWF) and node above cracked boll (NACB) data, a delay in cotton maturity was observed for treatments with giant ragweed present at a density of 1.6 m−1of cotton row for NAWF and 0.8 m−1or 1.6 m−1of row for NACB. Lint yield losses of 50% were estimated for cotton with rows growing along side of giant ragweed at a density of 0.26 plants m−1row. Cotton in rows located 140 cm away from giant ragweed required an estimated 1.85 plants m−1row to reduce yield by 50%. These data suggest that giant ragweed sphere of influence was at least 1 m wide. Cotton fiber quality was not affected by giant ragweed at any density. Giant ragweed is a highly competitive weed in cotton, even at low densities, and efforts should be implemented to control giant ragweed early in the season to prevent cotton yield loss.

A mosaic of phenotypic variation in giant ragweed (Ambrosia trifida): Local‐ and continental‐scale patterns in a range‐expanding agricultural weed

“…In its native habitats, giant ragweed generally occurs in early-successional and disturbed sites with moist soils (Bassett & Crompton, 1982), although it also occurs in drier upland sites (Regnier et al, 2016). Giant ragweed is also a problematic agricultural weed that causes substantial crop losses when not controlled early in the season (Barnett & Steckel, 2013;Ganie et al, 2017;Harrison, Regnier, Schmoll, & Webb, 2001;Webster, Loux, Regnier, & Harrison, 1994) and that has been found to have multiple instances of herbicide resistance (Heap, 2018). It has been a management concern for farmers in the Eastern Corn Belt for at least the past 30 years, but more recently it has been undergoing range expansion in both agricultural and successional habitats farther west and north into the Great Plains where the climate is drier and cooler and where historical agricultural practices differ (Regnier et al, 2016).…”

Global Meta‐Analysis of Cotton Yield and Weed Suppression from Cover Crops

“…Weeds reduce overall yields in many crops, including cotton (Wood et al, 2002;Barnett and Steckel, 2013;Ma et al, 2015). Effect sizes for individual studies were <0.95 for 101 (58%) studies, between 0.95 and 1.05 for 43 (25%) studies (negligible cover crop effect), and >1.05 for 30 (17%) studies.…”

Weed Problems, Ecology, and Management Options in Conservation Agriculture: Issues and Perspectives

“…Although, horseweed is reported to be easy to control with tillage (Kapusta, 1979;Brown and Whitwell, 1988), difficulty with postemergence soybean herbicides have been reported worldwide (Bruce and Kells, 1990;Moseley and Hagood, 1990;Vangessel et al, 2001) and the increased reliance on glyphosate under NT farming has increased the potential for the evolution of GR weeds (Davis et al, 2009b), like Giant ragweed (A. trifida) in cotton (Barnett and Steckel, 2013). Occurrence of resistant weeds in the Ebro valley maize fields has been significant (Peña-Asin et al, 2013).…”

“…GR crops are currently grown on approximately 70 million ha worldwide . With the development of HR crops, particularly GR crops, herbicides such as glyphosate minimized the need for tillage as a weed control tactic; the resulting crop production systems have been primary enablers for the success of USDA Natural resource soil conservation programs and the introduction of HR crops like cotton, soybean, and corn have provided post emergence options for difficult to control weeds such as giant ragweed (Barnett and Steckel, 2013). Herbicide-tolerant weed beet population could be difficult to manage irrespective of the crop rotation (Sester et al, 2007).…”