Skip to main content

Glyphosate-Resistant Horseweed (Conyza canadensis) Growth, Seed Production, and Interference in Cotton

  • Lawrence E. Steckel (a1) and C. Owen Gwathmey (a1)

Field studies were conducted to examine both density and duration of glyphosate-resistant (GR) horseweed interference in cotton. Two studies, one examining the effect of horseweed density and a second the duration of horseweed interference, were conducted on a site with a natural population of horseweed that were treated with glyphosate at 0.84 kg ae ha−1 prior to planting and at the 2nd and 4th cotton node growth stages. GR horseweed density effect on cotton height, maturity, and lint yield was determined at horseweed densities of 0, 5, 10, 15, 20, and 25 plants m−2. Duration of horseweed interference was evaluated when 20 horseweed m−2 were allowed to interfere with cotton from emergence to 2nd node, 6th node, 10th node, 12th node, and 1st bloom stage of cotton. The maximum cotton lint yield loss (46%) occurred when horseweed was allowed to compete with cotton from emergence to maturity at the two highest densities (20 and 25 horseweed m−2). When the data were fit to the Cousens model the estimated a (maximum yield loss) and i (yield loss per unit density as density approaches zero) were 53 ± 7.3 and 2.8 ± 0.6 SE, respectively. In both years of the study, horseweed interference from emergence to the 2nd cotton node did not reduce cotton lint yields. In 2006, cotton lint yield loss was 28% compared to 39% in 2005 when horseweed interfered with cotton from emergence until the 6th cotton node. Cotton lint yield loss was 37 and 44% when horseweed competed to the 8th cotton node in 2005 and 2006, respectively. Maximum horseweed seed production was 134,000 to 148,000 seeds m−2.

Corresponding author
Corresponding author's E-mail:
Hide All
Anonymous 2005. Cotton Varieties Planted 2005 Crop. Memphis, TN: United States Department of Agriculture Cotton-Program. Accessed July 30, 2005.
Anonymous 2007. Tennessee Agricultural Statistics. Accessed: July 31, 2007.
Askew S. D. and Wilcut J. W. 2001. Tropic croton (Croton glandulosus) interference in cotton (Gossypium hirsutum). Weed Sci. 49:184189.
Askew S. D. and Wilcut J. W. 2002. Ladysthumb interference and seed production in cotton. Weed Sci. 50:326332.
Bensch C. N., Horak M. J., and Peterson D. 2003. Interference of redroot pigweed (Amaranthus retroflexus), Palmer amaranth (Amaranthus Palmeri) and common waterhemp (Amaranthus rudis) in soybean. Weed Sci. 51:3743.
Brown S. M. and Whitwell T. 1988. Influence of tillage on horseweed, Conyza canadensis. Weed Technol. 2:269270.
Bruce J. A. and Kells J. J. 1990. Horseweed (Conyza canadensis) control in no-tillage soybeans (Glycine max) with preplant and preemergence herbicides. Weed Technol. 4:642647.
Bryson C. T. 1987. Interference of hemp sesbania (Sesbania exaltata) with cotton (Gossypium hirsutum). Weed Sci. 35:314318.
Burke I. C., Troxler S. C., Askew S. D., Wilcut J. W., and Smith W. D. 2005. Weed management systems in glyphosate-resistant cotton. Weed Technol. 19:422429.
Carmer S. G., Nyquist W. E., and Walker W. M. 1989. Least significant differences for combined analysis of experiments with two or three-factor treatment designs. Agron. J. 81:665672.
Clewis S. B., Wilcut J. W., and Porterfield D. 2006. Weed management with S-metolachlor and glyphosate mixtures in glyphosate-resistant strip- and conventional-tillage cotton (Gossypium hirsutum L). Weed Technol. 20:232241.
Coffman C. B. and Frank J. R. 1991. Weed-crop responses to weed management systems in conservation tillage corn (Zea mays). Weed Sci. 45:256260.
Crowley R. H. and Buchanan G. A. 1978. Competition of four morningglory (Ipomoea spp.) species with cotton (Gossypium hirsutum). Weed Sci. 26:484488.
Culpepper A. S. and York A. C. 1999. Weed management and net returns with transgenic, herbicide-resistant, and nontransgenic cotton (Gossypium hirsutum). Weed Technol. 13:411420.
Gleason H. A. and Cronquist A. 1963. Manual of Vascular Plants. Boston PWS Publishers. 734.
Hall M. R., Swanton C. J., and Anderson G. W. 1992. The critical period of weed control in grain corn (Zea mays). Weed Sci. 40:441447.
Heap I. 2006. International Survey of Herbicide Resistant Weeds. Accessed: April 1, 2006.
Higgins J. M., Walker R. H., and Whitwell T. 1985. Coffee senna (Cassia occidentalis) competition with cotton (Gossypium hirsutum). Weed Sci. 34:5256.
Knezevic S. Z., Horak M. J., and Vanderlip R. L. 1997. Relative time of redroot pigweed (Amaranthus retroflexus L.) emergence is critical in pigweed-sorghum [Sorghum bicolor (L.) Moench] competition. Weed Sci. 45:502508.
Knezevic S. Z., Vanderlip R. L., and Horak M. J. 2001. Relative time of redroot pigweed emergence affects dry matter partitioning. Weed Sci. 49:617621.
Koger C. H., Poston D. H., Hayes R. M., and Montgomery R. F. 2004. Glyphosate-resistant (horseweed) Conyza canadensis in Mississippi. Weed Technol. 18:820825.
Main C. L., Mueller T. C., Hayes R. M., and Wilkerson J. B. 2004. Response of selected horseweed (Conyza canadensis (L.) Cronq.) populations to glyphosate. J. Agric. Food Chem. 52:879883.
Main C. L., Steckel L. E., Hayes R. M., and Mueller T. C. 2006. Biotic and abiotic factors influence horseweed emergence. Weed Sci. 54:11011105.
McIntosh M. S. 1983. Analysis of combined experiments. Agron. J. 75:153155.
Miller J. H. and Miller K. V. 1999. Forest Plants of the Southeast and their Wildlife Uses. Auburn, Alabama Craftmaster. 454.
Molin W. T., Boykin D., Hugie J. A., Ratnayaka H. H., and Sterling J. M. 2006. Spurred anoda (Anoda cristata) interference in wide row and ultra narrow row cotton. Weed Sci. 54:651657.
Rushing D. W., Murrary D. S., and Verhalen L. M. 1985a. Weed interference with cotton (Gossypium hirsutum). I Buffalobur (Solanum rostratum). Weed Sci. 33:810814.
Rushing D. W., Murrary D. S., and Verhalen L. M. 1985b. Weed interference with cotton (Gossypium hirsutum). II Tumble pigweed (Amaranthus albus). Weed Sci. 33:815818.
SAS Institute 2000. SAS User's Guide Version 8. Cary, NC SAS Institute.
Sauer J. and Struik G. 1964. A possible ecological relation between soil disturbance, light-flash, and seed germination. Ecology. 45:884886.
Scott G. H., Askew S. D., Wilcut J. W., and Brownie C. 2000. Datura stramonium interference and seed rain in Gossypium hirsutum. Weed Sci. 48:613617.
Snipes C. E., Buchanan G. A., Street J. E., and McGuire J. A. 1982. Competition of common cocklebur (Xanthium pensylvanicum) with cotton (Gossypium hirsutum). Weed Sci. 30:553556.
Steckel L. E. 2005. Horseweed. University of Tennessee FACT sheet. W106. Accessed: July 31, 2007.
Steckel L. E., Craig C. C., and Hayes R. M. 2006. Glyphosate-resistant horseweed (Conyza Canadensis) control with glufosinate prior to planting no-till cotton. Weed Technol. 20:10471051.
Steckel L. E., Mueller T. C., Thompson M. A., Rhodes N., Hayes R. M., Brown B., and Sims B. D. 2005. Weed control manual for Tennessee field crops, forage crops, farm ponds, and harvest aids. PB 1580. P. 6.
Steckel L. E. and Sprague C. L. 2004a. Late-season common waterhemp (Amaranthus rudis) interference in soybean (Glycine max). Weed Technol. 18:947952.
Steckel L. E. and Sprague C. L. 2004b. Common waterhemp (Amaranthus rudis) interference in corn (Zea mays). Weed Sci. 52:359364.
VanGessel M. M. 2001. Glyphosate-resistant horseweed from Delaware. Weed Sci. 49:703705.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Weed Science
  • ISSN: 0043-1745
  • EISSN: 1550-2759
  • URL: /core/journals/weed-science
Please enter your name
Please enter a valid email address
Who would you like to send this to? *



Full text views

Total number of HTML views: 0
Total number of PDF views: 6 *
Loading metrics...

Abstract views

Total abstract views: 81 *
Loading metrics...

* Views captured on Cambridge Core between 20th January 2017 - 19th January 2018. This data will be updated every 24 hours.