Skip to main content Accessibility help

Imidazolinone-Resistant Soft Red Winter Wheat Weed Control and Crop Response to ALS-Inhibiting Herbicides

  • Timothy L. Grey (a1), George S. Cutts (a2) and Jerry Johnson (a3)


Inability to control Italian ryegrass in soft red winter wheat can result in reduced yields, reduced quality, or both and cause double-crop planting to be inefficient. Experiments were conducted at Plains, GA, to evaluate diclofop-susceptible Italian ryegrass control in a single-gene imidazolinone (IMI)-resistant wheat using imazamox, mesosulfuron, and diclofop. Treatments were applied at variable rates and tank mixtures to the IMI-resistant soft red winter wheat ‘AGS CL7’ at Feekes' stages 1 (EMERG) or 2 (POST). Lower Italian ryegrass control of 78% or less was observed with single treatments of EMERG or POST herbicide applications. Diclofop provided maximum Italian ryegrass control of 79% or greater with minimal injury to wheat cultivar AGS CL 7. Sequential applications of diclofop at EMERG followed by imazamox, mesosulfuron, or diclofop POST provided maximum Italian ryegrass control at 86% or greater. The efficacy of the acetolactate synthase (ALS)–inhibiting herbicides registered for wheat weed control for AGS CL7 and ‘AGS 2000’ (conventional) was also evaluated. Mesosulfuron at 40 g ai ha−1 resulted in 17% injury at 7 d after application (DAA), tribenuron at 40 g ai ha−1 caused 9% injury 7 DAA, and pyroxsulam at 190 g ai ha−1 caused 7% injury at 7 DAA, but was transient and not observed after heading or at harvest. No yield differences were noted between the nontreated control for AGS 2000 and AGS CL 7 for chlorsulfuron, mesosulfuron, thifensulfuron, tribenuron, prosulfuron, and pyroxsulam.

La inhabilidad para controlar Lolium perenne en el trigo rojo suave de invierno puede resultar en reducción de rendimientos y/o calidad y causar que la doble siembra de este cereal sea ineficiente. Se realizaron experimentos en Plains, Georgia para evaluar el control de L. perenne susceptible a diclofop en trigo con un solo gen de resistencia a imidazolinone (IMI), usando imazamox, mesosulfuron y diclofop. Los tratamientos se aplicaron a dosis y mezclas variables a la variedad de trigo AGS CL7 resistente a IMI en las etapas Feekes 1 (EMERG) o 2 (POST). Un control bajo de L. perenne de 78% o menos, fue observado con tratamientos de una aplicación de herbicida en EMERG o POST. Diclofop proporcionó el mayor control de L. perenne de 79% o más, con daño mínimo al cultivar de trigo AGS CL 7. Las aplicaciones secuenciales de diclofop en EMERG seguidas de imazamox, mesosulfuron, o diclofop POST proporcionaron el máximo control de L. perenne, 86% o mayor. La eficacia de los herbicidas inhibidores acetolactate synthase (ALS) registrada para el control de malezas en trigo para los cultivares AGS CL7 y AGS 2000 (convencional) también fue evaluada. Mesosulfuron a 40 g ia ha−1 resultó en 17% de daño a los 7 días después de la aplicación (DAA); tribenuron a 40 g ia ha−1 causó 9% de daño a los 7 DAA; pyroxsulam a 190 g ia ha−1 causó 7% de daño a los 7 DAA, pero éste fue transitorio y no fue observado después de la floración o en la cosecha. No se notaron diferencias en el rendimiento entre los testigos no tratados para AGS 2000 y AGS CL 7 y los tratamientos con chlorsulfuron, mesosulfuron, thifensulfuron, tribenuron, prosulfuron y pyroxsulam.


Corresponding author

Corresponding author's E-mail:


Hide All
Bailey, W. A., Wilson, H. P., Brann, D. E., and Griffey, C. A. 2004. Wheat cultivar tolerance to AE F130060 03. Weed Technol. 18:881886.
Bayer Corp. 2007. Cereal herbicide: Osprey® herbicide. Accessed: February 19, 2010.
Betts, K. J., Ehlke, N. J., Wyse, D. L., Gronwald, J. W., and Somers, D. A. 1992. Mechanism of inheritance of diclofop resistance in Italian ryegrass (Lolium multiflorum). Weed Sci. 40:184189.
Bravin, F., Zanin, G., and Preston, C. 2001. Diclofop-methyl resistance in populations of Lolium spp. from central Italy. Weed Res. 41:4958.
Brown, H. M. 1990. Mode of action, crop selectivity, and soil relations of the sulfonylurea herbicides. Pestic. Sci. 29:263281.
Crooks, H. L. and York, A. C. 2002. Italian Ryegrass Control with Mesosulfuron-Methyl. Accessed: February 19, 2010.
Crooks, H. L., York, A. C., and Jordan, D. L. 2003. Wheat (Triticum aestivum) tolerance and Italian ryegrass (Lolium multiflorum) control by AE F130060 00 plus AE F115008 00 mixed with other herbicides. Weed Technol. 17:881889.
Culpepper, A. S. 2007. Small Grain Weed Control. Georgia Pest Control Handbook. Athens, GA Cooperative Extension Service, University of Georgia College of Agricultural and Environmental Sciences. Accessed: February 19, 2010.
Culpepper, A. S. and York, A. C. 1997. Weed management in no-tillage bromoxynil-tolerant cotton (Gossypium hirsutum). Weed Technol. 11:335345.
De Prado, J. L., Shimabukuro, R. H., and De Prado, R. 1999. The effect of diclofop on membrance potential, ethylene induction and herbicide phytotoxicity in resistant and susceptible biotypes of grasses. Pestic. Biochem. Physiol. 63:114.
De Prado, R., Menendez, J., Gasquez, J., Gronwald, J. W., and Gimnez-Ezpinosa, R. 2000. Resistance to acetyl CoA carboxylase-inhibiting herbicides in Lolium multiflorum . Weed Sci. 48:311318.
Deeds, Z. A., Al-Khatib, K., Peterson, D. E., and Stahlman, P. W. 2006. Wheat response to simulated drift of glyphosate and imazamox applied at two growth stages. Weed Technol. 20:2331.
Eberlein, C. V., Guttieri, M. J., Berger, P. H., Fellman, J. K., Mallory-Smith, C. A., Thill, D. C., Baerg, R. J., and Belknap, W. R. 1999. Physiological consequences of mutation of ALS-inhibitor resistance. Weed Sci. 47:383392.
Ellis, A. T., Morgan, G. D., and Mueller, T. C. 2008. Mesosulfuron-resistant Italian ryegrass biotype from Texas. Weed Technol. 22:431434.
Frihauf, J. C., Miller, S. D., and Alford, C. M. 2005. Imazamox rates, timings, and adjuvants affect imidazolinone-tolerant winter wheat cultivars. Weed Technol. 19:599607.
Grey, T. L. and Bridges, D. C. 2003. Alternatives to diclofop for the control of Italian ryegrass (Lolium multiflorum) in winter wheat (Triticum aestivum). Weed Technol. 17:219223.
Hanson, B. D., Fandrich, L., Shaner, D. L., Westra, P., and Nissen, S. J. 2007. Recovery of imidazolinone-resistant hard red wheat lines following imazamox application. Crop Sci. 47:20582066.
Hanson, B. D., Shaner, D. L., Westra, P., and Nissen, S. J. 2006. Response of selected hard red wheat lines to imazamox as affected by number and location of resistance genes, parental background, and growth habit. Crop Sci. 46:12061211.
Heap, I. 2003. The International Survey of Herbicide Resistant Weeds. Accessed: March 1, 2010.
Johnson, J. J. 2010. Plant Variety Protection Certificates: ‘AGS CL7’ Wheat (PI 657987, PVP 200900285). FY10 Issued Intellectual Property. Accessed: June 28, 2011.
Johnson, J. J., Barnett, R. D., Cunfer, B. M., Buntin, G. D., and Bland, D. E. 2002. Registration of ‘AGS 2000’ wheat. Crop Sci. 42:661.
Justice, G. G., Peeper, T. F., Solie, J. B., and Epplin, F. M. 1994. Net returns from Italian ryegrass (Lolium multiflorum) control in winter wheat (Triticum aestivum). Weed Technol. 8:317323.
Kuk, Y. I. and Burgos, N. R. 2007. Cross-resistance profile of mesosulfuron-methyle-resistant Italian ryegrass in the southern United States. Pest Manag. Sci. 63:349357.
Kuk, Y. I., Burgos, N. R., and Talbert, R. E. 2000. Cross- and multiple resistance of diclofop resistant Lolium spp. Weed Sci. 48:412419.
Liebl, R. A. and Worsham, A. D. 1987. Effect of chlorsulfuron on diclofop-methyl phytotoxicity to Italian ryegrass (Loliumm multiflorum). Weed Sci. 35:383387.
MacCrae, A., Culpepper, A. S., and Grey, T. L. 2007. Oat (Avena sativa) and rye (Secale cereale) tolerance to mesosulfuron and tribenuron. Weed Technol. 21:938940.
Newhouse, K. E., Smith, W. A., Starrett, M. A., Schaefer, T. J., and Singh, B. K. 1992. Tolerance to imidazolinone herbicides in wheat. Plant Physiol. 100:882886.
Pozniak, C. J., Bark, I. T., O'Donoughue, L. S., Menard, C., Hucl, P. J., and Singh, B. K. 2004a. Physiological and molecular characterization of mutation-derived imidazolinone resistance in spring wheat. Crop Sci. 44:14341443.
Pozniak, C. J., Holm, F. A., and Hucl, P. J. 2004b. Field performance of imazamox-resistant sping wheat. Can. J. Plant Sci. 54:12051211.
Robinson, E. L. and Banks, P. A. 1983. The Effectiveness of Diclofop for Control of Italian Ryegrass (Lolium multiflorum) in Winter Wheat (Triticum aestivum). Research Report 428. Athens, GA The University of Georgia College of Agricultural and Environmental Sciences.
SAS Institute. 2001. The SAS System for Windows. Cary, NC SAS Institute.
Shaw, D. R. and Wesley, M. T. 1991. Wheat (Triticum aestivum) cultivar tolerance and Italian ryegrass (Lolium multiflorum) control with diclofop, BAY SMY 1500, and metribuzin. Weed Technol. 5:776781.
Stranger, C. E. and Appleby, A. P. 1989. Italian ryegrass (Lolium multiflorum) accessions tolerant to diclofop. Weed Sci. 37:350352.
Webster, T. M. 2008. Weed survey—southern states 2008. Proc. South. Weed Sci. Soc. 61:224243.
Webster, T. M. and Macdonald, G. E. 2001. A survey of weeds in various crops in Georgia. Weed Technol. 15:771790.
Wilson, H. P. and Hines, T. E. 1997. Weed Science Research Report. Painter, VA Virginia Tech. Research Rep. 197.
Yu, Q., Han, H., and Powles, S. B. 2008. Mutations of the ALS gene endowing resistance to ALS-inhibiting herbicides in Lolium ridigum populations. Pest Manag. Sci. 64:12291236.



Full text views

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

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed