Skip to main content Accessibility help

Influence of application timing and herbicide rate on the efficacy of tolpyralate plus atrazine

  • Brendan A. Metzger (a1), Nader Soltani (a2), Alan J. Raeder (a3), David C. Hooker (a4), Darren E. Robinson (a5) and Peter H. Sikkema (a6)...


Effective POST herbicides and herbicide mixtures are key components of integrated weed management in corn; however, herbicides vary in their efficacy based on application timing. Six field experiments were conducted over 2 yr (2017–2018) in southwestern Ontario, Canada, to determine the effects of herbicide application timing and rate on the efficacy of tolpyralate, a new 4-hydroxyphenyl pyruvate dioxygenase inhibitor. Tolpyralate at 15, 30, or 40 g ai ha−1 in combination with atrazine at 500 or 1,000 g ai ha−1 was applied PRE, early POST, mid-POST, or late POST. Tolpyralate + atrazine at rates ≥30 + 1,000 g ha−1 provided equivalent control of common lambsquarters and Powell amaranth applied PRE or POST, whereas no rate applied PRE controlled common ragweed, velvetleaf, barnyardgrass, or green foxtail. Common ragweed, common lambsquarters, velvetleaf, and Powell amaranth were controlled equally regardless of POST timing. In contrast, control of barnyardgrass and green foxtail declined when herbicide application was delayed to the late-POST timing, irrespective of herbicide rate. Similarly, corn grain yield declined within each tolpyralate + atrazine rate when herbicide applications were delayed to late-POST timing. Overall, the results of this study indicate that several monocot and dicot weed species can be controlled with tolpyralate + atrazine with an early to mid-POST herbicide application timing, before weeds reach 30 cm in height, and Powell amaranth and common lambsquarters can also be controlled PRE. Additionally, this study provides further evidence highlighting the importance of effective, early-season weed control in corn.


Corresponding author

Author for correspondence: Nader Soltani, Email:


Hide All
Ahrens, H, Lange, G, Mueller, T, Rosinger, C, Willms, L, Almsick, AV (2013) 4-Hydroxyphenylpyruvate dioxygenase inhibitors in combination with safeners: solutions for modern and sustainable agriculture. Angew Chem Int Ed 44:93889398
Blackshaw, RE (1989) HOE-39866 use in chemical fallow systems. Weed Technol 3:420428
Bollman, SL, Kells, JJ, Penner, D (2006) Weed response to mesotrione and atrazine applied alone and in combination preemergence. Weed Technol 20:903907
Bowley, SR (2015) Variance analyses––Gaussian. Page 57 in Bowley, SR, ed., A Hitchhiker’s Guide to Statistics in Biology––Generalized Linear Mixed Model Edition. Kincardine, ON: Plants et al.
Coetzer, E, Al-Khatib, K, Peterson, DE (2002) Glufosinate efficacy on Amaranthus species in glufosinate-resistant soybean (Glycine max). Weed Technol 16:326331
Corbett, JL, Askew, SD, Thomas, WE, Wilcut, JW (2004) Weed efficacy evaluations for bromoxynil, glufosinate, glyphosate, pyrithiobac, and sulfosate. Weed Technol 18:443453
Diebold, RS, McNaughton, KE, Lee, EA, Tardif, FJ (2003) Multiple resistance to imazethapyr and atrazine in Powell amaranth (Amaranthus powellii). Weed Sci 51:312318
Gower, SA, Loux, MM, Cardina, J, Harrison, SK (2002) Effect of planting date, residual herbicide, and postemergence application timing on weed control and grain yield in glyphosate-tolerant corn (Zea mays). Weed Technol 16:488494
Green, J (2012) The benefits of herbicide resistant crops. Pest Manag Sci 68:13231331
Hall, MR, Swanton, CJ, Anderson, GW (1992) The critical period of weed control in grain corn (Zea mays). Weed Sci 40:441447
Hawkes, T (2012) Herbicides with bleaching properties. Hydroxyphenylpyruvate dioxygenase (HPPD): the herbicide target. Pages 225232 in Krämer, W, Schirmer, U, Jeschke, P, Witschel, M, eds., Modern Crop Protection Compounds. 2nd edn, Volumes 1–3. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co.
Janak, TW, Grichar, WJ (2016) Weed control in corn (Zea mays L.) as influenced by preemergence herbicides. Int J Agron 2016:19
Johnson, DB, Norsworthy, JK (2014) Johnsongrass (Sorghum halepense) management as influenced by herbicide selection and application timing. Weed Technol 28:142150
Kegode, GO, Fronning, BE (2005) Artemisa biennis (biennial wormwood) control is influenced by plant size and weed flora at time of herbicide application. Crop Prot 24:915920
Kikugawa, H, Satake, Y, Tonks, DJ, Grove, M, Nagayama, S, Tsukamoto, M (2015) Tolpyralate: new post-emergence herbicide for weed control in corn. Abstract 275 in Proceedings of the 55th Annual Meeting of the Weed Science Society of America. Lexington, KY: Weed Science Society of America
King, CA, Oliver, LR (1992) Application rate and timing of acifluorfen, bentazon, chlorimuron and imazaquin. Weed Technol 6:526534
Knezevic, SZ, Evans, SP, Blankenship, EE, Van Acker, RC, Lindquist, JL (2002) Critical period for weed control: the concept and data analysis. Weed Sci 50:773786
Kropff, MJ, Spitters, CJT (1991) A simple model of crop loss by weed competition from early observations on relative leaf area of the weed. Weed Res 31:97105
Lee, SD, Oliver, LR (1982) Efficacy of acifluorfen on broadleaf weeds. Times and methods for application. Weed Sci 30:520526
Metzger, BA, Soltani, N, Raeder, AJ, Hooker, DC, Robinson, DE, Sikkema, PH (2018a) Tolpyralate efficacy: Part 1. Biologically effective dose of tolpyralate for control of annual grass and broadleaf weeds in corn. Weed Technol 32:698706
Metzger, BA, Soltani, N, Raeder, AJ, Hooker, DC, Robinson, DE, Sikkema, PH (2018b) Tolpyralate efficacy: Part 2. Comparison of three group 27 herbicides applied POST for annual grass and broadleaf weed control in corn. Weed Technol 32:707713
Mitich, LW (1991) Intriguing world of weeds: velvetleaf. Weed Technol 5:253255
Norsworthy, JK, Oliveira, MJ (2004) Comparison of the critical period for weed control in wide- and narrow-row corn. Weed Sci 52:802807
Obrigawitch, TT, Kenyon, WH, Kuratle, H (1990) Effect of application timing on rhizome johnsongrass (Sorghum halepense) control with DPX-V9360. Weed Sci 38:4549
Ontario Ministry of Agriculture, Food and Rural Affairs [OMAFRA] (2018) Publication 75A. Guide to Weed Control. Field Crops. (Cowbrough, M, ed.) Guelph, ON: OMAFRA
Page, ER, Cerrudo, D, Westra, P, Loux, M, Smith, K, Foresman, C, Wright, H, Swanton, CJ (2012) Why early season weed control is important in maize. Weed Sci 60:423430
Rajcan, I, Swanton, CJ (2001) Understanding maize-weed competition: resource competition, light quality and the whole plant. Field Crop Res 71:139150
Rojano-Delgado, AM, Menendez, J, De, P rado, R (2014) Absorption and penetration of herbicides viewed in metabolism studies: case of glufosinate and imazamox in wheat. Pages 159165 in Myung, K, Satchivi, NM, Kingston, CK, eds., Retention, Uptake and Translocation of Agrochemicals in Plants. Volume 1171. Washington, DC: American Chemical Society
Schabenburger, O (2007) Growing up fast: SAS® 9.2 enhancements to the GLIMMIX procedure. SAS Global Forum paper 177. Cary, NC: SAS Institute Inc.
Sellers, BA, Ferrell, JA, MacDonald, GE, Kline, WN (2009) Dogfennel (Eupatorium capillifolium) size at application affects herbicide efficacy. Weed Technol 23:247250
Soltani, N, Nurse, RE, Sikkema, PH (2016) Biologically effective dose of glyphosate as influenced by weed size in corn. Can J Plant Sci 96(3):455460
Sprague, C, Powell, G (2014) Evaluation of tolpyralate (SL-573) for weed control in corn. MSU Weed Science Research Program. Online. Accessed: December 11, 2018
Steckel, GJ, Wax, LM, Simmons, W, Phillips, WH II (1997) Glufosinate efficacy on annual weeds is influenced by rate and growth stage. Weed Technol 11:484488
Stoller, EW, Wax, LM, Matthiesen, RL (1975) Response of yellow nutsedge and soybeans to bentazon, glyphosate and perfluidone. Weed Sci 23:215221
Swanton, CJ, Weise, SF (1991) Integrated weed management: the rationale and approach. Weed Technol 5:657663
Swanton, CJ, Gulden, RH, Chandler, K (2007) A rationale for atrazine stewardship in corn. Weed Sci 55:7581
Tonks, D, Grove, M, Kikugawa, H, Parks, M, Nagayama, S, Tsukamoto, M (2015) Tolpyralate: an overview of performance for weed control in US corn. Abstract 276 in Proceedings of the 55th Annual Meeting of the Weed Science Society of America. Lexington, KY: Weed Science Society of America
Tursun, N, Datta, A, Sakinmaz, MS, Kantarci, Z, Knezevic, SZ, Chauhan, BS (2016) The critical period for weed control in three corn (Zea mays L.) types. Crop Prot 90:5965
Weaver, SE, Tan, CS (1983) Critical period of weed interference in transplanted tomatoes (Lycopersicon esculentum): growth analysis. Weed Sci 31:476481
Zimdahl, RL (2004) The effect of competition duration. Pages 109130 in Zimdahl, RL, ed., Weed–Crop Competition––A Review. 2nd edn. Ames, IA: Blackwell Publishing



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