Skip to main content Accessibility help

Tolpyralate Efficacy: Part 1. Biologically Effective Dose of Tolpyralate for Control of Annual Grass and Broadleaf Weeds in Corn

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


Tolpyralate is a new 4-hydroxyphenyl-pyruvate dioxygenase (HPPD)-inhibiting herbicide for POST weed management in corn; however, there is limited information regarding its efficacy. Six field studies were conducted in Ontario, Canada, over 3 yr (2015 to 2017) to determine the biologically effective dose of tolpyralate for the control of eight annual weed species. Tolpyralate was applied POST at six doses from 3.75 to 120 g ai ha−1 and tank mixed at a 1:33.3 ratio with atrazine at six doses from 125 to 4,000 g ha−1. Regression analysis was performed to determine the effective dose (ED) of tolpyralate, and tolpyralate+atrazine, required to achieve 50%, 80%, or 90% control of eight weed species at 1, 2, 4, and 8 wk after application (WAA). The ED of tolpyralate for 90% control (ED90) of velvetleaf, common lambsquarters, common ragweed, redroot pigweed or Powell amaranth, and green foxtail at 8 WAA was ≤15.5 g ha−1; however, tolpyralate alone did not provide 90% control of wild mustard, barnyardgrass, or ladysthumb at 8 WAA at any dose evaluated in this study. In contrast, the ED90 for all species in this study with tolpyralate+atrazine was ≤13.1+436 g ha−1, indicating that tolpyralate+atrazine can be highly efficacious at low field doses.


Corresponding author

*Author for correspondence: Nader Soltani, Department of Plant Agriculture, University of Guelph Ridgetown Campus, Ridgetown, ON N0P 2C0, Canada. (Email:


Hide All
Abendroth, JA, Martin, AR, Roeth, FW (2006) Plant response to combinations of mesotrione and photosystem II inhibitors. Weed Technol 20:267274
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
Anonymous, (2016) Armezon® Herbicide label. Mississauga, ON, Canada: BASF Canada Inc.
Armel, GR, Hall, GJ, Wilson, HP, Cullen, N (2005) Mesotrione plus atrazine mixtures for control of Canada thistle (Cirsium arvense). Weed Sci 53:202211
Armel, GR, Rardon, PL, Mccomrick, MC, Ferry, NM (2007) Differential response of several carotenoid biosynthesis inhibitors in mixtures with atrazine. Weed Technol 21:947953
Bilyea, D (2016) Ontario Weed Survey. Ridgetown, ON, Canada: University of Guelph Ridgetown Campus
Duke, SO, Powles, SB (2009) Glyphosate-resistant crops and weeds: now and in the future. AgBioForum 12:346357
Gianessi, LP, Reigner NP (2007) The value of herbicides in U.S. crop production. Weed Technol 21:559566
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 225–232 in Modern Crop Protection Compounds. 2nd ed. Volume 1. Weinheim, Germany: Wiley-VCH
Health Canada (2017) Tolpyralate and Tolpyralate 400 SC Herbicide. Ottawa, ON, Canada: Pest Management Regulatory Agency Proposed Registration Decision 2017-13.
Health Canada (2018) Health Canada Consumer Product Safety database. Tolpyralate 400SC Herbicide Reg. No. 32901. Accessed: February 12, 2018
Hess, FD (2000) Light-dependent herbicides: an overview. Weed Sci 48:160170
Hugie, JA, Bollero, GA, Tranel, PJ, Riechers, DE (2008) Defining the rate requirements for synergism between mesotrione and atrazine in redroot pigweed (Amaranthus retroflexus). Weed Sci 56:265270
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
Kim, J, Jung, S, Hwang, IT, Cho, KY (1999) Characteristics of chlorophyll a fluorescence induction in cucumber cotyledons treated with diuron, norflurazon, and sulcotrionem. Pestic Biochem Physiol 65:7381
Kohrt, JR, Sprague, CL (2017). Response of a multiple-resistant Palmer amaranth (Amaranthus palmeri) population to four HPPD-inhibiting herbicides applied alone and with atrazine. Weed Sci 65:534545
Matsumoto, H, Mizutani, M, Yamaguchi, T, Kadotani, J (2002) Herbicide pyrazolate causes cessation of carotenoids synthesis in early watergrass by inhibiting 4-hydroxyphenylpyruvate dioxygenase. Weed Biol Manage 2:3945
Metzger, BA, Soltani, N, Raeder, AJ, Hooker, DC, Robinson, DE, Sikkema, PH (2018) Tolpyralate efficacy: Part 2. Comparison of three group 27 herbicides applied POST for annual grass and broadleaf weed control in corn. Weed Technol (in press)
Page, ER, Tollenaar, M, Lee, EA, Lukens, L, Swanton, CJ (2009) Does the shade avoidance response contribute to the critical period for weed control in maize (Zea mays)? Weed Res 49:563571
Pannacci, E, Covarelli, G (2009) Efficacy of mesotrione used at reduced doses for post-emergence weed control in maize (Zea mays L.). Crop Prot 28:5761
Schulz, A, Ort, O, Beyer, P, Kleinig, H (1993) SC-0051, a 2-benzoyl-cyclohexane-1,3-dione bleaching herbicide, is a potent inhibitor of the enzyme p-hydroxyphenylpyruvate dioxygenase. FEBS Lett 318:162166
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
US Environmental Protection Agency (2018) Office of Pesticide Programs. Tolpyralate Substance Information.,3,31,7,12,25:P3_XCHEMICAL_ID:29470. Accessed: September 20, 2018
Weaver, S (2009) Pigweeds (Redroot, Green and Smooth). OMAFRA Factsheet Order No. 01-009. Accessed: February 10, 2018
Woodyard, AJ, Bollero, GA, Riechers, DE (2009) Broadleaf weed management in corn utilizing synergistic postemergence herbicide combinations. Weed Technol 23:513518



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