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Evaluation of Pethoxamid-Containing Weed Control Programs in Drill-seeded Rice (Oryza sativa L.)

  • John Godwin (a1), Jason K. Norsworthy (a2) and Robert C. Scott (a3)


Herbicide resistance to several of the most common weed species in US rice production, such as barnyardgrass and red rice, has made weed control extremely difficult with available herbicide options. No very-long-chain fatty acid–inhibiting herbicides are labeled for use in US rice; however, pethoxamid is one such herbicide under development for soil-applied use to control grasses and small-seeded broadleaves in rice and various row crops. Field trials were conducted in 2015 and 2016 near Stuttgart, AR, for rice tolerance and in 2016 near Colt, AR, and Lonoke, AR, for weed control with the use of pethoxamid-containing rice herbicide programs. Pethoxamid was applied alone and in a program at 420 and 560 g ai ha–1 with other herbicides labeled in rice including clomazone, quinclorac, propanil, imazethapyr, and carfentrazone POST. Injury less than 10% was seen for all treatments 2 wk after application in 2015 and 2016, except for pethoxamid at 420 g ha–1 to clomazone to one-leaf rice. Rice injury dissipated to less than 5% following all treatments by 4 wk after flood establishment. Barnyardgrass was controlled 95% or more near Colt and 93% or more near Lonoke for herbicide programs including clomazone PRE followed by pethoxamid plus quinclorac or imazethapyr at three- to four-leaf stage rice. Considering the minimal injury and high levels of barnyardgrass control associated with pethoxamid-containing weed control programs, pethoxamid provides a unique and effective site of action for use in US rice production.


Corresponding author

Author for correspondence: John Godwin, Department of Crop, Soil, and Environmental Sciences, 115 Plant Sciences Building, University of Arkansas, Fayetteville, AR 72701 (E-mail:


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Anonymous (2016) Pethoxamid. University of Hertfordshire Pesticide Properties Database. Accessed: November 4, 2016
Chauhan, BS (2012) Weed ecology and weed management strategies for dry-seeded rice in Asia. Weed Sci 26:113
Diggle, AJ, Neve, PB, Smith, FP (2003) Herbicides used in combination can reduce the probability of resistance in finite weed populations. Weed Res 43:371382
Doherty, RC, Barber, LT, Norsworthy, JK, Hill, ZT (2016) Residual weed control and crop response to pethoxamid systems in rice. Arkansas Agricultural Experiment Station Research Series 634:159162
Fuerst, EP (1987) Understanding the mode of action of the chloroacetamide and thiocarbamate herbicides. Weed Technol 1:270277
Godwin, JA, Norsworthy, JK, Scott, RC, Barber, LT, Young, ML, Duren, MW (2016) Evaluation of very long-chain fatty acid-inhibiting herbicides in Arkansas rice. Arkansas Agricultural Experiment Station Research Series 634:163168
Heap, I (2017) The international survey of herbicide resistant weeds. Accessed: May 3, 2017
Lingenfelter, D (2015) Introduction to weeds and herbicides. Penn State University Extension. Accessed: December 15, 2017
Miller, MR, Norsworthy, JK, Scott, RC, Barber, TL (2015) Identification, biology, and control of barnyardgrass in Arkansas rice. University of Arkansas Extension Service, FSA2175
Mutnal, SM, Kumar, P, Joshi, VR, Honnannavar, SY (1998) Effect of butachlor for weed control in sprouted direct seeded paddy field under rainfed conditions. Agric Sci 11:487489
Norman, R, Slaton, N, Roberts, T (2013) Soil fertility. Pages 69101 in Hardke JT, ed. Arkansas Rice Production Handbook. MP192. Little Rock, AR: University of Arkansas Division of Agriculture
Norsworthy, JK, Ward, SM, Shaw, DR, Llewellyn, RS, Nichols, RL, Webster, TM, Bradley, KW, Frisvold, G, Powles, SB, Burgos, NR, Witt, WW, Barrett, M (2012) Reducing the risks of herbicide resistance: best management practices and recommendations. Weed Sci 60 (Special Issue I):3162
Norsworthy, JK, Bond, J, Scott, RC (2013a) Weed management practices and needs in Arkansas and Mississippi rice. Weed Technol 27:623630
Norsworthy, JK, Scott, RC, Johnson, DB (2013b) A six-year summary of the herbicide-resistance weed screening program in rice at the University of Arkansas: 2006–2012. Arkansas Agricultural Experiment Station Research Series 609:153158
Powles, SB, Shaner, SL (2001) Resistance. Herbicide Resistance and World Grains. Boca Raton, FL: CRC Press. p 215216
Schlosser, HG, Hunt, B, Teicher, HB, inventors; Cheminova, AS, assignee (2016) Combination of pethoxamid and picloram. US patent 20160143281A1
Scott, RC, Barber, LT, Boyd, JW, Selden, G, Norsworthy, JK, Burgos, N (2016) Rice. Recommended chemicals for weed and brush control. MP44. Little Rock, AR: University of Arkansas Division of Agriculture. p 91106



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