Skip to main content Accessibility help

Critical time for weed removal in glyphosate-resistant soybean as influenced by preemergence herbicides

  • Stevan Z. Knezevic (a1), Pavle Pavlovic (a2), O. Adewale Osipitan (a3), Ethann R. Barnes (a4), Clint Beiermann (a4), Maxwel C. Oliveira (a5), Nevin Lawrence (a6), Jon E. Scott (a7) and Amit Jhala (a8)...


Widespread and repeated use of glyphosate resulted in an increase in glyphosate-resistant (GR) weeds. This led to an urgent need for diversification of weed control programs and use of PRE herbicides with alternative sites of action. Field experiments were conducted over a 4-yr period (2015 to 2018) across three locations in Nebraska to evaluate the effects of PRE-applied herbicides on critical time for weed removal (CTWR) in GR soybean. The studies were laid out in a split-plot arrangement with herbicide regime as the main plot and weed removal timing as the subplot. The herbicide regimes used were either no PRE or premix of either sulfentrazone plus imazethapyr (350 + 70 g ai ha−1) or saflufenacil plus imazethapyr plus pyroxasulfone (26 + 70 + 120 g ai ha−1). The weed removal timings were at V1, V3, V6, R2, and R5 soybean stages, with weed-free and weedy season-long checks. Weeds were removed by application of glyphosate (1,400 g ae ha−1) or by hoeing. The results across all years and locations suggested that the use of PRE herbicides delayed CTWR in soybean. In particular, the CTWR without PRE herbicides was determined to be around the V1 to V2 (14 to 21 d after emergence [DAE]) growth stage, depending on the location and weed pressure. The use of PRE-applied herbicides delayed CTWR from about the V4 (28 DAE) stage up to the R5 (66 DAE) stage. These results suggest that the use of PRE herbicides in GR soybean could delay the need for POST application of glyphosate by 2 to 5 wk, thereby reducing the need for multiple applications of glyphosate during the growing season. Additionally, the use of PRE herbicides could provide additional modes of action needed to manage GR weeds in GR soybean.


Corresponding author

Author for correspondence: Stevan Z. Knezevic, Northeast Research and Extension Center, University of Nebraska–Lincoln, Lincoln, NE 68588. Email:


Hide All
Adigun, J, Osipitan, AO, Lagoke, ST, Adeyemi, RO, Afolami, SO (2014) Growth and yield performance of cowpea (Vigna unguiculata (L.) Walp) as influenced by row-spacing and period of weed interference in south-west Nigeria. J Agric Sci 6:188198
Beckie, HJ, Harker, KN (2017) Our top 10 herbicide-resistant weed management practices. Pest Manag Sci 73:10451052
Buhler, DD, Liebman, M, Obrycki, JJ (2000) Theoretical and practical challenges to an IPM approach to weed management. Weed Sci 48:274280
Eaton, BJ, Russ, OG, Feltner, KC (1976). Competition of velvetleaf, prickly sida, and Venice mallow in soybeans. Weed Sci 24:224228
Elezovic, I, Datta, A, Vrbnicanin, S, Glamoclija, D, Simic, M, Malidza, G, Knezevic, SZ (2012) Yield and yield components of imidazolinone-resistant sunflower (Helianthus annuus L.) are influenced by pre-emergence herbicide and time of post-emergence weed removal. Field Crops Res 128:137146
Evans, SP, Knezevic, SZ, Lindquist, JL, Shapiro, CA, Blankenship, EE (2003) Nitrogen application influences the critical period for weed control in corn. Weed Sci 51:408417
Gilmore, EC, Rogers, RS (1958) Heat units as a method of measuring maturity in corn. Agron J 50:611615
Gustafson, TC, Knezevic, SZ, Hunt, TE, Lindquist, JL (2006) Early-season insect defoliation influences the critical time for weed removal in soybean. Weed Sci 54:509515
Hall, MR, Swanton, CJ, Anderson, GW (1992) The critical period of weed control in grain corn (Zea mays). Weed Sci 40:441447
Heap, I, Duke, SO (2018) Overview of glyphosate-resistant weeds worldwide. Pest Manag Sci 74:10401049.
Jeschke, MR, Stoltenberg, DE, Kegode, GO, Sprague, CL, Knezevic, SZ, Hock, SM, Johnson, GA (2011) Predicted soybean yield loss as affected by emergence time of mixed-species weed communities. Weed Sci 59:416423
Knezevic, SZ (2007) Herbicide tolerant crops: 10 years later. Maydica 52:245250
Knezevic, SZ, Elezovic, I, Datta, A, Vrbnicanin, S, Glamoclija, D, Simic, M, Malidza, G (2013) Delay in the critical time for weed removal in imidazolinone-resistant sunflower (Helianthus annuus) caused by application of pre-emergence herbicide. Int J Pest Manag 59:229235
Knezevic, SZ, Evans, SP, Blankenship, EE, Van Acker, RC, Lindquist, JL (2002) Critical period of weed control: the concept and data analysis. Weed Sci 50:773786
Knezevic, SZ, Evans, SP, Mainz, M (2003) Row spacing influences the critical timing for weed removal in soybean (Glycine max). Weed Technol 17:666673
Knezevic, SZ, Osipitan, OA, Scott, JE (2018) Sensitivity of grape and tomato to micro-rates of dicamba-based herbicides. J Hort 5:1
Knezevic, SZ, Streibig, JC, Ritz, C (2007) Utilizing R software package for dose-response studies: the concept and data analysis. Weed Technol 21:840848
Kropff, M, Joenje, W, Bastiaans, L, Habekotte, B, van Oene, H, Werner, R (1987) Competition between a sugar beet crop and populations of Chenopodium album L. and Stellaria media L. Neth J Agric Sci 35:525528
Odero, DC, Wright, AL (2013) Phosphorus application influences the critical period of weed control in lettuce. Weed Sci 61:410414
Osipitan, OA, Adigun, JA, Kolawole, RO (2016) Row spacing determines critical period of weed control in crop: cowpea (Vigna unguiculata) as a case study. Azarian J Agric 3:9096
Owen, MD (2016) Diverse approaches to herbicide-resistant weed management. Weed Sci 64:570584
R Development Core Team 2017. R: A language and environment for statistical computing. Vienna, Austria: R Foundation for Statistical Computing. Accessed: August 2, 2017
Soltani, N, Dille, JA, Burke, IC, Sikkema, PH (2017) Perspectives on potential soybean yield losses from weeds in North America. Weed Technol 31:17
Teasdale, JR (1995) Influence of narrow row/high population corn (Zea mays) on weed control and light transmittance. Weed Technol 9:113118
Trezzi, MM, Vidal, RA, Patel, F, Miotto, E Jr, Debastiani, F, Balbinot, AA Jr, Mosquen, R (2015). Impact of Conyza bonariensis density and establishment period on soyabean grain yield, yield components and economic threshold. Weed Res 55:3441
Tursun, N, Datta, A, Budak, S, Kantarci, Z, Knezevic, SZ (2016) Row spacing impacts the critical period for weed control in cotton (Gossypium hirsutum). Phytoparasitica 44:139149
Van Acker, RC, Swanton, CJ, Weise, SF (1993) The critical period of weed control in soybean [Glycine max (L.) Merr.]. Weed Sci 41:194200



Altmetric attention score

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