Control of waterhemp (Amaranthus tuberculatus) at multiple locations in Illinois with single preemergence applications of VLCFA-inhibiting herbicides

Seth A. Strom, Kip E. Jacobs, Nicholas J. Seiter, Adam S. Davis, Dean E. Riechers

Research output: Contribution to journalArticlepeer-review


Very-long-chain fatty acid (VLCFA)-inhibiting herbicides have been widely used for preemergence control of annual monocot and small-seeded dicot weed species, such as waterhemp, since their discovery in the 1950s. VLCFA-inhibiting herbicides are often applied in combination with active ingredients that possess residual activity on small-seeded broadleaf weeds, which can make their contribution to preemergence waterhemp control difficult to quantify. Bareground field experiments were designed to investigate the efficacy of eight VLCFA-inhibiting herbicides applied at their minimum and maximum labeled rates for control of Illinois waterhemp populations. Four different locations were selected, two of which contained previously characterized VLCFA inhibitor-resistant waterhemp populations in Champaign County (CHR) and McLean County (MCR). Two locations with VLCFA inhibitor-sensitive waterhemp populations included the University of Illinois South Farm in Urbana, IL and the Orr Research Center in Perry, IL. Soils at the CHR, MCR, and Urbana locations contained greater than 3% organic matter, but less than 3% organic matter at Perry. Non-encapsulated acetochlor and alachlor controlled CHR and MCR 28 d after treatment (DAT), whereas other VLCFA-inhibiting herbicides resulted in 61 and 76% control of CHR and MCR, respectively. In contrast, all VLCFA-inhibiting herbicides resulted in 81 and 88% control of the Perry and Urbana populations, respectively, 28 DAT. Waterhemp control decreased by 42 DAT, especially for the VLCFA inhibitor-resistant CHR and MCR populations. Overall, VLCFA-inhibiting herbicides remain effective for controlling sensitive waterhemp, but most are not effective for controlling VLCFA-inhibitor-resistant waterhemp populations. Proper herbicide stewardship and integrated weed management practices should be implemented to maintain VLCFA-inhibiting herbicide efficacy for waterhemp management in the future.

Original languageEnglish (US)
JournalWeed Technology
StateAccepted/In press - 2022


  • VLCFA inhibitor
  • Waterhemp management
  • preemergence
  • soil-applied

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Plant Science


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