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Australian Herbicide Resistance Initiative (AHRI)

Wild oat surveys

Wild oat

A number of surveys have been conducted in the WA grain belt over the last 15 years to determine the frequency and extent of herbicide resistance in wild oat in our cropping regions.

The graphs below provide a summary of the herbicide resistance status of wild oat for the herbicides listed. For a high resolution version, please click on the graphs below. For detailed survey information on individual cropping zones, please click here.

Bar chart

2005

At the end of the 2005 growing season, a random survey was conducted in which wild oat seed samples were taken from 150 crop paddocks across the WA wheatbelt.  Crop fields were surveyed over a 5 week period (November and December) just prior to the 2005 grain harvest. In total, 677 cropping fields were visited across 15 agronomic zones in the WA wheatbelt.

The herbicides used in the screening were diclofop-methyl, sethoxydim, clethodim, clodinafop, fenoxaprop, tralkoxydim, mesosulfuron, imazapic + imazepyr, trillate, flamprop and glyphosate. Herbicide effect was assessed by determining seedling mortality 21 days after herbicide treatment.

Major findings included:

  • Majority of wild oat samples collected from central WA wheatbelt
  • 43% of fields were infested with wild oat, with half of these at very low levels
  • Wild oat infestation varied between agronomic regions in the WA wheatbelt
  • 71% of populations exhibited resistance to diclofop-methyl
  • 23% of populations had resistance to fenoxaprop and sethoxydim
  • <5% of populations were resistant to clethodim, pinoxaden, clodinafop and tralkoxydim
  • No resistance found to mesosulfuron, imazapic + imazepyr, trillate, flamprop and glyphosate

2010 

In 2010, a random survey of 466 cropping fields across the WA wheatbelt at harvest. 128 wild oat populations were collected, and seedlings were screened to a range of herbicides at Australian commercial label rates, including diclofop, sethoxydim, fenoxaprop, clethodim  paraquat and glyphosate.

Major findings included:

  • 43% of fields contained wild oat at harvest time
  • Occurrence of wild oat varied between agronomic zones in WA wheatbelt
  • Resistance to diclofop-methyl was widespread, and resistance to other ACCase-inhibiting herbicides was variable
  • No resistance was found to glyphosate or paraquat
  • ALS herbicides, triallate and flamprop will be tested in 2013/14

2015

In 2015, a random survey of 509 cropping fields across the WA wheatbelt at harvest was conducted. A total of 128 wild oat populations were collected, and seedlings were screened to a range of herbicides at Australian commercial label rates, including diclofop, sethoxydim, fenoxaprop, clethodim, flamprop, mesosulfuron, paraquat and glyphosate.

Major findings included:

  • 43% of fields contained wild oat at harvest time
  • Occurrence of wild oat varied between agronomic zones in WA wheatbelt
  • Resistance to diclofop-methyl was widespread 52%, and resistance to other ACCase-inhibiting herbicides was variable and much lower
  • 18% of populations had plants resistant to fenoxaprop
  • 24% of populations had plants resistant to flamprop
  • 6% of populations had plants resistant to mesosulfuron
  • No resistance was found to glyphosate or paraquat

Herbicide rates

Herbicide rates used during resistance testing for samples collected during the 2003 and 2010 surveys.

Wild oat
Product Label rate Active ingredient Active rate (gai/ha)
Achieve® 500 g/ha Tralkoxydim 200
Atlantis® 330 mL/ha Mesosulfuron 9.9
Avadex® 2.0 L/ha Triallate 1000
Axial® 200 mL/ha Pinoxaden 20
Hoegrass® 1.0 L/ha Diclofop-methyl 563
Mataven® 3.0 L/ha Flamprop 270
OnDuty® 20 g/ha Imazapic + Imazapyr 10.5 + 3.5
Roundup® 1.5 L/ha Glyphosate 810
Select® 250 mL/ha Clethodim 60
Sertin® 1.0 L/ha Sethoxydim 186
Topik® 75 mL/ha Clodinafop 18
Wildcat® 350 mL/ha Fenoxaprop 38.5

Related Publications

Owen, M.J., and Powles, S.B. (2016) The frequency of herbicide resistant wild oat (Avena spp.) populations remains stable in Western Australian cropping. Crop and Pasture Science, 2016, 67, 520–527

Owen MJ, Powles S.B. (2009) Distribution and frequency of herbicide resistant wild oat (Avena spp.) across the Western Australian grain belt. Crop and Pasture Science, 60, 25-31.

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