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. You can use the following links to view the corresponding wild oat survey information:
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.
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
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
Herbicide rates used during resistance testing for samples collected during the 2003 and 2010 surveys.
|Product||Label rate||Active ingredient||Active rate (gai/ha)|
|OnDuty®||20 g/ha||Imazapic + Imazapyr||10.5 + 3.5|
|Roundup Ready®||1.5 L/ha||Glyphosate||810|