Most Australian farmers grow and conserve their own crop seed (especially cereals), however this seed can be contaminated with weed seed. Some seed cleaning operations are only partially effective and therefore weed seed is seeded into paddocks with the crop seed. For weeds such as ryegrass, wild oats, and wild radish, this weed seed can be herbicide resistant and it is therefore possible for farmers to unwittingly introduce herbicide resistance to crop fields.
Surveys were conducted on WA farms in 1999 (Powles & Cawthray) and 2008 (Michael et al) to address the issue of resistance mobility by seed movement by assessing grain samples (wheat, barley, lupins, canola) which were taken from crop planting seed stocks. This crop seed was then sieved to identify and quantify the level of contaminating weed seed and this weed seed was evaluated for herbicide resistance status. Information was collected on whether the crop seed had been seed-cleaned and perceptions as to contaminating weed seed.
The 2008 survey revealed that:
2015
Most Australian farmers grow and conserve their own crop seed (especially cereals), however this seed can be contaminated with weed seed. Some seed cleaning operations are only partially effective and therefore weed seed is seeded into paddocks with the crop seed. For weeds such as ryegrass, wild oats, and wild radish, this weed seed can be herbicide resistant and it is therefore possible for farmers to unwittingly introduce herbicide resistance to crop fields.
A follow up surveys were conducted on WA farms in 2015 to address the issue of resistance mobility by seed movement by assessing grain samples (wheat, barley, lupins, canola) which were taken from crop planting seed stocks. This crop seed was then sieved to identify and quantify the level of contaminating weed seed and this weed seed was evaluated for herbicide resistance status. Information was collected on whether the crop seed had been seed-cleaned and perceptions as to contaminating weed seed.
The 2015 survey revealed that:
**Uncleaned samples had 45-160 times higher levels of contaminations; therefore, any sort of grain cleaning will have significant effects of the level of weed seed contamination.
Related Publications
Michael, P.J., Owen, M.J. and Powles S.B. (2010) Herbicide-Resistant Weed Seeds Contaminate Grain Sown in the Western Australian Grain Belt. Weed Science, 58, 466-472.
Owen, M.J. and Powles, S.B. (2020) Lessons Learnt: crop-seed cleaning reduces weed-seed contamination in Western Australian grain samples. Crop and Pasture Science