An online survey of Australian grain growers reveals the number using some form of harvest weed seed control (HWSC) is likely to significantly increase in coming years.
It also suggests growers are likely to apply HWSC across a bigger proportion of their farms, and there will be an upswing in newer HWSC practices at the expense of narrow windrow burning.
Peter Newman, from the Grains Research and Development Corporation (GRDC)-supported Australian Herbicide Resistance Initiative (AHRI) and WeedSmart project, which is also funded by industry, said 269 growers took part in the survey conducted recently via Twitter.
While the survey was open to growers in all Australian cropping regions, WA growers comprised the highest proportion of participants (42 per cent).
“The results were very positive, with few people (2 per cent) indicating they intend to do ‘nothing’ for HWSC in three years’ time – down from 22 per cent in 2016 and 14 per cent this harvest,” Mr Newman said.
“This is good news, as the adoption of HWSC techniques is very important as part of an integrated weed management approach to reduce weed seed banks – using a combination of chemical, cultural and mechanical methods.
“The survey results reinforce that Australian grain growers are world leaders for managing weeds at harvest, with no HWSC practices being commonly used overseas.”
Mr Newman said the survey showed narrow windrow burning was the most used HWSC strategy in 2016 – employed by 40 per cent of respondents – but this had fallen to 32 per cent for the 2017 harvest and was expected to drop further to just 8 per cent in three years.
“The decline in narrow windrow burning is offset by a sharp increase in the number of respondents intending to use chafflining or weed seed capture and destruction technology,” he said.
“This is positive as, while narrow windrow burning as a HWSC tool is better than doing nothing, it is time consuming and has adverse implications for nutrient concentration as well as stubble and moisture retention issues.
“Growers who use narrow windrow burning also typically only use this practice on certain crops, and not across their whole cropping area – while the other HWSC techniques can effectively be used across a bigger area.”
Of the survey respondents, 27 per cent indicated they would use chafflining in three years, and 12 per cent expected they would use chaff tramlining (such as with a chaff deck).
Chafflining is a relatively new and cost-effective practice that makes a narrow windrow of chaff only down the middle of the harvester. Weed seeds are concentrated in that zone and straw is spread as usual.
Use of weed seed capture and destruction technology at harvest is also likely to grow, according to the AHRI survey findings, from 3 per cent in 2017 to 33 per cent in three years.
“The expected increased use of weed seed capture and destruction technology has a lot to do with this technology having matured and now being commercially available,” Mr Newman said.
“Many growers have delayed adopting other HWSC practices as they have been waiting for weed seed capture and destruction technology.”
Mr Newman said another point of interest from the survey was chaff cart use. This was expected to remain level, with 13 per cent using a chaff cart in 2017 and 14 per cent expecting to use one in three years.
“Chaff carts are often a suitable option for growers with mixed enterprises, as their stock can graze the chaff dumps,” he said.
The survey results will be used to help target AHRI and WeedSmart research and communications.