Resistance grows in the north
Northern graingrowers are facing the possibility that some of their most commonly used herbicides are no longer effective in controlling weeds in some wheat, chickpea and sorghum paddocks.
University of Queensland and QDPI researchers have reported resistance in seven of 17 weed species collected from the Goondiwindi, Moree and Roma districts (winter weeds) and the eastern Darling Downs and Central Queensland (summer weeds). Resistance was shown to one or other of the herbicides Glean, Topik, Puma S, and atrazine.
The resistances discovered were in turnip weed, Indian hedge mustard, common sowthistle, climbing buckwheat and African turnip weed (Glean); wild oats (Puma S and Topik) and liverseed grass (atrazine).
Records showed that resistance had developed after 3-10 years of selection with chlorsulfuron (Glean), five years Top' use (Topik and Puma S), and 2-15 years of selection with atrazine.
What's being done
An extensive awareness campaign by agronomists with QDPI and NSW Agriculture has alerted farmers and advisers to the now real threat of herbicide resistance in their region. Fifteen thousand copies of a colour brochure outlining the problem and ways to avoid resistance were snapped up by members of the grains industry.
Avoidance strategies include rotation of herbicide groups and rotation of crops, selective spray-topping and the use of more competitive crops and cultivars.
Contact: Dr Steve Adkins 07 3365 2072, Dr Steve Walker 07 4639 8838