Warding off herbicide resistance to rescue no-till
The unpalatable thought of losing his no-till farming system drives grain grower Geoff O’Neill, “Llano”, Bellata, NSW in his fight against the formidable threat of herbicide resistance.
Geoff says moisture retention via no-till farming is the key to crop success in an environment where rainfall is the major limiting production factor.
He says weed control is vital for maximising crop yield.
“We have a 610 millimetre annual rainfall and work on moisture retention the whole time so resistant weeds are going to be a big problem for us if means a return to cultivation for weed management.”
Geoff joined the no-till revolution in 1994 with the purchase of a no-till planter that allowed him to sow into higher levels crop residue on the heavy black clay and sodic grey soils of “Llano”.
“We had a few tough years learning the new system but since then it’s done a great job on these soils,” he said.
“Our production has become more stable under the no-till system.
“We work on a four-crops-in-five-years rotation which includes long fallow durum/chickpeas/short fallow wheat /long fallow to summer crop, either sorghum or cotton.”
Geoff is keen to use an integrated approach to herbicide sustainability management and follows WeedSmart strategies including: rotating chemicals and chemical groups, ensuring spray rates are accurate, rotating crops, diligently controlling weeds (including those in summer fallows) to stop seed set, considering alternatives to glyphosate, researching weed biology, and testing for resistant weeds.
“If herbicide resistance puts our no-till system under threat it would mean a big shift in thinking for us,” he said
“To go back to a conventional tillage system is just not possible. We could not do what we’re doing.”
He says rotation underpins his strategy.
“Rotation is the key word – we rotate crops, we rotate chemicals, we rotate chemical modes of action and we do use strategic tillage when we have to or we can.
“That’s not very often in a no-till system but we use strategic tillage at the end of the cotton cycle which ties in with pupae busting to manage helicoverpa and that’s given us another non-chemical option.”
Geoff welcomes Grains Research and Development Corporation (GRDC) funding into strategic tillage practices currently underway across the northern region by Queensland Department of Science, Information Technology, Innovation and the Arts (DSITIA) researcher, Dr Yash Dang.
“There’s more we can learn about strategic tillage including when and how and do we need to till the whole paddock?” he says.
Rotation is the key word – we rotate crops, we rotate chemical modes of action.
Knowing the herbicide resistance status of his paddocks and farm is important to Geoff and he has tested twice for barnyard grass which is the major weed of concern on “Llano”.
He says while the tests were negative the weed is notoriously difficult to control and he monitors the threat of developing resistance.
“We have trouble killing barnyard grass with glyphosate so timing and stress are obviously factors and we are working on that.”
He says the move to a Case self-propelled spray rig two years ago has provided a “tremendous efficiency boost” in weed control and allowed him to cover more hectares per hour.
The result has been better execution of the double knock technique for difficult-to-control weeds including fleabane.
“We had a trailing spray rig before and we found we couldn’t keep up with the double knock,” Geoff said.
“Using the self-propelled spray rig we can cover the ground more quickly if the conditions are right.
“We also use a disc planter now which allows us to conserve stubble in that we’re not burying stubble when we sow.
“In dry planting times we do miss the tyne planter but we haven’t had too many big issues.”