Case Studies

Always think about your impact on weeds Damien Sommerville from Spalding, South Australia, makes sure to consider the impact on weeds in every decision he makes Damien has a long association with the land. He has been involved with Sommerville Partners for nearly two decades and has seen a lot of different things in his time. His recommendation to growers is: Think about the impact on weeds with each and every decision you make, all year round. Damien is determined to help people in his area and further afield to understand the issue of herbicide resistance. “The issue affects growers everywhere. It’s obviously more high profile in the west but southern growers need to be aware and managing the issue whenever they can,” Sommerville said. “Growers have to use as many options as they can to prevent weeds setting seed. They can’t afford to lose one year in the battle as things spiral out of control quickly.” “There really is no one answer. What can work, if your conditions are right, is the use of lupins and or hay in your crop rotations. Using varied rotations each year is a great step towards managing weeds and resistance.”

Windrow burning beats wild radish Two key messages have emerged from long-term windrow burning trials in Western Australia’s northern wheatbelt – focus on trash from non-cereal crops and burn in the daytime where possible. Rod Messina, whose family farming business “Spring Park Farms” has hosted windrow trials for more than a decade, says the practice has underpinned their property expansion. “We find that when we buy a new property it always has a lot of weeds but after two or three years of integrated weed management (IWM) practices including burning windrows, it’s amazing how quickly weed numbers come down,” Rod said. “Weeds dictate what we do here, they’re our number one issue. So if a paddock’s dirty, rotation becomes vital and ultimately allows us to continuously crop. “It is quite expensive to leave paddocks out of production so with the rotation and windrow burning it allows our operation to be more profitable in the long run.” Rod farms 12,500 hectares with his father Charlie and brother Andrew on the Eradu sandplain east of Geraldton. They employ a wheat/lupin/wheat/canola rotation and strategically use herbicides to control radish in the cereal phase while windrowing canola and lupin crops to collect and destroy hard-to-kill wild radish seed. “Wild radish is one our most problematic weeds. We do have ryegrass but radish is our biggest concern because the seed is viable for so long,” Rod said. “In our lupin and canola phases we try to make sure we control all the seed set either through windrow burning or crop-topping. “We try to get a germination of wild radish before we sow but in this environment that is not always possible. “There is no doubt through our long-term IWM strategy, including windrow burning, autumn tickles, crop-topping, a double knock and now the mouldboard plough, that our weed numbers are decreasing.” The Messinas aim to stop seed set at every stage of the crop production and weed life cycle. “We deep rip to stimulate a germination of weeds that we can treat with a knockdown herbicide or double knock, then we’ll use one, maybe two post-emergent sprays followed by crop-topping lupins and windrow burning.” The Messinas have trialled a mouldboard plough and spading but chose to go with the mouldboard plough for its weed and non-wetting soil management benefits. Rod says the practice of windrowing as demonstrated by the GRDC-supported work by Department of Agriculture and Food WA (DAFWA) weed researcher Peter Newman has been proven over more than a decade. “The numbers are declining quite rapidly and one of the greatest benefits of windrowing is that it doesn’t slow harvest at all,” he said. “The hotter the fire the better it is and through the GRDC focus paddocks we’ve learnt that you do need a much hotter fire to control wild radish than for ryegrass. “We have to try and get the fire as hot as possible. It’s easy in lupins and canola because there is less chance of the fire spreading than in wheat so you can light the windrows up during the day and make sure you get a really hot burn. GRDC/DAFWA plots across the district are achieving 99% control of weeds using windrow burning. “In an ideal world you wouldn’t windrow your wheat because there is a chance you’ll lose the paddock but in a lighter year like this year we’ve windrowed all the paddocks in order to use that tool.” Rod says a cereal crop of more than two and a half tonne per hectare is too dense for windrowing due to the risk of burning the whole paddock and losing valuable soil cover. “If you’ve got a really dense windrow the fire will run across the top and won’t penetrate the windrow and research shows some of the seed falls to the bottom within about 24 hours.” He advocates burning late in the day rather than at night as the intensity of the fire drops as the temperature falls. “Five to seven years ago we windrowed every acre but now that we’ve got our numbers down we can just do the lupins and canola phases,” he said. “There is more opportunity to control wild radish during the wheat phase using herbicides and other tools and can manage the ryegrass during the non-cereal phases.”

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.”

Glyphosate resistance can be beaten – but it’s better to avoid it in the first place. In late 2008, Chris Reichstein, bought a new property near Esperance knowing that glyphosate resistant ryegrass was widely established. He was confident in his ability to bring the problem under control and set about using every tactic possible to reduce weed seed numbers on the farm. Starting with herbicide resistance testing to find out what still worked, Chris established a rotation plan to make the most of crop and herbicide combinations, including swathing and croptopping, narrow windrow burning, chaff carts, autumn tickle and a triple knock strategy of two chemical applications followed with a competitive crop. Containing the problem is now a permanent part of his farming system. More information: Glyphosate resistant weeds – beat them before they beat you It’s time for a glyphosate intervention AHRI Insight – Don’t waste glyphosate