Farm Industry News is known for covering key technology developments, and sometimes we circle back to make sure we're managing the tech we have properly. That's why we were happy to catch up with Dr. Stephen Powles, professor and director of the Australian Herbicide Resistance Initiative.
Powles was the first to raise the red flag on glyphosate resistance, which first occurred in his country when rigid ryegrass became resistant to what he calls the world's greatest herbicide - glyphosate. His key advice: "If something is working, change it."
On a visit to the United States to speak with folks at Syngenta, we caught up with Powles by phone to get our own refresher on this hot topic. And his advice offers you a potential mantra for managing herbicide resistance issues on your farm - or in fact avoiding them. "Farmers will not stop farming, and there are concerns about going back to earlier technologies," he notes.
The move to auxin herbicides as part of new-tech weed control tools offers farmers hope, but Powles cautions that bringing 2,4-D or dicamba into your herbicide mix won't help if those too are overused.
His essential message of change is good relates to every herbicide you're putting on the field. If you use a preemergence plan, change it up. Looking for a postemergence technology, don't rely on it too much. Newer tools like LibertyLink soybeans work well and offer producers an option but Powles adds: "If it's used in any way nearly the same as the way glyphosate is used, we'll be here talking about Liberty resistance in the future."
The key is keeping precious herbicide tools effective in a variety of settings. The move in the south to use manual hoe crews to clear fields of Palmer amaranth is almost commonplace again - after years of a break when glyphosate-tolerant cotton came on the scene. "We do have the technology [for beating weed resistance] and it means not reaching for the same jug all the time," Powles explains.
He recommends a few tips:
1 - start with as few weeds in the field as possible, which means a preemergence application to reduce the weed population.
2 - consider your weed seed bank, knowing where you had trouble and managing those weeds to keep the seeds out of the field. In Australia, there's wide-spread use of techniques at grain harvest to catch weed seeds and destroy weed seeds (more on that in a moment) - he notes that using a narrow chaff discharge width and burning those rows has been effective for many too.
3 - change it up. Select and rotate technologies to make sure you're not using the same site-of-action herbicide over and over. As more companies "number" their compounds you'll know what's the same and what's different.
Managing chaff, beating seeds
Tactics that U.S. farmers have learned is growing in popularity Down Under are called harvest weed seed control. For example, a cart behind the combine, capturing the chaff to keep weed seeds out of the field. The chaff is later burned or disposed of.
"The chaff cart is good, but farmers also funnel chaff into tramlines, a kind of controlled-traffic farming, which puts the chaff in the wheel tracks," Powles says. "That's a harsh environment and not many weed seeds survive that."
That controlled traffic trick is nearly cost free too - as other equipment will roll over the same areas and keep on crushing down the seeds so they don't germinate.
There's also the Harrington Seed Destructor, which has gotten some attention in the U.S. The original unit was a pull-behind machine and some are still testing it in North America.The Harrington Seed Destructor is one tool for helping keep resistant weed seeds out of your fields. University of Arkansas engineers hope to test an 'integrated' model this fall that would be installed right on the combine, versus as a pull-behind.
Jason Norsworthy at the University of Arkansas is planning on testing a Harrington iSD, or "integrated Seed Destructor" that would be installed on the combine. Norsworthy is hoping to test the machine - he doesn't have it yet - on a bench to see how it handles U.S. type crop and residue loads.
"We're going to collect chaff and test it through the machine," he explains. "We want to test 10 to 20 different weed species through the machine and test its efficacy." He adds that in the United States higher yields and heavier biomass crops like soybeans and corn provide a lot more material to deal with.
"I'm excited and looking forward to testing the unit under those conditions," he adds.
He notes that for now farmers in his area - to managing weeds in chaff - have been doing narrow windrow burning. A practice that's not always popular around the "neighborhood." He sees the integrated Seed Destructor unit as having the potential for major impact on weed resistance management.
We'll keep you posted.