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January 2018

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Switch it up: rotating bareground mixes helps fight weed resistance

The agriculture industry has waged a well-documented war against weed resistance for years. Overuse of some herbicides, such as glyphosate, in fields allowed tough weeds to build up resistance to herbicide treatments and take a toll on farmers’ crop yields, ultimately, spurring the development of innovative new technology to regain the upper hand against weeds.

Beyond the farmers’ fields, it’s something many in the Industrial Vegetation Management (IVM) industry also struggle with due to gradual overuse of not only glyphosate, but other active ingredients such as sulfometuron and diuron.

For years, these herbicides and many others were overused, especially in bareground use sites, giving rise to resistant kochia, Russian thistle and several amaranth species. The problem gets a temporary fix when new herbicides are introduced, but before long, the cycle starts again.

ScottFlynn “Even the best herbicide solutions can have a relatively short shelf life without proper management,” says Scott Flynn, field scientist for Dow AgroSciences. “Many times, when control issues begin, there is a tendency to continue to add more herbicide per acre each treatment cycle to get the total vegetation control required for rights-of-way safety reasons. It’s been shown that this is when many particularly tough weed species begin to exhibit signs of resistance.”

Extend the life of today’s bareground solutions
Not surprisingly, without action, the issue is likely to become more widespread. The solution?

“Maintaining a consistent rotation of bareground tank mixes that include herbicides with unique modes of action,” Flynn says. “This fights weed resistance while extending the life of today’s effective bareground products.”

Recently, Dow AgroSciences released Cleantraxx® herbicide, a new herbicide that provides preemergent and postemergent control of more than 65 grass and broadleaf weeds, with up to six months of residual. More importantly, it provides two modes of action, a chlorophyll biosynthesis inhibitor (oxyfluorfen) and an acetolactate synthase inhibitor (penoxsulam) in a single product. When tank-mixed with Milestone® or Opensight® specialty herbicides, it provides a very effective new rotational mix for use in bareground situations.

Flynn recommends Cleantraxx at a minimum of 48 ounces per acre for residual annual grass control. Mix Cleantraxx with either 7 ounces per acre of Milestone or 3.3 ounces per acre of Opensight for residual control of broadleaf weeds.

“Rotating herbicide programs will net you better weed control using less herbicide over time while reducing the likelihood of developing resistance,” Flynn says. “It’s beneficial to the environment, and while costs per treated acre may rise initially, not having to continuously increase rates can positively impact long-term budgets.”

For more information on herbicide resistance and the impact it’s having globally, visit the International Survey of Herbicide Resistant Weeds at www.weedscience.org. With the help and input of researchers around the word, the site monitors and designates herbicide-resistant weeds, as well as works to understand, prevent and manage their occurrence.