You’ve probably read recently about the issues facing the agricultural industry surrounding glyphosate resistant weeds affecting crop production. It’s an issue that has many farmers concerned, as it could lead to the rapid growth of tenacious new “super weeds.”

But the issue of weed resistance isn’t limited to farmers’ fields. It’s one that vegetation managers should be aware of and working to prevent. In fact, according to Homer Deckard, railroad IVM specialist with Dow AgroSciences, we are at a tipping point right now in terms of weed resistance. “In my opinion, if we don’t work as an industry to address resistance, our railroad properties, utility and pipeline rights-of-way, and roadsides could be overtaken by resistant “super weeds” like marestail (horseweed), kochia, pigweed and others.”

History of a Problem

But how did we get to this point? In order to demonstrate what has brought this about, you have to look back a couple of decades, according to Deckard.

“Prior to the 1990s, railroads and others in vegetation management used mainly proprietary herbicide products, which were herbicides like glyphosate, tebuthiuron and diuron at that time in vegetation management,” Deckard says. “In the 1990s, generic herbicides flooded the market, which drove costs down by 10 percent to 50 percent in many cases, while industry expectations in terms of weed control remained the same. Lower costs led to overuse in many cases, and now, because there have been few attempts to rotate to herbicides with different modes of activity, we’ve seen a tremendous spike in weed resistance, making these old standbys effective in fewer situations.”

As a general example, in 1990, a vegetation manager may have been able to treat an acre with 5 pounds of herbicide and get near 100 percent control of certain species. Then, in 2000, maybe it increased to 7 pounds of herbicide to get 70 percent control. Now, you could be looking at 10 pounds of herbicide to get 50 percent control of those same species.

Looking for Answers

So where do vegetation managers go from here?

In many cases, the resistance has become so specialized that you can’t just add more herbicide to achieve that same control. The vegetation manager now has to consider adding additional herbicides with different modes of action to traditional mixes to address one or two resistant weeds.

“The answer is to incorporate herbicides into tank mixes that aren’t as susceptible to resistance and are different modes of action from the initial herbicide that produced the resistance,” Deckard says. “It might push up costs per acre initially, but the control results will be significantly better, you won’t be contributing to resistance and over time you’ll use less herbicide, which is good for the environment.”

Additionally, Deckard recommends rotating herbicide programs from year to year, varying herbicides with different modes of action and addressing resistant species by adding appropriate tank-mix partners to herbicide programs.

Dow AgroSciences is always looking at ways to fight weed resistance. That means coming up with innovative and flexible tank mixes with new herbicides such as include Milestone^®, Capstone™ and Opensight^® specialty herbicides to help vegetation managers get improved weed control, while still fitting the treatments into their budgets.

“It’s important that vegetation managers don’t resort to simply raising application rates of programs that are failing,” Deckard adds. “This only accelerates resistant weed issues. Twenty years ago, resistant weed species could be counted on one hand; today, there are hundreds, mainly due to the use of the same herbicides year after year and increasing the rate as control declined. It’s time the industry banded together to fight this.”

For more information on herbicide resistance, please visit www.weedscience.org.

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When treating areas in and around roadside or utility rights-of-way that are or will be grazed, hayed or planted to forage, important label precautions apply regarding harvesting hay from treated sites, using manure from animals grazing on treated areas or rotating the treated area to sensitive crops. See the product label for details. State restrictions on the sale and use of Capstone, Milestone and Opensight apply.
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