Mississippi DOT Tests New Herbicide on Tough Cogongrass

Maintenance News DuPont Land Management August 18, 2011
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District 6 of the Mississippi Department of Transporation (MDOT) is in the midst of a trial fall application of an herbicide, using the product to specifically target cogongrass.

Chris Bryan, roadside development manager for District 6, said the weed is troublesome because it can grow nearly anywhere and has a dense growth habit.

“The main problem with cogongrass is that takes over any area where it has established, damaging a variety of ecosystems,” he said. “In our situation it takes over the desirable turf grasses of roadsides, which are bermuda grass and bahiagrass.”

They’ll begin spraying along four-lane highways in October. MDOT plans to apply the full, recommended dose of 11 oz. per acre annually.

MDOT began the trial application in late April-early May in the “bottom six” counties of Pearl River, Stone, George, Hancock, Harrison and Jackson. The 20-ft spray pattern of current spray trucks necessitated starting with two-lane roads.

“We started with the bottom six counties because that’s where you have 50-60% of the right-of-ways with cogongrass,” Bryan said.

The department decided to break the spring application into two stages, applying 5 oz. per acre to start. Over the summer, Bryan and his crews are mowing the covered areas and doing some additional trim work.

When discussing treatment options, Bryan said that looks are a factor. “With past cogongrass control applications, you get brown spots in the grass and that creates a bad aesthetic,” he said. “Motorists don’t want to see that as they’re driving along the highway.”

Efficiency also came into the decision; doing one or two sprays a year means more time for MDOT to focus on other projects and do some residual trimming.

So far the results have been satisfying. “It’s actually cleaned up our rights of way really well,” Bryan said. “The old herbicide was just not good for our turf, either, and that’s been a big improvement.”

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