Highway Mowing Aims To Help Control Invasive Plants

07/28/10 5:49PM By Melody Bodette

(Host) This is the time of year when road crews mow along the state highways. Officials say tall grasses and plants are knocked back just once a year, but timing is critical because they're dealing with at least a dozen invasive species.

In July, wild parsnip is in bloom in many parts of the state. The tall plant has yellow flowers and a sap that can cause serious, painful skin burns if exposed to sunlight, which is why some people call it poison parsnip.

Craig Dusablon is landscape coordinator for the Vermont Agency of Transportation. He says crews try to mow plants before they go to seed, but that can be difficult with the variety of invasive plants in the state.

Dusablon says studies have shown that mowing once a year is enough:

(Dusablon) "In a highway setting, different tests that have been done by the botanists and other scientists there prove that more frequent mowing actually makes the problem worse because what it does is kind of open up the area for more sunlight and depletes the native plants such as golden rod that kind of keep it in check."

(Host) The entire highway right of way is cut back every third year. But Dusablon says mowing isn't the only solution to invasives, because plants are spread many ways:

(Dusablon) "It's not spreading in a path from the roadways to the highway, it's spreading all over and it's carried by a number of different ways, by birds, by waterflow, winds and what have you."

(Host) Even after the roadsides are mowed, plants can still be found. Landowners can help control them through repeated mowing, digging it up or using herbicide.

Dusablon says it's unlikely that anyone will entirely get rid of wild parsnip and other plants.

(Dusablon) "It's here to stay. It's beyond the highway rights of ways, utility rights of ways, you name it. It's usually into fallow type fields where there isn't active use of the land, other uses such as farm uses, what have you. I think you're going to see more types of invasive species like that if you aren't using the land."

(Host) A study on the management of invasives is under way in the Green Mountain National Forest and if new plans are successful, Dusablon says management practices could carry over to the state highways.


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