Magnesium chloride stresses most roadside trees

Roadside trees are suffering where magnesium chloride is applied to unpaved roads. It’s used for dust suppression and road stabilization.

High concentrations of magnesium chloride were found in symptomatic trees within 20 feet of roads where it was applied, said Betsy Goodrich, an ecology graduate student at Colorado State. Goodrich and Bill Jacobi, bioagricultural sciences professor, studied 60 roadside plots on 15 unpaved roads in Larimer and Grand counties.

“We evaluated tree health, including surveying for disease and insect damage,” Goodrich said. “The strongest factor to explain the decline in health of the trees was the magnesium chloride.”

Researchers also visually surveyed more than 200 miles of 55 unpaved roads in Larimer and Grand counties and found 80-90 percent of roadside vegetation appeared healthy or only mildly damaged. Trees were found to be the most dominant roadside species affected by magnesium chloride. More severely damaged trees were found down slope of the road.

Water moves the magnesium chloride from the road into roadside soils, and trees absorb the magnesium chloride through the soil.

Next, Goodrich and Jacobi plan to determine if there’s a safe level of magnesium chloride to apply without damaging trees. They also plan to determine how long it takes magnesium chloride to have an effect on trees. They plan to partner with county agencies to determine best practices for its application.

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For more: Bill Jacobi, Colorado State University, (970) 491-6927, william.jacobi@colostate.edu.