Herbicide to control invasive plants in Grand Canyon

GRAND CANYON, Ariz. – The National Park Service says it will apply cut-stump and occasional spot spray treatments of herbicide along Colorado River’s banks in the Grand Canyon to control several invasive plant species.

The agency said the treatments will run from Monday through April 30.

The non-native plants targeted are Russian knapweed, camelthorn, pampas grass and perennial pepperweed.

An environmental assessment prepared a decade ago for the park’s exotic plant management said chemical pest control would be better than no action and deemed it would have no significant negative impact on park ecology.

The park service said the imazapyr-based herbicide is approved for aquatic use but will not be applied directly to water. The cut-stump method will be used when possible, applying the herbicide to a cut in the invasive plant’s main stem.