There’s so much to enjoy about North Carolina’s beaches in summertime, but while you’re there, be on the lookout for a pesky invasive species that is threatening to disrupt our coastal ecosystems.
Beach vitex (Vitex rotundifolia) is a deciduous, woody vine that was originally introduced to the southeastern United States in the mid-1980s as an ornamental landscape plant, but has since escaped cultivation and become a major threat to North Carolina’s native dunes. The plant can grow up to 6 feet tall and spreads by sending out runners that can reach up to 60 feet.
“It’s a bad plant to have around because it’s less effective at holding dune sand in place than native dune grasses are,” NCDA&CS Weed Specialist Jared Driscoll said. “Beach vitex outcompetes those native grasses, which means sand dunes can erode more quickly once beach vitex establishes itself. It helps promote dune erosion, which we don’t like to see.”
In addition to dune erosion and crowding out of native dune grasses, beach vitex provides a poor habitat for beach species, making life more difficult for – among other animals – sea turtles attempting to nest.
“Beach vitex is a low-growing woody vine with rounded leaves,” Driscoll said. “The flowers are typically mauve to purple in color and the leaves have a spicy fragrance when they’re crushed. Another defining feature is the underside tends to be silvery-green.”
Today, beach vitex isn’t rampant on the North Carolina coasts but nearly every seaside municipality has pockets of the plant. One of the reasons it’s difficult to get rid of completely is that beach vitex is a prodigious producer of seeds, which can then be transported by wind, birds or people. The seed floats, so when it reaches the water, it can drift along the coast to a new location and start a population there.
When beach vitex is suspected – by a citizen or beach protection group – the NCDA&CS Plant Industry staff visits to confirm that it is indeed beach vitex and then gets to work educating the community about the plant and how to fight against it.
Treatment consists of a herbicide that is applied directly to the vines of the plant. Spraying it with herbicide is not recommended due to windy conditions at the beach that risk blowing the herbicide onto other plants. Instead, the surface of the vine is scratched to expose the inside of the vine and then the herbicide is painted directly onto the exposed vine.
Treatment can only take place during the active growing season which runs from May to mid-to-late October, depending where on the coast the vine is. Once the vine goes dormant for winter, the herbicide can no longer translocate to the roots and kill the plant. A typical summer window will see three applications from Plant Industry staff.
If you suspect you’ve spotted beach vitex, please report it by calling 1-800-206-9333 or by emailing newpest@ncagr.gov. Department employees can then verify whether the plant is indeed beach vitex and take action.