Paintball gun herbicide application

The Nature Conservancy is the leading conservation organization working around the world to protect ecologically important lands and waters for nature and people. Invasive weeds are a major threat to natural areas and herbicides have made it possible to remove these unwanted species.

“Kaua’i is rugged and beautiful, but it is also threatened by a host of invasive plants and animals. One of those invaders is the Australian tree fern, a fast-reproducing ornamental that was brought to Kaua’i almost half a century ago to prettify resorts on the island’s North Shore. It rapidly grows frond to frond and crowds out native plants.

“I’ve been fighting weeds for 20 years and I’ve never seen anything like the Australian tree fern,” says Trae Menard, The Nature Conservancy’s director of forest conservation in Hawaii. “It’s a pretty bad weed.”

In 2001, The Nature Conservancy launched its program to fight the invaders. 

Much of the research and development has focused on the Australian tree fern—“an ecosystem dominator,” as Menard puts it—that has exploded across the island. Menard and his team have developed a wide-ranging arsenal that includes “the Stinger,” a precision herbicide dispenser slung underneath the helicopter, which Hobbs and other pilots use to spray individual Australian tree ferns. The team has also tested herbicide-packed pellets that can be fired by a crew member in the helicopter with a paintball gun. That kind of precision targeting, along with a formula tailored to the Australian tree fern, has allowed the weed fighters to kill a lot of plants with extremely small quantities of Imazapyr, a relatively short-lived herbicide that has almost no effect on animals.

“We treated over 4,000 tree ferns in a 5,000-acre area over a three-year period,” says Menard, “and we only used 11 gallons of herbicide.”

But the tide may be turning in the fight to save Kaua’i’s native forest. More than 90 percent of the mapped Australian tree ferns in  Wainiha Valley have been treated and killed, and Menard’s team is now preparing to attack ferns in neighboring Lumaha’i valley.”

Author: Jenkins, M.
Affiliation: Reporter.
Title: Pacific Invasion: on the Hawaiian island of Kaua’I, scientists are pioneering new technologies to combat a surge of superweeds that threaten native forests.
Source: Nature Conservancy. September/October 2013. Pgs. 51-59.