LIHUE — Herbicide-filled capsules — shot from helicopters with a standard paintball gun — are the latest tool used in the fight against invasive plants on Kauai.
James Leary, who has a doctorate in weed ecology and is a specialist with the Department of Natural Resources and Environmental Management at the University of Hawaii, is the man behind the invention, dubbed Herbicide Ballistic Technology.
“It is a weed management tool that is effective, safe and efficient,” he said.
The method involves a pilot, spotter and applicator (Leary), who flies over areas where miconia is known to be present. Once a plant is spotted, the helicopter moves in and Leary fires a capsule onto its large leaves or stem.
“I really try to emphasize the surgical nature,” Leary said. “We’re really dispelling the notion that large amounts of herbicides are needed to accomplish a job.”
Experimental testing of the technology was conducted between 2010 and 2011 during helicopter surveillance operations on Kauai and Maui.
An article detailing the experiment appeared in the April-June edition of the Invasive Plant and Science Management journal.
In 2012, Leary began operational use of the product, working with both the Kauai Invasive Species Committee and the Maui Invasive Species Committee.
HBT is capable of accurately treating miconia within a 30-meter range, with each projectile containing approximately 200 milligrams of the triclopyr herbicide, which Leary described as “miconia’s Achilles’ heel.”
So far, the technology is “proving to be effective in managing this serious problem,” he said.
Since 2012, Leary has led a total of three operations on Kauai, targeting a total of 24 plants. The last operation occurred in October 2012, with additional ones being canceled in February and June of 2013 due to poor weather conditions.
Unlike on Big Island, where large infestations are present, miconia on Kauai is believed to be limited to approximately 300 acres in the Wailua Game Management Area and Wailua State Park.
Still, KISC Project Coordinator Keren Gundersen said the plants pose a serious threat to Kauai’s native species and watersheds. She described it as KISC’s “No. 1 target.”
“It has the potential to destroy our entire watershed,” she said.
Although some may find the use of HBT in a watershed contentious, Gundersen maintains it is an important and effective tool.
“Our argument is, ‘Do you want to have a watershed (at all)?’” she said.
Native to South and Central America, miconia calvescens was introduced in Hawaii as an ornamental garden plant in 1961. Today, it is considered “the worst of the worst” of Hawaii’s invasive species, according to Gundersen.
The plant’s large, oval-shaped leaves shade out native species and quickly take over moist and wet forests, according to the Hawaii Invasive Species Council’s website. In addition, miconia reduces the amount of rainwater that seeps into the watershed and causes erosion.
In Tahiti, it has overwhelmed two-thirds of the forests, and is directly responsible for threatening 25 percent of its native forest species with extinction, according to HISC.
A mature tree often produces up to 3 million tiny seeds several times per year, which can remain dormant for up to 20 years.
By allowing KISC to survey and treat at the same time, Gundersen said HBT has improved the odds of eradicating plants before they mature and reproduce.
Leary also acknowledges that not everyone will agree with his method. However, he said he can actually show how the technology is reducing herbicide use over time.
The ultimate goal, Leary said, is to use HBT as a tool to address miconia while it is still a winnable battle, and before it becomes a “large, uncontrollable problem.”
“We can get a return on our investment,” he said, “which is the elimination of miconia on Kauai.”
In addition to being the inventor and developer of HBT, Leary continues to provide direction and supervision over all operations on Kauai, Maui and Oahu.
“Ultimately, everything runs through me because of the potential impact this technology can have if it’s used in the wrong way,” he said.
Leary and KISC will continue to conduct operations on a quarterly schedule. Eventually, Leary’s plan is to train KISC employees to use and apply the technology on their own.
Miconia — often referred to as the “purple plague” — is listed among the world’s 100 most invasive alien species in the Global Invasive Species Database.
• Chris D’Angelo, environmental writer, can be reached at 245-0441 or email@example.com.