Paintball Ambushes Invasive Weed

Since being introduced in Hawai‘i 40 years ago, miconia has spread through tens of thousands of acres. Listed among the world’s 100 most invasive species, the sun hogging, erosion promoting, prolific seed producer native to Central and South America has the potential to destroy of Hawai‘i watersheds.

James Leary arrived in 1997 to study weed science at the UH Manoa College of Tropical Agriculture and Human Resources. The Michigan native has Hawai‘i roots (his mother was raised on Maui and earned a nursing degree from UH Manoa). Still, he says, “I was like most malahini, fooled by the romance of year-round food production. In very short time, I found out that weeds grow year-round as well.”

While miconia has no trouble creeping up into Hawai‘i’s remote rainforests and watersheds, human access is quite limited, so Leary developed Herbicide Ballistic Technology, or HBT. He uses painball gun technologies in liquid encapsulation and pneumatic delivery systems, among others, to deliver pesticides with surgical precision  at long-range. He not only adapted and refined equipment, but also identified effective utilities in the field, established quality control in production facilities, and standardized safeguards for practitioners…a soup-to-nuts approach in technology transfer.

Collaborating with the Maui Invasive Species Committee and the National Park Service, Leary conducted more than 60 helicopter operations since 2012, eliminating more than 5,000 miconia targets and protecting more than 4,000 acres of the East Maui Watershed. HBT has reduced the density of incipient miconia populations by more than 90 percent while using less than 1 percent of the maximum allowable rate of herbicide. Leary describes using a pinpoint dose of herbicide to eliminate miconia that was choking a native ‘ohi‘a: “It’s what we like to call ‘releasing the hostage.’”

—From CTAHR in Focus, January 2014