U.S. Sen. Daniel Inouye announced Wednesday that the U.S. Department of Agriculture has approved a biocontrol project aimed at slowing the spread of fireweed, or Madagascar ragwort, on the islands of Hawaii and Maui.
Fireweed is a noxious, invasive species that has infected an estimated 850,000 acres on the two islands, more than 20 percent of the state’s agricultural pasture lands.
The weed has no natural predators in Hawaii and is resistant to drought which allows it to spread rapidly, and it is expected to spread to an additional 1.5 million acres in the next 10 years if left unchecked.
Agriculture officials plan to release a species of moth next month on the two islands. The moths, which, like fireweed, are native to Madagascar, have been studied under quarantine in Hawaii since 1999. They are known to feed on fireweed, which is toxic to livestock.
Tim Richards, president of Kahua Ranch and past president of the Hawaii Cattleman’s Council, said the news of the approval is huge for Hawaii, “and that’s an understatement.”
For the past 10 years, the cattle ranchers have been losing the battle against fireweed, using chemicals and mechanical means in an attempt to control it. But due to the immense size of the infestation, “those methods are not feasible or economical,” Inouye said.
“It’s an ongoing ecological wreck,” Richards said, spreading up from the coast into the rain forests. “Because of the drought it grows quickly.”
Fireweed is believed to have been introduced to the state in the 1980s through contaminated seeds, said Darcy Oishi, chief of the biological control section of the state Agriculture Department. The plants produce 30,000 seeds per year that are easily spread by wind, hiking boots, vehicles and animals.
The invasive plant contains an alkaloid that is toxic to livestock. When ingested, it accumulates in and damages the liver resulting in stunted growth and, in severe cases, death, according to documents filed with an environmental assessment of the project in 2008. The disease is progressive, with symptoms and death occurring weeks or months after consumption of the plants.
Without effective control, in 10 years, fireweed will likely consume more than half the agricultural pasture lands in the state, Richards said. Biological control is believed to be the only effective, practical, long-term means of limiting further spread of the highly invasive weed in pastures.
“This is a big day for the state,” Richards said. “Thankfully it’s finally approved.”
Oishi said federal and state environmental assessment studies have been conducted for the project and each determined there to be no significant impact. The moths are expected to be released in January or February but details have not been determined yet. Public notice will be provided in advance, he said.
“This is not just about controlling a weed,” said Oishi. “If not controlled, this is it for a way of life. We will lose our paniolo culture, the mystique. Our children will not be able to see it.”
“It is my hope that this effort will help to ensure that Hawaii’s cattle industry will continue to thrive and help the state move toward greater food self-sufficiency,” Inouye said.