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State will release
new fungus to fight
noxious Big Isle weed

By Rod Thompson
Big Island correspondent

HILO -- State researchers will release a fungus in the Big Island's Saddle Road area Monday in hopes of controlling gorse, a spiny bush that has taken over thousands of acres of pasture land.

Gorse has leaves like other plants when it is young, but as it matures it drops the leaves and the plant that remains is described as spines growing on spines. The plant grows five times faster here than in its native northern Europe.

"The shrub can reach up to 15 feet high and form impenetrable stands. Cattle will not eat or go near it," said a state Department of Agriculture press release.

The plant was brought here in the early 1900s as food for sheep. It has grown rapidly since eradication of sheep and goats from Mauna Kea began under a court order in the 1980s.

The weed now covers 35,000 acres on the Big Island and Maui, the state release said.

The organism planned for the attack on this pest is a rust fungus, so called because it produces rust-like brown spots on diseased plants. The particular rust fungus was extensively studied at the state Plant Pathology Quarantine Facility in Honolulu to be sure that would attack only gorse.

Infected gorse plants will be planted in the Humuula area near Saddle Road. Planting on Maui will come later.

Ken Teramoto of the quarantine facility said biologists might have used a water mixture with fungus spores and sprayed them on wild gorse, but the spores only grow under ideal conditions.

By planting infected gorse, the fungus will in essence wait until conditions are right, Teramoto said.

There's no hope that this battle will end in complete victory, Teramoto said. In fact, since the 1980s, two types of moth, a mite, and a weevil have been released to control gorse, with limited success, he said.

The hope is simply that enough biological controls will weaken gorse in the area until it becomes "innocuous," he said.

The Big Island gorse is on Hawaiian Homes land leased to Parker Ranch, Teramoto said.

Under a mandate from the Department of Hawaiian Home Lands to eliminate the weed, Parker Ranch has been poisoning the plants, he said.

The problem is that gorse can produce 100 million seeds per acre, and the seeds can lie dormant in the ground for 30 years.

State agriculture chief James Nakatani commented in the press release, "In Hawaii, gorse is one of the toughest noxious weeds to eradicate. With the introduction of this rust fungus, we can help nature keep this problem in check and hopefully return acres back to useful pastureland."