KAILUA-KONA >> Officials say a tree-killing fungus that covered more than 16,000 acres on the eastern part of the Big Island has now been discovered in the western areas of Holualoa and Kealakekua.

James Friday, Hilo-based extension forester with the College of Tropical Agriculture and Human Resources, said recent testing confirmed rapid ohia death has infected western trees, but researchers aren’t sure how this particular strain spread or where it originated.

Ohia wilt quickly takes over the tree’s water transport system and kills 50 percent of those it infects, West Hawaii Today reported. Scientists believe that humans can spread the spores on their clothing, vehicle and equipment.

"Don’t move wood around, don’t move plants around," Friday warned at a Council Chambers forum sponsored by Rep. Nicole Lowen. "Kaloko mauka is what I’m really worried about. You buy infected wood from Puna, cut it up in your driveway, the sawdust blows around, and you just infected your forest."

The affected area in Puna and mauka slopes above Hilo grew to 16,000 acres in 2014, up from less than 3,000 acres in 2012.

The Hawaii Department of Agriculture imposed an emergency ban on shipment of ohia logs in August in an effort to contain the disease. A ban on soil export will begin in January.