Our Fungus Badder And Bigger, Covering 1,500 Acres

Move over, Michigan. Make room for the REAL giant fungus.

Give the Wolverine state credit for the wake-up call on humongous fungi, but its armillaria bulbosa looks just like another spot of root rot when compared with Washington's armillaria ostoyae.

At 38 acres, Michigan's armillaria bulbosa fungus last month was informally crowned the largest living thing in the world, passing blue whales and sequoia trees.

But scientists say Washington's got a fungus nearly 40 times larger.

"We have the claim to fame as having the world's largest known organism," said Ken Russell, a forest pathologist with the Washington state Department of Natural Resources.

Grabbing the honors is a growth of armillaria ostoyae covering 1,500 acres - 2 1/2 square miles - just south of Mount Adams in southwestern Washington.

It might be even bigger if not for efforts over 20 years by the state and timber company Champion International to destroy the stumps the fungus prefers, and to replant the area in a species the fungus finds less tasty.

Russell and Terry Shaw, a forest pathologist at the U.S. Forest Service Rocky Mountain Experiment Station in Fort Collins, Colo., have been studying the giant Washington fungus for nearly 25 years.

Shaw told The Associated Press that while the Michigan and Washington fungi are similar, the ostoyae variety "has a greater ability to kill trees." Both fungi produce small, edible mushrooms. Except for mushrooms and signs of rot in attacked trees, there is little evidence of the existence of the fungi, which creep underground to attack their victims.

Shaw estimated the Washington fungus to be 400 to 1,000 years old.

"And I would suggest there are still bigger ones to find," he said. He said a monster armillaria ostoyae also exists west of LaPine, Ore., but it is not as big as Washington's biggie.

Johann N. Bruhn, a Michigan Technological University researcher who wrote the Nature article with two University of Toronto colleagues, said yesterday he never claimed that the Iron County, Mich., fungus was the world's largest, only that it was the largest yet identified.

He added it makes sense a larger fungus would be found in the West, where large uninterrupted stretches of forest with one species of tree make it easier for a fungus to spread.

Bruhn said the contribution he and his co-authors made was in using a 16-point genetic test to prove beyond doubt that the Michigan fungus was one organism.

Russell, Shaw and others have used simpler but less-definitive tests to back their claims, Bruhn said. Nonetheless, he said it's very likely Russell is correct in saying the 1,500-acre fungus is one organism.

The fungus in the southern foothills of Mount Adams has grown in pine forests. It invades and kills trees through direct root contact or through the roots of old stumps that it uses as a food base.

Russell said that, if left unchecked, the ring-like zones of infection can double in size about every 20 years.

Shaw said the size of the giant fungus was determined in the 1970s by comparing reactions of fungus samples placed in culture dishes in a laboratory. He said samples that acted compatibly were determined to be all part of one organism.

Giant fungi exist across the United States and in Europe. Shaw said they can be deadly threats for trees and are battled in places by the timber industry.

But he said that while control of fungi is appropriate, he said they are part of the ecosystem and have a part to play in nature - and they probably couldn't be killed off entirely anyway.