A Green Mold Is Stalking ‘Shrooms

There’s a green mold invading the mushroom houses of Pennsylvania, the nation’s largest mushroom grower, which could result in the loss of as much as 20% of the state’s harvest.

The green mold (Trichoderma harzianum) spreads rapidly through the windowless “greenhouses” in which commercial mushrooms are grown. It is a production problem--corrupting the growing mixture and stunting the size of the mushrooms--but it is not dangerous to consumers.

This is a big problem for East Coasters but not for Southern California because of the intensely regional nature of the mushroom industry. Almost half of the 800 million pounds of mushrooms grown in the United States comes from Pennsylvania, most of it bound for the population centers of the Eastern Seaboard. A reduction of 20% will probably have a significant impact on prices there.

Experts say that probably won’t affect the West Coast, though. Because of their fragile nature, mushrooms are rarely shipped more than 1,000 miles. That’s why Californians see few, if any, Pennsylvania mushrooms.

In fact, one of the largest U.S. growers, Monterey Mushrooms of Santa Cruz, has seven farms covering much of the West Coast.

“We don’t see any Pennsylvania mushrooms at all out here,” says Carl Fields, president of Monterey Mushrooms. “I don’t think [the shortage] will have any effect on prices in California. Mushroom prices are pretty stable at the retail level.”

There have been scattered reports of green mold in California mushroom houses, says Wade Whitfield, president of the Mushroom Council, an industry organization. But so far problems have been isolated.

“A couple of growers have had a little problem with it, but we’re hoping it doesn’t become as serious as it has back East. We’re keeping our fingers crossed and paying a lot of attention.”