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Last updated on April 20, 2014 at 14:04 EDT

Blackberry Fungus Enters U.S., Hits Oregon

July 25, 2005

PORTLAND, Ore. – A deadly fungus used to control the spread of unwanted varieties of blackberries overseas has landed in the United States, infecting numerous fields in Oregon, the capital of America’s blackberry industry.

First spotted this spring on the southern Oregon Coast, the rust fungus has spread to seven counties, according to officials with the Oregon Department of Agriculture.

Initially, the species was only spotted on the Himalayan blackberry, a weed.

Now it’s also been reported in virtually all of the fields of the commercially grown evergreen blackberry, the No. 2 blackberry crop in Oregon, accounting for roughly 9 percent of the state’s $30 million blackberry industry.

The fungus – which prior to its appearance in Oregon had never been detected in North America – has not attacked the Marionberry, Oregon’s state berry and one of the region’s most lucrative berry crops, said Bruce Pokarney, spokesman for the Oregon Department of Agriculture.

Officials said it was too early to estimate the potential economic damage.

“We’re at an early stage with the potential for serious economic damage, but we’re not at the stage where that serious damage has happened,” said Tom Peerbolt, a researcher with the Oregon Raspberry and Blackberry Commission.

The fungus has been used since at least the 1990s as a biocontrol agent to tame the growth of wild blackberries in Australia, New Zealand and Chile. As recently as last year, the U.S. Department of Agriculture approached blackberry growers in Oregon to discuss the possibility of introducing the fungus in the United States to control invasive varieties of blackberries – but the plan did not move beyond the discussion stage, said Pokarney.

Ken Johnson, a professor of botany and plant pathology at Oregon State University, theorizes that because the evergreen blackberry – which is not grown commercially in those countries – is native to North America, it might be more susceptible to the foreign pathogen.

While all the evergreen blackberry fields appear to have been infected in Oregon, so far only one grower has reported losing his entire crop.

“It’s appeared in all the Oregon evergreen fields, but it is not at the stage where it is causing real damage, except at this one site. Meaning we can find it, it’s on the leaves, but the crop is still intact,” said Peerbolt.

Agriculture officials are meeting this week to begin discussing possible remedies.

“The remedy is expensive – spraying,” said Johnson.

“It’s a huge problem because it’s something that can be battled and fought, but it takes a pretty rigorous spray program to do that,” said Mark Hurst, owner of Hurst’s Berry Farm in Sheridan.

While the disease has so far only been confirmed in Oregon, scientists and growers say it’s already crossed into southwestern Washington, where samples taken from several fields are currently being tested for the fungus.

Once infected, the leaves of the blackberry bush become stained with a mosaic of purple spots. Underneath, the foliage is tainted with yellow pustules.

“It was brought to my attention today,” said Dan Tsugawa, an employee at his father’s Tsugawa Farms in Woodland, Wash. “It’s so prolific that my workers have come out covered in yellow dust.”