Breakthrough Treatment Helps Trees Resist Sudden Oak Death

Oct 3, 2003
Breakthrough Treatment Helps Trees Resist Sudden Oak Death
By Mielikki Org
Associated Press Writer

BERKELEY, Calif. (AP) - The secret to preventing the spread of sudden oak death in coastal trees may be a gigantic booster shot.
University of California scientists have discovered that trees dosed with a chemical product normally used as a fertilizer can fight and even resist the deadly microbe that has killed more than 100,000 oaks throughout California and Oregon since 1995.

The new application, which was just approved by the California Department of Pesticide Regulation, stimulates parts of the tree that produce disease-fighting chemicals.

"It's not a cure, not a solution," said Matteo Garbelottoin, a forest pathologist at the University of California at Berkeley who discovered the effects of phosphite on infected trees in 2001. "But we have something we can use to defend against the disease."

The chemical now is dispensed to the tree in two ways- through a syringe that puts the product directly into the tree's vascular system, or through a spray that is absorbed through the bark.

Once the phosphite moves up the tree and enters the leaves, it stimulates the production of infection-fighting chemicals within a layer known as the cambium. The chemicals, although they do not affect the pathogen, boost the tree's natural defenses.

At least 60 percent of the oak trees susceptible to sudden oak death are on private coastal property, Garbelottoin said, which means that homeowners may benefit most from the new treatment.

Arborists and foresters who use the phosphite product, which is expected to cost about $30 per application, must be trained and certified before they can use the chemical on private trees.

California's 16 state parks, where an estimated 4,000 acres of oak trees show signs of sudden oak death, stand less to gain from the new product.

"We have so much acreage, so many trees," said Richard Rayburn, chief of natural resources at the California Department of Parks and Recreation. "I'm not sure if we have the physical, or fiscal ability."

United States Department of Agriculture officials said they plan to continue placing quarantines on nurseries and other places in California and Oregon where the pathogen has been known to spread.

This story can be found at: http://ap.tbo.com/ap/breaking/MGADW7R0DLD.html