Mystery Oak Disease pg.2
The disease is getting researchers’ attention across the USA, particularly where other varieties of Phytophthora infect native plants. “It’s certainly something that’s not being ignored just because we’re on the right coast,” says Don Ham, professor of forest resources at Clemson University in South Carolina. “Our oak species can be susceptible, and we want to be prepared.”
A federal quarantine ordered this month bans shipping soil and plants from more than a dozen host species outside 10 infected counties from Monterey to Mendocino and one Oregon county, Curry, that has a small infestation. Canada has gone further, prohibiting imports of soil and host plants — those infected by the pathogen — from anywhere in California. The state’s $3 billion nursery industry complains that’s overkill because the disease hasn’t been found in most of the state, including Southern California.
But in Northern California, particularly hard-hit Marin, Santa Cruz, Sonoma and Monterey counties, it has spread unchecked. Sudden Oak Death — it got its name before many non-oak hosts were identified — first caused alarm on the slopes of Mount Tamalpais in Marin County north of San Francisco. From a distance, dead and dying oaks look like random clumps of yellow and gray on the forested mountainside.
An evergreen hardwood species that lives up to 250 years, live oaks are indigenous to 10 million acres of the Pacific coast, prized flora that add value and aesthetic charm to property. They generally grow 20 to 40 feet tall at elevations between 3,000 and 5,000 feet. Though they are commercially worthless except as firewood because of their gnarled, crooked trunks and branches, those same features create beauty and endless variation on the coastal terrain.
Homeowners are appalled watching their precious oaks die by the thousands. Once they notice the spiky roundish leaves turning yellow, the rust-colored spots on the bark and a sticky black ooze bleeding from the trunk, it’s too late — the tree’s a goner.
