article reposted from the Two Rivers Tribune

Hoopa Tribal Forestry and UC Berkeley researchers are working to prevent the spread of an infestation of tree-killing spores which is now less than five miles from the boundary of the Hoopa Valley Reservation.

The spores, known as Phytophthora ramorum or Sudden Oak Death, can infect dozens of plant species and they kill Tan Oak trees. The disease has had devastating effects on forests in California and Oregon.

Darin Jarnaghan, the Hoopa Forestry Department manager, said, “The alarming thing is it’s getting closer. It’s moving eastward towards us.”

The disease is new, and isn’t fully understood yet by researchers and biologists. It wasn’t named until 2000, and was first found in Southern Humboldt in 2002. It has had devastating effects on forests in California and Oregon.

A Hoopa Tribal Forestry map shows an area of infestation (upper left), less than five miles west of the reservation (right). / Map courtesy of Hoopa Tribal Forestry

Yana Valachovic, the Director of the Humboldt and Del Norte University of California Cooperative Extension based out of Eureka, said that everyone was taken by surprise when the disease first appeared.

“This is an introduced pathogen to California. It’s not native, and we don’t know where it comes from,” Valachovic said. “The disease was discovered in Southern Humboldt around the Garberville/Redway area, but at the time they didn’t know what to do or how it spread.”

Since the disease was discovered, researchers learned that it can live on a lot of every-day garden plants, like rhododendrons, without doing much harm to those plants. When it reaches Tan Oaks, they die.

The disease is spread by spores, which can live in mud on boots, on tools, or on a vehicle for up to six months. Someone could spread the disease without even knowing it, by tracking mud from an infected area to an uninfected area.

Extreme close-up view of a Pytophthora ramonum spore infesting a Tan Oak.

Hoopa Forest Planner Jeff Lindsey said, “If you get into an infected area don’t go off road, but if you do go off road, wash your car before you come north.”

“The best thing is to use Lysol spray on your clothes and boots and anything you’ve got mud on,” Lindsey said.

Several people involved in fighting the spread of the Sudden Oak Death infestation said they suspected that the spores were spread to this area from Southern Humboldt by marijuana growers who are active near both areas of infestation.

“There’s a growing population adjacent to the border who may not even know, or care, because they’re making their money from what they’re growing,” Jarnaghan said.

Researchers from the UC Berkeley Cooperative Extension monitor close to 75 streams from Northern Mendocino County to Del Norte County.

They discovered Sudden Oak Death spores near the mouth of Redwood Creek in 2010.

Hoopa Forestry and others assisting in the monitoring program were able to track it upstream to an 11-acre infestation in the Lower Lacks Creek drainage just west of the Hoopa Valley Reservation.

Lindsey said, “We’re also monitoring our streams for any spores, so if you see a bag of Tan Oak leaves in a stream, leave it alone.”

So far, there have been no signs of any spores in any of the rivers or streams inside the reservation boundaries.

Valachovic said, “It’s so close to Hoopa and so close to the national parks. We’re working on an adaptive management strategy to handle the infestation, but it’s hard going.”

“The pathogen does really well in wet spring conditions, and we’ve had three very wet springs in a row,” Valachovic said.

There is a chemical treatment that will temporarily protect a tree against the spores, called Agri-Fos. The treatment costs $25 per dose, and must be applied to the entire tree.

Lindsey said that Hoopa hasn’t bought any of the chemical because it’s not cost effective to apply it to an entire forest tree by tree.

“We’re not in the business of saving individual trees, we’re in the business of managing entire stands,” Lindsey said.

Forestry plans to clear out weak and suppressed Tan Oak trees in a half-mile buffer zone along the western edge of the reservation, with the hope that the remaining healthy trees will be able to fight off the disease.

“Bay leaves are a major vector for Sudden Oak Death. It affects the leaves, not the Bay tree itself, but the spores from the leaves will kill nearby tan oaks,” Lindsey said.

Lindsey said, “We’re working on plans for which stands we’ll target first, and we’re looking at stands which have a high percentage of Tan Oak and Bay leaves.”

Researchers said that they’re still learning how to fight the spread of the infestation.

Valachovic said, “It’s going to take a lot more trials and efforts to know what’s going to work.”

Lindsey said, “Everything we’re doing is experimental, but doing something is better than doing nothing.”