The Cambrian

Sudden oak death seen near Cambria

Sudden oak death has been found in trees along Santa Rosa Creek Road, bottom right.
Sudden oak death has been found in trees along Santa Rosa Creek Road, bottom right. The Tribune

Warning: Sudden oak death could be coming soon to an oak tree near you. It’s been confirmed to be in some California bay laurel trees along Santa Rosa Creek Road.

For decades, North Coast residents, volunteer groups and governmental officials have worried about and worked hard to preserve and protect the area’s rare native stand of Monterey pines.

Now, according to forestry officials from UC Davis, Cal Fire and the UC Cooperative Extension, people here also should spend time researching, worrying about and caring for North Coast oaks, California bay laurels and other native species subject to sudden oak death or SOD.

Area residents are being enlisted to join in the next study, sometime in the spring when the disease is most active, to help confirm how widespread SOD has become in this county.

Among them are about 50 people who attended a meeting Nov. 9 to learn more about the devastating disease. SOD has decimated millions of oak forests and standalone oaks in California and Oregon.

Meeting attendees represented wide swaths of North Coast interests. They included ranchers, farmers and other owners of forested properties, environmental activists, leaders of conservation nonprofits, governmental representatives, forest-industry workers, members of the educational and scientific communities and lots of worried tree owners.

This was the first such gathering in this county since tests earlier this year confirmed that the disease is here, according to event coordinator Mary Bianchi of the UC Cooperative Extension. But there’ll be more meetings to come, she said, to spread the word about SOD.

The scientists seemed pleased, if a bit surprised, that the meeting had attracted such a large turnout at an early hour on the day after the election, and because the locals who attended seemed so knowledgeable about the forest and even about SOD itself.

“That’s a good question!” several speakers responded as attendees peppered them with in-depth queries about the disease.

Usually, the scientists had the answers, but not always. As they acknowledged, there’s still a lot to learn about SOD.

Coast live oaks

A dominant species in Cambria is coast live oak, with its oh-so-recognizable gnarled branches and gracefully twisted silhouettes.

There are many California bay laurel trees here, too. The bays and other species could be the hypothetical canary in the SOD coal mine, so to speak, because the pathogen often shows up there first.

Oaks don’t spread the disease to other oaks, according to Kerri Frangioso, a UC Davis staff researcher and ecologist who lives in Big Sur. It takes a SOD host species, such as a bay, tanoak or even poison oak.

SOD doesn’t always kill bay trees and other host species, she and Cal Fire forest health specialist Kim Corella said. But the pathogen damages the leaves, and those host bushes, trees and shrubs harbor the pathogen, which is then spread to the prized oaks.

“Almost every species you can see in the forest can harbor the disease,” Frangioso said.

The disease “girdles” an oak tree, cutting off the flow of nutrients and water from its trunk to the rest of the plant. Eventually, the tree dies.

Since the spores of the water-dependent pathogen are transmitted primarily by rain and wind, scientists associate the spread of the disease with normal or above-normal rainfall, especially in damp coastal areas with mild conditions, where the risk of contracting the disease is greater than it is in drier inland areas.

Almost every species you can see in the forest can harbor the disease.

Kerri Frangioso, a UC Davis staff researcher and ecologist

According to Cal Fire forest pest specialist Christopher Lee, the prolonged recent drought may have been why the disease hadn’t crossed the Monterey County line into San Luis Obispo County, even though for some time, SOD has been confirmed just slightly north of there.

Previous scientific tests had confirmed infestations of the disease as far south as Willow Creek (just north of the Monterey County line), Corella said. The most recent tests, which included a so-called “SOD Blitz” in parts of San Luis Obispo County, produced “confirmation that we also have SOD in oaks along the parking lot at Salmon Creek.”

The recent tests also confirmed that the SOD pathogen, phytophthora ramorum, is in some bay laurel trees along Santa Rosa Creek Road, others west of Atascadero near Highway 41 and along Stenner Creek and Prefumo Canyon in San Luis Obispo.

The tests, which are costly and labor-intensive, haven’t yet tracked the disease into urban Cambria and the Monterey pine forest. But SOD is probably on its way, if not already here, according to the scientists at the Nov. 9 educational session. Its presence just hasn’t been proven yet.

That’s why the next intensive survey, to be done next spring by foresters and the citizen scientists they’ll train, will include Cambria neighborhoods, ranches and other areas.

Meanwhile, regulating agencies are taking steps toward establishing a quarantine zone, which would primarily affect nurseries and firewood.

SOD Blitz

Meeting attendees were encouraged to sign up for the next SOD Blitz. They’d attend a Friday evening training session, and then spend the weekend spreading out throughout the North Coast and the county to look for signs of the disease and take samples for testing.

They’ll learn how to identify the effects of SOD, which can mimic those caused by other pathogens and insect attacks. Drought, too, has damaged some oaks, even though the species typically prefers the more arid seasons in this semi-Mediterranean climate.

Meanwhile, the experts encouraged those concerned about SOD to keep a close watch on their own trees, especially bays that are near oaks. SOD lesions show up as pixilated brown, black or gray areas on leaf tips and/or blotches.

“Look for the dead part of the leaf to be where the water would hang out,” Frangioso said, adding that the infestation also can be evident on leaf edges. She advised people to also look for “oozing cankers” on the tree, with sap coming out of the trunk but with no wound evident on the bark.

Lee said it can take five to 10 years for SOD to kill a tree.

There are treatments, he said, but there’s some scientific disagreement on what works and what doesn’t. For instance, he said, studies have shown that wildfire may not necessarily kill the pathogen in soil.

A specific treatment may work better in some areas than others, or on some oak species. Oaks in a pine forest may react differently than those on open range or open oak woodlands.

As noted SOD scientist Matteo Garbelotto, founder of the SOD Blitz, has told Lee, to fight SOD, “you have to learn to speak tree.”

To learn more

There are many sources of information about sudden oak death (SOD), such as www.suddenoakdeath.org, for the California Oak Mortality Task Force, and http://bit.ly/2f0I1F4 for the UC Berkeley Forest Pathology and Mycology Lab.

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