oaks

Serious new threat to Sonoma’s oak trees

Sonoma Ecology Center

The Mediterranean oak borer (Xyleborus monographus, MOB) is a very small invasive beetle which originated in Europe and North Africa, in regions surrounding the Mediterranean Sea. In their natural habitat, the beetles serve an important ecological role by helping break down wood in trees that are already dying, aiding in the tree’s decomposition and the eventual return of its nutrients to the soil. In the United States, however, the beetle is a rapidly spreading invasive species, aggressively infesting both healthy and stressed trees alike.

Female beetles tunnel into the trunks and branches of trees to lay their eggs and in the process introduce a fungus which spreads through the tissues of the tree, blocking water and nutrient flow. Further damage from the beetles’ tunneling weakens and eventually kills the tree over time.

Infestations of oak trees in Sonoma County were first confirmed in early 2020, and as of 2025, MOB has already killed hundreds of thousands of oaks in Sonoma County. Local infestations are found primarily in valley oak and some blue oak, but Oregon white oaks are also susceptible.

What you can do:
MOB spreads by natural dispersal of the female beetles and through the movement of infested firewood, untreated wood products, and yard waste or mulch. The beetles are extremely difficult to detect because they are approximately 1/10th of an inch, about the size of a sesame seed. Firewood in particular is one of the easiest ways invasive species like MOB spread. When it comes to procuring firewood, always try to follow the guideline “buy it where you burn it.” Ask your firewood seller where the wood is from and if it isn’t local, or the origin is unknown, consider obtaining your firewood somewhere else. Similarly, avoid bringing outside oak mulch or untreated oak products onto your property–ask what kind of wood your mulch is and where it was sourced.

Read more at https://sonomaecologycenter.org/serious-threat-sonoma-oak-trees/

Forests,

Sonoma County Supervisors approve updated tree ordinance

Press Release: PERMIT SONOMA

The Sonoma County Board of Supervisors on Tuesday approved an expanded version of the county’s tree protection ordinance, which will preserve more of the county’s trees and help to combat climate change given that woodlands pull carbon from the atmosphere.

The updated Tree Protection Ordinance protects more native species, lowers the size threshold of protected trees to support forest health, and exempts removals for public safety, defensible space and basic property maintenance. A second ordinance specifically enhances protections for oak woodlands, a sensitive and valued natural resource.

“Trees and woodlands are essential elements of Sonoma County’s rural and urban lands. They provide a range of fundamental services to the community including clean air and water, wildlife habitat, natural cooling and climate moderation, cultural and historical value,” said Supervisor Lynda Hopkins. “Climate change, natural disasters and development continue to imperil the health, diversity and distribution of local trees and the benefits they provide. This action will help mitigate those hazards.”

The original Tree Protection Ordinance, adopted in 1989, protected 11 tree species with trunks nine inches in diameter or greater. The updated ordinance includes 31 tree species with trunks six inches in diameter or greater. The protected species include: big leaf maple, black oak, blue oak, boxelder, California black walnut, California buckeye, canyon live oak, coast live oak, two cottonwood species, interior live oak, madrone, Oregon ash, Oregon oak, red and white alder, valley oak, two willow species, two cypress species, grand fir, six pine species, redwood, western hemlock.
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Sonoma County Supervisors approve updated tree ordinanceRead More »

Forests, , ,

Sudden oak death spreading fast, California’s coastal forests facing devastation

Peter Fimrite, SAN FRANCISCO CHRONICLE

It is the forgotten killer when compared to our increasingly frequent climate calamities, but the virulent pathogen known as sudden oak death remains active and is spreading death so fast it could destroy California’s coastal forest ecosystem, UC Berkeley scientists reported Thursday.

The deadly microbe has now established itself throughout the Bay Area and has spread along the coast from Monterey to Humboldt County, according to a study of 16,227 trees in 16 counties in Northern California.

Millions of coast live oak and tan oak trees have withered and died over the past quarter century, leaving acres of kindling for wildfires, but the outbreak this year was one of the worst. Oak trees have historically been abundant in California and southwestern Oregon, with hundreds of millions of them stretching all the way to Baja California.

The rate of trees infected almost doubled in 2019 — from 3.5% to 5.9% — and was 10 times higher in some places compared with the 2018 survey, said Matteo Garbelotto, the director of the UC Berkeley Forest Pathology and Mycology Laboratory, which tested leaf samples taken by 422 volunteers.

Read more at https://www.sfchronicle.com/environment/article/Sudden-oak-death-spreading-fast-California-s-14815683.php

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Wet winter in Sonoma County may have helped spread virulent oak disease

Derek Moore, THE PRESS DEMOCRAT

Now that the North Coast is finally drying out from an unusually wet winter, concern is growing over the potential rapid spread of sudden oak disease, renewing calls for the public’s help tracking the deadly forest pathogen.

“Now is when we might expect the pathogen to take off a bit,” said Kerry Wininger, a UC Cooperative Extension staffer in Santa Rosa.

Wininger is a local organizer of annual sudden oak death surveys known as the SOD Blitz. This year’s survey occurs from April 25 to 28 across Sonoma and Mendocino counties. Organizers are hoping for a good turnout of volunteers, who will become educated spotters and collectors to help scientists slow the disease’s spread.

A relatively dry winter in 2017-18, coupled with the attention paid to devastating wildfires, appear to have dampened public concern over sudden oak death. But experts say conditions are ripe now for a resurgence of the disease. In addition, there’s heightened worry about a new, more virulent strain of the pathogen gaining a hold on the North Coast and causing more devastation.

Wininger said one of the highlights of this year’s surveys is the unveiling of a new test for the European strain in time to possibly thwart its spread. The new strain has been detected in Oregon.

“We want to nip it in the bud, if it’s here,” Wininger said.

Phytophtora ramorum, the pathogen that causes SOD, most often is spread by water droplets blowing from the leaves of infected bay laurel trees. There is no cure, only preventative measures or destroying oak and tanoak trees that succumb to the pathogen.

Read more athttps://www.pressdemocrat.com/lifestyle/9481637-181/wet-winter-in-sonoma-county

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Sonoma County groups embrace return of the mighty acorn

Stephen Nett, THE PRESS DEMOCRAT

Oak trees are among the most visible icons of the ancient Northern California landscape. With dark limbs curling above a carpet of grass, they lend an almost parklike visage to the foothills. The ten native species here also have seasonally dropped vast quantities of edible harvests of acorns, which support a bounty of wildlife and once fed indigenous people, who used fire and other tested practices to protect and nurture productive “orchards” in the woodlands.

The acorn was the original California cuisine, a reliable, nutritious staple on every menu that literally grew on trees. But after thousands of years, the venerable acorn was ignominiously edged out, to be replaced by imports of wheat flour, French fries, instant rice and corn flakes.

Despite its culinary disappearance, appreciation for the humble oak tree nut was never completely extinguished, and now it’s making a modest comeback, thanks to renewed interest in local, sustainable, functional and even foraged foods.

A mid-February workshop at the Laguna de Santa Rosa Foundation entitled “Seed to Table: How to Process and Eat Acorns of the Laguna Watershed,” was nearly sold out several weeks in advance.

The wild acorn is also the focus of local tribal groups seeking ways to strengthen cultural ties, reclaim their rich California heritage, and restore links to healthy diets from ancestral lands. A local, indigenously produced new product, Acorn Bites, is set to hit the local market in February.

Read more at https://www.pressdemocrat.com/lifestyle/9247142-181/sonoma-county-groups-embrace-return

Agriculture/Food System, Forests, , ,

Nonprofit restores Sonoma County’s natural habitat with oak tree seedlings

Hannah Beausang, THE PRESS DEMOCRAT

When Natalie Portis first stepped onto her property in Sonoma nearly 20 years ago, she was immediately enchanted by the verdant natural landscape and the stately oak trees.

Portis’ wooded oasis was among the thousands of acres of forests and oak-studded landscapes that burned in the October 2017 Nuns fire, which claimed her home and an estimated 700 trees on her 10-acre Castle Road property.

“It still feels surreal,” Portis, 59, said. “It was devastating to go back there and see the singed trees. I just remember being there and feeling the grief and toll of such loss.”

She’s rebuilding her home and plans to move in this summer. It’s been a “painful” process, but a bright spot came last month as she planted 21 oak tree seedlings sprouted from acorns collected by local volunteers in the weeks after the devastating wildfires two years ago in Sonoma County.

“It was very playful and very sweet, and it put a huge smile on my face,” she said of planting the young coast live oaks on her property with help from members of the California Native Plant Society. “I feel like I’m going to get back home.”

Oak trees have long defined the bucolic landscapes of Sonoma County and played a critical role in shaping its natural habitat. Recognizing the need to preserve and proliferate the native species after the fires, the California Native Plant Society and its local Milo Baker chapter — named after the noted Santa Rosa botanist — quickly launched efforts in 2017 to harvest acorns from areas near burn zones in the county and surrounding communities.

“Oaks are really the powerhouses of our ecosystem here in California when it comes to native plants,” said Liv O’Keeffe, senior director of communication and engagement for the environmental nonprofit society. “A single oak can literally support hundreds of insects, pollinators, birds, critters and other plant species. Having those oaks in place keeps an ecosystem intact.”

Read more at https://www.pressdemocrat.com/news/9116919-181/nonprofit-restores-sonoma-countys-natural

Forests, Habitats, , , ,

Arborists: Charred trees may still regrow

Guy Kovner, THE PRESS DEMOCRAT
Danny and Sky Matula have tied bright green ribbons near the base of about 50 charred Douglas fir trees standing behind the ruins of their home in the rolling hills west of Kenwood.
“They’re just toast,” Sky Matula said, as light rain fell on the ashen remains of the home his father built on the wooded 10-acre parcel adjoining Trione-Annadel State Park.
The black, denuded firs — including two that stand about 150 feet tall — are almost certainly dead, and stand far too close for comfort to the once and future family home.
The green ribbons mark them for removal by one means or another.
But like countless other homeowners, the Matulas are stuck in an uncomfortable dilemma regarding the fate of fire-scarred trees, including stout oaks and tall, slender firs, that impart majesty to their property.
Like California’s iconic redwoods, oaks are cloaked in thick, protective bark that enables several of their species to survive all but the worst wildfires, experts say.
And as homeowners begin to plot their post-fire recovery, tree advocates are urging restraint in removing burned trees and shrubs in favor of waiting at least until spring to see if fresh green growth emerges from vegetation that has adapted to survive fire.
Read more at: Burned trees in North Coast fire areas pose dilemma for homeowners

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