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Posts Tagged: sudden oak death

Dry conditions keep sudden oak death in check, yet significant outbreaks continue

Google map shows results of the SOD blitzes available online at sodblitz.organd SODMAP.org. Green icons identify trees sampled that tested negative for SOD. Red icons were SOD-infected trees.
Sudden oak death, which has killed millions of trees in California over the past 20 years, is spreading more slowly, according to California's most recent citizen-science sudden oak death survey. The 2018 SOD Blitz results indicate Phytophthora ramorum (the pathogen known to cause SOD) infection is currently less prevalent in many wildland urban interface areas, though significant outbreaks are still occurring in some locations.

Overall, 3.5 percent of the trees (based on those areas sampled during the blitzes) were found to be P. ramorum positive, a threefold drop from 2017. Yet, in San Mateo, Santa Clara and Santa Cruz counties, infection levels were estimated to be as high as 19 percent, followed by 12.7 percent in the East Bay.

"SOD blitzes detected the highest levels of foliar infections by SOD in 2017,” said SOD Blitz founder Matteo Garbelotto, UC Berkeley forest pathology and mycology Cooperative Extension specialist and adjunct professor. “As predicted, those high levels of foliar infections were responsible for a high increase of infection of oaks and tanoaks by SOD.

"Oaks and tanoaks were infected last year and will be showing symptoms such as bleeding in the stem and canopy drying this year and in the next two years to follow. Hence, despite a reduction of SOD infection on leaves of California bay laurels and leaves of tanoaks in 2018, we can expect a sharp increase in oak and tanoak mortality in 2018, 2019 and 2020."

Notable outbreaks were detected in Alameda (El Cerrito and Oakland urban parks, San Leandro, Orinda, Moraga), Marin (Novato, Day Island, Woodacre, Sleepy Hollow, McNears Beach, China Camp State Park, north San Rafael, Tiburon Peninsula, east and west peak of Mt. Tamalpais, Marin City), Mendocino (south of Yorkville), Monterey (Carmel Valley Village, Salmon Creek Trail in southern Big Sur), Napa (east Napa city), San Mateo (Burlingame Hills, west of Emerald Hills and south of Edgewood Rd, Woodside ), Santa Clara (Los Altos Hills, Saratoga, Los Gatos, along Santa Cruz Co border), Santa Cruz (along the Santa Clara Co border, Boulder Creek), and Sonoma (near Cloverdale, east and west of Healdsburg, west of Windsor, east of Santa Rosa, west of Petaluma) counties.

Several popular destinations where P. ramorum was found positive during the 2017 Blitz were negative for the pathogen in 2018, including Golden Gate Park and the Presidio of San Francisco, the UC Berkeley campus, and Mount Diablo State Park. Samples from San Luis Obispo and Siskiyou counties were also pathogen-free as were those from the southern portion of Alameda County.

"We encourage everyone in affected counties to look at the Blitz results online and to attend one of the fall workshops to learn how to protect their oaks from SOD,” Matteo Garbelotto.

“It is encouraging that SOD has yet to be found in the forests of California's northern-most counties, San Luis Obispo County and southern Alameda County,” said Garbelotto.

“It is also encouraging to see that despite its continued presence in the state for more than 20 years, SOD infection rates drop during drier years,” he said. “However, in 2018, we identified a number of communities across several counties where significant outbreaks were detected for the first time, and the Salmon Creek find in Monterey County is the southernmost positive WUI (wildland-urban interface) tree detection ever. Until the 2018 Blitz, only stream water had been found positive in the Salmon Creek area. We encourage everyone in affected counties to look at the Blitz results online and to attend one of the fall workshops to learn how to protect their oaks from SOD.”

Citizen-science SOD Blitz workshops

SOD Blitz Workshops are being held this fall in Santa Rosa (Oct. 10), Portola Valley (Oct. 16) and Berkeley (Oct. 17). The trainings will discuss Blitz results and recommendations for protecting oaks in the WUI. Workshops are intended for the general public, tree care professionals and land managers (see www.sodblitz.org for details). Two International Society of Arboriculture continuing education units will be offered at each training. Data collected from the Blitz (both positive and negative samples) have been uploaded to the SOD Blitz map (www.sodblitz.org ) as well as to SODmap (www.SODmap.org) and to the free SODmap mobile app, which can serve as an informative management tool for people in impacted communities.

SOD Blitz volunteers collect leaf samples and record the location using the SODmap mobile app.

Twenty-five SOD Blitz surveys were held in 2018 in the WUI of 14 coastal California counties from the Oregon border to San Luis Obispo County and included three tribal land surveys. The 304 volunteers surveyed approximately 13,500 trees and submitted leaf samples from over 2,000 symptomatic trees to the Garbelotto lab for pathogen testing.

SOD Blitzes are a citizen science program, which train participants each spring to identify symptomatic tanoak and California bay laurel trees in the WUI and to properly collect samples in the interest of generating an informative map of P. ramorum disease symptoms over time. Samples are tested for the presence of the pathogen at UC Berkeley and results are posted electronically each fall. Now in its eleventh year, the SOD Blitz program is one of the first in the world to join researchers and volunteers in a survey for a tree disease.

SOD Blitz surveys were made possible thanks to funding from the US Forest Service State and Private Forestry, Midpeninsula Regional Open Space District, and the PG&E Foundation. The Blitzes were organized by the UC Berkeley Garbelotto lab in collaboration with the National Park Service, Presidio Trust, San Francisco Public Utilities Commission, Midpeninsula Regional Open Space District, Save Mount Diablo, Land Trust of Santa Cruz County, East Bay Regional Park District, Santa Lucia Conservancy, Sonoma State University, UC Santa Cruz Arboretum, Los Padres National Forest, City and County of San Francisco Department of Recreation and Parks, UC Berkeley Botanical Garden, and California Native Plant Society.

For information on the status of P. ramorum/SOD tree mortality in California wildlands, see the US Forest Service 2018 Aerial Detection Survey results at https://www.fs.usda.gov/detail/r5/forest-grasslandhealth/?cid=fseprd592767.

For more information on the SOD Blitzes, visit www.sodblitz.org or contact Katie Harrell at (510) 847-5482 or kmharrell@ucdavis.edu. For more information on Sudden Oak Death and P. ramorum, visit the California Oak Mortality Task Force website at www.suddenoakdeath.org or contact Harrell.

Posted on Tuesday, October 9, 2018 at 12:27 PM
  • Author: Katie Harrell
Focus Area Tags: Environment Natural Resources

Sudden oak death moving to urban areas; 3 steps to protect oaks

Doug Schmidt, standing, and Matteo Garbelotto examine a bay laurel on the UC Berkeley campus.
Drought is decreasing but not defeating the pathogen that causes sudden oak death, according to a citizen science-assisted survey conducted this spring by a UC Agriculture and Natural Resources forest pathologist.

Results of the 2015 Sudden Oak Death Blitz survey reveal coastal mountain infestations in areas such as Big Sur (19% infection), the Santa Cruz Mountains (13% infection), and western Sonoma County (12% infection) remain high despite an overall decline in infection rates from 4.4% to 3.7% across California's 15 infested counties.

Sudden oak death (SOD) symptoms have been seen in Alameda, Contra Costa, Humboldt, Lake, Marin, Mendocino, Monterey, Napa, San Francisco, San Mateo, Santa Clara, Santa Cruz, Solano, Sonoma and Trinity counties.

“Understanding the current disease distribution is key to preventing sudden oak death spread. Citizen scientists have been an invaluable help with this task over the last decade,” said Matteo Garbelotto, UC ANR Cooperative Extension specialist in the Department of Environmental Science, Policy and Management at UC Berkeley, who organizes the annual SOD Blitz.

Several new SOD outbreaks of note were identified during the blitzes. Two infected California bay laurel trees were confirmed near UC Berkeley's West Gate, a high-traffic, high-risk area with many heritage oaks. An infected California lilac shrub was found in the Presidio of San Francisco's (part of the Golden Gate National Recreation Area) southeastern quadrant. An infected California bay laurel tree was confirmed in Danville (eastern Contra Costa County) in an area where SOD had not previously been reported, and an urban park in Saratoga was found infested for the first time.

These bay laurel leaves show P. ramorum symptoms.
“In an effort to protect habitat restoration in the Presidio, we are working to strengthen Best Management Practices to prevent the spread of SOD based on the Garbelotto lab recommendations,” said Christa Conforti, integrated pest management specialist at Presidio Trust in San Francisco. “In partnership with UC, the National Park Service, and the Golden Gate National Parks Conservancy, we are developing a Phytophthora prevention, detection and control strategy, which includes active participation in SOD Blitzes.”

Nineteen citizen science-based SOD Blitzes (largest number of blitzes to date) were held this spring, two of which were new this year – one in Trinity County and one on Kashia Band of Pomo Indian land in Mendocino County. The 504 volunteers surveyed nearly 10,000 trees from San Luis Obispo County, north to Mendocino and Trinity counties. Each volunteer was trained to identify Phytophthora ramorum (the plant pathogen known to cause SOD) symptoms on California bay laurel and tanoak leaves. “Blitzers” had up to three days to collect and record locations of symptomatic samples, which were then sent to the Garbelotto lab for DNA analysis to determine the presence or absence of the pathogen.

The SODMap mobile app shows a map of sampled trees.
SOD management workshops

Garbelotto is sharing results from the spring blitzes as well as new recommendations for SOD management at workshops being held around the Bay Area. Workshops will be held in Sebastopol on Nov. 3, in Berkeley on Nov. 4, and in San Rafael on Nov. 13. For details, see “Community meetings” at sodblitz.org.

For landowners in infested areas concerned about protecting their oak trees, Garbelotto will reveal his updated three-step SOD management plan. He will show them how to:

  1. Use the SODMap mobile app to help assess risk of oak infection (see sodmapmobile.org).
  2. Determine if California bay laurel trees near high-value oaks should be considered for removal (using a new buffer zone new chart - http://nature.berkeley.edu/garbelottowp/?page_id=2345).
  3. Apply phosphonates to high-value oak and tanoak trees to boost immunity (updated dosages and application frequencies at http://nature.berkeley.edu/garbelottowp/?page_id=2348).

Infection on California bay laurel and tanoak leaves indicates arrival of P. ramorum to an area, but true oak (California black oak, coast live oak, canyon live oak and Shreve's oak) infection typically requires a couple of years with wet conditions after pathogen arrival. Therefore, preventatively treating oaks to help ward off infection is best done when early indicator species first show symptoms, prior to oak infection and optimal conditions for the pathogen – cool and moist.

These surveys are made possible thanks to funding from the USDA Forest Service and the PG&E Foundation as well as help from the California Native Plant Society.

For more information on the workshops, go to sodblitz.org or contact Katie Harrell at (510) 847-5482 or kpalmieri@berkeley.edu. For more information on sudden oak death and P. ramorum, visit the California Oak Mortality Task Force website at suddenoakdeath.org.

 

Posted on Friday, September 25, 2015 at 11:38 AM

Recycling Christmas trees helps curb the spread of pests

Recycling Christmas trees helps prevent the spread of pests.
If you have a real Christmas tree, University of California pest management experts ask that you to recycle the tree to prevent the spread of insects and diseases that may harm our forests and landscape trees.

“Invasive insects, diseases and plant seeds can move on cut Christmas trees and other holiday greenery,” said Janice Alexander, UC Cooperative Extension forest health educator in Marin County. “These pests can escape out into backyards and neighboring forests to begin new populations, upsetting the balance of our native ecosystems. Proper purchasing and disposal of holiday greenery helps reduce that risk.”

Alexander recommends taking advantage of local tree recycling programs.

Sudden oak death symptoms are shown here on Grand fir. Photo by Gary Chastagner.
“Many municipalities and service organizations offer this service right at your curb,” she said. “If you aren't able to find or use this option, take the tree to your local solid waste facility, dump or landfill. This will keep any pests that might be in the tree from spreading and the landfill uses the material as cover.”

“You should not try to burn the wood indoors as fresh sap can create fire hazards,” she added, “and don't set the tree out in a backyard brush pile where pests and weed seeds could escape onto your property.”

“The most worrisome pests that might be traveling on Christmas trees or greenery this year include P. ramorum, pine shoot beetle and gypsy moth,” Alexander said.

The movement of some fresh trees is regulated. For example, Douglas fir trees are regulated because they are hosts for Phytophthora ramorum, which causes sudden oak death. The disease has killed millions of tanoak trees and several oak tree species in forests throughout California since the mid-1990s.   

Pine shoot beetles can stunt and even kill pine trees.
Pine shoot beetle and gypsy moth are not currently in California, but they could damage the state's Christmas tree plantations and forests if they were to become established.

Pine shoot beetles, Tomicus piniperda, feed on shoots, stunting the growth of pine trees. Large populations of the insects can kill apparently healthy trees.

Gypsy moth, Lymantria dispar, attacks forests and landscape trees, including manzanita, western hemlock, Douglas fir and live oak. Gypsy moth caterpillars feed on hundreds of plant species and are capable of defoliating trees at an alarming rate. A single gypsy moth caterpillar can eat up to one square foot of leaves per day, according to the California Department of Food and Agriculture. 

A single gypsy moth caterpillar can eat up to one square foot of leaves per day. Photo by Roger Zerillo.
“According to the Don't Move Firewood website, Christmas trees are generally deemed safer than firewood in terms of invasive pests,” Alexander said. “However, safe disposal of trees is still important.”

For more information about sudden oak death and forest health, visit Alexander's website at http://cemarin.ucanr.edu/Programs/Custom_Program816. More information about holiday greenery pests can be found at the USDA APHIS website and the Don't Move Firewood website http://www.dontmovefirewood.org/HolidayGreenery.

 

 

 

 

 

Posted on Friday, December 19, 2014 at 8:35 AM

Coast redwoods increasingly susceptible to fire damage

Fire consumes a once-healthy California redwood tree. (photo: USFS)
California’s renowned coast redwood trees, previously believed to be fireproof, are now more than four times more susceptible to wildfire injury in coastal forest areas infested with the sudden oak death pathogen. These redwoods are now as susceptible to wildfires as other trees.

Millions of trees, including tanoaks, coast live oak, California bay laurels, and many other forest species have been killed by sudden oak death in coastal areas of central and northern California, and Oregon. The pathogen, Phytophthora ramorum, was first linked to the massive tree death in the mid-1990s.

David Rizzo, professor in the Department of Plant Pathology at UC Davis, and his research team are studying how the coastal forest ecology is changing since sudden oak death appeared, and why coast redwoods (Sequoia sempervirens) are subsequently so much more susceptible to fire.

It is the presence of the sudden oak death pathogen in forests that poses heavier fire risks for redwoods.

“If redwoods didn’t live in forests affected by the disease, they could withstand fires just fine,” says Margaret Metz, a postdoctoral research scholar working with Rizzo.

Professor David Rizzo, UC Davis.
An initial explanation for the higher redwood mortality following wildfires is heavier fuel loads (such as fallen, dead branches from tanoaks) in forests affected by sudden oak death. Tanoak, Notholithocarpus densiflorus, is the primary host dying from sudden oak death and the main source of pathogen inoculum.

According to Rizzo, “The disease likely created more fuel for wildfires as dead tanoak branches fell. The loss of the oaks also would have decreased the amount of shade, drying out the forest and turning it into a tinder box, one not even redwoods could survive.”

A real key, though, is the finding that dead tanoaks, still standing, carry flames high into tree canopies, scorching the crowns of adjacent redwood trees. It’s this crown injury that is believed to have caused so many redwood trees to die in a number of fires that occurred in 2008.

Dead tanoaks in a redwood forest in the scientists’ California study area, pre-fire. (photo: Kerri Frangioso/UC Davis)
“Humans are causing widespread changes throughout our world, including greater wildfires related to changing climate and from increasing infectious disease due to more modes of transportation,” said Sam Scheiner of the National Science Foundation, which funded some of this research.

Rizzo, noting that an increase in fire severity is resulting from climate change and global movement of species, says, “There may be all sorts of consequences, among them, dead and dying coast redwoods.”

Additional information:

  • California's iconic redwoods in danger from fire and infectious disease. National Science Foundation report on Rizzo group’s work, August 2013
  • The effects of sudden oak death and wildfire on forest composition and dynamics in the Big Sur ecoregion of coastal California. General technical report
  • Ecology research article, Ecological Society of America
  • California Oak Mortality Task Force website
Posted on Wednesday, September 4, 2013 at 7:21 AM

Community effort beats back sudden oak death in Humboldt County

From left: Mark Rodgers, Julie Lydick, Pete Angwin, Rizzo, Valachovic, Phil Cannon, Ed Burton, Stephen Smith, Jack Marshall, Chris Nota and Russ Henly
Sudden oak death is a misnomer because it doesn't fell a tree like a lightning strike nor does the disease limit itself to oaks. Nonetheless, the moniker has stuck and UC scientists remain committed to containing the culprit. 

UC, federal and state agencies and landowners in Humboldt County recently received national recognition for their collaborative efforts to halt the spread of sudden oak death. Kathleen Merrigan, U.S. Department of Agriculture deputy secretary, praised the partnership during her visit to Davis on May 16.

Yana Valachovic, UC Cooperative Extension advisor in Humboldt County, and Dave Rizzo, professor in the Department of Plant Pathology at UC Davis, were joined at the USDA offices in Davis by their partners from USDA Forest Service, CAL FIRE and the Natural Resources Conservation Service to accept the Two Chiefs’ Partnership Award. Merrigan presented the award on behalf of the “two chiefs” – the head of NRCS and the head of the Forest Service.

For me, it was a pleasure not just to see Yana’s efforts rewarded, but also to see Dave Rizzo. About a decade has passed since the days I was on the phone and email almost daily forwarding reporter requests for interviews to the UC Davis plant pathologist. Rizzo was first to identify Phytophthera ramorum as the pathogen that causes sudden oak death in 2000.

Matteo Garbelotto of UC Berkeley demonstrates sudden oak death diagnosis and treatment for members of the media at the Berkeley campus.
As tens of thousands of California's beloved oaks fell to the disease, Rizzo and his colleague Matteo Garbelotto, UC Cooperative Extension specialist at UC Berkeley, an expert in forest pathology, were thrust into the limelight.

Although SOD doesn't make the news as frequently as it did in the early 2000s, it continues to spread. Garbelotto’s "SOD Blitz," his annual survey, found in 2011 that the rate of infection in trees between Napa and Carmel had grown as much as three times the rate of the previous year.

Since the disease was first reported in Marin County in 1995, it has been found in 14 coastal California counties and killed over 5 million tanoak, coast live oak, California black oak, Shreve oak and canyon live oak trees, according to the Forest Service.

UC Cooperative Extension employees were surprised in the spring of 2010 when routine  monitoring near the mouth of Redwood Creek in Humboldt County detected P. ramorum in leaf samples. It meant that trees were infected somewhere in the 200,000-acre watershed – more than 50 miles from the nearest known infestation and farther north than the pathogen had ever been detected in California.

UCCE staff coordinated a swift management response, embarking on the largest SOD management project ever to occur in California. They collaborated with the Forest Service, NRCS, CAL FIRE, tribes, local timber companies and private landowners to remove infected plant material. Rizzo pitched in with diagnostics for the project and matching funds to qualify for a federal grant.

From left, UCCE staff research associate Chris Lee, NRCS forester David Casey and Yana Valachovic inspect the treated area for signs of sudden oak death.
“We’ve been closely monitoring the disease for years and anticipating a scenario like Redwood Valley, so we were ready to take action and respond quickly,” said Valachovic, a forestry expert.

It’s still not clear how the pathogen got to Redwood Valley, said Valachovic, but it could threaten the dense tanoak forests of the surrounding area, killing trees and leaving behind dry brush, which could fuel wildfire. 

Landowner support has been critical to the success of the project, according to Valachovic. More than 20 landowners in the valley have allowed monitoring and treatment activities on their properties, recognizing that their cooperation may keep the disease from spreading to other areas.

The first phase of treatment is currently wrapping up, and UCCE is beginning to monitor project efficacy and watch for spread of the pathogen beyond project boundaries. The Yurok and Hoopa tribes will be paying close attention to this effort, as they are only a ridge away from the infestation. 

“Oaks are an important part of our culture and history, and we will do what we can to keep sudden oak death out of our forests,” says Ron Reed, a Yurok tribal forester.

The OakMapper app and website enable hikers and others to report SOD.
The Redwood Valley project highlights the benefits of people working together. If you would like to report sudden oak death, you can download the OakMapper smartphone app or submit reports at the OakMapper website. The website also features a map showing suspected and confirmed cases of sudden oak death.

Scientists, managers, regulators and policymakers will gather June 19-22, 2012, to discuss the latest news about the disease at the Fifth Sudden Oak Death Science Symposium in Petaluma.

For more information about sudden oak death disease, visit the California Oak Mortality Task Force website at www.suddenoakdeath.org.  

 

Posted on Wednesday, May 30, 2012 at 12:01 PM

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