SAN FRANCISCO — A coast live oak tree in Presidio National Park has been found infected with Sudden Oak Death (SOD).

The Park has been monitoring and sampling for Phytophthora ramorum (the pathogen that causes SOD) since 2003; however, this is the first time it has been confirmed on the grounds.

Responding to a request from the Presidio Trust, the federal agency that manages the interior 80 percent of Presidio lands, Matteo Garbelotto of UC Berkeley’s Forest Pathology and Mycology Laboratory sampled the symptomatic tree and determined that it was infected with a strain of the pathogen that is typically associated with nurseries.

Healthy Coastal Live Oak

Ornamental plant may be source of infection

“This finding suggests the source of the Presidio infestation may be an infected ornamental plant. While a relatively uncommon event, the fact that nursery plants can still be a source of infection is an issue affecting not only California but also other states in which the SOD pathogen has only been found in nurseries but not in the wild,” said Garbelotto.

“I was surprised by the finding because the Presidio is located in an urban setting, far from any other known infestation,” continued Garbelotto. “With a few exceptions, all known infestations are close to oak woodlands or redwood forests.”

Additional inspections of the site show no other sign of infection. The finding is not a likely source of further infection as P. ramorum is not spread by infected oak trees, but rather by spores produced from infected hosts that contract leaf and twig infections such as bay laurel, toyon, and rhododendron. The Presidio Trust and Garbelotto continue to monitor the Park, in an effort to insure no further infections are present.

A comparable situation was reported several years ago in Golden Gate Park, but at that site, infected California bay laurel and oaks were found in close proximity to an area where rhododendrons were held before being planted throughout the park. With bay laurel and rhododendron leaves supporting pathogen sporulation, there was a clearer picture of the pathogen’s path.

“Here at the Presidio, we found toyon near the oak,” Garbelotto said. “Toyon is a native California species that can become infected and potentially spread the disease to oaks. Currently these toyons are healthy. Our best guess at this time is that the oak was infected in 2006; hence the toyons may have been temporarily infected at that time, but lost their infection because of the 2007-2009 drought.”

Securing the site

Upon confirmation of the pathogen, Presidio personnel took steps to secure the site, which now has fencing up around the oak, preventing foot traffic from moving soil and plant material directly beneath the tree to other areas. Signs have also been posted near the infested site informing visitors of measures they can take to assist in prevention efforts.

“We’re doing all we can to prevent the spread of SOD in the Presidio’s forest, including ongoing testing in the area and educational outreach with Park neighbors and users,” said Christa Conforti, integrated pest management manager for the Presidio Trust.

The Presidio Trust will be conducting a “SOD Blitz” April 29 to May 2, 2011, when hundreds of samples will be taken throughout the Presidio and vicinity. Training for the community/Presidio-based cooperative effort to sample for the pathogen will be provided by Garbelotto on Friday, April 29, 2011. Residents near the Presidio have been invited to participate in the training as well as follow-up sampling efforts on their properties.

For more information on Sudden Oak Death, contact Katie Palmieri at (510) 847-5482 or go to the California Oak Mortality Task Force website at http://www.suddenoakdeath.org. For more information on the SOD Blitz in the Presidio, contact Presidio Trust Public Affairs at (415) 561-5331.

Featured Plant Care

Vanda Orchid Plant Care

Vanda Orchid Plant Care

in Orchids
Orchids are as easy as A - B - C!
Bamboo Care and Propagating

Bamboo - Care and Propagating

Bamboo Care & General Information:
Akebia trifoliata Monthly Plant Care

Akebia - Three Leafed (Akebia trifoliata) - Monthly Plant Care Calendar

in Edibles
You can have these monthly Plant Care Reminders sent directly to you each month!
Passion Vine Plant Care Reminders

Passiflora spp (Passion Flower) - Monthly Plant Care Calendar

in Vines
You can have these monthly Plant Care Reminders sent directly to you each month!

Latest Articles

Peach Leaf Curl

Peach Leaf Curl - Information Hub

Peach leaf curl is a common problem found on leaves of Peaches and Nectarines (and their…
Avocado Information Hub

Avocado - Growing and Plant Care Information Hub

in Edibles
We're bringing relevant information about Avocados (Persea americana) to one fantastic…

Popular Articles

Using the Mulch for Home Gardeners

Home Gardener: Using All The Great Features on the Mulch

You Can Use The Great Features on the Mulch For Free!
Baseball Field Maintenance

Baseball Field Maintenance - A General Guide for Fields of All Levels

in Lawn
More great baseball field resources can be found here (including a pdf version of this…
Queen Palm Care & Use

The Queen Palm (Syagrus romanzoffiana) Care & Use

in Trees
Jungle Music Palms and Cycads is a family owned and operated business established in 1977

What are Microgreens and How to Grow Them

in Edibles
Microgreens are tiny leafed vegetables that are grown from seed and require very little…

User Guides (Slide)

Popular Recommendations (Slide)

Upcoming Events

View All Events

Who's Online

We have 2425 guests and no members online