Most likely the redwood is experiencing symptoms related to cycles between drought and rainy periods. However, if there is a significant presence of California bay laurels intermixed with redwoods, there may be enough pressure from the SOD pathogen to also cause problems on redwoods, both native and exotic. Any SOD oak infections are likely directly connected to bay laurels, as both oaks and redwoods can become infected by the large number of spores produced on bay laurel leaves. The pathogen does not move from oaks to other trees.
It is always advisable to first have a tree tested before removal to be sure P. ramorum is present. If you are noticing symptoms in spring, attend a nearby SOD Blitz for information on sampling and lab submissions. For more information, go to sodblitz.org.
SOD Blitzes include a training session for blitz volunteers on SOD and proper sampling, followed by time in the field for collecting and marking sample locations. All necessary collection materials are provided to volunteers during the training session for use either the same day of the training or the day after. All samples are to be dropped off at a designated location (location announced at the training session). There are approximately 20 SOD Blitzes in areas of California that have sudden oak death or at risk of disease establishment. Most of the training sessions are offered on Saturday mornings. SOD Blitz schedules for the coming year are posted annually during the last week of January at www.sodblitz.org.
If a homeowner suspects SOD is affecting their trees, there are a few options to get them tested. SOD kills several oak species and tanoaks, but it is primarily spread via infected California bay laurel leaves. Parties interested in testing for the presence of SOD can contact their local UC Farm Advisor or county Department of Agriculture to find out if they accept symptomatic bay laurel leaves for testing. (Go to Hosts and Symptoms on the California Oak Mortality Task Force [COMTF] website to learn what symptomatic bay leaves look like.)
Another option is to participate in a spring SOD Blitz. These are community-based, volunteer sampling efforts that are organized in cooperation with the Garbelotto lab. Training dates and locations are posted February 1st of each year for the upcoming sampling season at www.sodblitz.org. Training and sampling take just over an hour each and happen on the same scheduled weekend.
For infected oaks, call an arborist. A list of arborists that have attended a SOD training within the last 3 years is available on the Arborists and Applicators page of the COMTF website. NOTE: This list is only intended to be an additional filter for those looking for an arborist. It is not a list of recommended professionals.
Oak testing is routinely done by arborists. It is a rather involved and tedious process that requires a fair amount of finesse and know how as it entails wounding the tree by shaving off the outer layer of bark to collect infected tissue. If you decide to have your oaks tested for SOD, consider going to the Trained Professionals List for arborists that have recently attended an official SOD seminar (Not intended to be a list of recommended professionals, this list does serve as an additional filter when trying to identify arborists that are up-to-date on the latest science-based SOD information.).
Alternatively, a less invasive method of determining the presence or absence of SOD on your property is to sample symptomatic bay leaves (See Hosts and Symptoms for SOD symptoms.). Keep in mind that any infested bay in the general vicinity (typically within 200 ft of an infected oak) may be the inoculum source for infection of your coast live oak. If bay sampling is your preferred method for pathogen detection, you can call your local UC Cooperative Extension office to find out if the California Department of Food and Agriculture is processing leaves from your county and, if so, what the protocol is for sample submissions. In lieu of submitting samples through your county, you can go to www.sodblitz.org to find out when a SOD Blitz will be held in your region (Dates for each year are posted by January 30th. Blitzes typically occur from March to June). Attending a blitz will afford you the opportunity to learn more about SOD, including the latest disease control strategies, during a 1-hour training session. At the end of the session you will be given all sampling materials and instructions for submissions. Blitz participants are free to submit as many leaves as necessary, meaning that you can send in all suspicious leaves from your property as well as from the neighborhood or nearby local parks. All leaves are processed at UC Berkeley and all sampling results are published in a database available at www.sodmap.org or through the free App SODmap mobile.
