This spring my blue oak tree’s leaves are changing to reddish brown and falling off. What is happening?

Both prolonged drought and a leaf disease called anthracnose (highly infectious during very wet years) can cause early leaf drop, especially in blue oaks, but also in other oak species. So, a single year of early leaf drop is almost never problematic.  Leaves should reemerge next year.  You may observe some die back of a […]

We have a tree with fungi growing at the base of the trunk. What should we do?

You may want to hire a tree care professional and have them submit portions of the fruiting bodies growing at the base of the tree for analysis. For information on how to send in a sample, go to www.wooddecay.org. The sample must be sent in with a completed submission form and a signed donation letter […]

How do I know if my area has been evaluated for sudden oak death?

If you live in a California county that is known to have sudden oak death (SOD), you can check to see if your area has been evaluated for the presence of the pathogen that causes SOD (Phytophthora ramorum) by downloading the free SODMAP Mobile app.  Doing so will allow you to see if trees have […]

My redwood has severe dieback and is near a coast live oak with SOD. Could the redwood have SOD?

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 […]

How do I determine the distance from trees on my property to P. ramorum-positive trees on SODmap?

When looking at SODmap, you may wonder if P. ramorum-positive trees are close enough to pose a threat to trees on your property. Use the free App SODmap mobile to get the answer. Just tap the App risk function and it will tell you whether  infected trees trees are within 200 m (high risk) or […]

I have a very small bay tree that has leaves with P. ramorum symptoms. Should I just remove the tree or take a sample first?

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.

I just cut down a small infected bay. Do the root shoots carry P. ramorum?

Bay shoots do not carry P. ramorum because the pathogen is not systemic in bay.  Each leaf is infected independently. Additionally, there is no root infection in most P. ramorum hosts,  particularly California bay laurel.  However, when bays re-sprout, they may be re-infected.  

I have an oak in the Bay Area that is oozing liquid from the trunk base. Should I test it for SOD? If so, how?

When trying to determine if an oak may have SOD (caused by the plant pathogen Phytophthora ramorum), the first step is to determine if the tree lies within 1 km of a known outbreak.  This can be done by accessing SODMAP at www.sodmap.org or by uploading the free “SODMAP Mobile” app to your smartphone.  Stand next to […]

How long can Phytophthora ramorum survive in wood chip mulch?

Survival of P. ramorum (SOD pathogen) in wood chips depends on a few factors: Were the chips allowed to become wet? What size are the chips? Is green waste present? What time of year was the wood chipped? Where in California are the chips located? Chips that are piled wet or tarped and include infected […]

How long can Phytophthora ramorum survive in soil moved from an infested area?

Survival of P. ramorum (SOD pathogen) in dead hosts or non-plant substrates is extremely variable and strongly affected by climatic factors. Although a comprehensive study on this topic has not conducted, extrapolating from several studies we can say the following: Soil becomes more infectious from late winter to early summer in the presence of rainfall, […]

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