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 […]

Is it okay to cover the base of a tree with extra soil?

The buttress or basal portion of a tree should never be covered by soil as this practice increases the chance that the tree will suffer from root pathogen attacks in the submerged part of the trunk. The soil should be removed until root flares at the base of the tree are clearly visible. Attacks by […]

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 […]

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 […]

Other than for copper-based sprays, what control methods are available for cypress canker?

There are several  products that have been tested for controlling cypress canker. The following paper maybe the most useful one to compare products. Della Rocca, G., Di Lonardo, V., Danti, R. 2011. Newly-assessed fungicides for the control of cypress canker caused by Seiridium cardinale. Phytopathologia Mediterranea. 50 (1), pp. 65-73. The most effective active ingredients […]

Which trees give off the most oxygen?

Assignment levels of oxygen emission are not precise and different methods can give different results. That said, it is well documented that oxygen release is proportional to the overall leaf mass, also known technically as Leaf Area Index. There is general agreement that: Pines are at the bottom of the list in terms of oxygen […]

How often do you administer phosphonate to oaks to help protect them from sudden oak death?

Phosphonate injection treatments to help prevent sudden oak death infection of susceptible oak species (coast live oak; California black oak, Shreve’s oak, and canyon live oak), if applied in the fall (after October 30th ), need only to be applied once every other year (biannual frequency). If your first phosphonate treatment is in the spring, then […]

How can I be sure I’m not spreading SOD with my tools?

The most important part of ensuring that tools will not spread SOD is to be sure that no organic debris or soil is present on the tools. This applies to all portions of each tool, including parts that may not be visible (like the return of a chain in a chainsaw or the interior of […]

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.

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