We have bays 100 feet downwind from a coast live oak that seems to be dying of SOD. How do we have our oak tested and how do we determine if the bays are carriers?

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 […]

Were the initial outplantings of P. ramorum-infested plants ever traced back to a source nursery?

Phytophthora ramorum was not discovered as the causal agent of sudden oak death until 2000-2001.  Prior to then, it was not understood to be a nursery issue; therefore, there was no concern about spread from nurseries into the wildlands.  Since then, DNA analysis has confirmed that the pathogen was unknowingly introduced to both California and […]

Armillaria is slowly killing my Thuja hedge. What is a comparable replacement hedge that will give me the same amount of privacy and be resistant to this fungus?

The first question to ask is what type of irrigation is being used currently on the hedge. Most landscape oak root fungus problems are due to overwatering in summer months. However, Thuja orientalis (=Platycladus orientalis) is quite susceptible to Armillaria even without heavy irrigation as highly susceptible species do not require excessively high soil moisture […]

Is it okay to prune coast live oaks in the winter if there is no SOD inoculum in the area? Are there other pests that are active in the winter that are of concern?

Although there may be few insects flying in the winter, the wet winter season (actually fall through spring) is a prime time for production of fruiting bodies by many wood decay fungi. The combination of fresh pruning wounds (especially large wounds), high spore densities of wood decay fungi, and moist conditions (favoring spore germination) can […]

After taking down a P. ramorum-infested bay tree, can the foliage be left onsite to decompose?

Once down, spores from bay foliage will not travel nearly as far as they do in the canopy. The concern on the ground is that infested leaves, while still fresh, could have spores picked up during a wet event from soil splash onto the trunk of the tree. So, spread bay foliage in a thin […]

Can the Garbelotto lab analyze wood chips for pathogens?

The lab can, upon request, analyze wood chips at cost ($90 US dollars per sample).  Testing would confirm the presence or absence of any known dangerous pathogens.

TreeFAQs

Tree Health Answers and Questions. Ask the experts any questions about tree health, diseases, and management.

What can I plant under my oaks?

As a general rule, avoid planting under the canopy of oak trees. It is recommended that you remove non-native plants from under oaks but avoid disturbing the soil or drainage patterns in the process. If you need to plant something, choose species that require similar soil types and watering. Avoid azaleas and rhododendrons as they […]

When should I remove a tree?

Tree removal is most likely required if the tree is a hazard to property, people, or places where people congregate (paths, camp grounds, etc.) Bear in mind that individual limbs may be more of a hazard than the failure of the entire tree. A certified arborist should be consulted to determine whether tree removal is […]

What is Sudden Oak Death?

SOD is an exotic disease caused by the microscopic pathogen Phytophthora ramorum, estimated to have been introduced into California 20-25 years ago from unknown region of the world. P. ramorum was unwittingly introduced into California’s natural landscape when infected ornamental plants, such as Rhododendrons and Camellias (which carry the disease), were outplanted into the environment. […]

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