Recommendations for Sites with Sudden Oak Death

If Sudden Oak Death is Present in a Portion of the Property, Remember to:

Schedule all landscaping and construction operations to occur first in the SOD-free area.
Ensure that equipment is cleaned after work in the SOD infested area.
Minimize all activities and operations in the Spring. Fall is the best work to avoid spreading infection through disturbance. Pruning of large branches and stems in multi-stemmed oaks should occur possibly in late November, and never in February-June.

If the property is downwind and down slope from a dense mixed forest with significant infestation, ensuring that water runoff is properly channeled may be beneficial to avoid spread of the disease by water.

Oaks that have a buffer area of at least 30 feet around the main trunk, devoid of any bay laurels or rhododendrons, are less likely to become infected. Identify valuable oaks and clear a 30-foot area around them by removing all small and medium bays, or by pruning large bay laurel branches of large trees that may come into the “buffer”. Bay laurels need to be treated with systemic herbicides at least a couple of weeks before being cut down, to minimize re-sprouting.

Avoid all overhead irrigation and summer irrigation near oaks.
For oaks over 32″ in diameter, clear to as much as 50-65 ft.

If oaks are not infected, they can be protected with a single yearly phosphite treatment in November and early December. If treating in the Spring for the first time, repeat in the Fall and switch to a single yearly Fall treatment.

Treatments are not a cure but will increase resistance in about three quarters of treated plants.
Phosphite treatments have no known damaging side-effects on the environment and their action enhances the natural defense mechanisms in the plant.

If injecting the product, we recommend alternating with bark applications every other year, to minimize wounding.

No chemical treatment of bay trees is known to be effective, and (so far) other treatments of oaks have been shown to be ineffective in controlled experiments.
Lesion removal from oaks is still untested and could have unknown side effects.

Dead oaks represent a significant hazard to people and property and increased fire hazard.

Oaks that are infected by SOD and are apparently green may be equally hazardous. In SOD-infested areas, monitor oaks closely and tanoaks that are near homes, access roads, paths, yards, and play areas, and remove trees that show significant SOD symptoms and may be hazardous due to their location.
Dead standing oaks, whether still green or brown represent a serious hazard for homeowners and are documented to fuel hotter fires that can kill medium sized redwoods.
There are no known resistant cultivars of live oaks available.
Species of oaks in the white oak group are not susceptible (Valley oaks, Blue oaks, Oregon oaks).