The pathogen that causes sudden oak death tends to spread during rainstorms, so with forecasts of a wet winter ahead, now is the time to apply a protective treatment to trees in high-risk areas.
According to Katie Palmieri, the public information officer for the California Oak Mortality Task Force at UC Berkeley, spraying the protective substance directly onto the trunk of vulnerable oaks is the easier method.
Injecting the spore-fighting material directly into the oaks is more complicated, in no small part because the process is a little different for each tree.
The California oak Mortality Task Force has developed guidelines and an instructional video to aid homeowners in the proper application of Agri-Fos as part of the resources available at their website. Below is an illustrated explanation of the pathogen that causes the disease, how it spreads, and the way it affects the trees that get infected.