Understanding and Managing Sudden Oak Death in California

3.2.2. Removing California Bay Oak forests—

Removing small understory California bays to reduce SOD risk to canker hosts can be justified in most stands. However, a thorough analysis of stand conditions and management objectives is needed before contemplating extensive removal of overstory California bays. For example, if oaks are already infected but have not yet developed visible symptoms (see Sidebar 2-3—Time Considerations and SOD), oak mortality could develop after California bay overstory trees are removed. If California bay is the only other canopy tree in the area, the combined loss of canopy due to SOD-related mortality and California bay removal could be excessive.

Before stage—

In areas that are not yet infested with P. ramorum, reducing or eliminating California bay canopy near oaks can reduce the overall likelihood that the stand will become infested with P. ramorum. If the noninfested stand is far from known P. ramorum sources, focus initial California bay removal efforts on understory seedlings and saplings and low branches of larger trees. California bay foliage near the ground has the highest risk of being infected by P. ramorum spores that may have been introduced via infested soil, plant debris, or water. If SOD-infested areas are close enough that P. ramorum spores may reach the area via long-range spore dispersal, more intensive localized or area-wide California bay removal efforts may be justified.

During stage—

Once P. ramorum is established in an area, reducing or eliminating California bay canopy near susceptible oaks can reduce the amount of inoculum that will be splashed onto the oaks, reducing disease risk. California bay removal can be used alone or in combination with preventive chemical applications to further reduce SOD risk. Tanoak forests—

Tanoaks near California bays are commonly the first in a stand to become infected and killed by SOD. Hence, California bay removal may be beneficial for delaying SOD establishment in noninfested stands. Once P. ramorum is introduced into a tanoak stand, removing California bay near tanoaks may slow the local epidemic. However, California bay removal alone will not eliminate risk in tanoak stands. California bay removal in tanoak stands is primarily useful: