USDA Forest Service
 

Pacific Northwest Research Station

 
 
 
Pacific Northwest Research Station
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Portland, OR 97204

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Technology to Manage Fuel Loads and Reduce Tree Mortality

Economic recovery hirees in this project are field-testing alternative approaches to reduce tree mortality from a combination of sudden oak death (caused by Phytophthora ramorum) and insect attacks. If found to be effective, this technology may provide land managers with a new method for mitigating excessive tree mortality from these organisms. Healthier forests will provide more products, services, and benefits to local communities. Fewer dead trees will reduce the amount of available fuel and lessen the risk of uncontrollable wildfire and its impacts on nearby communities. Individuals hired for these field and laboratory jobs will have the opportunity to advance their knowledge, skills, and training in the field of forest health protection. So far this project has provided employment for two individuals who have since left to accept permanent jobs as forest health specialists. A new employee is anticipated by February 2012.

This project was initiated in late spring 2010 with a search for and selection of suitable study sites in the vicinity of Novato, California (photo 1). The first field experiments were started in September after obtaining the necessary permits from the agencies responsible for managing the sites selected. So far, results from this work have shown that sapwood from within P. ramorum cankers (photos 2, 3, and 4) on stems of coast live oak trees contain much higher concentrations of ethanol than adjacent healthy sapwood outside the canker, or compared to sapwood from nearby healthy trees. The research also demonstrated that traps baited with ethanol lures (photo 5) attract species of bark and ambrosia beetles known to selectively attack inside the boundaries of the P. ramorum cankers and subsequently reduce the trees’ probability of survival. These same beetle species were shown to attack coast live oak logs when sealed holes in their sapwood were filled with ethanol solution. The researchers concluded that ethanol associated with P. ramorum cankers is the primary attractant and attack stimulant for the bark and ambrosia beetles that colonize the cankers and accelerate tree death. Others have reported that preventing beetle attacks could extend the trees’ survival by 5 to 9 years. The trapping experiment described above found that adding either a-pinene or 4-allylanisol to traps baited with ethanol lures greatly reduced the trap catch, indicating that these compounds are repellents. The a-pinene also dramatically reduced beetle attacks on the coast live oak logs with ethanol infused sapwood provided the a-pinene release rate was high enough. This project continues through 2012.

 

Click photos to enlarge

 

The yellow line marks the boundary of a P. ramorum canker on the stem of a coast live oak. Arrows point to small gallery entrance holes of bark or ambrosia beetles attacking the canker. The silver nails mark where tissue samples were removed with an increment borer.

Coast live oak killed by Phythophthora ramorum (causal agent for sudden oak death) near Novato, California.Coast live oak killed by P. ramorum (causal agent for sudden oak death) near Novato, California.

Maia Beh setting up an insect trap with an ethanol lure. Maia joined the project in August, 2010 and will start her new job with the University of California Cooperative Extension in January, 2012. Way to go Maia!Maia Beh setting up an insect trap with an ethanol lure. Maia joined the project in August, 2010 and will start her new job with the University of California Cooperative Extension in January, 2012. Way to go Maia!

Isabe Munck on a foggy day points to a potential P. ramorum canker just starting on the stem of a coast live oak. Isabel was hired as a Post-doctoral Scholar at Oregon State University to initiate this project. Isabel accepted a permenant job with the USDA Forest Service, State and Private Forestry, Forest Health Protection during the summer -- Congratulations Isabel!On a foggy day, Isabel Munck points to a potential P. ramorum canker just starting on the stem of a coast live oak. Isabel was hired as a postdoctoral scholar at Oregon State University to initiate this project. Isabel accepted a permanent job with the USDA Forest Service, State and Private Forestry, Forest Health Protection during summer 2010.

A bleeding canker on a coast live oak stem infected with P. ramorum. A bleeding canker on a coast live oak stem infected with P. ramorum.

 


 

 

US Forest Service - Pacific Northwest Research Station
Last Modified: Tuesday,18November2014 at11:49:02CST


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