SOD Blitz 2013

I recently attended a lecture at University of California, Berkeley (UC Berkeley, or Cal) by Dr. Matteo Garbelotto, to summarize the results of the 2013 SOD Blitz. Dr. Garbelotto is an adjunct professor at UC Berkeley. He received his B.S. and M.S. degrees in Forestry from the University of Padua, Italy, and then completed his graduate and post-graduate work in forest pathology at UC Berkeley. He has been studying SOD since its discovery in California, and is an engaging speaker, making information accessible for both scholar and community. Fittingly, the lecture was held under a mature oak tree outside Tolman Hall on the UC Berkeley campus.

SOD Blitz—or Sudden Oak Death Blitz—refers to an event where professionals and trained “citizen scientists” join forces to fan out over Northern California, look for evidence of Sudden Oak Death, and gather specimens. The specimens are tested and analyzed in the lab. In this way, a lot of field data has been gathered in the last six years to study the introduction and spread of SOD in California. Data is published online, and available via a free app for Android or iPhone. Professionals include USDA Forest Service and the UC Berkeley Forest Pathology and Mycology Laboratory. SOD Blitz also refers to community outreach to inform the community about Sudden Oak Death.

Symptoms of ramorum leaf blight on California bay laurel. Photo by Joseph
O'Brien (Creative Commons Attribution 3.0 License).

Several items interested me. In general, the overall infection rate of tanoaks and live oaks decreases after a dry year, and then spikes after a wet year. However, a comparison between 2012 and 2013 research shows some deviation - increases were observed in two colder areas, and decreases in hotter areas. This supports observations that the disease operates differently between coastal forests and inland forests. Infestation typically happens during the spring rains (March, April, May), and not the early rains in November, December, January, February), so you should avoid pruning during spring rains.

Plants such as bay laurel, Rhododendron, and Camellia are intermediate hosts for Phytophthora ramorum; removing them from the presence of a high value oak can reduce chances of its infection. Use of phosphonate to treat healthy oaks is very promising, but they are reevaluating delivery mechanisms, since plugs may cause damage to the trees. Additionally, Dr. Garbelotto observed that the disease is relatively slow moving, which is giving scientists a chance to study it. These lectures are offered periodically and well worth your time.