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.
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