UC Master Gardeners of San Mateo & San Francisco
University of California
UC Master Gardeners of San Mateo & San Francisco

Sudden Oak Death

Sudden Oak Death Update

 On Friday Nov 1, 2013, Master Gardeners Green Mann and Lisa Erdos attended the lecture, "Sudden Oak Death (SOD): What Have We Learned” by Dr. Doug Schmidt, UC Berkeley.  He spoke about the results of the SOD 2013 Blitz in which citizen scientists go out and count the number of Bay Laurel Trees that are the vector for SOD and map which ones are carrying SOD.  As the Bay Laurel is the vector, it is really important to know where these trees are and their proximity to Tan Oaks and CA Oaks.   The lecture was packed & focused on the results up and down the CA coast. The SOD Blitzhas been happening since 2008 and is the biggest citizen scientist effort in the USA and the data is well respected.

SOD symptoms cardv2011

It was interesting that he mentioned in Atherton where lots of infected bays had been found in years past - that homeowners had proactively removed Bay Laurel trees 30 feet or so from proximity to oaks and that this year in the 2013 Blitz survey - NO new infections were found.

We found out the Oak is a dead end host and that it will not spread out of the oak. Coffeberry and Toyon do not appear to be vectors like the CA bay laurel.  “Fog” is not a ‘positive’ correlation with respect to getting the disease, nor is population density.   Recent dry spells have resulted in the disease receding - kind of going into remission.   It was interesting to find out that the disease exists in England and Europe, as well.

On the website you can look at the data, view all of the cool maps showing data by city location up and down the Bay Area & CA coast and most importantly sign up as a volunteer for the Spring 2014 SOD Blitz in your area.  They need volunteers. The SOD Blitz survey is always held in the spring when SOD is not dormant.  The schedule for the 2014 Blitz will be posted in January 2014 on the website and there is a free 'SODMAP Mobile App' for iPhone and Android.

The organism (Phytophthora ramorum) now thought to be closer to an ‘algae’, is found living on the leaf tips of the California Bay Laurel - and symptomatic bay leaves are often the first sign that SOD is in the area, generally preceding oak infections.  The pathogen spores, spread with rain and wind.  It tends to spread in the spring when the temperature and rain conditions are just right.  If it is rainy and cold in January - it is too cold and will not spread, but if it is rainy and warm enough in May - it will really spread. Leaves of the CA bay laurel stay on the tree about 2 - 2.5 years which is a long time - harboring the spores

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