Sudden Oak Death in California

If you aren't from California, you may be unaware of the Sudden Oak Death blight that is devastating the northwest. I came across this article from ScienceDaily & even though I am a Yank, I am still saddened by the struggles of indigenous tree species as they fight to reclaim the dominance taken from them by introduced European diseases.

One of the most hazardous elements of introduced species are the new, exotic virus strains that might come along for the ride, wreaking havoc on the unprepared ecosystem. New diseases can wipe out an entire species in the matter of a few years, like what happened to elm trees & chestnut trees in New England.

Sudden Oak Death (SOD) is sweeping through California, decimating the oak & tanoak populations there. SOD is caused by the pathogen Phytophthora ramorum, which manifests itself on the twigs & leaves of more than 100 species of trees.

It's important to be aware of diseases affecting plants in our local area so we can manage the spread. Fungus & diseases that affect plants are hard to manage & control because of the ease of transmission & the ferocity in which the virus attacks its host & like any virus, they can mutate. P. ramorum produce spores that travel through the air & have the ability to swim in water & withstand harsh conditions. One of the major mechanisms of mobility is rainwater splashing pores onto susceptible plants. It would be very easy to walk over a muddy forest floor & track spores back to your neighborhood.

Contrary to its name, Sudden Oak Death affects many other tree & shrub species including California Bay Laurel & rhododendrons. Some infected plants show evidence of cankers bleeding tar-like sap, wilting roots on new shoots & brown leaves on the branch.

One way to prevent the spread of Sudden Oak Death is to reduce the introduction of ornamental plant species in your yard. This fungus can be accidentally spread via firewood, leaves, twigs, bark, acorns, & soil. If you are visiting an area known to be infected by Phytophthora ramorum, be mindful to not remove any foliage, as you may be responsible for spreading the disease to healthy trees! Washington state knows how easily & how accidentally an infection can spread:

In June 2003, Phytophthora ramorum, the causal agent of sudden oak death was confirmed for the first time in Washington. Infected rhododendron plants were shipped to a Des Moines nursery from its affiliate in Clackamas County, Oregon.

Luckily, the outbreak was contained & after a thorough study, know known cases of SOD were discovered outside the nursery.

I am always saddened with giants of the forest are felled, by man or otherwise. Chestnuts in my local forests are nothing like they used to be, struggling to grow more than two inches in diameter where the once dominated the forest.