Sudden Oak Death: Battling an Invasive Disease

Point Reyes National Seashore


Documentary Video Transcript: Sudden Oak Death: Battling an Invasive Disease

[outdoor sounds, such as the sound of a stream and birds singing and bees buzzing]

[ominous music]

[Narrator] Every year in the Bay Area, hundreds of oak trees are destroyed by a disease that is so quick and deadly it is known simply as sudden oak death.

This plague has killed so many trees that vegetation experts at Point Reyes National Seashore are concerned about what sudden oak death may mean for California's future.

[upbeat music]

[Jane Rodgers] When considering the possible effects of sudden oak death here at Point Reyes National Seashore, you need to really picture of what's going on in the environment. Here you've got oaks that are being lost in the understory. These oaks produce acorns that are really important to the dusky-footed woodrat as a food source. And, unfortunately, these dusky-footed woodrats are a primary prey source for the spotted owl.

Not only that, these trees are starting to die and fall down and build up fuel in the understory of both redwood and Douglas-fir forests. And we may be seeing some of the effects of sudden oak death, recently, in the Big Sur fires where there may have been an abnormal increase in fuel loading as a result of this disease.


[Jane Rodgers] Diseases is common. It is a natural process around the entire planet. What is not common, is to move a disease from one area and bring it into a completely different setting. And that's what's happened here. We've taken a disease that's co-evolved with species in perhaps Asia and the European area and brought it to the United States where we have species that are not adapted to this disease.


[Narrator] As people travel from continent to continent, they bring with them organisms that can act like diseases in a foreign land. In the 1930s, elm trees lined many streets in America. That is, until an exotic species called Dutch elm disease devastated the elm community.

[Narrator] More recently, the kudzu plant from East Asia has ravaged the American countryside with its thick and fast-growing vines. But sometimes, the most deadly species are the ones you can't uproot or cut down, because they are microscopic.

[Jane Rodgers] Sudden oak death is caused by a water mold. It's actually a brown algae known as Phytophthora. The water mold, itself, can be found on leaves of plants out on the coast of California, and also attacking oaks, uh, in the form of a bark canker. And what's happening is that the canker is actually spreading throughout the cambial layer, which is the living tissue on the outside of the tree. And unfortunately, if that disease continues around the entire trunk of the tree, it will girdle it and eventually kill the entire tree.

The disease itself attacks a variety of species, but it actually only has a really negative effect on a few types of species, and those are the oaks and the tanoak that you find in the California coast.

[Narrator] Tanoak has the highest mortality rate from sudden oak death disease than any other kind of oak tree. These trees are native to the West Coast and can be found from northern California all the way up to southern Oregon. They are an irreplaceable species and play an important role in California's forests.

However, sudden oak death may soon change all that.


[Jane Rodgers] The water mold Phytopthera we believe to come from either Europe or Asia, and the exact origins are unknown at this point. Sudden oak death disease was first detected in the 1990s in Marin County, and, unfortunately, that continued to spread pretty dramatically and rapidly throughout the area.

At Point Reyes National Seashore, we detected sudden oak death up on Bolinas Ridge, and that's the area where we continue to see infections spread. And, again, that's mostly on tanoaks that we find up on a ridge. And we're assuming that redwoods are actually the foliar hosts for that disease.

The future of sudden oak death in California, and this is beyond Point Reyes, unfortunately, is not a very positive picture.

The expansion of this disease does spread through water droplets, which, unfortunately, is a very effective means of moving around for the organism itself and makes it very difficult and problematic to control.

Here at Point Reyes, we're estimating that we've lost about 95% of our tanoaks up on the Bolinas Ridge, and we may, in fact, lose the species in the next ten years.


[Narrator] Wait a minute.

If the tanoaks at Point Reyes are doomed to extinction from sudden oak death disease, then what about all the other oaks up and down the California coastline?

Well, as it turns out, there's still hope left for these trees, and their salvation may depend upon a commonality.

[Jane Rodgers] We know that sudden oak death occurs in Marin County. We're very infested here. The disease is not going to go away.

So, what our main focus is is preventing the disease from expanding out into other counties, uh, that's in California, as well as Oregon and Washington. What we're doing here is very poactively trying to keep the disease local by cleaning any tools and equipment and any clothing that might leave this area and go to another park.

A good example of that includes our firefighting crew. Now this crew has tools, they have their boots, they have the tires of their cars, that may leave an infected area here at Point Reyes and travel to somewhere else that's uninfected, like Yosemite National Park.

Because of that, it's critical that our staff pay close attention to this and go through the hygiene procedures to prevent the spread from occurring.


[Narrator] By preventing the spread of sudden oak death to areas like Yosemite National Park, Californians are protecting the natural beauty of their state's native species and habitats. These indigenous plants and animals describe a unique tapestry of biological diversity that makes California so special and is worth defending from invasive species.


[Jane Rodgers] Sudden oak death, and the water mold that is associated with it, is an example of a non-native species that's moved from one area to another and had a dramatic effect on local biodiversity. Local biodiversity is critical to the management of not only our national parks, but of our environment. Having the full suite of species that could be resilient to things like global climate change or other non-native species that may move in is really one of the keystones of the future of these systems.

Sudden oak death really tells us the story of the effects of humans on our environment, and, unfortunately, this is playing out here at Point Reyes. We're seeing that moving things from one area to another can have negative effects. And this is only, not only, negatively affecting the biodiversity and the web of life here at Point Reyes, but it could affect the local community. We may see an increase in accumulated fuels in our forests' environments, and that could lead to increases fire frequency and fire intensity.


[Narrator] The firefighters at Point Reyes aren't the only ones affected by sudden oak death disease. The increased intensity of California wildfires may affect your neighborhood in the near future. There are many local programs and assistance funds available to help communities remove dead trees and reduce fire hazards.

For more information, visit, and connect with other concerned citizens, like yourself, who want to protect California's natural beauty and save the oak trees.

[music and credits]


In the 1990s, a newly-introduced disease was found to be killing the oak trees in Marin County. This documentary explores the story of Phytophthora ramorum, a brown water mold of foreign origins which causes the disease known as Sudden Oak Death.


9 minutes, 27 seconds


Pacific Coast Science and Learning Center / Benjamin Bettenhausen

Date Created


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