A recent excursion into Sudden Oak Death infected lands (lots of photos)!

Lab Note #4
Mar 06, 2015


Earlier this week I joined my friend, Chris Benemann, for two days of fieldwork. Chris is a MS student at Oregon State University studying Sudden Oak Death. Her field sites are located close to Brookings, Oregon (on the coast near the southern border of Oregon).

Chris excited to be in the field!

I want to share this trip with you because Sudden Oak Death is an example of a disease caused by an accidentally introduced microorganism, Phytopthora ramorum. The organism was practically unknown until it started killing trees in California and Oregon.

Think about the last time you had a cavity or went to the dentist because of a toothache. As expected, the dentist probably said something like "If you had flossed your teeth more, or if you had them professionally cleaned more regularly, you wouldn't have the cavity". There is a reason your health insurance considers teeth cleaning appointments as preventative treatments. Similarly so, if we had discovered and researched Phytophthora ramorum before it was spread to the forests in California and Oregon, we may have been able to prevent it from becoming an epidemic (a cavity). That is exactly what I want to do in South Africa. Help us find what is out there before we accidentally spread it somewhere else where it will cause problems.

Below are some pictures that I took during our excursion!

A typical collection site, notice the soil core and her super advanced water collection buckets :D

Chris is interested in what is going on in the soil with regards to the disease infection cycle. Phytophthora ramorum, the water mold that causes Sudden Oak Death, can survive in the soil for long periods of time. Some other Phytophthora species, such as P. lateralis—the species responsible for Port-Orford cedar root rot—can move through soil and infect the roots of trees. Thus, it is important to sample the soil if I am really trying to see which species are present in the forests of South Africa.

A dead tanoak next to other infected-but-healthy-looking tanoaks.

One reason Phytophthora ramorum is so difficult to control is because it is spread 'aerially'—meaning, the spores are produced on the leaves of the trees and spread to other trees through the wind, rain or possibly even the fog. Therefore, Chris is also sampling the rain dripping out of the canopies of infected trees. She also has a bait bucket at each site. What is a bait bucket?

Bait buckets are buckets that include delicious food for plant destroying microbes (like Phytophthora species!). This is how you fish for Phytophthora species. In this project, Chris is using rhododendron leaves as baits. I intend to use similar baiting methods to discover Phytophthora species in the canopies of forests in South Africa!

Chris you need a name for this beast!

Yes you can accidentally transport Phytophthora species in the soil on your hiking boots! (Don't worry, Chris and I sanitized our gear before leaving the infected area).

I also want to sample soil for my project in South Africa. However, I am hoping citizen scientists and recreational users will want to dig holes, collect soil from their hiking boots, or scrape the soil from their mountain bike tires for sample submissions (some ideas for getting citizens involved).

Carpenterville Rd, Brookings, Oregon.

The hillsides surrounding Chris' sites are covered with dead/dying tanoak trees like these ones.

Phytophthora ramorum symptoms on tanoak leaves. More tanoak symptoms Symptoms on tanoak basal sprouts. Does it look like necrotic tissue occurs where rain drops have fallen? Rain drip from the canopy frequently infects plants in the understory. Symptoms on a rhododendron underneath an infected tanoak.

Rhododendrons are just one of the 100+ hosts (carriers) of Phytophthora ramorum —another reason, the disease is so difficult to control!

Soil, litter, baits, and water samples ready to take back to lab!

Okay, here is my take home message: Sudden oak death is an example of a disease caused by a microorganism that was accidentally introduced into forested lands in the US. The organism was practically unknown until it began killing trees in California and Oregon. The photos presented above illustrate the importance of discovering and researching similar microorganisms before they are accidentally moved around the world and begin causing problems. If you agree,I encourage you to share this lab note with a friend.

Thank you for checking out this lab note! Feel free to use the photos for your own stuff (please give me credit if you do), or you can contact me for original versions.

Special thanks to Chris Benemann for a great time in the Sudden Oak Death wonderland of Oregon!

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