Episode 54: Phytophthoras

In the Woods - Episode 54: Phytophthora

Introduction to In the Woods Podcast

Lauren Grand: From the Oregon State University's Extension Service, you are listening to In the Woods with the Forestry and Natural Resources Program. This podcast brings the forest to listeners by sharing the stories and voices of forest scientists, land managers, and enthusiastic members of the public. Each episode, we will bring you research and science-based information that aims to offer some insight into what we know and are still learning about forest science and management.

Stick around to discover a new topic related to forests on each episode.

Jacob Putney: All right.

Meet Your Hosts: Jacob Putney and Norma Klein

Jacob Putney: Welcome back to in the woods podcast presented by the forestry and natural resource extension program at Oregon state university. I'm Jacob Putney extension agent and Baker and grant counties and your host for today's episode. I'm excited to be joined today by my extension colleague on the South coast, Norma Klein.

Norma is the extension forester and Coos and Curry counties, as well as an associate professor of practice in the department of forest engineering resources and management at Oregon state. She has been with Extension since 2016, following a 20-year career with the Oregon Department of Forestry. Norma holds a Master's in Forest Management from Northern Arizona University and a Bachelor's in Forest Management from the University of California at Berkeley.

Norma Klein's Background and Current Projects

Jacob Putney: Why don't you tell us a little bit about your background and some of the things you've been working on down on the South Coast?

Norma Kline: Thanks, Jacob. Yeah, I'm so happy to help out with this podcast today. So, we have a lot going on regards to forest health in my area, and we'll be taking a deep dive in just a moment about all those phytophthoras that are causing tree mortality. But I've also been working with my colleagues, my Extension colleagues, on a number of interesting topics designed to help woodland owners meet their management objectives.

And so, including workshops, for example, to help landowners get started with digital mapping apps, and a publication on things to consider if you're thinking about planting redwood in Oregon, for example. My colleagues in Extension, we all have all these really interesting projects we're working on.

Understanding Phytophthora: The Plant Destroyer

Jacob Putney: Well, as Norma mentioned, uh, today we're going to be talking about forest health and specifically a genus of plant damaging pathogens called Phytophthora. So, if you're from Curry County, one you might be familiar with is Phytophthora remorum, or the pathogen that causes sudden oak death.

Norma Kline: Yeah, so Phytophthoras are a really interesting genus of plant pathogens. The name in Greek literally means plant destroyer. And they are members of a group of organisms called Oomycetes commonly referred to as water molds. And so, they're more closely related to brown algae than fungi, for example. And Phytophthoras have some really interesting genes.

distinctive and interesting characteristics. One of them is that they produce a mobile spore called a zoospore, and these zoospores have a structure that allows them to swim in water. So, they, that's why they're called water molds, they get around. So, Phytophthoras also produce chlamydospore that can survive long periods in plant material and soil.

And so cataphors have both sexual and asexual modes of reproduction. So, they're Really an interesting genus. So, it's important to point out that Phytophthoras are microscopic organisms and requires diagnostic testing to know if you, if there's a plant infested with them. Phytophthoras are a significant cause of plant disease worldwide and some notorious species include Phytophthora infectants, which is called the late Phytophthora.

light of potato and tomato. And so, this is the species which led to the Irish potato famine between 1845 and 1852. Another species, Phytophthora agathida, that's called cowrie dieback is threatening the cowrie trees in New Zealand. And in Australia, Phytophthora cinnamomi. Causes die back and is a significant threat to their native ecosystem.

All told, there are over 150 known species of Phytophthora worldwide.

Jacob Putney: I had no idea that the Phytophthora caused the disease that caused the potato famine, that's really interesting.

Phytophthora Species in Oregon

Jacob Putney: So which species do we have here in Oregon?

Norma Kline: So, we have a number of Phytophthora species in Oregon. Many of them are exotic. In other words, they're introduced pathogens that cause serious disease in agriculture, horticulture, and forests. So exotic pathogens are problematic because our native forests are not adapted to them. So, in other words, our native trees and shrubs may not have any defense mechanisms against them.

Just to name a few phytophthoras that we have. Phytophthora remorum causes sudden oak death. and remorum leaf blight and shoot dieback. And Phytophthora remorum has killed hundreds of thousands of Tanoaks in California and Oregon. And it's also a pathogen that's a problem in plant nurseries as well. And so, Phytophthora lateralis causes Port Orford Cedar Root Disease and has caused substantial mortality of Port Orford Cedar in the native range of the state in southwest Oregon and northern California.

Phytophthora lateralis is easily spread via moving infested soil around the machinery and even on shoes. We also have Phytophthora syringae, which causes significant economic losses in nursery production of shade trees, for example. And so that's just really a few of a number of other phytophthoras that are unfortunately found here as well.

Jacob Putney: So, you mentioned some of them are exotic. Like I assumed that Those got here from transporting plant matter across the United States over time. And

Norma Kline: Phytophthora lateralis, the phytophthora that causes porphyrin cedar root disease, was initially detected in the U. S. somewhere, I believe, around the 1930s, and then was detected in Coos County in the 1950s in the forest lands. And how are these things getting over here? Possibly collectors of plant material inadvertently.

It's hard to track down.

Jacob Putney: so, you mentioned that these can be active in the water and in the soil, how long can they persist in both like the water and the soil? Can they stick around for a long time and be viable, these spores?

Norma Kline: So yes, since they do produce that thick walled Plamidus, they can survive for quite a long time in the soil. And you're right, they can spread in the soil, the water, infested plants, plant debris. They're especially problematic in moist areas.

Detecting and Managing Phytophthora Infections

Jacob Putney: So, say that I owned a woodland and was concerned about a potential infection. And you know, what are some things to look for that would indicate some diseases of Phytophthora?

Norma Kline: Phytophthoras can cause a range of symptoms, and these include leaf blight and wilt leaf spots, shoot dieback. Some species cause cankers and lesions on the stem or trunk of the tree. And other phytophthoras affect mainly the root system and can rot the fine roots. of a plant. So, I always encourage woodland owners to pay attention to the general health of their forest and to take note of any unusual signs of disease or mortality.

Don't just pay attention to your trees, pay attention to your understory species as well, such as the shrubs and hardwoods and see how they're doing. And so, if you do see unusual symptoms on your woodland, it's really important to take, if you can, take clear photos of what you're seeing, close up photos, if possible, if there's lesions or leaf spots, as well as a photo of the entire plant in the setting, in the general setting.

And so, if you're using a smartphone or a tablet, it’s great if you can drop a pin and label it and get that long information so we know the location. So, in terms of who to reach out to, if it's a garden plant, the OSU Master Gardener Plant Clinic in your area would be a good place to start. By sending a photo and a description, and if it's a native forest species, a tree or a native shrub, then sending clear photos and description to your extension forestry agent, that would be a really good place to start.

And so of course, I can't help reiterating here, lab testing was needed to confirm the presence of Phytophthora.

Jacob Putney: Yeah. From the symptoms you mentioned too, is it easily confused with other forest health issues and things like drought mentioned some of the leaf spots and branch dieback. My first thought might've been drought, but I guess you mentioned that lab diagnostic testing is needed to actually confirm it.

Norma Kline: That's correct. And the symptoms can be confusing. You know, there's a number of other pathogens and environmental considerations that can be causing the tree to exhibit sometimes similar looking symptoms. And if folks are observing tree decline in their area and reaching out to their extension forestry agent, Taking note of the location, taking photos, and that can all be really helpful and allow us to track down what, if it needs to go, if samples need to go to the lab, or if there are some other clear culprits that are causing that problem.

Jacob Putney: So, since these pathogens can persist in the water and the soil and persist for a while, it sounds like prevention is probably the primary focus of controlling the spread.

Norma Kline: That's absolutely correct. Prevention is really critical because once the disease is introduced into an ecosystem Control measures are very costly and difficult. So, it's really. A good practice to make sure that any equipment that you're using on your woodland on your property is cleaned of mud and vegetative debris before it arrives.

So, for example, requiring contractors to pressure wash their equipment before they move on to your property is a really good practice. And this will also help prevent invasive weeds as well. No one wants gorse on their property either, which is another issue in my area. So, it's a good practice to make sure that shoes and boots are clean.

For example, I always make sure to clean any mud off the bottom of my boots with a brush and water. And I also take an extra precaution because I am in known areas of infestation. Yeah, I spritz the bottom of my shoes with Lysol spray. You can also use a 10 percent bleach as well. There's a nice little tool as it's actually used by people who have horses.

It's a hoof pick that has a brush on one side and a pick on the other. And that's just a really nice little, small tool that I carry with me that I can use both sides to really get all the mud and debris out from my boots before I leave an area if I've gotten my boots dirty. But any sturdy brush will do the job.

It's just a really good practice.

Jacob Putney: No, I was going to say, I never thought about using a hoof pick before that. That's a really good idea. Cause for me, it's getting all of the like cheatgrass seeds, Medusa head, bentonata seeds out of my boots. That could be a real pain to get some of those tricky seeds that really dive themselves into

Norma Kline: Yeah, so it's such an easy way. A brush. It just takes a few moments and there are a number of prevention techniques as well. For example, if folks are planning restoration projects in sensitive ecosystems, it's a really good idea to make sure that any container stock is, that they're using to plant with is healthy and are coming from nurseries with excellent phytosanitary best management practices.

And so, we have a few OSU Extension resources that I suggest for folks involved in planting native plants in restoration projects. And one is a brochure called How to Prevent Phytophthoras in Restoration Planting on Your Woodlands. And another is a more comprehensive resource called Preventing Phytophthora Infestations in Restoration Nurseries, a Key to Protecting Wildland Plant Communities.

And so, both those super useful publications are available online in the OSU Extension Catalog. So lastly, another tip It is to plant disease resistant species, if available, the disease. For example, I mentioned that Port Orford Cedar is very susceptible to Phytophthora lateralis. And I always suggest that folks who are interested in planting Port Orford Cedar, they really only should be planting the disease resistant seedlings.

Jacob Putney: and have the disease resistance seedlings been pretty effective at resisting that as time has gone by.

Norma Kline: Time will tell. They've been fairly recently introduced to landscape plantings and monitoring, and it's been at this point some really optimistic results on that.

Sudden Oak Death: A Serious Threat

Jacob Putney: Let's circle back to sudden oak death. That's one that's talked about a lot and taken very seriously, especially in Curry County. So, what can you tell us about that? When was that first identified and what steps have been taken since then?

Norma Kline: Yes, sun oak death is a really serious issue in my area. It's caused by Phytophthora remorum, and that's a federal and state quarantine species. Sun oak death was First detected in Oregon in 2001, and it was described in California in the mid 1990s. So, Phytophthora remorum has many hosts, but in Oregon, the main host that's known to spread the pathogen through sporulation is tanoak.

That's, if you're not familiar with Tan Oak, the genus and species is NoHo, lithocarpus, dsa, florist. It's a mouthful. So Tan Oak is a very susceptible host and generally dies within one to two years after infection. Phytophthora morum can also infest true oaks, including California black oak and California live oak, although those species are not known to spread the disease via foliar spores’ correlation.

The wet and windy climate of southern Oregon is really conducive to pathogen spread. Once canopy trees are infested, spores are spread from infested trees to healthy trees, treetop to treetop across landscapes in the wind and the rain. And so, the rain also washes the spores from the treetops onto tree trunks, shrubs, and the vegetation on the forest floor.

And so, there's a number of symptoms on Tanoak that folks in the area of Tanoak can look out for, including bleeding kinkers from lesions on the trunk. But sometimes the first thing that people notice is that the tree suddenly dies, although, in reality, it's likely been infested for a couple years. And since 2001, there have been three lineages of the pathogen that have been detected in Oregon.

And the most recent detection was in the Port Orford area. And so, like I mentioned, sudden oak death has a number of host species, including a number of species in the heath family, such as huckleberry, salel, and rhododendron. And rhododendron, unfortunately, is another host that can spread the disease via sporulation.

There's also been a few detections of Phytophthora morum in gardens in Oregon, and most recently up on the North Coast. I believe that was in 2022. So, sun oak death, it's affecting our native ecosystem. Tan oak is an important mast producer. In other words, it produces acorns that are important for wildlife.

And dead tan oak is a fire and safety hazard as well. And the disease has economic consequences. And I always like to point out that landowners planning on shipping logs. From infested areas in Curry County need to check in with their Oregon Department of Forestry Stewardship Forester to make sure that they are complying with the restrictions because there are some restrictions about shipping.

regarding shipping out of infested areas. And so, the Oregon Department of Forestry has a really nice fact sheet on that subject called Forestry Operations Within the Sudden Oak Death Quarantine Area in Curry County, and that can be accessed on the ODF website. And so, there's also concerns that if the pathogen were to reach Coos County, there might be additional quarantine restrictions involving log export from the international port of Coos Bay.

Efforts to Control Sudden Oak Death

Jacob Putney: Since 2001, what efforts have been taken to help prevent, control the spread or stop the spread of sudden oak death? You mentioned the quarantine, but what other efforts have? Been going on down there.

Norma Kline: But there are a number of ongoing efforts, and that quarantine is a good thing for folks to understand if they're in the area because it restricts movement of post plants and soil from inside. They don't want that. Material moving outside quarantine area and interagency team has been working to slow the spread of the disease.

And so, the strategy. includes survey and detection and laying out treatment areas at the leading edge of the disease. The treatment includes cutting tan oak and sometimes other host species as well within infested areas. This is to help slow the spread of the disease from sporulation from sporulating tan oak.

And so, as I mentioned earlier, the pathogen infests the foliage and spreads, and it spreads in the wind and rain to healthy tanoaks. So, bringing that canopy of infested tanoak down, that will help slow the spread.

Jacob Putney: Has it been effective?

Norma Kline: There have been some studies that have demonstrated it has been effective at helping slow the spread of the pathogen. Additionally, a strategic plan was developed by the legislatively funded Sun Oak Death Task Force. To help coordination and collaboration between all the various agency, tribes, local government, and private landlords that are affected by this.

There's broad interest in collaboration on this topic as well. As part of my role in the extension, I collaborate on a number of community education and outreach projects, including workshops, webinars, I help write brochures. I also coordinate a citizen science project for the early detection of sudden oak death in Curry County, which is a collaborative effort with the OSU Laboldus Lab.

And so, landowners set out bucket and stream baits and submit samples to the lab. These bucket baits are deployed under apparently healthy tanoak in the rainy season. And then we have other folks who are deploying stream baits, and that's typically in the summer months. Our

Future of Phytophthora Research

Jacob Putney: So, what do you think the future holds for not only sudden oak death, but these phytophthoras, do you have any insights on the current research or what you kind of see as how these pathogens will continue to affect these ecosystems over time?

Norma Kline: concerns regarding shifts in temperature and rainfall that could influence how phytophthoras behave in our native forest ecosystems. Dr. Jared Leboldus, who runs the Leboldus Lab at OSU, is conducting research on a number of topics, including the relative aggressiveness between the various lineages of Sun Opia.

And he's also working with the USDA on work related to finding genetic resistance in Tanoak as well. Yes, there's quite a bit of research at OSU and at universities on the West Coast. Nationally, and quite frankly, worldwide, because these pathogens have such an effect on both our native ecosystems and on agriculture.

Jacob Putney: Has there been any promising results from looking at a resistance like in tan oak, for example?

Norma Kline: Early days. And so, at this point, my understanding is that they're really looking closely at finding surviving tanoak in areas that have been heavily infested, and then collecting those acorns and growing them out.

Jacob Putney: So, I'm not an expert on Tanoak by any means, but considering its native range, where else is it found?

Norma Kline: Oh, that's a great question. So, it is a fairly restricted range. It's southwest Oregon down into California. And at this point for Sudden Oak Death, that's Tan Oak in Oregon at least, is the main species that is pathogen. So that knowing the range of Tan Oak is important to know the risk.

Jacob Putney: So, is there a concern that it may not be able to slow or stop the spread throughout the entirety of the Tanoak's range? Not to be doom and gloom about, I'd note.

Norma Kline: They're the group, the interagency group is working really hard. And landowners are very concerned about it, both small woodland owners, industrial landowners state and federal landowners, and everyone is just collaborating, working together on this. It's just a really good example of a collaborative effort against an invasive, exotic problem.

Jacob Putney: We're nearing the end here, but I want to make sure we don't miss anything. So, Norma, do you have any parting thoughts on Phytophthoras or sudden oak death prevention?

Norma Kline: It seems like there's a lot of doom and gloom around these invasive pathogens. I can't help emphasize that prevention and early detection is really critical because treatment is costly and difficult and honestly not always possible. Oh,

Jacob Putney: thank you so much for sharing your expertise with us today. I know these pathogens are an important part of your work on the South Coast, and it's clear why they are called plant destroyers.

Lightning Round: Fun Questions with Norma Klein

Jacob Putney: And before we wrap up Norma, we conclude each episode with what we call our lightning round or a few questions that we ask each of our guests. And so the first one is what is your favorite tree?

Norma Kline: that's such a great question. I love Port Rupert's Cedar. Which is, I'm in the native range of it, and of course it's being infected by phytophthoras. The wood smells amazing, and it's just a beautiful tree.

Jacob Putney: Definitely. That's a good one. I always find this is a really difficult question because I feel like it's too cliche to say Douglas fir, but that's also a great one. I feel like my favorite tree kind of rotates depending on where I'm at or what I'm talking about right now. It's Western arch, of course.

Norma Kline: Ah, yes, such a cool species.

Jacob Putney: The second question here is what is the most interesting thing you in the field? So, whether in your field kit or whatever you might be bringing out when you're in the field.

Norma Kline: I am so old school. I kind of love this question because a lot of folks probably don't know what this tool is. Maybe some old timers out there. I carry a mechanical rangefinder with me for measuring distance. It requires no batteries. It relies on mirrors and a calibrated dial. It's a kind of an awkward metal piece of equipment.

In summary, it's about 9 to 12 inches long. I have this little piece of plastic tubing that I have lashed to my cruiser's vest that I have that range finder that sits in this plastic tubing. It can work when nothing else does. Thanks.

Jacob Putney: Now that is an interesting one. I can't say that I've ever used a mechanical range finder before. I usually am just pacing it out. I did recently get one of the Nikon laser rangefinder. So, I was pretty excited about that, but for a long time, I just used my clinometer and pacing.

Norma Kline: You know, I love it. I love laser rangefinders. They have so much applicability. Except they don't work very well in the freezing fog.

Jacob Putney: Oh yeah. I never thought about that, and it's been a while since I worked on the coast too. So going up and down on some pretty steep slopes and pretty rainy situations.

Norma Kline: Yeah, we have special consideration. Yeah.

Jacob Putney: Yeah, it's pretty dense.

Conclusion and Resources

Jacob Putney: And then the last question is, I know you mentioned a few of them already, but, uh, you know, what resources might you recommend to our listeners if they're interested in learning more about all things related to phytophthoras and these diseases that they cause.

Norma Kline: In addition to the resource, I've already mentioned there's a nice little publication in the extension catalog called Sun Oak Death Prevention, Recognition, and Restoration. A guide for homeowners, small woodland owners resource managers, and conservation groups. The basic information is still solid in that pub and it's available online.

Jacob Putney: Great. Thank you again for being here today, Norma. I don't spend a whole lot of time on the coast these days, but I'm always intrigued about the different forest health issues we face across the state. And these pathogens are definitely some of the most destructive. This concludes another episode of In the Woods.

Thank you all so much for listening. Don't forget to subscribe and we will see you all next time. Bye everyone.

Lauren Grand: The In the Woods podcast is produced by Lauren Grand, Jacob Putney, and Scott Lovingood, who are all members of the Oregon State University Forestry and Natural Resources Extension team. Other members of the team who've been involved in the podcast include Carrie Berger, Jason O'Brien, and Stephen Fitzgerald.

Episodes are edited and produced by Carrie Cantrell. Music for In the Woods was composed by Jeffrey Hino, and graphic design was created by Christina Friedhauf. Funding for In the Woods Is provided by Oregon State University, Forestry and Natural Resources Extension, the Oregon Forest Resources Institute, and the USDA Renewable Resources Extension Act funding.

We hope you enjoyed the episode, and we can't wait to talk to you again next month. Until then, what's in your woods?