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Soilborne Root Pathogens with Tim Paulitz


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Episode Transcription:

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Drew Lyon: Hello and welcome to the WSU Wheat Beat Podcast. I’m your host Drew Lyon and I want to thank you for joining me as we explore the world the small grains production and research at Washington State University. We have weekly discussions with researchers from WSU and the USDA-ARS to provide you with insights into the latest research on wheat and barley production.

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Drew Lyon: My guest, today, is Timothy Paulitz. Dr. Paulitz is a research plant pathologist with the USDA-ARS Wheat Health Genetics and Quality Research Unit in Pullman. He has been located in Pullman since 2000. He specializes in soilborne root pathogens of wheat, barley, canola, and rotation crops. Both fungal, such as Rhizoctonia, Pythium, and Fusarium, and nematodes, such as the Cereal Cyst Nematode. He is also interested in soil microbiomes and using next-generation sequencing to look at the effects of farming practices on bacterial and fungal communities. Hello, Tim

Tim Paulitz: Hi, Drew.

Drew Lyon: So, since your arrival in Pullman, almost 20 years ago, now, what are some of the key findings you have made on these diseases that you think are important for growers to know?

Tim Paulitz: Well, when I first got here, one of the questions I wanted to ask was, “Who are the players out there?” Now, Jim Cook had done a lot of work on these three main groups, Pythium, Fusarium, and Rhizoctonia. But with the development of molecular techniques around that time, we could go out and really identify them much quicker and in much more detail than just using morphological characters. So, based on that, we found that we had nine different species of Pythium that were out there. Three big groups of Rhizoctonia, and two big groups of Fusarium. Then, the next question we wanted to ask was, “Are all these really pathogenic or virulent?” So, we did a whole series of greenhouse testing and determined that of that nine species that are out there of Pythium, only about three of them are highly virulent. The other groups are probably more like wheat pathogens, nibbling the root, etcetera. And then, when we looked at the Rhizoctonia, we found we really had three different groups, there. The AG8, which causes the bare patch. Another one called Rhizoctonia or Rhizi, which is widely distributed and attacks not only wheat but other rotation crops. And then, we discovered a third one that was really more specific for brassicas or canola, and that was called “Two Dash One”. So then, after we did that, we then developed a whole series of technologies that could quantify the levels of the pathogen in the soil, using something called PCPR or Polymerase Chain Reaction. And we, through a series of papers, we actually licensed that technology to a lab down in Parma, Idaho, called Western Labs. But then that enabled us to really do a survey and go out all throughout eastern Washington. And then, asked the question, “Okay, we know who the players are. But where are they?” And based on that, we did studies and found, for example, that, that Fusarium Crown Rot, we know we have two different species. The Fusarium pseudograminearum in the air was more in higher, or higher temperature drier areas. Whereas, the chlomorum was in wetter cooler areas. So, we were able to then superimpose upon these survey distributions some of the climatic conditions and try to get a better idea of really where they were. So then, once we did that, the other thing that I’m really interested in is management. And over the years, we’ve done a lot of different work looking at different management techniques. For example, the problem with most of these soilborne pathogens is we don’t have any chemical controls for them, to speak of. It’s not like rusts, where we have fungicides. Now, we do have seed treatments. And over the years, we’ve done a lot of seed treatment testing with the chemical companies. So, for example, Vibrance was one that we had, we had tested out. So, that’s probably the only chemical option. But then, there are a lot of cultural options that we looked at. For example, seed opener disturbance, residue management, and green bridge management. And then, finally, under management, the other thing that’s been a real important part of my program is working with the plant breeders. Because I think that resistance is going to be the major way of most economically controlling these diseases. Now, we started out by trying to look for resistance to Pythium and Rhizoctonia. And unfortunately, were not able to make any progress in those. But there’s two diseases that we’re presently working on, now, with Kim Campbell. One if the Cereal Cyst Nematode, which has very specific resistance genes that we could look at. And then, the other is Fusarium Crown Rot. Both of these projects have been funded by the Washington Grain Commission. And so, I think that those are really going to show the most progress. So, that’s kind of where my work has gone in working with the growers. Then, of course, a lot of extension talks. Talking with the growers. And in fact, the good resource that I can recommend that just came out last year, was a book called ”Advances in Dry Land Cropping System”, available from extension, and also a free PDF. So, a lot of our results and findings were summarized in a chapter on that. So, that in a nutshell, is kind of the philosophy that I’ve taken, here, in working with identifying problems with the growers. And then, getting the scientific background. And then, trying to come up with some sort of management technique.

Drew Lyon: Okay. And, and in addition to these wheat diseases, I know you’ve spent some time in recent years, particularly, looking at canola diseases. One of these that’s caused some concern in recent years is Blackleg. I was wondering if you could tell us the status of Blackleg on canola in Washington?

Tim Paulitz: Yeah. That’s an interesting question. Until, maybe, six or seven years ago, the Pacific Northwest was really considered to be free of this disease. And it’s the most important disease, worldwide, on canola. It’s a big problem in Canada. Big problem in the Midwest. But we were kind of lucky in that we never had the problem. Then, in 2011, we reported a find up in northern Idaho, near Bonners Ferry. Then, in 2014, a huge epidemic broke out in the Willamette Valley of Oregon. And of course, there, they grow not only canola, but a lot of vegetable brassicas. And then, it became a big problem there. And then, in 2015, about a year later, we started to pick up finds in the Camas Prairie of Idaho, from Winchester all the way up to, to Moscow. And so, then there was a lot of concern about this disease. And at that point, a group of us from Washington State, Karen Sowers with the Oilseed Group, Lindsey du Toit, and others. We got together a team to try and survey Washington, to see whether this was going to be an important problem. And the reason we were so concerned was because this is a seed borne disease. And one of the ways that it can be moved into a new area is if growers bring in seed that’s contaminated with this pathogen. So, we picked up some finds in Okanagan Valley, I think in 2016. Last year, we picked up some more finds around Othello, Odessa, Ritzville, that area, there. But so far, we’ve been lucky in that, even though we picked it up, it really hasn’t become epidemic in the area. And that could be because of climate conditions. But I think a bigger reason is because of the quarantine regulations that the Washington State Department of Agriculture has enacted. So, about two years ago, they enacted regulations that say any brassica crop, so that could be canola or that could be cover crops, has to be certified and tested to be free of this disease. And also, treated with fungicides. And I think, in a way, that’s going to keep the disease from spreading. Because the other important part of this is we just think in terms of canola. But in the Skagit Valley, they grow probably 79% of all the brassica vegetable seed production for the country. And they’re really concerned that they keep it out of that area. Because once it gets into a seed production area, then you’ve essentially lost your market. So, I think, basically, the situation still looks pretty good. Growers are being vigilant. I’ve given a lot of talks showing growers how to recognize it. But I think even though we’re detecting a few finds, I think Washington State, so far, has kind of lucked out in that we’ve been able to keep this disease under control. Now, if it does become endemic, like it is in Idaho, then they’ll have to use fungicides to control it. And they’re using a lot of fungicides, now, as insurance just to keep it from spreading around. So that’s basically the summary of that disease. Again, very interesting example of how new diseases can move into areas where they haven’t been, and then cause a lot of problems.

Drew Lyon: Something for our listeners to keep an eye on and listen for in the future. But it sounds like we’re in okay shape, right now.

Tim Paulitz: Yep.

Drew Lyon: Thanks, Tim.

Tim Paulitz: Okay. Thanks, Drew.

Drew Lyon: Thanks for listening to the WSU Wheat Beat podcast. If you have questions for us, that you’d like to hear addressed on future episodes, please email me at drew.lyon@wsu.edu. You can find us online at smallgrains.wsu.edu. You can also find us on social media on Facebook and Twitter @WSUSmallGrains. Subscribe to this show through iTunes or your favorite podcasting app. The WSU Wheat Beat podcast is a production of CAHNRS Communications in the College of Agricultural Human and Natural Resource Sciences at Washington State University. I’m Drew Lyon; we’ll see you next week.

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