Wheat Stripe Rust – Bethany Garbow

(Jim) I’m Jim Shroyer, Extension Wheat Specialist at Kansas State University. And I am Erick DeWolf, Extension Plant Pathologist for Kansas State University. And joining us here today is Bethany Grabow, who is a graduate student, graduate research assistantship with me here in Plant Pathology at Kansas State University. (Jim) We are in McPherson County and one of the things that I think, several of the things I think about, disease wise in McPherson County is leaf rust, stripe rust and barley yellow dwarf mosaic virus. And I know Bethany is working on stripe rust. (Erick) That’s right. Certainly stripe rust is one of the more important diseases in the state. Maybe leaf rust is a little more common or frequent causing outbreaks. But stripe rust has really emerged as a major problem here in central Kansas. So, we’ve been trying to work on prediction models and the idea with these predictive models is to try and give farmers some advance notice of when conditions are favorable for the outbreaks of disease. And Bethany’s research is to develop some of those predictive models. And I was wondering if you could tell us a little bit about some of what your early preliminary models are showing as growers looking for things that are favoring the development of stripe rust epidemics. (Bethany) Well, what I found is that in the early season, so in the fall we’re able to use the moisture conditions that are in Texas, Oklahoma and Kansas to estimate when, or to figure out whether or not it’s associated with stripe rust epidemics here in Kansas. And then also in the spring we are able to look at temperatures that are conducive and look at the accumulation of those hours over the course of that month to say whether or not we are going to have higher or low disease pressure in that year. (Erick) That’s right. So were there particular time periods you mentioned kind of winter time frames, what are some of the critical months that you think are important. (Bethany) We are finding times during the fall, so October and November and December for some of those conditions in the Great Plains. And then also in February, was another strong association. (Jim) February in Kansas, or in Texas and Oklahoma? (Bethany) In Texas, Oklahoma and Kansas. (Jim) Oh, all three, OK. (Bethany) Yes. (Jim) I’m sorry. (Erick) So I think that’s one of the great things about some of Bethany’s work here is that it’s very early in the growing season that seems to set up the whole cascade of events that seems to set those stripe rust outbreaks or epidemics in motion. So what Bethany is indicating is fall conditions, maybe things that are conducive to that fall stand establishment. Maybe the same kind of things that set up the over wintering of the stripe rust or maybe even other rust pathogens throughout the region. Not only here in Kansas but also to our south in Texas as well. (Jim) But we don’t have usually much stripe rust over winter. It usually comes up from Texas and Oklahoma, right? (Erick) Yeah, I think so. So certainly the classic example would be the stripe rust that would be overwintering in Texas. And then around that February time frame is often when we start to see the disease get out of control in Texas and even southern Oklahoma. And that’s sometimes our early warning. And that’s part of what I think Bethany’s model is starting to pick up, some of those same type of weather patterns as well. (Jim) And by weather patterns we’re talking about wind too. Wind patterns as well. (Erick) I think so, so you know, a lot of what Bethany is focused on is some of the drought indices as well, so in this case we are using them as overall indicators of just moisture availability for the crop. So it’s not that drought is associated with it. It’s actually drought is suppressing development of the disease. But it’s the presence of moisture, abundance of rain that kind of conditions that over wintering location and then favors it like you were just bringing up that movement from the southern states on the winds to Kansas to be kind of established here locally. (Jim) So a day like today, it could move… stripe rust could move pretty far, huh? It’s kind of windy. (Erick) It’s extremely windy here today. And we certainly would expect that to be able to move spores a long way. What do you think some of the factors that maybe limit the movement of wind on bright sunny days, even though it’s windy? (Bethany) Well, UV can actually decrease the spore viability in transport from Texas to Kansas. (Erick) Yeah. (Bethany) That’s one of the main ones. (Jim) So bright, sun shiny days then (Bethany) Yea. (Jim) Cloudy days are better for it? (Bethany) It can be. (Eric) So windy, stormy days sometimes where you… if you’ve ever looked at the radar and seen storm systems move up through Texas and Oklahoma. (Jim) Right, right. (Erick) It seems to be depositing all the way, all the way up from the Gulf. And those are the kind of storm systems that I think we would key in on that would be a good indicator of stripe rust moving. Of course, it’s got to be developed and out of control in some of the areas to our south to pick up the spores to move. (Jim) So you can actually go back in all the stripe rust epidemics that we’ve had and look at the weather patterns, that’s basically what you’re done. (Bethany) That’s what I’ve done, yes.Closed Captioning Brought to you by the Kansas Soybean Commission.
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