I’m Jim Shroyer, Extension Wheat Specialist at Kansas State University. And I’m Erick DeWolf, Extension Plant Pathologist for Kansas State University and joining us today is also Dustin Deisher, who is a Graduate Research Assistant working with me in the Plant Pathology Department there at Kansas State University. (Jim) We are in McPherson County today and while we don’t normally think of Wheat Streak Mosaic being a major problem, a serious problem year in and year out, it’s more like leaf rust and stripe rust and
barley yellow dwarf mosaic virus. Wheat streak is more in western Kansas. But boy the last few years some pretty bad symptoms, damage with wheat streak in the southeast part of the state. (Erick) That’s right we certainly have had some major out breaks of wheat streak mosaic right here in McPherson County, Saline County just north of here, where we’re at today. But usually that Wheat Streak Mosaic is associated with volunteer wheat and one of the things that we are interested in is, in our laboratory, is trying to predict what are the situations that really release those epidemics or outbreaks of wheat streak. And Dustin’s project in particular is trying to develop some of those predictive models. And what are some of the things that you’ve found in the early stages of your research that look like good indicators of when we might have problems with Wheat Streak Mosaic? (Dustin) Well, we’re most concerned when we have kind of cool summers that allow a green bridge for the wheat chromite which allows Wheat Streak Mosaic. So this green bridge allows… during the cool summers, allows them to find a good host and we’re also concerned with warm, wet falls that are also favoring mites and mite movements to harbor the virus. (Erick) That’s right. So I think that’s really the key there is that volunteer wheat is going to be one of the key hosts as Dustin has indicated, that’s often what we call a green bridge. And any variable, or any weather factors that seem to favor that volunteer wheat is cause for concern for our predisposing us for the risk of Wheat Streak Mosaic outbreaks here in the central part of the state. (Jim) So you can kind of model, you can set up models based on what the weather is going to be if it’s El Nino or La Nina or that sort of thing? (Erick) That’s part of the goal is we like to see how far, just how far in advance we could go to try and predict it, so we’re certainly looking at some of the summer months. Anything in particular that you think would be important? (Dustin) I just think that like hot, very hot summers we’re not going to have the pressure of Wheat Streak as much. (Jim) Because the wheat kernel mite doesn’t survive? Is that what you are saying? (Dustin) Correct. And cool air, wetter summers, that we would see volunteer wheat later on and in the late season of wheat offers that chance for the mite to jump over to a new host. And then keep the virus continuating into the fall planting season. That’s what we need to worry about. (Jim) I know that when I… whenever I go into an area like now, we have hail damage in this Moundridge area, I automatically think, OK hail injury we’re going to have a lot of shattering, we’re going to have lots of volunteer wheat, but only if the growing conditions allow for it. (Erick) Right. So, it’s some of those observations of agronomists like Jim that have also tipped us off that hail damaged wheat, pre-harvest hail damage puts a lot of seed on the ground and then sets up the whole situation for a high risk of volunteer wheat which can set the risk for the Wheat Streak Mosaic at a high risk also. So what are some of the prospects of looking for using those hail reports that are recorded by the National Weather Service. Do you think that might be a possibility of something we might consider as well? (Dustin) Definitely. It just ultimately depends on when these hail events happen and if they’ll..if the kernels are viable to shoot up volunteer then we’re definitely worried about that. So, we kind of have to look at a specific time frame of that. (Erick) So how long after flowering does it take before wheat seeds become viable? Is it the hail that happened here seven days ago? (Jim) As he was talking about that I was just thinking, was this hail that we had a week or so ago, was it too early to do… to cause some problems, with wheat shattering and volunteer wheat? Really, basically it takes the first 10 days to make the length of the kernel and after the 10 days, probably in the single digits to virtually no survival. But from that day 12 to about day 18 it goes up exponentially well, it goes up percentage wise quite a
bit. So that by milk stage you’re probably 50 percent, right at 50 percent germination. And obviously anything later than that, now you’re approaching mature seed.