(Jim) I am Jim Shroyer, Extension Wheat Specialist, Kansas State
University. (Erick) And I am Erick DeWolf, Extension Plant Pathologist also for Kansas State University. This is our County Extension Demonstration Plot Tour season and we visit all the County Extension Variety Plots and so far this past week we’ve been to Harper, Barber, Kingman, Pratt, Edwards and Kiowa County. And today we’re in Sumner County looking at the plots here. And what we’ve seen this past week is a lot of short wheat. Anywherefrom very drought stressed… we’ve had drought stressed wheat, we’ve had heat stressed wheat, we’ve had freeze damage, all in the same field. And what basically we’re seeing this year is that a lot of very, very short wheat, small head size and that’s going to lead to fewer kernels per head and of course much lower yields than the farmers would like to see. (Erick) The other thing that we’ll often talk about at a lot of these variety demonstration plots is what the disease situation is. And this year it’s been a pressure type of situation. Some of our major diseases that we’ll often face in Kansas – leaf rust, stripe rust are largely absent this year, have been absent, not only here in Kansas, but throughout the region. And it’s largely been those dry, hot conditions that have held these diseases in check as well. Jim, you know some of the things that we’ve been having growers ask us about is just how does wheat deal with the drought and the heat that it’s been under? You know we’re kind of amazed that the wheat is looking… that it’s held on as long as it has. (Jim) Well, let’s go back to the fall. I think some of the reasons we’re having some of the problems that we’re having right now was set up last fall with dry conditions here in the central part of the state, south central, central part of the state, it was much dryer than normal and the wheat it was almost like western Kansas. Historically western Kansas has problems with stand establishments. That was the problem here in the central part of the state, so I think the wheat didn’t come out of the ground quickly. It got shocked by the cold temperatures in the fall and then we had really cold temperatures after the first of the year. But to answer your questions – one, we end up with shorter plants, smaller head sizes because it’s drought stressed when the head size is being… was being formed. And then we have, if the drought lasts long enough, then we start losing tillers. And as we saw last week,
the plants were brown from 2/3 down from the head. So, there weren’t very many leaves left for those grain to develop. And the flag leaf. You know, this year, this is a fairly good size flag leaf. Last week we were seeing flag leaves about three inches long. So, basically the photosynthetic factory for the plant is not there. So, that’s what we end up with fewer heads, fewer grain, lower yields. (Erick) The other things that a lot of growers were asking was just having to do with will the grain fail if there is any rain to be had? (Jim) Exactly. Basically, will rain help at this particular point? Yes, rain will help clear up to the early node stages. So, anywhere from boot stage to the node stage, any rain will help. But the later it goes the less it will help.
(Jim) I am Jim Shroyer, Extension Wheat Specialist at Kansas State University. (Erick) And I am Erick DeWolf, Extension Plant Pathologist for Kansas State University. You know Jim as we’ve been doing a lot of programs here in the south central area a lot of farmers have been asking us during these programs what’s the chance if we do get some rain that a lot of this drought stressed wheat will go ahead and fill its green. (Jim) Rain would be good at any time, okay, we don’t usually worry about too much rain in the course of the year. There have been some years we wished it would stop raining but this year is not one of them. And really Erick you have to think about is the peak water use of the plant. The peak water use of wheat is somewhere just before heading, boot stage, early boot stage to late milk, early soft dough, so really at flowering and that first 10 days after flowering is probably the peak water use. Now we were just looking at this particular head just a second ago, and it flowered about 8 to 12 days ago somewhere in that ballpark, so it still has about 20 days to go. And it’s really not… it’s just building the structure of the kernel at this particular point. So from about 10 days on, it starts putting materials into it, starches, protein and that sort of thing. Day 16, 17, 18 we’re at milk stage, so at that particular point you’re just about half way done through the filling process. So, to answer your questions – yes wheat in this particular stage if we were to get an inch or two of rain that would be what the doctor ordered, that would be wonderful. But what’s probably going to limit us is head size, number of kernels per head have already been determined. So really at this point the kernel weight or size is the last thing to be determined. Now, if it doesn’t rain, we’re in trouble because these kernels here are going to be smaller, shriveled maybe even aborted and so we’ll have that tiller type loss. So, really we’re in the peak watering use in this area, so rain would help. It would go ahead and fill, help fill the kernels we have. So, I’ve got to ask you a question what about diseases from this point on? (Erick) Well, the diseases have been largely absent this year. We’ve talked about the absence of leaf rust and stripe rust and a lot of these programs for the most part even to our south Texas, Oklahoma have not reported any of these rust diseases that historically survive in the southern United States and then move into our crop and can become established around the flag leaf emergence or heading stages of growth. Since we’re not seeing them already established prior to flowering in these early stages of grain fill I think even if they were to arrive late… (Jim) Might outrun it… (Erick) The crop should outrun it and be able to finish, go ahead and fill without any threat for disease losses. (Jim) Now, I don’t want to be overly pessimistic here, but you know we haven’t had any rain or very, very little up to this particular point. What I’m afraid of is that, this is the pessimistic part, is it’s going to start raining right at harvest time. So, when that happens we run into potential some sprouting problems, some other, maybe some late season diseases. What would be problematic at that particular time? I am thinking more about volunteer wheat and that sort as well. (Erick) Sure, sure. Well another aspect that we might think about if we do get into a situation where we have drought stress wheat that has really small kernels, you could have a lot of wheat that’s blown out of the back of the combine, or even fields that are just ending , and that sets the stage for volunteer wheat, that could be a green bridge or allow wheat chromite and wheat streak mosaic to really become established during those summer months and… (Jim) Hessian fly. (Erick) Hessian fly and really set the stage for some of those insect and disease problems for, not this year, but next year’s crop as the new wheat is emerging as that volunteer wheat is sprayed or persists into the fall months.
(Jim) I am Jim Shroyer, Extension Wheat Specialist at Kansas State University. (Erick) And I am Erick DeWolf, Extension Wheat Disease Specialist for Kansas State University. (Jim) You know the last week or two we’ve been getting a lot of questions about white heads, wheat turning white. There are several reasons- some of the more obvious are heat and drought, but there’s others as well. But what we have here- we have some freeze injury symptoms. You can see the feathery look. Probably what happened in this particular case is that the wheat head was just coming out of the boot stage and just had cleared the flag leaf here and we had that freeze. But also, some heat damage. You can see the tips of this particular head, the top of the head here the flora has been damaged and finally over here you can see the loss of… the brown leaves, loss of tillers and some white heads. Well, there is some freeze in there as well. But there are some other things that can cause white heads that are not heat or drought. (Erick) That’s exactly right Jim. There are a few other diseases that can cause problems, we might think about Fusarium Head Blight or head scab. And compared to the freeze injury we have groups of spikelets or groups of the mesh, the berries that are attacked by the fungus. In this case, Fusarium right around the heading stages of growth. But you often will get just groups of spikelets that are damaged or portions of the head, as opposed to the freeze damage that can largely sterilize portions of the head and you get these areas of the head that are shrunken where there’s no kernel development at all. (Jim) Now, you’ll see some pink in there too won’t you? (Erick) That’s often the case right, that Fusarium fungus does produce a lot of pink chemicals and many times you can see some pink discoloration of the kernels as they struggle to fill. The other thing that we can sometimes see is insect feeding called wheat stem maggot. And there you’ll have the entire head and the stem leading down into the leaf is completely white and if you give that a little tug, it pulls right out of the leaf sheath, where the leaf wraps around that stem, because the maggot in this case, has chewed that stem off and allows it to pull easily out of the leaf sheath. (Jim) So, those are some of the things that can cause… those are the most common things that can cause white heads in wheat. And we’re seeing, unfortunately, more of the heat and drought stress. I don’t think I have seen wheat stem maggot this year and scabs more wheat after corn and have some moisture right at firing time but we haven’t had that moisture. (Erick) I agree I think of those diseases, the head scab and insects have largely been absent this year and I think most of the white heads are either resulting from some of the freezes or heat and drought stress that we have certainly experienced this year in Kansas.
I’m Jim Shroyer, Extension Wheat Specialist at Kansas State University. And I’m Erick DeWolf, Extension Plant Pathologist for Kansas State University. (Jim) And one question that we get every time, every year, every place is, “What are the best wheat varieties to grow for my locality?” And of course, wheat yields are the big thing. And you know, a variety this year may not be the best variety next year. So consistency over a general area is always good, a few years worth of data. You know down in this area we’re fortunate we have Oklahoma State varieties to look at as well. We’ve got new wheats,
Gallagher, Ruby Lee to look at. We’ve got a few new west bred varieties, Red Hawk and WB4458. Cedars Hawk has been around a few years from West Bred is a good one, is a little short rascal, but it’s a good variety. And of course Everest has been a good variety. But besides wheat yields, now we have some diseases to think about as well. So Erick. (Erick) That’s right. So some of our big disease enemies we would be trying to face in the south central area might be diseases like leaf rust, stripe rust probably number two. Maybe in this part of the state, south central region, we might put barley yellow dwarf up there as well. And maybe a close fourth the tan spot septoria type of leaf spotting complex. So there are a number of diseases that the variety resistance goes a long way to try to hold these things in check. In some recent years some of our popular varieties, Armour, Everest have lost some of their resistance, particularly to stripe rust. Everest leaf rust resistance and barley yellow dwarf resistance is still holding up pretty well so I think some of our more popular varieties are still hanging in there although they have a few weaknesses also. (Jim) But in this particular year with the drought, the freeze, picking varieties is going to be tough for producers this year. Like our demonstration plot here, there’s probably not going to be five bushels difference between high and low, so just the yield potential this year is so much lower. It is going to be much more difficult to select varieties, so again, we’re probably going to have to look at the historic, how the varieties have done over the past few years and hope that we can forget about this year, the dry conditions and plan for high yielding varieties next year. (Erick) Yeah, that’s right. I think we will probably use a lot of our disease readings from previous years and also some of those from some of our research colleagues where they have deliberately exposed some of the wheat varieties to certain diseases and we use the rating from those plots to keep things up to date. You know Jim, one of the other things that often comes out in many of our programs and growers are asking is, “What about acid soil tolerance here in the south central area?” That might be a criteria that’s important for varieties. (Jim) Oh good point. Excellent point. Really 5.2 pH is where I start really getting really worried. And of course it would be good if everybody lined their soils when the pH got below 6, that would be probably the best bet but sometimes that Ph sneaks up on us. So, really 5.2 is that tipping point, it’s really not soil Ph that hurts the wheat, it’s the aluminum that becomes available in the soils solution. Once that pH goes below 5.2 so there are some varieties that have some tolerance to low pH, like I mentioned the Gallagher, Cedar. WB4458 and Redhawk are not quite as good as the Gallagher and Everest and some of these varieties but they have some tolerance. Obviously the worst variety on soil pH is Fuller, the K-State wheat but if you’ve planted Fuller and it didn’t do well down in this area, you’ve probably got low pH soil. So low pH soil is something we really have to manage. Liming is the best bet, adding phosphorus with a seed and then variety selection.
(Jim) And one thing that we get besides varieties and what the yield potential is going to be around the state is, “How is the wheat doing around the state?” We’ve talked a little bit about how it’s doing down here in south central Kansas. And what we’ve seen last week and this week as well. And it would have been good if it had rained an inch or two some weeks and months ago. But southwest Kansas it’s almost to the point of no return in that part of the state. However, some areas got a little rain out in that area and it will help. Really, I think that the area of the state that’s probably got the best potential and you probably agree too, is that north central moving over to northwest because, one, the wheat is a little behind and it got moisture a couple of weeks ago. (Erick) I think so, from the areas that we saw at least as far as the spring goes, is probably that central and north central areas that have caught a little bit more rain that still have some potential for yield potential. Other areas of the state that really struggled with drought and heat and just haven’t gotten the timely rains that they need. One thing that most of the state has going for it this year is that the rust disease, leaf rust, stripe rust even barley yellow dwarf and wheat streak mosaic, some of the more common diseases that we face year in and year out, have been largely absent this year. The rust diseases have been held in check by those dry conditions and
the warm temperatures. So from a disease perspective, I think we are looking at a low disease year, but unfortunately I think the drought and the heat have really hurt our yield potentials outright. (Jim) Basically what’s good for wheat is also good for the diseases that come in later in the season like about now. (Erick) That’s right a lot of these diseases are diseases of high yield potential crops, so when we don’t have the yield potential because of the drought and the heat stress, we also see low levels of disease or disease outright absent. (Jim) One thing in the western part of the state is that in the past we have had problems with the stand establishment in the western part of the state due to lack of surface moisture. They may have good subsoil moisture in the past, but not good surface moisture. Last year, last fall, it was just kind of the opposite. They got some moisture in August and into September. So they had good surface moisture at planting time so really good stands, but sub soil moisture was not there. Now there were some areas that caught a little bit of rain and some snow through the year but this has been a big… missed opportunity for some of those folks out west because they’ve got good… had good stands but then they didn’t have the moisture through the season. Again, some areas caught snow; some of that snow was coming in at 90… excuse me, parallel to the soil surface at the time so it didn’t stick around. So really again, areas in northwest Kansas a little bit further behind and moisture there will do the biggest good. (Erick) You know one of the problems that we saw in northwest or central Kansas this year was some potential for winter injury or winter kill. Kill as well. (Jim) Oh that’s right. (Erick) It’s not that everything is ideal in those areas either some of them had a hard time getting their wheat established and then also with winter kill, just struggling with cold temperature injury to the wheat. There was a lot of thin fields in that central Kansas, north central area as well. (Jim) A lot of it.