 Well, thank you very much. Can you hear me okay with this microphone? Okay. Well, you have to ask yourself, barley yellow dwarf is a disease, and so why am I an entomologist talking about barley yellow dwarf? But the main reason is that the way we manage yellow dwarf is to work on the aphid that spreads the virus. So that's why I as an entomologist am spending this time on barley yellow dwarf management. Barley yellow dwarf that we call it, I kind of put it in quotes, it's really two different diseases. Not only they more or less have the same symptoms within the wheat, it also attracts oats and some of the other crops, but I'm going to focus on wheat. So one of them is called cereal yellow dwarf, and another one is called the barley yellow dwarf. I'm just going to try to remember to refer to them as yellow dwarf diseases, but the symptoms are the same, the management is the same, but the virologists who work on this disease insist they're, you know, it's actually two. What goes on with barley yellow dwarf, with the yellow dwarf viruses is that infection with them, it affects the photosynthesis it messes up how the products of photosynthesis are translocated up and down the phloem. You end up with stunted plants, the tops are stunted, the roots are stunted, which is very critical which means that you have a lot of problems because of that reduced tillering, the whole nine yards of things that would affect the kernel weight and the number of kernels and all that sort of thing. And in some cases if it's bad enough you can see yield lots of up to 80%. So this thing can be a big problem. Mostly what happens is that it's a sneaky disease. It'll be out there in the field but it won't be dramatic like having your field wiped out by army worms or wiped out by Hessian fly, but year in, year out it probably is responsible for more yield loss than our other insects that get on, that cause problems in wheat. And a survey that Hank Van Riesen did years ago, the average percent yield loss was what you can see there, 33 to 39%. So that's quite a lot that you're just subtly losing just from this disease. So I want to show you a few pictures of it and then talk a little bit more about how it's spread. You can see from here the yellow dwarf symptom, the yellowing of the leaves, especially the upper leaves. Sometimes the leaves turn red. It depends on the variety that you have of the wheat. Here's another one where it's turned red. So as I said, these yellow dwarf diseases routinely reduce wheat yield but we can manage them. So what I want to talk about today is the best kind of management strategies for handling this insect and handling this disease and the key to, I think the understanding a little bit more about the aphids that bring it in and how they bring it in and how they spread it will help you understand a little bit more about that. So it's not a hopeless problem or a really tough problem to handle like the sugarcane aphid or the sugarcane beetle. It's something that's really easy to manage and everyone who grows wheat should be managing for this insect. I mean for these insects that spread the disease. So what are the players? We've got two different viruses that spread it and each one of those have several different strains. We have several different aphids that will be involved in vectoring the disease. In red I put the ones that are most important in Alabama. We have two strains of the viruses. We have our PAV and RPV and as far as the aphids that get on wheat there's like six of them that we do find on wheat but two of them really, the race root aphid and the bird cherry aphid are the primary ones that are causing, that are involved with the spread of these viruses. These aphids, I put three of them on this slide you've already seen the corn leaf aphid up in the upper right that Scott showed that picture. It's a known vector but it's timing of when it occurs in wheat seems to make it a very minimum player in this. The two big ones are the bird cherry aphid up there on the upper left and the little rice root aphid down here. Now the rice root aphid is sneaky because most of the time it's feeding on the roots as you can tell from its name and sometimes it'll come up and feed on the base of the plant. So what happens? How do we get started with this whole problem with Burley Yellowdorf? Well the aphids bring it in. This is a slide that I stole from Ames Herbert who stole it from Dr. Harrington in England but just so you remember that there's certain stages of these different aphids have a winged form and they come flying into the field and in the process of coming in to colonize that field that's how they bring in the virus. When did they bring in the viruses? This is a very busy slide but what I want you to take home from it this is the suction trap we had up in Guntersville who ran it for several years. We're doing the number of aphids we trap per week so it's set up as the dates at weeks after September 24th so basically we wanted the fall season over here and then it goes on and then the harvest season of wheat will be about here. See that corn leaf aphid, it's much more common and we find it flying around much more in the summertime when you might expect it since corn and sorghum are some of their hosts. But you can see that these aphids are starting, they're bringing the aphid, they're flying and we're catching them even into December but most of this activity is occurring then there seems to be a lull when it's colder. We don't find them flying up here high in the air where we can catch them in the traps so these aphids are definitely a period when they come in and they tend to come in in a sequence they tend to come in in a sequence, the green bug which can cause some direct damage to wheat on its own but does not spread the southern strains of barley, yellow dwarf and cereal, the yellow dwarf viruses tends to come in earlier and then the rice root aphid and the bird cherry oat, we find them, they're coming off whatever hosts they were on and then they are also out flying around and available to colonize wheat. Only a small percentage of the aphids these winged aphids are going to be carrying the virus. My graduate student did some work on this and it was far less than 1% and a 3% infection rate would be very, very, considered very, very high in terms of these aphids, how many of them are actually out of the virus inside their body and they're capable of transmitting that virus into the plant as they feed. So it's only a very, very small percentage. So this is meant to be my wheat field. I don't know if you can see that with my nice reddish brown Piedmont soil and then I've got some little green plants there. Now, the white circles, those are going to be aphids that are not carrying the viruses and the yellow were the aphids that came in. So pretend that all of those aphids land and start feeding on the wheat plants there. So there's only just a few. They may tend to be around the edges more than in the middle of the field just because of the way they're flying their small insects and they're flying in and they're caught on wind currents and stuff and they often will land in the shelter of a hedge row. So you might find them more often on an edge of a field, particularly if it's got woods all around. Now, this is not a serial aphid, but this is showing what's very common when you go out early in the fall when the wheat is just coming up and you look and you'll see a winged aphid sitting there and that winged aphid will have a bunch of babies surrounding her just like this big potato aphid here has got these little babies. And if you look closely, she's giving birth to a baby right there. They give birth to the living young and it doesn't take long before they grow up and start having babies on their own. And so as Scott mentioned, these aphids in general have a very large reproductive potential. So anyway, so here we have the virus beginning to replicate in the plant if the aphid feeds on it and that virus gets in the plant. It's going to start growing. We've got aphids that are growing right on that plant and after a certain period of time the tighter, what they call the tighter, the amount of virus in that plant is going to get high enough so that these aphids that are on the plant can pick it up as they're feeding these babies of that winged adult that originally started there. And they can take that virus and if they walk to another plant, you see they can move and they can feed on that plant and then infect that plant. So what we have is the first stuff that comes in with the winged aphids. We call that the primary spread of the virus and then we have these wingless aphids that are going to be moving around and spreading the virus from there on out until the next batch of flights, some more flights of winged aphids occur. So as I said, most of this within-field virus spread is going to be due to these wingless aphids. So after a while you can imagine that what might happen and now pretend that these yellows are showing infected plants within our wheat field you can see that these areas depending on how the aphids move will start getting bigger and you could imagine that you would have different patches. So I think this next slide is hopefully you're going to be able to see that there were actually a lot of patches in this field. If you start looking, there's little hits here. They call them yellow dwarf hits so you can see there's one there and there's another one here. Now they don't they're in a place that's not like every single plant and every single tiller is going to be yellow but you'll definitely see concentrations of yellow color that's sort of a, probably all of that is responsible that hit, what we call that barley yellow dwarf hit, started with just one aphid. Now the earlier a plant is infected the greater the yield loss the more that individual plant is going to be affected, it's going to be more stunted but also the greater the yield loss even to the entire field because if it becomes infected early and then aphids feed on it and then move to other plants in the field the chances are greater that there are going to be still more infected plants and more yield loss. So early infection is a lot worse than a later infection and that is key for when you think about if you think I'm going to tank mix and insecticide because I have to go across the field anyway there are times when that would make sense and there are times when that would not make sense because of this. Now aphids are very cold-blooded so the warmer it is the faster they're going to grow. If you get down below about 50 degrees they're not going to be reproducing they're kind of going to be sitting there. So for a good portion of the winter time and I think Scott and we have talked about this is that the aphids that come in in the fall if there's not a lot of warm weather are going to be more or less the aphids you have later on towards the end of winter. They may have reproduced a little bit if we get a warm spell it's obviously going to depend on Brenda's climate phases like if the ones that were predicting a warmer winter in your region you would have a greater chance of aphid reproduction happening but generally you have to remember that we're growing wheat where it's warm for a little bit in the fall then it gets fairly cold and then it warms up again. So we always remember that the aphids are because they're cold-blooded they're just limited in how fast those populations will increase. This is an example from David Bunton talking about the effective planting date on aphid numbers in the winter wheat and in this particular case he's got three planting dates and notice this red one. So if you plant early you're going to end up with more aphids in the fall. I do a little line here sort of at December 1st and then you're going to have sort of and then you're going to have in the springtime when these aphids do start building up because you had more here you're going to have more throughout the season and the later you plant so this one was a November 17th date and this was the December so that you can see that there's fewer warm days and there's less time for aphids to grow and develop. Here's another example I actually had more development in the fall it must have been warmer so in this particular year there were more aphids occurring in the fall and ready to start reproducing and moving around once the weather warmed up towards the late winter and early spring. Now I put this in because I want to say that I am not saying plant late because if you plant late you'll avoid aphids and I didn't show you the slides but you would also have much lower levels of yellow dwarf virus at the end of the season with late planting. There's a point where if you plant too late and I think you guys did you talk about that yesterday Brenda about planting date at all? Brenda's got a great publication about that that you should look up and you don't want to plant your wheat too late because you will be losing a lot of yield potential that way so I have just put this in to remind myself that even though I'm saying that later you plant the fewer aphids you have you have to keep in mind the best times for planting wheat in terms of getting your yield and this is what these dates are right here so you can see whatever it is for your particular region. So we can kind of see that the number of aphids we have in the field before winter is going to depend on several different things. We've got the planting date itself, we've got the number of the aphid flights that we have and the number of flights and how big they were, how many aphids came in and the weather, whether it was favorable or not for the buildup of aphids. Natural enemies also come into play here sometimes natural enemies can clean up an infestation of aphids in the fall. And as I mentioned the risk of the virus spread is also going to depend on the number of these aphids that you have that actually are carrying the virus itself and that can vary from year to year. Now we've got a problem with our aphids in that they are very hard to scout for. They're often on the undersides of the leaves. The undersides of the leaves are a long, long way down and the older I get the further down they seem to be. And the rice root aphids are very hard to find a lot of times they're underground most of the time anyway. When the weather's cold even the ones that might have end up on the leaf when these plants were getting bigger those things are going to be down near the base of the plant too. So it's very, very hard to scout for aphids and as you know if anyone, if you've ever heard me give talks or anything you know that I'm always talking about make sure you, you know how many insects are there you need to scout and you need to know how many are there and if there are enough then that's the time to spray. So that's not what I say about burly illidwar virus because it's very hard to scout for them to get accurate numbers. So what are we going to do? More years than not it's going to pay to control the aphids that are spreading burly illidwar virus and serial illidwar virus. Now you might not, if you spray there might be years where you don't win and there might be years where you win but overall you're going to come out further ahead if you try to control those aphids in some way. Various methods have been proposed with the three most common ways to think about controlling your burly illidwar, your aphids that are spreading the illidwar viruses are to use an at planting seed treatment to apply a foliar application of insecticide in the fall about 30 days after planting or to apply a foliar spray sometime in the late winter or early spring before the aphids really get going again in the spring time. Picking, you need to sort of pick which strategy is going to be most likely to pay off in your situation. Now Scott Stewart has some beautiful data on this from Tennessee so I want to start out with his data because it brings several different concepts into play here. So this data Scott that you've been doing right where you've been applying your insecticide sometime in the late winter, late January early February sort of. He's got the number of years here it's got the number of bushels per acre increase over the untreated control. Now what you can see here is in most years you're going to have a positive thing here, positive return. Average was 6.2 bushels per acre. Now you notice that that wasn't guaranteeing that you were going to get 6.2 bushels per acre more every year but on average that's what you had. So some years it was less, some years it was more but overall it paid to put on that application to kill those aphids in the winter time. Comparing that, I'm sorry I hope I didn't hit somebody in the eye when I just did the pointer instead of the, there we go. Compared to the seed tree but here's also a slide from Scott where they had data back to 1993 which is a huge data set showing that on average his mean yield response was 3 bushels per acre. So in Tennessee on average when you look at that you come out farther ahead if you're only going to spray once to control those aphids you're better off controlling them in late winter. So what are we talking about in terms of thinking about those fall versus the late winter treatments? I've mentioned this already and talked about this but I just want to reiterate that there's very little of the aphid reproduction and virus spread between about 30 days after planting and between this green up when the aphids start reproducing again and depending on when you plant there may be like no time for aphid buildup if you're planting late and then it turns cold right away. The best time for the foliar treatment might vary from crop season to crop season. So in some of those years and Scott I think in your email you mentioned that okay if we treated perhaps in the fall one year we might have had more return or we might have had less you know it just depends on when those aphids come into the field and how many of them there are but the key is to control those aphids before they start to have that increase in the spring because that increase when the populations can grow so rapidly of the aphids in the late winter and early spring and that is a time when they move the virus around and the virus still has time to infect the plant and affect yield. Alright I just wanted to reiterate this concept I put David Button's pictures back in here I took the early planting out of this year and just sort of showing here's like what I call the start of winter I'm just calling that December 1st. So depending on the year you might have more or less numbers of aphids here in the fall and but there's usually sort of this gap where nothing's happening in the in sort of what I call the you know the dead of winter is cold as it gets down here. So in North Alabama this is what I would be advising to do based on some of the data and I'm going to show you a little bit of that if I have time. How am I doing on time? Okay good. So for people that are planting towards the beginning of that recommended planting date I'd call that sort of a more of the early planting season I would say either a seed treatment or this foliar spray three days after planting could I would I think be the best way to go in this area and then take a look I know it's hard to scout for these aphids but take a look in February for example right before some nitrogen is going on or before you're coming across the field with the herbicide or something like that go out when it's warm and look to see if you see some aphids and if you do see aphids at that time then put on that second you might want to put on that second treatment but if you're planting towards the end of that planting window or just after the end of that planting window the chances are you're not going to have a lot of aphid build up there in the fall and 30 days after planting might take you it might be Christmas or New Years or something so you're into that area anyway where the thing to do would be to apply that foliar spray in late January to late February so again controlling those aphids but if you're tending towards a forward end the earlier end of that planting window then you might consider that the trying that fall 30 days after planting spray or using the seed treatment. I want to show you a little bit of data to kind of I'm going to go through the regions and then give you a little bit of data to back this up. Central and South Alabama it seems to me the way to go would be a foliar spray late January to late February because generally they are planting a little bit later there and there's less build in the fall. Here's an example just sort of showing that if you don't have pressure from insects you can lose a lot of money by using an insecticide and seed treatment on wheat. It's not like corn where in the southeast some kind of insecticide seed treatment is a good idea most of the time. So the only place where this is one of a bunch of tests that Keira Bowen and her colleagues have done here in Alabama to sort of show that the places where we see a positive return on using a seed treatment are in North Alabama, the Crossville, the Belmina areas like that. So seed treatments might well be an option in insecticide seed treatment in the north. Here's an example in Griffin Georgia where getting at that point that based on when the wheat was planted and the recommended planting dates and all the increase over the untreated, the higher bars were here where they were sprayed 30 days after planting but they also got a good return spraying when it was at full tiller, spraying when it was later in the season towards late winter early spring. What you do notice is what you do notice here is spraying and heading doesn't do much for you at all. That is because by the time you're spraying and heading you're killing at that point, it's going to be too late in terms of if they were spreading burly yellow dwarf or cereal yellow dwarf virus into the plants, that virus would not have time to replicate and effect yield. So there's really no point in trying to control aphids to control the yellow dwarf diseases much later than I would say the 10th or 15th of March would be the very latest and February would be a better time to treat. This is an example with Leonard. I don't know if Leonard is here. I'll have to tell him I showed his slide. When he was working with the extension system, he did a bunch of demonstrations in Otago County which is in Central Alabama and in this case this is where some of our data shows on these number of tests showing that you would get four bushel increase by treating in this late winter early spring time frame. This is from the coastal plain of South Carolina but we've had similar results David Button has in Georgia and Kira has had similar results in Alabama that when you get into this area where you're planting your wheat fairly late in the year, the best time to apply your insecticide so that you get fewer burly yellow dwarf symptoms here and the highest yield is going to be spring here. They were spring on the 17th of February which is very consistent with all the information that Scott has gathered over the years so I just want to show you that while there are local variations and it's going to somewhat depend on the weather that happens in the fall but generally treating those aphids at some point before they start building up in the spring is key to controlling the disease. I just want to point out in terms of insecticide seed treatments we do have several options and thank you Scott for putting this nice slide together but notice the rates here the amount of these materials that are being put on because there are a bunch of seed treatments out there. Cruiser Max some of the other ones the new one with the I can't think of the name of it but there's a lot of these that have a very very low concentration of insecticide in that mix so if you start looking at it there's lots of different fungicides on that but the pounds of active ingredient or on a hundred weight of seed of these insecticides with some of these materials are very very low. The cruiser vibrant says that I was trying to think of. So when you're looking at these make sure that you're picking ones that have an adequate amount of active ingredient per acre and these products here applied at about that 0.8 to one ounce rate are very very adequate for controlling your aphids in the areas where we've shown the seed treatments to work. As far as foliar insecticide we've had very good luck with the pyrethroids. On the winter weeks lambda cyhalothrin, zeta cyphermethrin have been very effective and relatively long lasting. Now as I mentioned and I'm just going to mention it again because this is very important spraying after for aphids after March 15th is not going to substantially reduce your yellow dwarf. The only time we're spraying for aphids later on might make sense is if you scout your weed as you're going out looking at your weed and looking at it when the heads are emerging if you saw a lot of an aphid called the English grain aphid. So if you saw 10 aphids or more per head when those heads are emerging. I'm going to show you what this aphid looks like. It's a big aphid. It's got these black corticals. It's got these black antennae. It'll be all clustered along the heads. So if you find a bunch of aphids on the heads of your plant and head emergence that would be the only time that I would recommend spraying for aphids after mid-March. And that's because these things can do direct damage to the weed itself by their feeding. I want to acknowledge that a lot of the data that we've gathered here in Alabama was, the funding was provided by the Alabama Wheaton Feed Grain Checkoff Fund. Do we have time for questions? Alright. Anybody have any questions? I guess I had a comment, Kathy, that when I've done that February spring at times of that English grain aphids in the fields and I've got beautiful pictures where when I spray them at that time there's apparently not a lot of colonization going on in the spring and they just don't come back. So if I did at that time I'd never get English grain aphids in the hills. I've seen that in the unspray. It's remarkable how long that treatment effect will last a lot longer than the insecticide will last. Yes it is. It's sort of like it's just a population dynamic thing that it just seems to knock them back far enough and so that's a good point. So any other questions? Alright, is anyone heart broken if we move on to the next speaker early?