Brian McCornack – Sugarcane Aphid

(Brian) Brian McCornack, Department of Entomology at Kansas State University and today I would like to give you a little bit of an update on sugarcane aphids, which is a new pest for us in sorghum. This is a new pest for us this year, we didn’t have it last year, but it has been a problem in the southern plains especially Texas and Oklahoma. It was first reported in Sumner County which is just a few miles from the Oklahoma border by Scott Armstrong at the USDA ARS in Stillwater. And again that was in late August and more recently we found some populations as far north as Sedgwick County. Of the ten fields that we sampled here last week, we found it in nine of the ten fields. So, going from very, very few fields in late August to almost all the fields that we have looked at with few populations much like we see in the picture here. Again, this is a migratory pest, so coming in from weather events from Texas, Oklahoma as populations start to build up. This is an aphid, has very fast reproductive rates, can develop within a few days and is kicking out aphids for about 15-20 days of its life. And what we saw here in Kansas at least what we’re interested in, was looking at whether or not some of these hard freezes, this hard frost were going to affect populations, some of these which we are building up. And what we saw is when it hit down to 22 degrees at least in the fields that we looked at, populations had essentially crashed. And so we look here, we can see some of the pre-freeze mortality of these dark discolored aphids, going from something that is more healthy up in the right hand, left hand corner here to these discolored aphids here along the rib. And then even a couple of days after that we’re nearly 100 percent of the population that died. So, this was a concern for I know growers in Sedgwick County that had spotted this aphids and seen some of these colonies start to build up. And one of these trigger signs that at least we look for, is these shiny leaves. And so as you’re walking through a field a really good diagnostic to see whether or not sugar cane aphids, or most other aphids that you might be familiar with, was this honey dew substance, this shiny surface. And that’s mainly because the aphids are feeding on the underside of the leaf they are depositing these honey dew droplets, and that makes that really shiny diagnostic for us to spot. And so this was pretty easy for us to see in those nine fields that we walked in. Usually within a couple minutes time, we could find some plants that had really high populations that you’re seeing here. And for most of the other plants was not a problem. But where it has been a problem especially in Texas and Oklahoma and parts of Louisiana is that there is so much dew that the augers clog and so this becomes a really big problem at the time of harvest. So there is
physiological loss where the aphids are feeding directly on the plant and causing that plant to lose some of its photosynthesis, but at the same time, it becomes a real mechanical mess when you have plants that are completely coated in sugar. But also causes a problem for some of the natural enemies, so the biological control that usually feed on these aphids, like ladybugs and lace wings. We actually have a colleague out in Hays, Dr. J.P. Michaud who is looking at some of the more native lady beetle and other natural enemy communities to see what kind of response or essentially the army that we have already can do for this aphid, and hopefully in the future. As far as the general concern for us in Kansas I don’t want to get everybody all worked up as this is a new and a well established pest. There is a lot yet for us to know. Most of which is- does it over winter? Is this something we’re gonna see early on next year. That’s something that my lab is interested in looking at primarily from the standpoint of temperature. Much like what we saw here with looking at a hard frost and the impacts on that species. But at the same time, when are we going to get this next year? What type of weather that might bring this in? When should we start sampling for it? As far as any like controls, unfortunately there’s nothing registered for it in Kansas. The Kansas Grain Sorghum Commission is working with the Kansas Department of Ag. We’re also working in conjunction with them, but they are doing most of the legwork to try to get something registered for its use in case this were to become a problem for us. But unfortunately until we can find something or find populations that are really causing some type of economic loss, our hands are somewhat tied. But we are fortunate enough this year to get some data on it to understand what its potential is here in Kansas. And actually the experiment we put out here last week, you can see we wrote on some of the leaves. This actually came from a Twitter post from a grower down in Sedgwick County. I happened to be following his extension agent in Sedgwick County, said, hey I’d like to get a colony started cause we’re really interested in learning more about this species and what the impact might be in Kansas grain sorghum. And then I think it was on Wednesday, the very next day, we were setting up cages and looking at ways of capturing some of this data using grower fields, using production sorghum fields. So for me that’s kind of been a really interesting twist on using use of social media to kind of answer some of these very pertinent questions that are facing some of our growers. Bottom line is- it’s an aphid. We know what aphids can do in sorghum especially those that have experienced green bug. But at the same time with research we can be working together towards potential solutions. What those solutions might be for sugarcane aphid really has to do with understanding when is it going to be here, how much time do we have before, between that time and harvest? And what are some of the environmental conditions that are mostly going to affect its population growth? So again, this is a great example where social media can help connect people. And so again with that grower taking the time to post a Tweet that had a picture of an infested plant got me to his farm a couple of days afterward. to put in some plots. And for me what I really like to do is on the farm research. So working with those that have that problem and finding practical solutions for helping them in the future. So, I do encourage you to stay connected with your county agents, with researchers like myself either through Facebook or Twitter. And again, stay connected in the research process.

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