Protecting your corn fields from insects (From Ag PhD #1157 - Air Date 6-7-20)

All throughout the growing season, we want you to be scouting your cornfields for insects. So, today we're going to talk just a little bit about some of those bugs that you may see out there. The bugs we're going to run through, and roughly from early in the season to late in the season, include cutworms, armyworms, stalk borers, grasshoppers, then we get to European corn borer, western bean cutworm, I remember back in 1997, the first year that we were doing filming out in the field for Ag PhD, and we got a call from a farmer who said, I've got some cutworms out here, would you mind coming out to take a look? And I said, sure. We got out there, it was overcast, it was cool, and it was damp. And all the cutworms were out on top of the ground during the day. So often we see with hot, bright, sunny days, those cutworms are coming out at night and you don't see them during the day. And I'll talk to farmers that say, you know, I know something's cutting my plants off, but I can't find any bugs, and they have to do some digging before they find the cutworms. Cutworms can come really early in the season, completely chop off your plant, sometimes it'll be above the growing point and that corn will regrow, other times it may not be, but you definitely don't want to have this happen on your farm because you're going to lose some yield. There's no question about it, when you lose two leaves on your corn plant, now that's going to reduce how much sunlight that plant's going to capture. So, spraying cutworms with a pyrethroid is really important. Don't listen to people that say, well, they're going to be gone, they're almost at full grown and they'll be gone. No. Spray them, kill them, wipe them out. BRIAN One of the big problems I think we have as farmers, I know I do myself, is we kind of get lazy because we say, well, I've got a Bt trait that controls that bug and I've got seed treatment out there. Oh, and by the way, I also use some Capture LFR or Aztec or Force, so I've got plenty of insecticide out there, I'm good. I don't care how good you think you are, there could be bugs that move in. Darren mentioned cutworms, probably not that bug if you've used three different insecticide things, you know, the trait and the seed treatment and something actually in-furrow, but how about armyworms? Armyworms are called that because they will move in like an army and just all of a sudden, in one day, they can wipe out acres of your field. So, that's one of the reasons why we want you out there scouting all the time. DARREN It's one thing to scout in your field, but you also need to scout around the edges because sometimes you'll see bugs move in from the grassy areas around the outside of a field, like grasshoppers are a great example of that, and another one is common stalk borer. We see stalk borers generally in the first few rows in the outside edge of the field, they can make a mess and totally destroy your corn plants, so keep your eye out for them. BRIAN Then we get to the European corn borer. One of the things that drives me crazy is as a farmer, I have to have 5% refuge. So, 5% of my plants are going to get eaten up by corn borers. I can't stand that. Drives me crazy. I hate to go spend the money on an insecticide for the whole field when literally only 5% of my plants need it, so it's hard to justify that, but I don't like the logic of, oh, I'm just going to let the bugs feed on 5% of my plants. If you do not have a traded crop, let's say you have conventional corn, you need to be scouting for corn borers. I would suggest starting at about knee-high corn, and then you've got to scout all the way up at least every week. DARREN And you're looking for egg masses on the plant, and this is one of those things. When you're out scouting your fields, look really closely on the upper surface and the underside of the leaves, because oftentimes you'll see egg masses for different things. Now, it may be something like corn borer, it also may be a beneficial like ladybugs. So, you're going to have to learn how to identify between the different egg masses that you might see there. Fortunately, there are a lot of pictures available to help you with this, but do the scouting on the leaves, on the plants, and along the edges and the ditches, too. BRIAN Yeah, and don't forget about western bean cutworm. That would be another one you might find some egg masses for. Now, you're not going to look for egg masses with this, but corn rootworm beetles – so that's the adult stage of the corn rootworm that would feed on roots. You usually see those around tassel time, and if you have quite a few of those, you actually could justify spraying foliar. The good thing, too, when you spray foliar, yes, you'll prevent the silk feeding, and so you should hopefully have better pollination, but the other side of it is if you spray early enough before they mate and lay eggs, you'll have fewer corn rootworms next year. DARREN That's a great point. If you are going out with a fungicide application, make sure you're scouting for these bugs ahead of time because you can get a free ride for your insecticide when you're going out there with the fungicide. Another thing that you may scout right around this time is corn leaf aphids. We see corn leaf aphids preferring certain hybrids over others. Like, for example, you walk through a corn hybrid trial, you may see aphids only on certain numbers out there, but, man, they can get thick, and it can be a mess out there, so do keep your eye out for those corn leaf aphids as well. BRIAN The last one I'll throw out is earworms. Hopefully, you don't have this problem because it's really hard when you've got something that's in the stalk or that's actually infeeding on the ear inside that husk. How are you going to get insecticide in there? It's impossible. So, literally, you'd have to spray when the adult is out laying eggs. It's just a real challenge. The good news, again, if you have a trait that will kill some of these bugs that you could have later on in the season, hopefully, that's going to take care of it, but we absolutely do encourage you to scout all the time, all throughout the season. Insecticides are quite inexpensive. DARREN While you're out there doing all that scouting, keep an eye out for our Weed of the Week. We'll show you how to stop it. It's coming up next.