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Episode 1

White Grub Management with Nikki Hendrickson

On our first episode of the Around the Turf Scene Podcast, Nikki Hendrickson joins Rusty to discuss white grub management in turfgrass. Control options for preventing white grubs include imidacloprid (Merit), clothianidin (Arena), and chlorantraniliprole (Acelepryn), and curative treatment options include trichlorfon (Dylox) and carbaryl (Sevin). Tune in to learn about application timing, insecticide resistance, pheromone traps, scouting for beetle populations, and how to decide whether or not to treat.

About Our Guest:
Nikki Hendrickson is a graduate of Purdue University with a Bachelor of Science in Entomology and Horticultural Production and has a Master of Science in Entomology from the University of Kentucky. For the last 20 years, she has held various roles in the green industry, including being a sales representative for Advanced Turf Solutions and positions with multiple trade associations. Nikki is the current president of the Midwest Regional Turf Foundation and a member of the Purdue Ag Alumni Association Board of Directors. She has served as the past president of both the Indiana Professional Lawn and Landscape Association and the Green Industry Alliance.

About Our Host:
Rusty Stachlewitz is a Seed Product Manager at Advanced Turf Solutions. Rusty received his Bachelor of Science in Crop and Soil Science from Michigan State University with an emphasis in Turfgrass Management. He has been a Golf Course Superintendent and General Manager in the industry. He’s also been the turfgrass department head of two colleges and the Program Director of The Lawn Institute.

Rusty Stachlewitz 00:02
If you could only see a lawn when it’s grubby, maybe you’d understand. Why I feel this way about white grubs and what I must do? If you could only see what the skunks do to the turf, indeed you would treat. When your turf is grubby. It’s almost the season when the beetles fly. We’ve got some treatments to shorten their lives. See white grubs what you do. You spray or you don’t. When you’re lawn is grubby.

Rusty Stachlewitz 01:20
Welcome to Around the Turf Scene. I’m Rusty Stachlewitz, and this is your periodical podcast about all things turf. Today our guest is Nikki Hendrickson. She’s going to talk to us about white grubs and white grub management.

And let’s get at it. With us today we have Nikki Hendrickson from Advanced Turf Solutions, we’re going to talk about white grubs. Nikki, if you could do a little introduction of yourself instead of me running through everything.

Nikki Hendrickson 01:48
Well, I am an entomologist by trade, and when I say that I have my bachelor’s degree in entomology and horticulture production from Purdue University. And then I went on down to the University of Kentucky and got my master’s in entomology under Dan Potter. So, anybody in the who’s delved into the white grub world probably has heard of Dan Potter. He’s one of the best turfgrass entomologists out there and we did a lot of research on grubs.

Rusty Stachlewitz 02:23
So, let’s start off with some basics and we’re not going to get crazy into ID and things like that. But I think everybody who’s listening to podcasts hopefully knows what a white grub is. So we won’t start at that point and go from there. But what are your control options for treating for white grubs.

Nikki Hendrickson 02:46
So, most of the time in our turfgrass world when we talk about control options that we can go pre and then we can go post and for the most part, we tend to go pre and I’m guessing that’s kind of what you’re talking about here in what you want. So, imidacloprid, the Merits of the world, are still probably the most common preventative grub control that goes out and imidacloprid’s been on the scene for a while. We also have clothianidin. So, in the products like Arena, you have clothianidin, and then the newer products are it I shouldn’t say are is Acelepryn. So, it’s Acelepryn. It’s been out for a while, but as far as those kind of products go, that’s the newer one. And the Acelepryn has, I would say it’s got a little wider range of control, than does imidacloprid or clothianidin. Imidacloprid is one, it’s very water-insoluble. When you put it down, wherever you water it down to, that is where that product is actually going to stay. So, that watering in is pretty important. And you can go you know closer to that time of hatch. Clothianidin, it’s a little more water-soluble than imidacloprid. So, there’s kind of the preventative you can get into a little bit of post there. But the key to Acelepryn is it takes a little while for it to get activated in that soil and for you to get the best grub control out there. So, when you’re putting that product down, do not use for grub control, do not put it down right at hatch. For the most part, with the imidacloprid and clothianidin, we’re talking about putting that product down, you know, in mid-June. The extension entomologist always here in Central Indiana, July 4, that is your time to put it down. And that is the key. And with the Acelepryn, you’re probably going to want to be, at least in May, if not before, putting that product down.

Rusty Stachlewitz 05:12
Yeah, that’s one of the nice pluses with the Acelepryn is you can have the luxury of putting it down early. But you do need to put it down early. If I’m not wrong, the efficacy drops as you get closer to the hatch date.

Nikki Hendrickson 05:27
Yeah. You need to put Acelepryn down early versus imidacloprid. But that also allows you, we’re not talking bill bugs here, but that also allows you to catch some of those other earlier season pest like billbugs, at least in the home lawns. Because if you put imidacloprid down that early, you’re going to be waning on that residual, by the time that white grubs are, you’ll catch him at the beginning, but those eggs that hatch later, you’ll be missing out on getting control on those.

Rusty Stachlewitz 06:08
Okay. I’ll remind everybody that Nikki is in Indianapolis. So, when she says dates, if you’re further south of that, you want to go sooner, if you’re further north, you can go a little bit later. But geographically speaking, in cool-season turf, she’s about in the center, so it’s perfect for a good barometer there. There’s a lot of talk about switching products from year to year, like we do with fungicides so that you don’t have resistance. Is that a concern? Is that something we should worry about with white grubs?

Nikki Hendrickson 06:42
Most of the research still says that we don’t, we don’t get a lot of resistance to our traditional white grub chemicals. Partly because our beetles are strong fliers. If we’re talking Japanese beetles, you know, they’re very strong fliers and we don’t, we can get a new population to come into an area. Um, I can say that if somebody is really concerned, you know what, it will never hurt to just switch up chemistries and prevent it. I did read, actually, probably about a month ago, in one. I got to remember where it was that I read it at. But, I was reading some articles online. And it was, I thought it was one of the university guys who is looking into this a little bit more now because some people have swore up and down that they’re developing resistance. But I don’t know that it’s scientifically proven yet that we have reached, you know. And we’re probably really talking imidacloprid here in those neonics. That we have resistance to neonicotinoids. But it can never hurt to change chemistries. And so, and remember when we say change chemistries, I don’t mean going from really imidacloprid to clothianidin. I mean going from imidacloprid or clothianidin to something like Acelepryn. And I hear Bayer is coming out with a new chemistry this year that could be thrown in that mix, too.

Rusty Stachlewitz 08:31
Yeah, it’s going to be similar timing to Acelepryn, I believe.

Nikki Hendrickson 08:35
Yes. Yeah, I think it’s related. I think it’s going to be in that same class a family as an Acelepryn.

Rusty Stachlewitz 08:41
Okay. So, most of our turf managers and lawn care operators either pick a side and they treat every year or they don’t treat every year. And there’s a few that scout and try and make a decision based upon beetle populations and things like that. How would you base your decision on if you’re going to put out a product or not?

Nikki Hendrickson 09:06
I would base my decision. I wouldn’t necessarily look at beetle populations. But I would probably kind of continually monitor damage from year to year and monitor my grub populations from year to year. You might, I mean yes, you would think that in a year where we have more beetles, and you’re seeing beetles, you are probably more likely to have damage that year and especially if you are on irrigated turf. So, you know, those beetles emerge. Around here we start emergence, like Japanese beetle emergence coincides with Linden bloom. So wherever you are, if you have Lindens around you, start looking for those Linden buds to swell and that is when your adult Japanese beetles are going to emerge. Your masked chafers of the world, which there is a northern masked chafer, there is a southern masked chafer. The timing is about the same, but they can be a little earlier. And then I know when we get up into northern Indiana, there, there are some like the European chafer is hitting up there. I think the Asiatic garden beetle is hitting up there. And then we do have those other, I’m going to call them the weird grubs. So, our green June beetles, which, which aren’t really truly feeding on the roots, and then we have our, our June beetles. So, the bigger, brown June beetles, and those can be two or three-year grubs. But when it comes to scouting, for the most part, we’re still talking about, you know, Japanese beetles and chafers. The past few years, I have actually, whenever we have breakthrough, and I go out and look at it, I always see masked chafers and not Japanese beetles. I don’t see Japanese beetles a lot. So, a lot of people think, oh, when I see a huge population of Japanese beetles, you know, or I’m not seeing Japanese beetles, so I don’t need to treat. And my guess is that for the most part, most of your population out there is chafers and not Japanese beetles. So, we kind of need to be looking at other things versus just Japanese beetles.

Rusty Stachlewitz 11:38
Okay, what are your thoughts on pheromone traps? A lot of people use pheromone traps for scouting. And pheromone traps basically use scents related to sex for the insects, so they’re, they’re drawn into those traps. What, is that a good tactic in your mind?

Nikki Hendrickson 11:59
Not really. Um, so back when I was in Potter’s lab, you know, we used a lot of traps. And for the most part, when you buy those, you know, bag of bugs and they come with either the pheromone lures. So, pheromone lures: you are primarily only collecting males. You’re, you’re only collecting males. And then there are the floral lures and the floral lures were pretty potent. We would put them out and, like on the research farm, there was this one spot where we would hang them in some hackberries. And if anybody knows Japanese beetles, like, I mean, they’ll feed on just about anything, but hackberry is not one of their favorite trees. And we actually got to the point where we had that tree almost 1/3 defoliated, because so many were flying in from all over. I mean, they were just so attracted to it. When you use either the pheromone lures or the floral lures, you will bring them in from, from all over. And it will actually look like you have a lot more than you, than you probably do if you’re basing it off of that.

Rusty Stachlewitz 13:18

Nikki Hendrickson 13:19
So, I say no.

Rusty Stachlewitz 13:21
Excellent, excellent. So, so we’ve talked about preventative control with those three different products. If you miss that window or you somehow have breakthrough, what are your choices for curative control if you’re getting some white grub damage?

Nikki Hendrickson 13:38
Good question. You know, the most popular one that’s going out is still probably Dylox. Dylox is a product that, it’ll give you really quick knockdown, very short residual. Dylox in general, that efficacy as far as what, what percentage of population that you’re going to control is really probably only a 70% population, but it tends to be enough to knock down that damage. I have seen it applied where you know, you go back out and you struggle to find a live grub out there. But through the research, since I worked for Bayer for quite a few years, and seeing a lot of that research, it really was only about a 70% effective product. Your other options, you know most people think of clothianidin and imidacloprid as being only preventative products. Back in the day, Bayer had research showing that, you know, you could actually get 80% control putting imidacloprid out in mid-August. You know, August to early September, you could actually get 80% control. It just takes a while. You know, you’re going to be out there for a week before you kind of get that not that population knocked down. If you have animals digging, that’s not a good thing. You want immediate knockdown, and that’s where the Dylox can, can really help. Then there’s clothianidin, which will also do, you can use it curative. And speed-wise, it’s kind of in-between imidacloprid and Dylox. So, just kind of depending on when you’re seeing, when you’re seeing that breakthrough, and how fast. You know, do you have animals digging, because if I had animals digging out there, I’m using Dylox. Sevin is also an option. Sevin, you know, carbaryl. I don’t know that many people who truly use it, but it can be used for spot applications. Sevin on that label, you cannot broadcast spray Sevin, but you could go in and treat some hotspots to get a fairly quick knockdown, too.

Rusty Stachlewitz 16:03
Okay. And then the other benefit I think of using products that are also preventative is if there are grubs deeper in the soil, when you put Dylox out, they could potentially still come up and that’s kind of where that 70% control comes from, I think.

Nikki Hendrickson 16:21
Yep. Yeah, it’s, and, you know, I look at that, too. If I’m in, if I’m at the beginning of August, and I’m like, oh, crap. So you know, I already have grubs out here. They’re doing damage, and I didn’t get it down. Though, you know, you can still get egg lay and egg hatch for, you know, for the rest of that month. So, I would rather have something with a little bit longer residual, too. And that’s really where I think, you know, imidacloprid and clothianidin can shine in those areas. Like, I would put imidacloprid down in a heartbeat if, if I’m at the beginning of August, and I still have a whole month left of beetles flying around and laying eggs.

Rusty Stachlewitz 17:06
Right. Potential, potential damage.

Nikki Hendrickson 17:08
Yeah. Yeah.

Rusty Stachlewitz 17:11
Is there anything else on the white grub front that we should think about before we wrap that up?

Nikki Hendrickson 17:20
Um, am I missing something?

Rusty Stachlewitz 17:22
I don’t think so. I wanted to make sure I wasn’t missing something.

Nikki Hendrickson 17:27
Yeah, I can’t think of anything. You know, like, every now and then you’ll get a call where you’ve got some of those bigger grubs and products aren’t working quite as well. And I think a lot of people with imidacloprid want to go towards that lower rate, too. The lower rate on imidacloprid works really good on Japanese beetles, but you need to go a higher rate to get really good control of those chafers. And when you’re talking about those two or three-year grubs, you might have a third instar grub out there that’s doing damage. If you’ve got, you know, I always say they’re the Phyllophaga species. That’s the genus Phyllophaga. There are several of those June beetles out there. And if you’re applying, if this is your first time applying and you’ve got those bigger grubs out there, you’re going to need to go either at a higher rate or that might be an area where, you know what, you might have to go Dylox on those because, technically, if it’s a third-year grub or a second-year grub, you’re really doing a curative and not a preventative. So, something to think about when you’re looking at breakthrough, look at your rates, look at the amount of water going down with those products. Most golf courses, you know, if they’re spraying their grub control, they’re probably putting down quite a bit of water. I know some guys who will put it down with a wetting agent to require less watering in of those products. In the lawn care world, you know most of ours is going out on a granular and really, if your lawn is irrigated, if you’re only putting a little bit of water down and you’re not getting enough water, then you have breakthrough, it’s really because the product didn’t get to where it needed to be.

Rusty Stachlewitz 19:30

Nikki Hendrickson 19:30
So, thing, things to consider. But for the most part, we haven’t had a, you know, a lot, I don’t see a lot of breakthrough.

Rusty Stachlewitz 19:40
No, and I don’t either, at all, honestly. And I said we weren’t going to talk about it, but I think we need to go into some of the basics really quick that some of the grubs do have different life cycles. You’ve touched on a couple of times that some are one-year grubs and some are three-year grubs and so there’s a big difference there. You know If you’re coming into an area that hasn’t had preventative treatment, you may run into some of these grubs that have grown to the size where a regular treatment won’t harm them.

Nikki Hendrickson 20:11
Yeah. So you know, we all look at that, the white grub complex, so to speak. And they always start off, if you’ve ever looked at those graphics, the big green June beetle grubs, which, like I said, they’re not really feeding on the grubs. They’ll be in the soil. They’ll come up at night. They’ll actually feed on the leaves of the plant, those grass blades. They do that and then they’ll go back in the hole at night. So, I don’t think I’ve ever seen damage from green June beetles. I like the beetles. I had a swarm of them a couple of years ago. It was like my first year with Bayer. So, it was probably back in, what 2008, and I was sitting in my home office and I just hear this thump, thump, thump, on the side of my house. I’m like what’s going on. I look out and there’s just like hundreds upon hundreds of green June beetles flying around my tree. And I was so excited. I’m like out there with my net. Woo! I’m going to catch these things. Putting them in a killing jar. 4-Hers all over had green June beetles that year in their collection because I had them. But, I’ve never really seen them do a lot of damage. The bigger ones are those masked chafers, and I’ve only had calls twice on the Phyllophaga species. And those were, for some reason, they were always on a golf course. Never had them as an issue in a home lawn. But a couple of areas on a couple of golf courses twice, where guys hadn’t treated for a couple of years because they haven’t had issues, and all of a sudden, they’ve got an issue. And the issue was the bigger, that third year, Phyllophaga grub. And they, they had an issue getting control of. And it’s not that, the damage with them is never quite as widespread. But because of the size of that grub, you’ll see, you know, a little that one grub can do, it’s feeding on quite a few more roots and can cause more damage. You don’t need quite that count that you do with Japanese beetles. I also had one year, I think it was at Audubon Country Club down in Kentucky when John Ballard was there. He actually called, he’s like, “Nikki, I came out this morning and I’ve got all these dead grubs on top of my green.” He’s like, “I don’t even know what caused it.” He’s like, “you know, there was a spray. I think there might have been a spray last week or something. But I think they were green June beetle grubs or something that came out to feed and then got caught with a late frost or something.” Yeah, I mean, they basically got too cold and died. It was really a weird situation. But they were bigger white grubs.

Rusty Stachlewitz 23:29

Nikki Hendrickson 23:30
I didn’t actually see them.

Rusty Stachlewitz 23:32
You heard the story.

Nikki Hendrickson 23:33
I wasn’t down there. Yeah.

Rusty Stachlewitz 23:37
Thank you for listening to Around the Turf Scene, your periodical podcast about turfgrass management. Around the Turf Scene is a production of Xylem Marketing. I’m your host, Rusty Stachlewitz. I hope to see you again soon.