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Crepe Myrtle Bark Scale: Scouting, Recommendations

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Tuesday, January 8, 2019 - 7:00am

Announcer:  Farm and family is a production of the Mississippi State University Extension Service. 

Amy Myers: Today we're talking about crepe myrtle bark scale scouting and control recommendations. Hello, I'm Amy Taylor and welcome to Farm and Family. Today we're speaking with Dr. Blake Layton, Mississippi State University Extension Entomology Specialist. 

So Blake, crepe myrtle bark scale. This is an insect that can heavily affect our beautiful crepe myrtles here in Mississippi. What exactly is this insect?

Blake Layton: Well Amy as you've indicated, this is a serious new insect pest for the state. We didn't have it in Mississippi until this year, so it's a non native pest. It showed up for the first time in Texas in 2004 and since then it's spread to isolated areas in several other southern states. It's a very important past of crepe myrtle, because of course, crepe myrtle is one of our favorite landscape plants here in the south.

Amy Myers: Now, how do we know if our crepe myrtles have this insect?

Blake Layton: That's a good question because we want everybody out there in our hearing audience to be watching their crepe myrtles to see and the first key is if you have crepe myrtles that are black with sooty mold because of excessive honeydew production. Now the caution there is we do have aphids that show up on our crepe myrtles and they will cause crepe myrtles to be black with sooty mold. But check those crepe myrtles a little more closely and if you see little patches of white felt like material, an individual scale is only a 10th of an inch long, but that's big enough to be easily visible with the naked eye. 

But often an individual limb or twig will be totally encrusted with these white patches. So that's really hard to miss once you examine it up close and if you need a further confirmation that you're looking at crepe myrtle bark scale, poke one of those little white felty things with a knife or a pencil point or a broken twig and if it bleeds pink then it's absolutely crepe myrtle bark scale.

Amy Myers: Okay, and what do we need to do if we indeed have this problem?

Blake Layton: Well, of course we do have some treatment recommendations for crepe myrtle bark scale. These are based on some research that's been done primarily in Texas and Arkansas. Those states that were unfortunate enough to get this critter before we did and so there are several treatment recommendations out there and these are now available at your local county extension office. You can call them and ask for a copy of our crepe myrtle bark scale scouting and control recommendations. We don't quite have anything up on our website yet because this is such a new pest and control recommendations are kind of changing as we go right now.

Amy Myers: So there is an insecticide that we use?

Blake Layton: That is the recommendation. There are some soil applied insecticides that homeowners can use or that they can contract with a licensed professional applicator to apply to the soil they're taken up and they help control this scale. Unfortunately, these treatments do not give a hundred percent control by themself. So if somebody has an infestation, let's say in a nursery or a single plant, then they want to be a lot more aggressive. If it was me, I'd want to totally eliminate that infestation, even if it meant cutting down and destroying that plant on site to keep it from spreading to other sites. That's going to be really site specific depending on if you think that's the only plant, that's what you would do. If you think you got it on 20 plants and your neighbor has it too, obviously that's not the step to take.

Amy Myers: Okay. So can we prevent this and if so then how can we prevent it?

Blake Layton: Yeah. Prevention is what we really want to focus on now. Let's try not to bring any infested plants into our county, into our neighborhood and the best way to do that is to work closely with your nurseryman. Really working with them to make sure those plants, if you're buying crepe myrtle to plant, that those plants are absolutely crepe myrtle bark scale free. It's real easy to overlook the scale at low level infestations, unfortunately.

Amy Myers: So if we buy these then we should ask about that and make sure that they get looked over really good.

Blake Layton: Absolutely. 

Amy Myers: So this is something that spread from like a nursery. It's not a native insect is it? 

Blake Layton: It's not a native insect and it's spread in two ways. We have this insect in Mississippi now, it's in Ocean Springs, Mississippi. I was down there two weeks ago looking at that. We also have it in Olive Branch, Mississippi. So both ends of the state. 

It's initially brought in by being transported on infested nursery stock, but then that infested tree can produce crawlers, immature scales, and they can be spread either by wind or by hitching a ride on other flying insects or even on the feet of a bird and they can spread locally. I was observing this kind of local spread down in Ocean Springs two weeks ago. We'd find the infested plant and then if you looked at another plant 100 yards away, you could find a low level infestation on it. And so we're seeing the infestation spread in Ocean Springs.

Amy Myers: Okay. So if we want more information then we can get in touch with our Mississippi State University Extension Office, our local office, and ask them for a copy of more information. 

Blake Layton: Exactly.

Amy Myers: Today we've been speaking with Dr. Blake Layton, Entomologist. I'm Amy Taylor and this has been Farm and Family. Have a great day.

Announcer: Farm and family is a production of the Mississippi State University Extension Service.

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