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Emerald Ash Borer: Signs & Symptoms

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March 1, 2019

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

Amy Myers: Today we're talking about the emerald ash borer, signs and symptoms. Hello, I'm Amy Taylor Myers and welcome to Farm and Family. Today we're speaking with John Willis, Mississippi State University Assistant Extension Professor. John, the emerald ash borer is an insect that we can sometimes have in our ash trees. But what exactly is this emerald ash borer?

John Willis: Well, the emerald ash borer itself is a beetle that came from, we believe, Asia. It got here the mid 90s, but we didn't discover it until the early 2000s. And since that time it has wrecked havoc on our eastern hardwood forests, where it's caused billions of dollars of devastation.

Amy Myers: That doesn't sound good. Now where is this insect now?

John Willis: Well, currently, and this is breaking news, it has just reached Texas. I believe it is in 26 states. It is in all the neighboring states of Louisiana, Tennessee and Georgia. It has not been reported in Mississippi at this time. But we are surrounded on all sides.

Amy Myers: Okay. Now why has this insect become such a problem?

John Willis: The main problem with emerald ash borer is that our native ash species are not adapted with the insect, and so they have no natural defense. So if you take the scenario of the southern pine beetle, a native insect, which our southern pines have developed over time with, if we thin our trees and we make them more vigorous, they have a natural defense mechanism to combat an attack from the pine beetles. With emerald ash borer it's the exact opposite. Because they've never been exposed to the ash borer before, they end up, even if they are vigorous, succumbing to attack. A good example of this would be we actually planted North American species of ash in the 1980s in Asia, and all of the North American species died.

Amy Myers: So what are some signs and symptoms of this insect? How do we know we have it?

John Willis: That's a really good question, and unfortunately, it's a difficult question. The first thing that folks will generally see is a tree's crown fading. Now I wanna emphasize that there's lots of reasons that a tree crown can fade. So just because you see a crown fading does not necessarily mean you have the emerald ash borer, but it is a symptom, obviously, that the tree has stress. The biggest problem with tree crowns and the emerald ash borer is you generally do not see it for up to two to three years after the attack. So by the time you see the crown fading, the tree's already gone. A good sign and symptom to look for is a D-shaped exit hole or a crescent moon shape. That is the exit hole that the larvae will make that will be there the first year after attack. There again, though, the problem lies in that they generally attack high in the tree, so it can be difficult to spot. Another thing I like to suggest is woodpecker flex. Woodpeckers use the AB larvae as food, so if you see lots of woodpecker flex around your tree and some exit holes, that's a very good cue that you may emerald ash borer. At that point I would definitely recommend calling a forester or the Mississippi Forestry Commission.

Amy Myers: So there's no early way to find out if you have it?

John Willis: Unfortunately there is not. It is a delayed reaction and we are unable to specifically trap for the insect because they don't use the same type of pheromone communication that bark beetles do.

Amy Myers: Now does emerald ash borer attack other trees, or only the ash?

John Willis: 99% of the time, only ash. So it's not like it's attacking our maples, our oaks, or gums or anything like that. There is an isolated case that's been reported in Ohio of it attacking the white fringe tree, which is an ornamental tree lots of people plant. The key here is that it's in the same family as ash, and so there might be some evidence that EAB in areas where a lot of the ash resource has gone down, that it's actually starting to switch hosts. We haven't seen that by and large. And I wouldn't consider that a huge concern at this time.

Amy Myers: So is there any way that we can make our forests become more resistant to this?

John Willis: Well, the answer, there's two parts. For a rural owner who owns a forest on landscape scale, the answer's probably no. Thinning would be our typical answer, but that has not shown to be promising in any localities. If it's a tree in your yard or a city park or on a city street, there are insecticide options out there, but it will cost around $100 a tree, at this time, to treat it. However, it will keep your trees safe for up to two to three years.

Amy Myers: And there's a workshop in September that you wanna mention, right?

John Willis: Yeah, that's right. We're gonna hold a emerald ash borer preventative measures workshop in Vicksburg, Mississippi. And this will be in mid-September. We'll let people know when we have a date specifically laid out.

Amy Myers: Today we've been speaking with John Willis, Mississippi State University Assistant Extension Professor. I'm Amy Taylor Myers 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.

Department: Forestry

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