How to Treat Winter Moth
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Winter moth larvae feed on the budding leaves of deciduous trees in early spring. Dave talks with tree expert Dave Ropes, of Tree Specialists, about strategies for protecting shade trees from winter moth damage.


Dave Epstein: Hi I'm Dave Epstein this is Growing Wisdom I'm here today with Dave Ropes a tree specialist from Tree Specialists Inc. And we’re going to talk today winter moth, and you may have winter moth at your house and so Dave first, what is winter moth? Dave Ropes: The winter moth is an introduced moth species and what we’re concerned with is the larva which is a small caterpillar or inchworm that feeds on the leaves of just about every deciduous tree species in our area. Dave Epstein: How does a homeowner they have it? Dave Ropes: Well that’s part of the problem Dave because caterpillars come out very early in the spring when the buds are just opening up they're about the size of a grain of rice and maybe only half of stick and they climb inside the opening buds where they begin to feed, so homeowner can’t see them at that point. It isn’t until the leaves open up and begin to get to their full size that you can see they’ve been eating the pieces. Dave Epstein: And what about the moth Dave, do I actually see that? Dave Ropes: In the fall, the adult moths fly around that’s when they mate and then lay the eggs that will hatch out in the spring. Dave Epstein: So the problem really is a spring time problem. Dave Ropes: It’s the feeding of the larva on the leaves so that’s where we need to focus our control. Dave Epstein: What can a homeowner do in order to control this? Dave Ropes: Well we spray with a couple of different materials. One is BT which is bacterium and its actually listed safe in organic settings and then we use another product called Spinosad that’s another biorational. It’s a derivative of a bacterium, so it’s a naturally produced material and that’s sprayed on the trees and on the developing leaves. Dave Epstein: So Dave if someone has really big trees like we’re standing under this maple, someone should call an arborous at that point. Dave Ropes: Yeah, you really need specialized equipment that could give you the pressure and the volume in order to reach the tops of shade trees. Dave Epstein: Can a homeowner get a hold of some of those products that you’ve talked about and do the smaller things around their property themselves? Dave Ropes: Yeah Dave. Depending on the laws in your state, very often BT and Spinosad are available over the counter and it’s perfectly fine to spray your own trees. You can even use a small step ladder to get to the top of a flowering cherry or whatever. Dave Epstein: If I do call a professional, when do I want them to be spraying? Dave Ropes: This is a tricky part. The insect develops in relation to accumulated temperature in the spring. So in a warm spring it’s going to be early. On a cool wet spring it’s going to be late. And then another wrinkle is that within a landscape different trees are leaping out at different times. So very often we have to do two applications to cover the early bloomers and the late bloomers. Dave Epstein: Well Dave thanks as usual. I appreciate it. Excellent information. Dave Ropes: My pleasure. Dave Epstein: Now you're armed with some information on winter moth and we have hundreds of videos with great horticultural information for you at Growing Wisdom.