Sound Ag Advice

Even though most trees go dormant in winter time, environmental injury from cold weather and animals can occur. Joe Zeleznik, NDSU Extension forester, joins Sound Ag Advice to discuss how to keep your trees healthy in winter time.

What is Sound Ag Advice?

“Sound Ag Advice” presented by the NDSU Extension Service features NDSU Extension specialists and staff talking about current crop and livestock issues. “Sound Ag Advice” is free and can be used in any way you see fit.

Speaker 1: Kelli Anderson, NDSU Ag Communications Specialist
Speaker 2: Joe Zeleznik, NDSU Extension Forester

Kelli: This is Sound Ag Advice, a weekly feature presented by NDSU Extension. I'm Kelli Anderson, and I've got Joseph Zeleznik, NDSU Extension forester here with me in the studio today. So, Joe, what's going on with trees this winter?

Joe: Well, it's a good question. It's funny, of course, because trees are dormant. There's not doing a whole lot right now. But there's a lot of things going on with trees. There's the environment. Of course, it's wintertime, it gets really cold. But you know what we get that end of winter or what I call the midwinter fake out, when we hit nice and warm in January and February, maybe March, and then it gets cold again. And that's really tough on conifers, especially some of our native trees like green ash or Box elder. They don't fall for that trick, they know to stay dormant. But the conifers, especially blue spruce, when we get that midwinter fake out, they tend to get what is generically called winter injury. And so you might see in the middle of winter needles turning brown, or sometimes they have a purplish color to them. And it's a little tough on trees, but unfortunately, there's not a whole lot we can do if they get tricked into thinking it's time to come out of dormancy.

Kelli: Now if you're anything like my family, it feels like we're putting down a lot of salt on our sidewalks and driveways so that we don't slip, can that transfer over to trees that are in the area?

Joe: You know, it's a question of amount. I'm all for clear driveways and clear sidewalks. But just be aware that that could cause problems. Usually, it's more of an issue with turf. But it can cause a problem with trees too. And I think the best thing you can do is that in the spring, just make sure all that extra salt gets flushed away, either deeper into the soil profile or off the driveway, off the sidewalk, into the street.

Kelli: Now let's talk about animals. I've seen a lot of rabbits in my yard chewing on lower branches. Is that going to affect my trees in the spring?

Joe: Yeah, well, protecting trees and shrubs from animals. Unfortunately, there's not a whole lot that can be done at this point really that needed to be done last fall, it's a question of how much damage is done. If you're losing a few individual branches, as long as it's not more than a quarter of the tree or the shrub, it's no big deal. If it's more than that, say half, it's starting to stress the tree. If it's a lot more than half, it could be so much stress that the tree is done for. What we often see though is on especially fruit trees like apple trees, or pears, the bark on the stem gets chewed away and it gets girdled, the tree gets girdled all the way around. And then at that point the tree is a goner. Even if the top is still remaining strong, if there's no bark on the stem, that top is going to die. The tree will sprout from the base, which may or may not be a good thing, but you got to be careful with that.

Kelli: Now on your NDSU Extension lawns, gardens and trees Facebook page you've recently posted about forest tent caterpillar and spring and fall cankerworm. Are those things people should be looking for right now? And what can they do to prevent those?

Joe: Can they look for them now? Yes, sort of what we're finding right now, at this time of year, the caterpillars certainly aren't out. But the way the insect overwinters is in the eggs, the egg stage and you see these massive eggs around a twig. And very simply you can just pull that off the tree. Obviously, you have to be looking at twigs, you have to look really close to find these things. Where I live, I tend to find the forest tent caterpillar and I see them on occasion, and I'll just pull those egg masses off if I see them.

What we had last year in eastern North Dakota and especially central North Dakota were these cankerworms..spring cankerworm and fall cankerworm they're closely related. They both come out in the spring, the caterpillars are defoliators, the egg mass looks very similar. I fear that we're going to have another bad year for canker worms. Pulling off an egg mass will help but it might not help enough. But if you see that pulled off, it certainly won't hurt and heads up this spring. Once the leaves start coming out, that's when the caterpillars are going to start coming out.

Kelli: Great ways to keep your trees healthy this winter from Joseph Zeleznik, our NDSU Extension forester. This has been Sound Ag Advice a weekly feature presented by NDSU Extension.