Root Rot

Root Rot

Part of Ep. 1102 Root of the Problem

Learn how root rot weakens trees. Plant pathologist Brian Hudelson from UW-Extension explains what to do when your tree has root rot and what can be done to make it healthy again.

Premiere date: Jun 25, 2003

TRANSCRIPT+
Wisc Gardener Transcript: 

Shelley:
We're on the UW-Madison campus and we're standing in front of a rather unhealthy looking Sugar Maple. In the middle of summer, this should look a lot prettier. What's really scary is it looks just like one in my own backyard. So, Brian Hudelson, UW Extension Plant Pathologist, I've come to you to save my tree. Help!

Brian Hudelson:
I have a tree that looks just like this one in my yard too, and unfortunately they aren't very attractive. This particular tree is showing a lot of thinning in the crown, you can see all the way through the canopy.

Shelley:
Yeah, where's the shade!

Brian:
Yeah, not very much on this particular tree. Also, look at those leaves. They're very, very small, not the nice big shape that you normally associate with the Sugar Maple.

Shelley:
Yeah. Well, and look at all those seeds, is that normal?

Brian:
No, that's typically an indication of a tree that's under stress as well.

Shelley:
And my tree at home it lacks color and it's middle summer, so.

Brian:
Yeah, so is mine, and so is this particular tree. It's turning orange as well.

Shelley:
Okay.

Brian:
So there are lots of different things that might cause this, but what I'm worried about today is a problem called root rot.

Shelley:
Is it going to kill my tree?

Brian:
Possibly, yes. This particular tree has been under decline for quite a while--

Shelley:
So has mine.

Brian:
and I would expect it to survive for probably another five to ten years, but if we can figure out what the problem is, then we might be able to provide some advice on what to do to make this a little healthier tree.

Shelley:
I might be able to save it. Okay, what do we do?

Brian:
Well, what I've done here is I started to collect a root sample from this particular tree. I've gone out to the drip line, which is the edge where the branches extend, digging down about three to six inches and looking for these kind of woody looking roots that would be typical of a tree root.

Shelley:
Okay. Those aren't the turf roots then?

Brian:
No, the turf roots are quite a bit smaller than these and usually more fleshy than these, these are quite woody.

Shelley:
Okay.

Brian:
And then we collect up a handfull of these, usually from two or three sites along the drip line of the tree.

Shelley:
Okay.

Brian:
And then stick them in some moistened paper toweling to keep them moist in the mail and then into a plastic bag and then get that into the mail to my clinic and we'll try to figure out what's causing the problem.

Shelley:
And we'll give the address to your clinic in a few minutes. And obviously I assume fairly promptly get this to you, don't let it sit on the hood of our car for--

Brian:
The sooner the better for us, because we'll be able to find more for you if we have a fresh sample.

Shelley:
So what are you going to do with it?

Brian:
What we'll do is we'll take some of those little bits of root, we'll put it on a growth medium that will coax out those root rot fungi and then we'll try to identify them for you. And if we can figure out which fungi are causing the problem, then we'll be able to make some fungicide recommendations that will hopefully make this tree look a little bit better.

Shelley:
So there may be a chemical that I can apply that might save my tree.

Brian:
Possibly. It depends on how far along the root rot problem really is. At this point it might be a little bit late, but if you catch the problem early, the chances of being able to treat and get in good control are quite good.

Shelley:
Well, I've had it for a while, so--

Brian:
Yeah, you may be able to get some control, but what you may have to do is end up cutting down the tree and replacing it with something else. And then it becomes an important issue to know if you've got root rot problems even then--

Shelley:
Why?

Brian:
--because a lot of the trees and shrubs we plant in our landscapes are susceptible to root rots and so you want to try to prevent problems with those new transplants.

Shelley:
So this root rot will stay in the soil?

Brian:
For a long time. There are certain root rot fungi that produce structures that can survive in the soil for up to 40 years.

Shelley:
Oh good.

Brian:
So they can be around forever basically.

Shelley:
So after I send it to you I either try to save the tree or I still need to know. Okay, let's say I waited too long, which is kind of likely--

Brian:
Okay, alright.

Shelley:
we know I have a root rot, what do I do now if I want to plant something there then?

Brian:
Well one of the things you may want to consider is take a look at your soil and select the appropriate plant for that soil type. If you have a heavy clay soil you might want to select a tree or shrub that's more adapted to a lot of soil moisture in a heavy soil. That tends to be a problem in a lot of our urban landscapes that have really crummy soils.

Shelley:
Yes.

Brian:
What I've normally recommend though is what people would consider modifying the soil. Add organic matter to heavy clay soils to improve drainage, because it's really those wet soils where we have more of our root rot problems.

Shelley:
And then our wet Springs probably don't help at all.

Brian:
They've contributed as well.

Shelley:
What about planting depth?

Brian:
Also a problem. And I brought an example of a tree that has some serious problems due to improper planting. This is another tree from the UW-Madison campus

Shelley:
Oh good.

Brian:
And when it was planted the soil line was actually where this tree was cut off.

Shelley:
Off the trunk here?

Brian:
Yeah, and actually it should have been planted probably way down here so you could see some of this root flare, what's called the root flare.

Shelley:
So we want to see a little bit of this coming out when we're planting then. Most of us are planting too deep then.

Brian:
That's right and it's a common problem for many of the trees and shrubs that are planted in our urban settings. And you can see there's a lot of browning underneath the bark. The bark has fallen off here and this browning is typical of a root rot.

Shelley:
Uh oh. Okay. So we look for thinning leaves, we look for bark falling off the trunk. We look basically at the tree in my backyard.

Brian:
Hahahaha.

Shelley:
Brian, I think I need to borrow your trowel.

Brian:
Here you go, have fun!

Shelley:
Thanks!

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