Evergreen Diseases

Evergreen Diseases

Part of Ep. 1004 Winter Interest

Learn about diseases that strike evergreen trees with UW-Extension plant pathologist, Brian Huddleson.  He talks about how to identify disease and some control options.

Premiere date: Dec 22, 2002

TRANSCRIPT+
Wisc Gardener Transcript: 

Shelley:
Looking to try something a little different in your garden this year? We're going to look at some uncommon annuals at Rotary Gardens in Janesville. And I'm with the Landscape Manager, Mark Dwyer. Mark, thanks for letting us join you.

Mark:
Sure.

Shelley:
I'd like to start by looking at some of the plants you've got in this beautiful container. This is very nicely done.

Mark:
Thanks, Shelley. Actually, the first thing we do with a container is consider textures in the way it's arranged. In this case, what you can see is a central plant, or a back plant, with a vertical element, a nice height to it, tapering down to a central plant. Now, all the plants in here are planted for mainly foliage. And as you taper down, you see a trailer coming off, cascading off the end of the pot.

Shelley:
So, we've got a really nice design to keep it interesting with the foliage, that's also the texture, the shapes, not just the leaf color itself, then.

Mark:
Right. The primary interest is foliage.

Shelley:
Let's look at some of the plants you've got in here. This looks like a variegated corn, almost.

Mark:
It looks a lot like a corn. Actually, this is called Variegated Giant Reed. It's a neat grass, that in this pot, will obtain a height of about five feet. But out in the bed, in full sun, it would get over eight feet tall.

Shelley:
Be careful where you put it.

Mark:
Right.

Shelley:
And what's this? The leaf actually looks a little bit like a maple.

Mark:
Well, with the five-pointed leaf, it looks a lot like a maple. That's incorporated into its common name, which is Flowering Maple, or Abutilon. This is actually one called Speckled Flowering Maple, and its primary interest is its leaf.

Shelley:
Not these pretty flowers?

Mark:
Well, the flowers are neat, a neat bell-shaped flower, but they hang in the interior of the plant. So, the leaves are the main interest.

Shelley:
And with the yellow on them, you can see them from more of a distance, too.

Mark:
Right, they show up at dusk and it goes well with the grass.

Shelley:
This is not hardy, like our maple trees.

Mark:
Right, it's a sub-tropical.

Shelley:
And this is a sweet potato vine, isn't it?

Mark:
Right. This is a variety called Blackie. It's a neat trailing or cascading plant that does well at the edge of a container such as this, or even in a hanging basket.

Shelley:
Now, you said normally, this cascades right down to the bricks.

Mark:
It's been trimmed by woodchucks, if you can see toward the bottom there. They keep it off the bricks for us.

Shelley:
See, that's nice. A question that I have to ask-- People have asked me and I don't know the answer. These are sweet potato vines, so they have the tubers like the edible ones. Can we eat this?

Mark:
Well, the short answer would be yes, they are edible. But through the cultivation process, they're not real tasty. They're very mealy. And it's not recommended for consumption.

Shelley:
So, if I was stranded on a desert island, I could eat them if I had to, but they're not going to taste good. Now, I know the sweet potato vine and the flowering maple are readily available. But some of the things we're looking at today are harder to come by. Where would you recommend I start looking?

Mark:
Well, at the gardens, we do a lot of looking through catalogs. The Internet provides a lot of information on new varieties, and just keeping an ear out.

Shelley:
And we always try to provide a source list on our Web site, too, but I know that some of these are a little bit more of a challenge. Now, this one, I may have to do some searching for. What is that? They look like little miniature carnations.

Mark:
Yeah, that's a nice, delicate plant. It's called Tassle Flower. And we put it here, not only for its red color, but the delicate touch that it lends to this border.

Shelley:
These are beautiful. And it stays about this height?

Mark:
It stays that height. And it's these airy sprays of red, instead of an overpowering massive red. it's a nice addition to the border.

Shelley:
Do you have to deadhead it to keep it, though, with this display?

Mark:
We haven't had to deadhead it. It just keeps branching off the original stem. It's a reliable bloomer, May through September.

Shelley:
Great. Now, here's something else with incredible foliage. I don't think we even care about the flowers. What's this?

Mark:
That's an Amaranthus. It's called a Fountain Plant. And this is a variety, Illumination. And you would really understand the reason it's called that at dusk. You can really see the bright new growth coming out of the center, giving that luminescent pinky-orange color. The leaves age to green as the plant gets taller.

Shelley:
So, it looks like it glows in the dark. At dusk, it actually almost does.

Mark:
It really does, yes.

Shelley:
Wonderful. Is this one of the edible varieties that I've heard about?

Mark:
It is an edible variety. Actually, another name for it is Chinese Spinach. And the new, tender growth is used in salads or as a stir fry.

Shelley:

Shelley:
With winter one of our longest growing seasons in Wisconsin, you can see why evergreens in the landscape would be so highly prized. This is a Colorado Blue Spruce, and it's gorgeous. I'm at the UW-Madison Arboretum. And I'm with UW Extension Plant Pathologist, Brian Huddleson. We're going to talk about some of the problems with some of our favorite, gorgeous evergreens.

Brian:
That's right. We have a lot of common evergreens in our city landscapes. And unfortunately, they have quite a few disease problems. This Colorado Blue Spruce is showing--

Shelley:
This is the healthy part.

Brian:
That's right. This is really, really beautiful. This is what we want it to look like. But unfortunately, on this tree, what we're starting to see is something that looks like this, where we're losing a lot of the interior needles of the tree. This is a disease called Rhizosphaera needlecast. And it's caused by a fungus that infects the needles and causes them to fall off. And you can actually see some brown needles here that have dropped into this healthy foliage. And this kind of naked branch with a tuft of nice, green foliage on the end is very typical of particular disease.

Shelley:
So, attractive when it was young.

Brian:
Unfortunately, yeah, as these trees get older, we tend to see more of this disease and you get a lot of loss of needles and they become very, very thin and not too attractive. There's also another problem. You can see a branch here at the base, where you've got a lot of purpling of the needles.

Shelley:
Oh, here, yeah.

Brian:
And that's usually an indication that the branch isn't getting enough water. In this particular case, there's an infection farther back on the branch, a lot of sap production, bleeding. And this is a disease called Cytospora Canker, a fungal disease. A fungus gets into the branch, girdles the branch and kills it off. And this is actually a much more serious disease, because it will actually kill branches and cause defoliation of the entire bottom portion of the tree. It will make the tree so ugly that you will wish that it was dead. So, one of the reasons not to use this particular tree. Although when they're young, they're quite beautiful.

Shelley:
They're pretty. Okay, how about if I plant a pine, instead?

Brian:
That's certainly an option, but there's some problematic pines, as well. Austrian Pine is a real problem. A very common one in urban settings because it's salt tolerant. But there's another fungal disease, again, those fungi. It's called Sphaeropsis Tip Blight. Again, it gets into the branches, girdles those branches and causes them to die. So, if you drive by an Austrian Pine and see a lot of brown tips, that's the disease.

Shelley:
Okay, that's my yard. Another common tree, I think, in a lot our backyards, junipers.

Brian:
Less problematic, probably, than Colorado Blue Spruce and Austrian Pine, but also there are some disease problems. I'm a plant pathologist, so I can think of disease problems for virtually anything. The common disease on junipers is Cedar-Apple Rust. It's a fungal disease. And the fungus actually spends part of its lifetime on the junipers and part of it on things like apples, crab apples, hawthorn trees.

Shelley:
So, it's one of those alternate host diseases.

Brian:
Yes, it goes back and forth during the growing season. What you see on junipers are these little brown galls, little swellings on the branches. At about mid-May into early June, you'll start to see what looks like orange marmalade hanging from your tree. And that's the fungus producing its spores.

Shelley:
Well, Brian, you're talking about three of the most popular trees in our backyards. What do we do?

Brian:
Well, there are some control options. They're usually pretty difficult in older trees. If you're interested in that sort of information, we have some wonderful fact sheets that you can pick up from your county Extension office. Usually, what I recommend, though, is that people think about what they're planning in their landscapes before they establish their landscapes. That is, you should be choosing other types of trees.

Shelley:
Because once these get it, they're going to get ugly regardless of what you do. The damage is done. I assume a shorter life span on all these guys.

Brian:
Probably, yes, for many of these diseases. So, it's better to choose another tree as a replacement.

Shelley:
Go to a reputable nursery, ask intelligent questions. Do you have some favorite options?

Brian:
Well, as an option for Colorado Blue Spruce, if you have a nice, well-drained site, I would suggest something like a Concolor Fir. They're they same color, pretty much the same shape. They're actually a beautiful tree. And they're not as prickly as a spruce is, so I kind of like those. There are certainly other options for the other diseases that we talked about as well today.

Shelley:
Thanks, Brian. Then there's hope for all of us. The young leaves, then.

Mark:
Right.

Shelley:
This would be a wonderful addition to any garden. That's beautiful. Thank you, Mark.

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