Rhododendron or Madrone? Also, what's this disease?

laurell(8 - Washington)April 29, 2009

This is in the corner of the back yard of my 35 year old house. I assumed that it was a rhododendron considering that the rest of the shrubs around the house are either hydrangeas, azaleas or rhodies (pretty much all wal-mart varieties).

This particular bush has madrone-like bark, and is the second largest on the lot. The rest of my rhodies have begun "budding up" getting ready to flower, and this one has no indication that it will be blooming any time soon. I limbed it up off the ground as I suspected that lack of air flow under the plant was contributing to its disease.

It also has this black spot hoopla. A few months ago I went to HD and bought a rhododendron black spot treatment thing and sprayed it a couple times. It seems to have helped, all the new foliage appears to be clear, or at least much less affected than the older stuff.

If you have any clue what it is, I'd appreciate at least a push in the correct direction, whether this is really a rhodie or an arbutus of some sort, and what the disease might be so I can continue treating for it in the correct manner. Thanks!

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morz8(Washington Coast Z8b)

Rhododendron. And we didn't have Walmart 35 years ago, or Lowes or Home Depot either - don't be too quick to pass these off as insignificant plants until you've had a year or two (without the vinca, or anything else, growing over the root zones) to water and care for them....drought in late summer and fall (our driest months) can be a critical time for supplemental water for bud set. Reddish brown peeling bark is not entirely unusual, is thought to be an added ornamental feature to some varieties. Keep in mind too we had a harsh winter this year and many evergreens are not looking their best, even those with consistent care over the years.

"There are a number of leaf spots or burns caused by fungi such as Botryis, Pestalotia, Phyllosticta, Septoria and others. Many are secondary infections happening after mechanical damage or environmental stress, such as sunburn, drought, winter damage or windburn. They generally occur during wet weather and many times are self limiting with drier weather. Good sanitation is helpful, so remove brown and fallen leaves. Also provide good air circulation. Spraying with Benomyl or similar fungicide can be useful, but is frequently not necessary." Harold Greer, Rhododendron Basics

In many cases, fungicides are preventative rather than curative and spraying as leaf buds begin to open will do more to insure good new foliage than it will to resolve older leaves. If you want a more specific name for your particular leaf spot problem, take an example leaf to a nearby full service nursery, not a box store, or take one to your county extension agent office. (for some reason I'm thinking I've read you are near Molbaks, that would be one good place but there are others)

    Bookmark   April 29, 2009 at 8:27PM
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laurell(8 - Washington)

I certainly would like to see it bloom, and it's one of the only rhodies in the yard that I want to keep, due to it's size, placement, and great bark. I think it's a beautiful plant.

I don't expect the already damaged leaves to "heal" but would like to prevent the black spots from moving over to newer foliage.

This spot of my yard is slightly drier than the rest of the yard due to being partially under a couple fir trees. Is it likely that this is the cause of it not flowering? The rest of the rhodies seem to have swollen buds that will be ready to go quite soon, despite a couple of them having droopy leaves after the harsh winter that we experienced. If the dryness is expected to be the cause of lack of flowering, I'll begin watering it when the weather dries out.

    Bookmark   April 29, 2009 at 9:00PM
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botann(z8 SEof Seattle)

I'd have to say it's an Arbutus menziesii. (Madrone)It has been pruned hard and often. The peeling bark and the smooth bark under it is a dead give away. It likes sun with good drainage. There are probably more in your neighborhood that haven't been pruned. It will drop a lot of interior leaves in June, and when large, can be rather messy.

    Bookmark   April 30, 2009 at 6:49AM
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morz8(Washington Coast Z8b)

Botann, I'm the last person to be identifying specific rhododendrons but it looks like possibly rhododendron thomsonii to me. I'm not seeing a close up of bark though, I'm seeing a shot of the plant in entirety, close up of bud and leaves, 2 red x's following that...Have I missed something?

    Bookmark   April 30, 2009 at 10:57AM
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laurell(8 - Washington)

morz8 - If you refresh, you should see all of the photos. They still work for me and I haven't moved them in my photobucket acct. The bark doesn't look like thomsonii bark, it looks remarkably like a madrone, red, thin, oniony papery bark with a creamy green yellow underneath.

    Bookmark   April 30, 2009 at 12:57PM
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botann(z8 SEof Seattle)

Morz8, Did you see picture #4? It clearly shows what laurell describes. There is no question in my mind that it's a Madrone. They aren't often pruned this hard so it looks way different than normal. I've seen one other like it and that was at a cabin on Hood Canal.

    Bookmark   May 1, 2009 at 6:37AM
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morz8(Washington Coast Z8b)

No, wish I could see it but I'm seeing the two I described and two red x's. Right click, show picure, took me to a Photobucket page with no photos to view. Frustrating. The plan had been to replace this 6 yr old computer immediately after the holidays, recent economy has delayed that for a few months :(

    Bookmark   May 1, 2009 at 10:35AM
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botann(z8 SEof Seattle)

E-mail me and I can send you the picture.
I'm at AOL

    Bookmark   May 1, 2009 at 12:54PM
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morz8(Washington Coast Z8b)

That would help me - I've emailed you.

    Bookmark   May 1, 2009 at 8:51PM
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Embothrium(USDA 8 Sunset 5 WA)

1. Arbutus

2. Rhododendron

3. Arbutus

4. Arbutus

Many Arbutus are having disease problems in this area. The term Black Spot is used for the notorious disease of roses and is not what you have. Read about diseases of madrona trees and then decide what to do about yours. Do not spray anything on this - or any other shrubs - in future without knowing exactly what is wrong with it - and what specific approach is recommended.

Leaves of madrona trees on my friend's Camano Island property turned almost entirely black this winter. Some years ago there was an entire conference held on diseases of madrona. Blackening of strawberry tree and manzanita (incl. bearberry) also frequent here.

    Bookmark   May 1, 2009 at 11:26PM
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morz8(Washington Coast Z8b)

Oh, Wow. The close up of the bark 'sheds' a different light on the shedding bark question - Thanks, Botann, for forwarding the photo to me, I do appreciate you taking the time.

Laurell, I'm changing my vote to arbutus, that's a little too much shagging going on for even thomsonii, hope I didn't mislead you.

    Bookmark   May 2, 2009 at 2:18PM
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laurell(8 - Washington)

bboy - the photos are all of the same plant. Should I assume that since the majority of the photos suggest that it's an arbutus, I should assume that it is one that's just been heavily pruned?

What can I do to let it turn back into a tree? Let the shoots that are sticking up keep going and hopefully give it some height? Limb it up a bit? What arbutus do you think it is, the big daddy menziesii? Is there a more appropriate forum to be posting this in? Thanks guys!

    Bookmark   May 4, 2009 at 10:20AM
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botann(z8 SEof Seattle)

If you let one of the leaders of the Arbutus menziesii grow up into a tree you won't be able to treat it. Air circulation has very little to do with the disease as evidenced by the leaves in the open sun being infected. I would keep it as a shrub myself, or thin it out abit and make it look like a giant bonsai in the wind.

    Bookmark   May 5, 2009 at 7:37AM
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laurell(8 - Washington)

That's a shame. I've been wanting a madrone in the yard for a while, and now that I know I have one, I can't let it grow into a madrone shape. I suppose I'll let it get a little taller and trim it up a bit more, I'd like to block out the view of a neighbor's house kitty corner to my yard, and I only need a few more feet.

    Bookmark   May 5, 2009 at 11:40AM
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botann(z8 SEof Seattle)

A few more feet looks like it could be done without a problem. Prune when growing, but not late in the summer.

    Bookmark   May 6, 2009 at 6:22AM
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Embothrium(USDA 8 Sunset 5 WA)

Rhododendron thomsonii has different bark and rounded leaves. The madrona should be allowed to assume a natural shape. Much more attractive than the unnatural congested dome it is at present. Bark will also show better.

If leaf problems become unacceptable later, cut it down and plant something less problematic. Species is a large-growing tree, eventually becoming massive on suitable sites.

Continued pruning to control size may also interfere with flowering and fruiting. Some wild individuals fruit heavily some years, producing quite a show.

    Bookmark   May 7, 2009 at 12:58PM
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laurell(8 - Washington)

Will it eventually assume it's natural shape if I cut back some of the roundness and let the top keep growing?

    Bookmark   May 7, 2009 at 6:21PM
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Embothrium(USDA 8 Sunset 5 WA)

I'd just stop pruning it and let it correct itself.

One in a commercially maintained landscape near me has been getting tightly sheared in recent years ("maintenance shearing" having become epidemic here, despite the years of effort by the Plant Amnesty membership organization) and now looks quite ridiculous. The leaves have been cut into sections (same problem as with shearing of English laurel hedges) and only the bark below the meatball globe of foliage is visible.

    Bookmark   May 8, 2009 at 5:55PM
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