It's the Plants, Darling

Is another reason to avoid Norway maples needed?

Leafspot
Photo by JP Thimot.

It’s been a bad year for maple trees. Norway and silver maples across the Northeast and Midwest are ravaged this year by tar spot (the Rhytisma acerinum fungus) and (maybe less widespread) anthracnose, as I posted on GWI last week.

In Western New York, the Norways look the worst; their shriveled leaves have been falling since August. The silver maples (shown at top) aren’t quite as bad. If I needed another reason to dislike these trees, this blight provides it. Apparently, the soaking we got in May gave the fungus what it needed; it is visible almost every year, but usually not so much that we don’t get some decent color.

Treatments other than conscientious leaf removal (which I always do anyway) are not advised by the various extension sources I’ve consulted, and I’m glad there are no plans by the city to carpet bomb the streets with fungicide. I did hear of one possible remedy—though I’m doubtful. A Facebook friend contacted me after my GWI post, and said she noticed the problem in midsummer and her arborist did this: “provided in-ground injections of concentrated fertilizer. Within one week, the tree markedly improved, and has been fine since that time.”

I’ve never fertilized any of my trees, other than the usual additions of mulch and compost to the garden beds that surround them, and I’d never heard that injecting fertilizer would help with disease. Well, I’m only vaguely aware of the practice of injecting fertilizer—I’ve certainly never done it.  Interesting!

Posted by on October 3, 2011 at 5:00 am, in the category It's the Plants, Darling.
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18 Responses to “Is another reason to avoid Norway maples needed?”

  1. tai haku says:

    This would also be another reason to go with Crimson King if you are gonna go for A. platanoides – the spots won’t be as obvious.

  2. eliz says:

    I think they are Crimson King. Anyway, these are street trees, which–unless they fall down on their own–I cannot replace. And if one did fall down, I wouldn’t replace it with any tree. It’s really a question of “enough with the trees” on my street.

  3. tibs says:

    Sigh. I have such fond memories of the Norway maple in my grandma’s yard. It was just the right size for a nine year old to climb. With those thick leaves I could sit up there and be totally invisiable to the next door teen age boy washing his car in their drive. It was my first major crush and I only wanted to worship from afar.

  4. Lisa, Ontario says:

    There are so many nice trees out there, but I have 2 Norway maples in my front yard that belong to the town. There is no fall colour, and the leaves drop late. Why couldn’t I have a nice sugar maple instead?

  5. Kate says:

    Ohh I’m right with you there — I’m currently sitting in Plant Pathology class looking at so many Norway Maple pathogens and diseases and they just look ugly. I’m a fan of the Silver Maple that’s native to here in Ontario

  6. commonweeder says:

    A Norway maple was planted 20 years or so in front of a local library to provide a good climbing tree for young library patrons. It did its job, but has been slowly dying. Now, with a new library addition, the library landscape is getting a renewal. The Norway maple is coming down and a new climbing tree planted. Once they decide which new climbing tree. Any ideas?

  7. I’ve heard of similar treatments being applied for fungal disease called black spot on Aspen trees here, but it is usually in conjunction in with the application of mychorrizae, which is what is supposed to help the tree overcome the fungal disease. The fertilizer is just to help the tree with its overall health. At least in theory.

  8. Dave says:

    Fertilizer does not cure the leaf spot fungus, but disguises it by pushing the growth of new leaves. The new leaves have not been subjected to the environmental conditions that caused the initial fungus, so they remain unspotted. By the time the leaf spots are noticeable there’s no cure for the damage, except to keep the fungus from spreading (which is rarely a problem), and in most cases leaf spot is an aesthetic problem only.

  9. Winnie says:

    Did you sneak into my yard to take that picture? Had it last year too.

  10. cellbioprof says:

    Norway maple: Invasive non-native tree. Who needs any other reason than that?
    Silver maple: Native, but fast grower with weak wood that makes it prone to split in high winds. Very good for carbon sequestration, though. Plant it in the back 40 where nothing will be harmed if it drops limbs.

  11. tai haku says:

    @Eliz – the leaves on Crimson King is bright purple year round but I totally hear you on “enough with the trees”

    @commonweeder – there used to be a program whereby one could buy clones of historic american trees (Johnny Appleseed apples, trees from various historic settings, president’s houses and so on and even clones of trees grown from seeds that went to the moon). I reckon there’d be something perfect for the library amongst them if you can find the nursery website (a google search has failed me).

  12. Eliz says:

    Yes, Tai–they are purple. That is, when they are not shriveled and covered in black spot. My photo shows a silver maple.

  13. tai haku says:

    Ah! Sorry Eliz; totally missed the silver maple ref to the picture (and evidently didn’t look close enough to note the species difference). Now I really hear you with “Enough with the trees”!

  14. greg draiss says:

    Tar spot is not a major issue. Just unsightly. The major issue with these large maples is the ever encroaching root zones that choke out lawns.
    Since this is an anti-lawn forum these trees should be right up your alley

    The TROLL

  15. eliz says:

    Why yes, the fact that the trees demand creative ground covers is their one benefit.

  16. janice says:

    I dont know what kind of Maple grows in Michigan but mine all have that by the end of the year, especially if its a dry summer. Would like to know how to avoid it
    Janice

  17. Thanks for the info, Elizabeth! We unfortunately have a silver maple as do most of the neighbors on our block. I hate the fungus spots on our leaves, but I don’t know if injecting fertilizer into the ground is worth the bother at this late date.

  18. eliz says:

    Chris, from what I am hearing, it would not work anyway. We just have to endure this. or replace the tree.

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