Thursday, March 17, 2011

Maples Under Attack

Maples (Acer species) are popular trees.  The Acer genus includes many choices which offer a wide variety in size, form, foliage texture and color, bark texture, not to mention glorious fall color.  
Japanese Maples are a personal favorite, as I wrote here

Large Maples do have drawbacks - the shallow roots can damage nearby paving; those roots combined with their deep shade, makes growing grass under them a challenge.  
But there's a more serious reason to reconsider before planting more Maples.

Maples are under attack in several areas of the US.  
They are the preferred host of the Asian longhorned beetle (ALB).  
Asian longhorned beetles lay their eggs under tree bark.  The emergant larva burrows deep into the tree and feeds on the woody tissue, which weakens the tree, and continues to live within the tree until its adult stage.  Adult female ALB often lay eggs on the same tree until it dies. 
Asian longhorned beetle (ALB)
photo from

The ALB was first found in 1996 in Brooklyn, NY.  It has since been found in Illinois, Massachusetts, New Jersey and New YorkWhile extensive efforts have been undertaken and quarantine zones have been established to restrict the spread of this pest, everyone should be aware of the danger and the signs to look for (read about it here).

Additional information can be found at: 
US Forest Service
Asian Longhorned Beetle Look-Alikes

Diversity is not only important in investments. 
It's also an important tool in the fight against devastating pest damage.  Diversified plantings, especially on a large scale, minimize the overall loss when trees of a particular genus are destroyed.  It is argued by the authors of Street Tree Diversity that Maples have been overplanted, and that the ALB has the potential to destroy large portions of urban tree populations.  A list of recommended trees for the ALB quarantine zone and surrounding areas, compiled by the New Jersey Forest Service, is included.

Although Maples are the preferred host of ALB, other trees which are in danger include:
Ash (Fraxinus), Birch (Betula), Elm (Ulmus), European Mountain Ash (Sorbus), Hackberry (Celtis), Horsechestnut (Aesculus), London Planetree (Platanus), Mimosa (Albizia), Poplar (Populus), Willow (Salix) and Katsura (Cercidiphyllum). 

You may wonder if any trees are safe from ALB.  Some of the unaffected large scale trees are:
Littleleaf Linden (Tilia cordata), Japanese Zelkova (Zelkova serrata), American sweetgum (Liquidambar styraciflua - 'Rotundiloba' is a fruitless variety), and Honeylocust (Gleditsia triacanthos - f. inermis 'Skyline' is fruitless).

What can you do? 
Diversify your plantings.  As wise a strategy in gardening as in investing.  
Educate yourself about the signs of ALB
and report any evidence (find out where here)
©Copyright 2011 Garden Sense. All rights reserved. Content created by Chris for Garden Sense.


Carolyn @ Carolyn's Shade Gardens said...

How depressing. It seems almost every tree is under attack from some disease or beetle. I think our polluted atmosphere has something to do with it especially acid rain. The trees are weakened and can't fight off the attack of these various insects and pathogens.

Anonymous said...

I agree with Carolyn. I too see so much more of this in the last few years.Every year Cornell reports a new list of insects or disease in which to deal.

Toni - Signature Gardens said...

Yeesh! I have 20 Japanese Maples and 2 Shantung maples in my yard. Have not heard about the ALB venturing southward...yet. Thanks for the information!

Karin / Southern Meadows said...

Ugh! How depressing. I love maples! I have several. Thanks for posting this information.

Chris said...

Carolyn: It is discouraging, to say the least. Globalization is one of the culprits - they believe that ALB traveled to the US in wood packing material from Asia.

GWGT: So much good has come from globalization, but the introduction of new pests, for which our plants haven't developed resistance is one of the consequences.

Toni: You're pretty far from the affected areas in Texas. But here in PA, they're too close for comfort. You have such beautiful Japanese Maples - I enjoyed your spring foliage post with their pretty spring colors highlighted.

Karin: I'm sorry to be the bearer of bad news if you weren't aware of ALB. But I feel it's better to be informed, than to remain blissfully in the dark.

Janet said...

Great information Chris, good to know.

Chris said...

Janet: While it's not pleasant information, it is important. A local municipal code I reviewed for work recently lists 20 recommended street trees - of those, 9 are Maples and 2 are Ash (which is susceptable to the Emerald Ash Borer). Such an emphasis on two susceptable trees will set the stage for disaster if ALB spreads to this area.

Alistair said...

Hi Chris, beautiful sunny mild day here in Scotland. I was just preparing a few areas in the garden for planting some oriental lilies which are due to arrive next week, and also admiring my Japanese Acers the buds are swelling nicely and it wont be too long before the leaves open. Thought I would check out a few of my gardening friends to see what's going on, you are my first call for today. Oh my very depressing right enough. Glad you told me about this threat though, very important information. Apparently this beetle has not arrived in the UK yet and if it does it is expected to strike in the warmer areas, will not be complacent though.

debsgarden said...

As a lover of Japanese maples, I read your post with trepidation. I am glad ALB hasn't been spotted in my area, but you made an excellent point about diversification. I was thinking just yesterday what my front garden would look like without my Japanese maples. Pretty bare, I confess. Of course I do have other trees, but they are the stars of this particular area out front.

Chris said...

Alistair: I'm glad that you stopped by, and that this undeniably depressing info has had your ear. The more people are aware, the better, so any new spotting will be reported.

Deb: Japanese Maples are great. But we should think twice before putting all our eggs in one basket, especially with ALB on the move.

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