Is a Red & Silver Maple cultivar (Autumn blaze) juglone tolerant?

Asked May 24, 2018, 1:49 PM EDT

Two questions on juglone (in)tolerant trees and exposure to juglone: 1. Is an Autumn blaze (a red and silver maple cultivar) juglone tolerant? 2. Are crape myrtles juglone tolerant? 3. Can a tree or shrub that exhibits juglone intolerance (wilting, dead branches) be saved if it's removed from the exposed site/soil and pruned? Hello, I recently had to remove a medium-sized black walnut from my backyard (lightening had struck it years ago and it was dropping branches), and from what I understand, remaining juglone will be in the soil for several years, and at great distances from the tree. Before I knew about juglone, I'd purchased a red/silver maple cultivar to plant near the site of the felled tree to block and ugly view and get some shade. I read online in some places that this cultivar *is* juglone tolerant because it's part red maple, but then other gardeners pointed out it wouldn't be because it's still half silver maple (the only maple type that does not do well with juglone). I'm watching it leaf out and noticing they look sort of droopy and thin. I'm wondering if the NAY votes were correct and I should get it out of that area ASAP. I also cannot find any information online about black walnuts and crape myrtles, even though they are both very common in the region. We planted some but then dug them all out because we couldn't confirm they were safe near a black walnut, and they seemed to have many dead branches after a few months in the ground (also before we knew about juglone). All the other trees and shrubs planted are native and established to be juglone tolerant. It's just these two trees we cannot figure out. Please help!

Montgomery County Maryland shrubs trees crape myrtle juglone tolerance autumn blaze maple

4 Responses

How does your tree look today?
The leaf wilt could indicate thirst (newly planted, new roots on a hot day), insects feeding (check for small aphids), disease (like anthracnose) or possibly juglone damage. We don't know how the DNA of the crossed maples turned out, so it's impossible to say whether the tree is juglone-resistant or not.

Our plant pathologist is out of the office today. With the long holiday weekend we won't get to run it by him until Tuesday. We will consult with him then, but wanted to let you know we are working on it.
Enjoy your weekend.

cm

Thanks for this, and I look forward to hearing more from the plant pathologist on juglone tolerance of this maple cultivar (though as you say, we cannot know its DNA) and cape myrtle trees as well. The maple looks the same today. To answer your other questions: There are no aphids or bugs making a home on it; the tree has been watered (but not overwatered) since it was planted about a month ago, with soil conditioner to help the new roots; and it has looked like this on cool and on warm days, so it's not the heat. I hope the plant pathologist can also tell me whether juglone-sensitive plants exposed to juglone can recover if removed from the site/soil under the black walnut drip line... Much appreciated!

We would move the tree to a new area, away from the juglone soil.

Crapemyrtles don't show up on juglone lists so it's best that you moved them.
The "dead" part you hold in your hand in the photo is normal however. That was the blooming stem from last season.

cm

Got it! I noticed that on a neighbor's crape myrtle and thought maybe it was normal. Phew. I'll move the tree farther away from where the black walnut was (it was taken down very recently because it had been struck by lightening and was dropping branches; though I know juglone stays in the roots and soil for years). It looks like I need a need new home for the maple too, since it's still looking dried up.