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Black Walnut and Japanese Maples

Posted by ezochi z5a/b (My Page) on
Sat, May 5, 07 at 13:14

This maybe helpful to a few gardeners out there. I have a large 50 foot Black Walnut tree that came with my property when I bought it, and of course didn't know about Juglone (poisonous to many trees/shrubs) that comes off of its roots and fruits, etc.. Anyhow, this year my Scotch Pine is almost dead. I planted it last year, and everything seemed fine. I watered it adequately. Its roots were fine, etc.. Now inexplicably it is beyond life support.

Now its not conclusive but I believe that the Walnut is within range of the Juglone to work its poison (within 40 feet). It may be the culprit for its demise.

On the other hand I have an AP 'Hogyoku', and an AJ 'Aconitifolium' right under the canopy of this old beast. It rained down those messy fruits in the fall, etc., and has not had any effect on them (of course I removed the fruits whenever they fell nearby). Thankfully, despite my ignorance, I found out that Acer Palmatums are immune to Juglone.

What is odd is that the Scotch is in the backyard seemingly far from its canopy but it seems extra sensitive, and the APs are under the canopy and they are fine.

Follow-Up Postings:

RE: Black Walnut and Japanese Maples

Bw's effect many trees and bushes but from I understand Jm's are not one of them ..I do not know the reason why not I guess they are not "poisoned" from the excreeded Juglone. David

RE: Black Walnut and Japanese Maples

Well, without doing any research I don't recall if Pinus sylvestris is tolerant or if it isn't. Definitely the Maples are fine. The roots of Acer palmatum host the scions (to be trees) of the other species maples, USUALLY. It's a known fact though that compatibility among several Maples exist, but again, the norm is for growers to supply palmatum rootstocks.

Your Scot's Pine I know nothing about. Maybe it had a bad hair day. I wouldn't exactly discount Juglone being the culprit, but I wouldn't want to guess either. Heck maybe it was a result of one of ten's of things.

Thanks for the shared information. Wish I knew what happened to your conifer for ya. Heck I didn't even know Juglone eased from other parts of the tree, however, that now makes sense to me.



RE: Black Walnut and Japanese Maples

Good to know...I was under the impression that practically nothing should be planted under walnuts or pecans.

Regardless, I would still prefer not to take my chances as I tend to think things are "resistant" to poisons rather than "immune". But, keep us updated on their condition as I may run into an issue with that one day.

RE: Black Walnut and Japanese Maples

I have about eight 100 foot plus black walnut's on the property. OSU website has a nice discussion about whats safe and whats not. The only conifers I try to grow near them is hemlocks.

JM's are fine. Hydrangea do well too. They'll gobble up Rhodie's

RE: Black Walnut and Japanese Maples

Wish we could grow rhododendrons here. People get them from walmart and lowes and plant them sometimes, but they die in like 3 years from root rot or heat stress.

Although I have managed to keep one of my mothers alive for almost 4 years, but it is in the shadiest possible part of the yard (she has a brown thumb sometimes so I take care of her yard).

RE: Black Walnut and Japanese Maples

Hi mattlwfowler, uhhh... It's the Black Walnut only I believe.

Now does "brown thumb" mean she gets down and dirty in the dirt or does that mean something else? Just kidding... There's always more than one way to joke around and look dumb like I'm doing right now.

Put a hose in her hand! That's what makes a gardener, a "gardener" quams. No if's, and's, or - but's!

hah hah! just kidding again for the intellectually challenged, in case.


RE: Black Walnut and Japanese Maples

I have several Black Walnuts and many thriving Spruce, both White Spruce and Norway Spruce. One is growing directly under a huge Walnut. Red bud is supposed to be juglone tolerant and mine are doing well so far. All evidence is questionable. If you search this site using juglone as your search word, you will find that some people can grow one thing and someone else can't. I've gotten so I blame every failure on the Walnuts, but if I get a grip and ask myself: "What else could be causing this?" I almost always find an alternate explanation. I don't think the Walnuts blanket an area in poison and stop everything from growing. It seems more hit and miss. I do have one narrow band, about 18" wide, which must follow the path of a root. I call it the valley of death.

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