A tree question

[kyosa]

I suppose this isn't really a 'gardening' question since it's really more concerned with trees, but here goes. I know the roots of Black Walnut trees put off a growth-inhibiting chemical called 'juglone' and that it's also contained in their leaves. What I'm wondering about is whether English, or Carpathian, Walnuts also produce juglone? Also Pecans. I have two Carpathian Walnuts and three Pecans in the yard and I'm wondering about using their leaves as a soil-builder in the garden. I know I've asked this question SOMEWHERE before, but I think it was on a gardening forum somewhere else. My CRS disease has apparently progressed into full-blown CRAFT disease now! Anyway, if anyone knows the answer I'd appreciate hearing. If these leaves are 'bad' I'll avoid them when I'm collecting for the garden.

[Kathy]

Darryl, here's the info, I think you're safe with the English Walnuts & Pecans.
This link talks a lot about Black Walnuts & how the juglone works on surrounding plant life.

Other trees closely related to black walnut also produce juglone, including butternut, English walnut, pecan, shagbark hickory, and bitternut hickory. However, all produce such limited quantities compared to the black walnut that toxicity to other plants is rarely observed.

www.wvu.edu/~agexten/hortcult/fruits/blkwalnt.htm

[Kathy]

An opposing view:

English Walnut Mulch

Dear Doyenne,
Do you know if English Walnut leaves are good to use as garden mulch?

Thanks,
JP

JP,
English walnut (Juglans regia), much like the native black walnut (J.nigra) contains toxins that may be harmful to other plants -- particularly members of the Solanaceae family, which includes tomatoes. When using the leaves as a mulch, make sure they are very well composted before applying around the base of plants.

Best, KL

www.npr.org/programs/talkingplants/why/archive/010607.html

[kyosa]

Contradiction! Confusion! Indecision! In other words, my usual state. I think I'll play it safe and avoid those trees when I collect my leaves. There's a pretty good supply without taking any chances, although they would probably decompose enough over the winter that it wouldn't be a problem. Thanks for finding that information, Kathy. I 'googled around' a bit but what you found was better.