Walnut Leaves

Busy shredding a huge mountain of leaves to use as mulch and mostly in a huge compost pile. There are a few English Walnut leaves. Now, somewhere I either read or heard that Black Walnut leaves were toxic to garden plants and shouldn't be used for either mulch or in compost. Is that true? Or is the English Walnut a baddie too?

Regards, Bill

Reply to
Bill Litchfield
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"Bill Litchfield" wrote in news: snipped-for-privacy@corp.supernews.com:

I don't know but a search for juglone may turnip the answer. yeah i said turnip.

Reply to
Salty Thumb

The roots of Black Walnut ( Juglans nigra L.) and Butternut ( Juglans cinerea L.) produce a substance known as juglone (5-hydroxy-alphanapthaquinone). Persian (English or Carpathian) walnut trees are sometimes grafted onto black walnut rootstocks. Many plants such as tomato, potato, blackberry, blueberry, azalea, mountain laurel, rhododendron, red pine and apple may be injured or killed within one to two months of growth within the root zone of these trees. The toxic zone from a mature tree occurs on average in a 50 to 60 foot radius from the trunk, but can be up to 80 feet. The area affected extends outward each year as a tree enlarges. Young trees two to eight feet high can have a root diameter twice the height of the top of the tree, with susceptible plants dead within the root zone and dying at the margins. The juglone toxin occurs in the leaves, bark and wood of walnut, but these contain lower concentrations than in the roots. Juglone is poorly soluble in water and does not move very far in the soil. [from Ohio State University Extension Fact Sheet HYG-1148-93 by Richard C. Funt and Jane Martin]

The Ohio State University Extension and the American Horticultural Society have reported that R. nudiflorum, Pinxterbloom Azalea, and Exbury Azaleas Gibraltar and Balzac will grow near Black Walnut and Butternut trees.

Reply to
Stephen M. Henning

I bring back leaves from all over the neighborhood, which inevitably includes some black walnut leaves. I've never had any problems. It's my understanding that the roots release juglone. I suspect that the leaves contain minimal amounts (if any). I useThe leaves for mulch as well as composting.

Reply to
Pat Kiewicz

Great information from everyone on this thread. Thanks muchly to you all!

Regards, Bill

Reply to
Bill Litchfield

All parts of black walnut trees contain juglone and can cause problems. The highest concentration is in the roots and the soil near the roots. You are probably not getting many black walnut leaves. My experience in Pennsylvania is that the black walnuts are the first to shed their leaves, much earlier than any other trees. By the end of summer most walnut leaves have fallen. Then come down over a long period of time. When the main mass of other leaves fall, the black walnut leaves are gone, either from mowing and being mulched or have blown away.

Reply to
Stephen M. Henning

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