By far the greatest concentration of juglone is in the trees roots, although some is in the leaves and wood of the Black Walnuts. Butternut and Hickory are in the same family as the Black Walnut with somewhat the same properties of plant growth suppression and the waste wood from these is used as mulches and mixed in compost with little thought or concern.

If I had other sources to choose from I would not use the black walnut. If you are not sure about the toxicity of the shavings and composting it will not remove the juglone from the mix why take the chance? Does anyone know how sensitive, for example, tomatoes are to the effects of juglone? Chemical toxicity can be as little as a few parts per billion for any given substance. I do know that the one time my horses were unintentionally exposed to black walnut sawdust they developed a rash on all 4 legs and on their underbelly's. Fortunately for me I had not yet added the stall cleanings to my compost pile.... I dumped it all in the woods. Didn't want to take the chance...

Yes. Juglone in the presence of bacteria lasts days. In particular, in the presence of the common pseudomonas it lasts minutes. compost them first with some N-rich stuff, but really, you do not even have to fully compost them. they just need to look rotten.

I would be wary, but glib and kimmsr know much more about this stuff than I do!
Could you compost it and use it somewhere besides your vege garden to see how it works out? Maybe a flower bed or a bed that isn't quite so important as your main vege garden? Nancy
PS Call it an experiment!

nancyjane, I have already done those experiments with Black Walnut wood and leaves and have found that they have no observable adverse affect on plant growth., except the leaves. Many times I have shredded the leaves and put them where I have a lot of Quack Grass growing and found they did suppress that growth, but caused the perennial Rye to grow quite vigorously.
These were not controlled experiments, however.

I thought we had a thread awhile back where someone (maybe even me) found a research paper listing how much juglone is in various parts of the tree. In any case, here's a link to another thread which has a quote from a University publication saying that juglone in leaves will break down pretty fast in the compost, but sawdust, not so much. They recommend against it for 'juglone sensitive plants.' I don't know why that would be except for the naturally slow breakdown of any sawdust - because it's wood after all. I would suggest making a batch with a measured amount of walnut sawdust and then try growing some tomatoes in it. Unless you can find more definitive info.

Hey Tox, where's the link? I could see avoiding sawdust as a mulch, but composted it should be fine. I use BW leaves, sticks and some hulls in my compost without issue, but my compost is on a 1 year cycle (stuff amassed this year is used next year). Time and oxygen alone will break down juglone.

tj

Well shoot, I must have not pasted the link. Try searching this forum for 'juglone' and it will turn up. Sorry bout that.

break down = aerobic bacteria. you bury BW sawdust in heavy, sterile soil, the juglone will be there a long time. You put it in a tumbler with, say, spoiled fruit and other wetting kitchen garbage, it will be gone in days.

Juglone in black walnut sawdust will never break down in soil for the very reason that it's not there. Juglone is only in living roots, green leaves and twigs, and husks. Juglone in fallen leaves and twigs is quickly rendered harmless just by natural drying.

"The causal agent is a chemical called “juglone” (5 hydroxy-1,4-napthoquinone), which occurs naturally in all parts of the black walnut."

"Leaves, bark, or wood chips of black walnut should not be used to mulch sensitive landscape or garden plants. Even after a period of composting, such refuse may release small amounts of juglone."

From:Purdue Cooperative Extension

I have black walnuts in my yard and I avoid adding any part of the tree to my compost. For me, it just isn't worth the risk. Maybe others have anecdotes to refute this, but I'd proceed with caution if I chose to use any BW in my compost.

If anyone has other information, I'd like to see it.