View Full Version : black walnuts and juglone

03-13-2004, 01:14 PM
I have read that black walnuts produce a substance toxic to many plants called juglone. Is juglone an effective organic herbicide? Is it for sale? Does it come from the leaves? Do composted leaves still contain it. Would I need to have a license to spread that compost? I was thinking of experimenting with a composted leaf mold using walnut leaves.

03-13-2004, 01:57 PM
Nice concept, but not too practical. Juglone is secreted from the roots of the walnut tree. The roots constantly secrete it during the growing season. Unless you were to apply juglone everyday, your results would probably be less than desireable, as juglone does not remain active in the soil very long. Also, not every plant shows toxicity to it. Grass and many weeds are not affected by it, so if you were to use it for weed suppression in beds, you'll end up with nothing in the beds but weeds and grass.

03-14-2004, 03:52 PM
I was thinking of topdressing lawns with compost this season. Do I need to worry if that compost had a high concentration of the black walnut leaves? Or alternately, if I compost those leaves seperately, will that compost discourage some weeds? I hand weed a lot in the summer. Those weeds are the "greens" in my compost. Will juglone in the compost help keep any stray weed seeds fro germinating.
P.S. Compost for topdressing is available at county sites, I don't make enough myself. I had in mind a special pile for a couple of customers who are organic purists. They have a lot of creeping charlie which is innefective to pull by hand. I don't have a license yet so corn meal is not an option.

03-15-2004, 07:52 AM
compost all the walnut leaves you want. There should be no adverse effects. If your compost pile gets hot enough, most of the weed seeds will be killed. Also, check with your local Ag Dept. - you may be able to apply corn meal without a license.