Since black walnut trees affect the plants growing around them, do the yields of more tolerant plants have yields affected by the toxin to produce less?


Does juglone (an allelotoxin from black walnut) affect (positively or negatively) the yield of juglone tolerant crops?

Look into allelopathy... it's talked about in this SE as well as around the internet. I'm certain that this is a long winded answer with lots of examples. In general, allelotoxins affect the field like the desert provides a life for cacti. Without the desert, cacti would be out-competed by other plants. Although I would expect that very few plants would be positively affected by juglone, I'd bet that there are a few... besides other walnut trees... perhaps parasitic plants like trumpet vine would be stimulated in the presence of juglone (I asked myself this question years ago as I was considering how well the trumpet vines were growing on the walnut trees in my area).

Allelotoxins, like juglone from black walnut and sorgolene from sorghum, have been studied for many years to improve crop yields with rotation and companion planting- and for making herbicides- and for other discoveries. There are some new herbicide products on the market derived from the research.

Juglone especially affects tomatoes and solanaceous plants.


  • Really? I thought that Juglans nigra and many other trees did this on a regular basis so as not to have to compete with their progeny. Why would this toxin be harmful to the solanaceae group? I gotta go check you out...are you an organic chemist??? – stormy Jul 16 '16 at 22:46
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    @stormy here's a link about juglone toxicity toward solanacea... but there are many. It is a well documented observation/fact. The reason is for competition is practically the story of life. I've never heard about the toxicity of juglone toward othewr walnut trees (or progeny)... seems counterintuitive, but still plausible; stuff like that happens- biology is ironic and harsh. Do you have a report about juglone toxicity against other walnut trees or progeny? – Ben Welborn Jul 17 '16 at 15:41
  • Ben! I just went to LOOK AT YOUR profile and wow...a Jack of a hell of a lot of great trades! A chemist! Hands on landscaping! And and and...my goodness, how exciting. I'll go check your link out and check on a few things I need to bone up on and I shall be bugging you an awful lot! – stormy Jul 17 '16 at 19:54
  • Well, there must be something to the fact that BOTH these genus are some of the most toxic of plants! If I were to do a study I'd want to see how the two different toxins interact. How fascinating that the Walnut wants or needs to eliminate Solanaceae! I was taught that Walnuts and other trees (gotta go remember which trees) produce toxins to eliminate competition from their 'progeny'...to also include Solanaceae is a head-tilter! Working with walnut to make furniture or whatever is a big deal! Is there are difference between the two toxins? – stormy Jul 17 '16 at 20:06
  • @stormy Juglone and sorgolene are different chemicals, but they both contain something like a benzoquinone (di-ketone) moiety. So they may act in a simiar manner. Bayer has been working with tri-ketones based on allelopathy research (triketones are little different, but perhaps similar in effect) to inhibit 4-Hydroxyphenylpyruvate dioxygenase (HPPD) an enzyme which catalyzes the catabolism of tyrosine. Excess tyrosine stunts plant growth. Mechanism: the plant suffers from oxidative damage due to lack of tocopherols (vitamin E), so chlorophyll is destroyed due to lack of protective carotenoids. – Ben Welborn Jul 18 '16 at 15:31

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