Fortunately, there is no juglone present in the fruits of these trees, so walnuts and pecans are a healthy and delicious addition to foods, which makes them agriculturally valuable. <a href="http://www.madsci.org/posts/archives...1900.Me.r.html">http://www.madsci.org/posts/archives...1900.Me.r.html</a> Adverse Reactions Allergic reactions to black walnut in animals and humans have occurred. 17 Allergy studies involving skin testing with black walnut pollen (and