Juglone is found in the tree’s trunk, leaves, bark, twigs, fruit husks, and roots, which may extend 50 feet or more. The chemical can also appear in the soil directly under the tree.

They produce a chemical toxin called juglone, which can stunt or ultimately kill a lemon tree, says Tammy Sons, CEO and founder of TN Nursery. Juglone is unsafe for many other plants, too ...