Juglone is a chemical produced in the leaves, fruit hulls and inner bark of trees in the walnut family (Juglandaceae) including: black walnut (highest producer), Persian walnut, butternut and pecan. With rain, the chemical is leached into the soil. The fungicidal and insecticidal properties of juglone make it toxic to many plants causing wilting and stunting. Plants grown closer to these allelopathic trees may show worse symptoms as they come in contact with the tree roots. Susceptible plants, such as tomatoes, grown next to a walnut tree may wilt and die prematurely whereas those grown further away may have stunted growth, but survive. Even if the affected plants do produce fruit, it may have a less desirable, nutty taste.
Symptoms of walnut wilt may resemble those of fusarium and verticillium wilt including wilting and yellowing leaves that eventually drop. Stem tissue may also turn brown. The diseases can be distinguished by the presence of trees from the walnut family.
Tree removal does not provide an immediate control as the toxicity can remain in the soil and debris for multiple years. Avoid growing the following susceptible plants near Juglandaceaes: tomato, potato, blackberry, apple, lilac, asparagus, chrysanthemum, peony along with many other herbaceous and woody plants. Some walnut wilt resistant plants include, but are not limited to: black raspberry, corn, bean, carrot, dandelion and zinnia. (Cynthia Domenghini)
Symptoms of walnut wilt may resemble those of fusarium and verticillium wilt including wilting and yellowing leaves that eventually drop. Stem tissue may also turn brown. The diseases can be distinguished by the presence of trees from the walnut family.
Tree removal does not provide an immediate control as the toxicity can remain in the soil and debris for multiple years. Avoid growing the following susceptible plants near Juglandaceaes: tomato, potato, blackberry, apple, lilac, asparagus, chrysanthemum, peony along with many other herbaceous and woody plants. Some walnut wilt resistant plants include, but are not limited to: black raspberry, corn, bean, carrot, dandelion and zinnia. (Cynthia Domenghini)
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