My eggplants are dying and some of my tomatoes. And my peppers stopped producing. I was starting to think my thumb was black. The symptoms were very strange. Healthy plants suddenly just wilting and then perking up again. The eggplants in particular would grow, produce flowers, wilt and then perk up again. But too late to produce an eggplant. Some of the tomatoes started to do it too.
I was completely puzzled. My tomato plants suffered from little pest damage, were planted in beautiful compost, and had received PLENTY of rain, sun and heat. I really was convinced that I was just a bad gardener and resigned myself to never finding out what I had done wrong.
Then, during a search for blight symptoms for my squash (another story!), I found this from the horticulture department at Iowa State University:
Walnut Toxicity
Black walnut trees produce a toxic material (juglone) that can injure and kill solanaceous crops (tomatoes, potatoes, peppers and eggplant) and other juglone-sensitive vegetables in the garden. Symptoms of walnut toxicity include stunted growth, yellowing and wilting of foliage, and death of susceptible plants. Juglone is present in all parts of the black walnut tree (fruits, leaves, branches and roots). The sources of juglone in the soil include both living and decaying plant material. Rain droplets leach juglone from the buds, leaves, and twigs. The decomposition of leaves and other plant debris by soil microorganisms also releases juglone. Living roots exude juglone into the surrounding soil. Generally, the greatest concentration of juglone in the soil exists within the dripline of walnut trees. Nothing can be done to save juglone-damaged tomato plants. Simply remove and destroy dead plants. Gardeners who have large walnut trees near their gardens should consider alternate sites. If alternate sites are unavailable, plant tomatoes and other susceptible plants 20 to 25 feet beyond the dripline of walnut trees to minimize walnut toxicity problems. Corn, beans, onions, beets, and carrots are tolerant of juglone and can be planted closer to walnut trees provided the area receives sufficient sunlight. Walnut trees that are 75 to 100 feet from the garden shouldn’t be a big threat to tomatoes and other juglone-sensitive vegetables.
Walnut Toxicity! Who knew? Certainly not me! I have three black walnut trees in my yard and one has a dripline that hangs directly over – guess where? Yup, the tomatoes. We’ll just have to wait it out this year and move the tomatoes out to the corner next year! Urban farming certainly isn’t easy – but I’m happy with cuke production as I just canned about 12 pints of pickles!
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