Juglans nigra
While at the Virginia Agricultural Experiment Station in 1921, M.T. Cook found that tomato plants in the vicinity of "Juglans nigra" were negatively affected, most notably by their wilted leaves. Schneiderhan found that "Juglans nigra" and "Juglans cinerea" were damaging apple trees in Virginia. The trees that were within an average of 11.9 meters from the walnut trees were found dead. All damaged trees in their vicinity average about 14.3 meters away. In addition, he found that certain local variations of the apple trees tended to be more resistant to the walnuts.