Walnut Blight

Walnut blight Common name Walnut blight Causal agent It is caused by a bacterial pathogen belonging to the genus Xanthomonas. Although it affects all species of walnuts, Persian walnuts are more susceptible to the disease. Scientific name Xanthomonas arboricola pv. juglandis Symptoms & Signs Walnut blight is identified through black, sunken lesions on the leaves, flowers, and side of the nuts. If the infection spreads to the inside of the nut, it may even destroy the kernel. The twigs also display cankers that secrete bacterial cells and transfer the disease. Infected leaves and nuts fall early. Transmission The bacterial cells spread through wind, rain, and insects and enter healthy plants through wound openings. Rainy, wet seasons favor the growth and spread of the disease. Time of concern Spring to late summer Common hosts Walnuts