Trees affected with bunch disease show a typical bunching symptom, caused by excessive growth of lateral buds. Normally only the most distant bud will break dormancy and develop into a twig and finally a limb. A large percentage of the buds on bunch infected trees will break dormancy at one time. This results in a dense growth of small twigs. In some cases only one or two limbs will be infected by the organism.
Nut production is very limited on bunch infected trees.
Nuts from infected trees are restricted in size. There is no effective control for bunch disease, except tree removal. The disease occurs most commonly following rainy periods, in areas of high relative humidity and on leaves of poor vigor trees. The fungus grows on the lower surface of the leaves, a growth of white tufts that contain spore masses. Articularia leaf mold does not occur on trees in orchards that have been sprayed regularly for disease control.