TWO FUNGI ASSOCIATED WITH THE DEAD-ARM DISEASE OF GRAPES

Abstract

Whereas Cryptosporella viticola (Reddick) Shear (Phomopsis vilicola Sacc.) has long been recognized as the causal agent of the dead-arm disease of grapes, pycnidia of Physalospora obtusa (Schw.) Cke. (Sphaeropsis malorum Peck.) have also been found in lesions on trunks, canes, and tendrils. Both fungi were isolated in about equal proportions, either alone or together, from lesions on trunks and stubs. On the other hand, P. vilicola, but not S. malorum, was isolated from a few lesions on current season shoots and the foliage. Both fungi were capable of infecting freshly cut stubs artificially inoculated with spore suspensions and could be re-isolated from the resulting lesions. The significance of S. malorum in the etiology of the dead-arm disease is at present uncertain.