Venturia Acerina, The Perfect Stage of Cladosporium Humile

Abstract

On August 30, 1940, while out collecting in the vicinity of Ithaca (near Buttermilk Falls), Professor H. H. Whetzel called attention to prominent spots on leaves of red maple (Acer rubrum) which appeared to be distinctly different from any of the common leaf spots of maple. He thought that this might be a new or undescribed disease. A cursory examination of the specimens, disclosing the fasciculate conidiophores and the oblong conidia, suggested that the fungus might be a Cercospora. He therefore turned the specimens over to Dr. Chupp, who, in turn, asked the writer to make a critical examination of the material in an attempt to determine the identity of the fungus. The writer made additional collections of the same leaf spot on red maple on October 2, 1940, near Enfield Glen, N. Y., and again a week later at Watkins Glen, N. Y., on the same suscept. Then on February 28, 1941, in examining various specimens collected near Millinocket, Maine, on August 22, 1940, the same fungus was found on spots on red maple leaves. The spots on the Maine material were, for the most part, small and not typical. Still later on May 12, 1941, the same spots were found on fallen maple leaves in the Lloyd Preserve, McLean, N. Y. So it is evident that this disease, although nlot very colimmon, is not particularly rare.