The Large Leaf Spot of Chestnut and Oak

Abstract

This disease we have named the leaf in contradistinction to the -small leaf spot, the latter being common on chestnut leaves, and, as is well known, caused by the fungus, Septoria ochroleuca B. & C. In the summer of I9IO, during a survey of the diseases of the forest trees in the Southern Appalachian region, in collaboration with the U. S. Forest Service, the writer found the large leaf spot occurring abundantly on leaves of Castanea dentata in Bedford County, Virginia; in Transylvania, Jackson and Macon Counties, North Carolina, and in Rabun County, Georgia. It was found commonly also on leaves of Querclus rubra L. in Transylvania County, North Carolina. A similar disease has been briefly mentioned by Stevens and Hall1 under the title of Monochetiose, in their recent book on Diseases of Economic Plants. Stating that it is abundant in the forests on chestnut leaves, and causes much loss of vigor to the tree, they refer to Monochaetia pachyspora Bubak as the fungous agent. The disease which they mention may be the same as that observed by the writer, and if this is so, it is probably more correct to refer it to Monochaetia Desnmazierii Sacc. This point, however, will require further investigation.2 Beyond the brief statement in the above mentioned work, we have been unable to find any other definite reference to such a disease in the literature.