THE LARGE LEAF SPOT OF CHESTNUT 

 AND OAK 



Arthur H. Graves 

 (With Plate 69, Containing 5 Figures) 



This disease we have named the " large leaf spot " in contra- 

 distinction 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 19 10, 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 Bed- 

 ford County, Virginia; in Transylvania, Jackson and Macon 

 Counties, North Carolina, and in Rabun County, Georgia. It 

 was found commonly also on leaves of Quercns rubra L. in Tran- 

 sylvania County, North Carolina. 



A similar disease has been briefly mentioned by Stevens and 

 Hall^ under the title of Monoclietiose, 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 cor- 

 rect to refer it to Monochaetia Desmazierii Sacc. This point, 

 however, will require further investigation.^ 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. 



Symptoms 



On leaves of the chestnut, the large leaf spot begins to make 

 its appearance (about August i, in the localities visited) as small, 



^ Stevens, F. L., and Hall, J. G., Diseases of Economic Plants 438. 1910. 

 ^ No material of this leaf spot described by Stevens and Hall is at present 

 available, but in all probability a new supply will be obtained this summer. 



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