A general discussion of diseases of the common lilac (Syringa vulgaris L.) was recently published by Klebahn (3). This author enumerates a number of diseases, such as the one of bacterial origin ascribed to Pseudomonas Syringe, various leaf diseases due to species of Microsphcera, Glwosporium, and other leaf parasites, and a disease -due to Botrytis cinerea. The major part of the work, however, deals with a disease due to Heterosporium;Syringw Oud., affectinig the leaves, and a serious twig blight due to Phytophthora Syringw Klebahn. Subsequent papers by various writers deal with one or the other of the diseases mentioned by Klebahn. During recent years a destructive trunk disease of the common lilac (Syringa vulgaris L.) has been noted a number of times in the Missouri Botanical Garden, and in grounds in the vicinity of St. Louis. The affected plants were usually old bushes which had been more or less neglected, and the tops of the leading trunks were frequently dead. Long shoots from the root and others from the part of the -trunks near the ground made a dense tangle around the main stem; on the latter sporophores of Polyporus versicolor were found in -various stages of development, sometimes isolated, but more frequently in groups. Sections were made of the trunks on -which this fungus was growing and it was found that such trunks were invariably diseased, while those close by, either from the same root system or from adjacent bushes-which were free from the fungus-were always sound. Inr pI. 8 fig. 1 two affected -trunks are shown cut at points about -three feet from the groutid. In both cases the larger part of -the stem was alive, -.as evidenced by the presence of Vigorous shoots along the entire length. P1. 8 fig. :2, and pI. 9 figs. 1, 2 represent sections of lilac trunks taken. from different bushes to show different stages of the disease.