Trochila Populorum Desm

Abstract

In a recent article, Potebnia* has called attention to the probable connection between Marssonia Castagnei (Desm. and Mont.) Sacc., a common fungus on certain species of Populus, and the discomycete, Trochila Populorum Desm. This connection had previously been suggested to him by Jaap. However, Potebnia is of the opinion that the discomycete is a Pseudopeziza rather than a Trochila. He arrived at this latter conclusion mostly from the similarity of artificial cultures obtained from Marssonia Castagnei spores, to cultures obtained from Pseudopeziza Salicis, the perfect stage of Gloeosporium Salicis. His material of the perfect stage of the Populus fungus was too scanty to be studied. During the past three years, I have had this fungus under observation, trying to connect the Marssonia stage with the perfect form. While the study is not complete, and the connection between the Marssonia and the Trochila is not absolutely proven, it is impossible to carry on the study further on account of being out of the region where the fungus grows, and it is thought best to publish the observations as far as made. The study of the poplar Marssonia was commenced in the summer of I907, at Ithaca, New York. The fungus is very common in that region on Populus alba, forming numerous small dead spots on the leaves. The acervuli develop in abundance on the upper side of the spots. Two sorts of conidia develop in the spots, the large two-celled spores typical of Marssonia, and some small, somewhat cylindric to ellipsoid, one-celled spores. The small spores have since been found by Potebnia and are illustrated in his article.