The Spherical Gall Rust of Jack Pine

Abstract

Three types of gall rusts have been found in Quebec on Pinus Banksiana. Two of them are well known: the fusiform gall caused by Cronartium Conllmandrae and the effused gall of the base of the stem caused by C. Comptoniae. A third type, which has been observed for several years in Quebec, presents true globose galls (FIG. 1, A4, B, C) related to the eastern gall rust of Cronartiurm Quercuunm and more closely to the western one known under the name of C. coleosporioides. Although the existence of C. Quercuum has been mentioned on Pinus Banksiana of the northeast, all spherical galls cannot easily be considered as belonging to this species. These galls are mostly found in far north regions where oak, the alternate host, is from 200 to 300 miles distant at least. The known range of C. coleosporioides of western species of hard pines has also left much doubt on the possible relationship with our eastern gall on Jack Pine. The striking similarity of this disease with the Woodgate rust of Pinus sylvestris, so common in plantations in this part of the continent, has also complicated the problem. Several attempts have been made to directly inoculate pine by aeciospores but no successful result was obtained. This problem was left unsolved for many years up to the end of the summer 1941. In a Jack Pine stand, located on the north shore of the St. Lawrence River at about 300 miles northeast of Quebec city, the author was looking for possible secondary hosts of the two existing pine rusts: the fusiform and the spherical type, when the telial stage of C. Conmmandrae was abundantly found on Commandra livida. Associated with this herbaceous plant and shrubby species like Vaccinium VitisIdaea and V. pennsylvanicum, another plant, identified as Melampyrum lineare was also found bearing telial columns (FIG. 1, D).