© 1973 by Institute of Chartered Foresters
The Occurrence of Crumenula sororia Karst. on Lodgepole Pine in the United Kingdom
Department of Forestry and Natural Resources, University of Edinburgh
The ascomycetous C. sororia was found attacking Lodgepole pine in widely separated forests in Scotland.
After colonizing small patches of bark, C. sororia invaded phloem and xylem, and produced intracellular hyphae with some haustoria. Subsequently infection was associated with more numerous, but shorter and narrower, tracheids than in the healthy counterparts. In contrast infection was associated with taller and more seriated rays and more numerous and wider resin ducts. These effects were noted in areas of stem actually invaded and also in uninvaded sections on each side of the developing canker. Together, they were associated with increment losses of 7–40 per cent. The effects on forest yields where healthy trees may react to the lack of competition by accelerated growth is as yet unknown.
The characteristic dark staining of wood and bark noted in Corsican pine infected with C. sororia was completely absent in infected Lodgepole pine. Moreover, lengths and diameters of tracheids in hosts other than Lodgepole pine were unaffected. In both Corsican pine and Lodgepole pine the size of the ray cells was increased by infection; in Corsican pine the number of cells was unaffected so that the maximum height and height range of rays were increased, whereas in Lodgepole pine, although the maximum height of rays was not increased, there was an increase in frequency of rays in the top height class and a consequent reduction in the numbers of cells in the tallest rays. In contrast, Peridermium pini attacking Scots pine produced an increase in the number of cells per ray.