Interactions of ecologically similar saprogenic fungi with healthy and abiotically stressed conifers

Saprogenic fungi are distinguished in part by their inability to cause disease in healthy hosts, and relatively high ability to kill or accelerate the decline of stressed hosts. We sought to determine the degree to which Leptographium terebrantis and L. procerum, ecologically similar, ophiostomatoid fungi, are saprogenic. In inoculation experiments, Leptographium terebrantis was better able to colonize roots of both mature and seedling Pinus resinosa than was L. Procerum. In addition, L. terebrantis colonized roots of shade-stressed seedlings to a significantly greater extent than it colonized roots of non-stressed seedlings. L. procerum exhibited no such trend. Due to its greater virulence within stressed than healthy hosts and related traits. L. terebrantis was judged to have a relatively high degree of competitive saprogenic ability as compared with L. procerum. This study indicates the biologically important differences which may occur between closely related, ecologically similar fungi and may have implications to studies of declines and diseases with which L. terebrantis and L. procerum have been associated.