Interactions between ectomycorrhizal and saprotrophic fungi on agar and in association with seedlings of lodgepole pine (Pinus contorta)

Pairwise interaction of ectomycorrhizal fungi on agar showed that Cenococcum geophilum and Lactarius rufus were the strongest competitors. Interactions between ectomycorrhizal and saprotrophic basidiomycete fungi on agar showed suppression of the ectomycorrhizas in all cases. Fungi with rapid growth rates ( Paxillus involutus and Suillus bovinus ) colonized roots more rapidly than slower growing fungi. Interactions between fungi on roots showed various effects. L. rufus stimulated growth of and root colonization by S. bovinus and P. involutus. Laccaria laccata , however suppressed mycorrhizal formation by both S. bovinus and P. involutus . In studies of interactions between the saprotroph, Collybia maculata and the mycorrhizal fungus, P. involutus , the rate of colonization of lodgepole pine seedling roots by P. involutus is significantly retarded. These interactions could detrimentally influence colonization and survival of artificially inoculated tree seedlings when outplanted.