PERSISTENCE OF LACCARIA SPP AS ECTOMYCORRHIZAL SYMBIONTS OF CONTAINER-GROWN BLACK SPRUCE

Picea mariana (Mill.) B.S.P. seedlings were grown in containers under three levels of N-P-K fertilization. They were inoculated with one of three levels of mycelial slurry of either an isolate of Laccaria bicolor (Maire) Orton or of Laccaria longipes G.M. Mueller. Seedlings were grown for 16 weeks in a glasshouse before planting on two different sites (organic and mineral soil) in northern Minnesota. Persistence of the two fungi was monitored over a 2.5-year period. Dikaryotic-monokaryotic pairings indicated that trees on the mineral soil site, inoculated with L bicolor, remained colonized by that isolate for the entire test period. Controls and L longipes treated seedlings on the same mineral soil site became colonized by indigenous isolates of L bicolor. The half-strength fertilizer treatment produced significantly taller seedlings.