Formation of ectomycorrhizae following inoculation of containerized Sitka spruce seedlings.

Containerized Sitka spruce, [Picea sitchensis (Bong.) Carr.] were inoculated at sowing with pure cultures of either Pisolithus tinctorius (Pers.) Coker & Couch, Laccaria laccata (Scop. ex Fr.) Berk. & Br., Astraeus pteridis (Shear) Feller, Amanita pantherina (D.C. ex Fr.) Schumm., or Cenococcum geophilum Fr. Seedlings were grown in 66-cubic centimeter cells for 6 months in greenhouses at Corvallis, Oregon, and Petersburg, Alaska, and environmental growth chambers at Juneau, Alaska. At Corvallis, Petersburg, and Juneau, respectively, 100, 85, and 100 percent of the seedlings inoculated with L. laccata and 100, 80, and 98 percent, of those inoculated with C. geophilum formed mycorrhizae. Percentage of short roots on colonized seedlings that were mycorrhizal at Corvallis, Juneau, and Petersburg, respectively, were 92, 38, and 77 for L. laccata, and 91, 7, and 12 for C. geophilum. Positive mycorrhizal formation by the other test fungi could not be confirmed at any location.