Abstract Basidiospores of Pisolithus tinctorius (2.2 or 0.22 X 10 6 ) mixed dry in 800 cm3 of soil were more effective mycorrhizal inoculum on 1obolly pine seedlings than the same quantities of spores suspended in water and added to soil. Roots of nonmycorrhizal seedlings dusted with spores formed more ectomycorrhizae than did seedlings dipped in a water slurry of spores. Water extraction of a spore pigment appeared to decrease spore viability. A concentration of 5.5 X 10 7 spores mixed in soil prior to planting seed formed significantly more ectomycorrhizae than did greater or lesser spore concentrations. Dry storage in darkness at 5°C from 1 wk to 34 mo of different basidiospore collections did not significantly affect ectomycorrhizal development. Vermiculite and kaolin functioned as physical carriers of basidiospores for soil infestation more effectively than did sand or water. Ectomycorrhizal development from spores was first detected 2 mo after seed germination. A 50 percent increase in ectomycorrhizal development between the fourth and fifth months was associated with a 170 percent increase in seedling growth. These results suggest that basidiospores of P. tinctorius can be effectively used in tree nurseries as inoculum to ensure ectomycorrhizal development on tree seedlings. Forest Sci. 22:13-20.
Donald H. Marx (Mon,) studied this question.