Effect of Scleroderma Spore Density and Age on Mycorrhiza Formation and Growth of Containerized Eucalyptus globulus and E. urophylla Seedlings

Greenhouse trials with containerized Eucalyptus globulus and E. urophylla seedlings were made to determine effective inoculum spore densities (Scleroderma cepa from temperate Australia, and S. citrinum from sub-tropical China) and spore storage conditions (fresh spores or spores stored for 5 years at room temperature or at 4 °C; S. albidum, S. areolatum and S. cepa from Western Australia). Inoculation with 10⁶ or 10⁸ spores/seedling increased eucalypt growth by up to 46% in height and 42% in dry weight compared to non-inoculated seedlings at 12 weeks after inoculation. Mycorrhizal formation was poor at 10² spores/seeding. Spores stored at 4 °C for 5 years were as effective in forming mycorrhizas as freshly collected spores when a standard density of 10⁶ spores/seedling was applied. It is recommended that spore densities ≥10⁴ be used for inoculation of containerised eucalypts and that spores be stored at 4 °C until use.