Specificity of ectomycorrhizal fungi towards Eucalyptus viminalis Labill and E. dunnii Maiden.
The ability of 19 ectomycorrhizal fungal isolates (mainly Pisolithus tinctorius) to infect E. dunnii and E. viminalis was studied under greenhouse conditions. Fungal inocula were grown for 45 d at 25°C in a vermiculite-peat mixture (4:1, v/v) moistened with nutrient medium (MMM). The colonized substrate was then added at a rate of 1:10 parts of a mixture of sand-vermiculite-peat (50:45:5, v/v/v) and distributed in plastic pots (60 ml/pot) before sowing. Seeded pots were maintained in the greenhouse at 25±5°C and 16 h of daily photoperiod for 101 d, after which the seedlings were harvested. The roots were removed from the shoots, gently washed from substrate and examined with a stereomicroscope to determine the extent of mycorrhizal development. Of the fungi tested, 3 P. tinctorius isolates were specific for E. dunnii, but none was specific for E. viminalis. One isolate of P. tinctorius showed greater colonization of E. dunnii than E. viminalis. Two isolates from Pinus spp. infected both Eucalyptus species. The results indicated that the fungi differed in their compatibility for host species and pre-screening is important for success of mycorrhization control programmes.