Index >> Mycorrhizae >>Techniques of Ectomycorrhizal Inoculation

Fast growing species of fungal symbionts are easily grown while fastidious slow growing ones need growth factors to generate enough inoculum biomass. Satisfactory results have been reported in experiments with Pinus radiata with isolates of Rhizopogon luteolus, Suillus granulatus, S. luteolus, Cenococcum geophilum and Pisolithus tinctorius.

The fungus is grown for 3-4 months .in 2 litre jars containing sterilized peatmoss-vermiculite substrate moistened with a suitable nutrient medium. The inoculum is washed well in tap water to get rid of the unutilized substrate and spread on nursery beds and mixed with soil for a depth of 8-10 cm. It is necessary that the soil for nursery beds must be fumigated with a methyl bromide­ chloropicrin mix or any other sterilant to minimize the population of other microorganisms which may inhibit the growth of the ectomycorrhizal in­oculum.

Other methods of inoculation are the transfer of soil from the root region of well established particular species of a tree to constitute a nur­sery bed so that spores and propagules from the already established tree stands serve as natural inoculum.

Sporocarps, spores and other fruiting bodies of fungi near a particular tree stand may also serve as a natural source of inoculum. These are labour intensive practices and subject to transfer of other tree pathogens to nursery beds. Planting mycorrhizal "nurse" seedlings or incorporation of chopped roots of ectomycorrhizal roots of a given tree species have also proved useful in certain instances.