Commercial use of vesicularndash;arbuscular mycorrhizae (VAM) may be an alternative to rising agricultural energy and fertilizer costs. Vesicularndash;arbuscular mycorrhizae may be able to increase crop yields while reducing fertilizer and energy inputs. Since mycorrhizal fungi are naturally present in most soils, their unique fertilizer abilities are already being utilized by most crop plants. Commercial uses of VA mycorrhizal fungi are therefore currently restricted to situations where the natural populations of VAM fungi have been destroyed or damaged such as in fumigated or chemically treated areas, greenhouses, and disturbed areas such as coal spoils, strip mines, waste areas, or road beds. Commercial production of VAM inoculum is presently being attempted at several locations in the U.S. Vesicularndash;arbuscular mycorrhizal inoculum is produced by growing VAM fungi on the roots of suitable host plants under aseptic greenhouse conditions The inoculum consists of the host-plant growth medium and host roots associated with VAM hyphae and spores which have been ground and dried. Most large-scale uses of VAM involve the establishment of the mycorrhizae on seedlings which will be transplanted to the field. Large-scale methods for direct inoculation with VAM have not yet been devised, but in small trials, layering, banding, broadcasting, and pelleting seed with VAM inoculum have proved effective. Methods for determining what soils are most likely to benefit from applications of VAM fungi are available. The potential for employing VAM fungi on a wide scale in agriculture is dependent on the development of crop growth-promoting strains of VAM which are superior to native soil populations of VAM fungi.
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