How can one know that inoculation with mycorrhizal fungi is needed?
Most all agricultural crop plants can form VA mycorrhizae, but some are much more dependent on them than others. Highly dependent plants will need to be inoculated if natural inoculum is not likely to be present in sufficient numbers, as when the soil has been fumigated to kill pathogens, weeds, or insects; or plants are grown in soilless media devoid of mycorrhizal inoculum. Highly disturbed sites like road cuts, mine sites, highly eroded or salinized soils, or soils that are very nutrient deficient or drought stressed should be inoculated or plants to be grown in them should be preinoculated.
