Viability of soilborne spores of glomalean mycorrhizal fungi

Spores of glomalean (arbuscular) mycorrhizal fungi indigenous to soils in a central Kentucky cropping system were about 50% viable. The range was 35 to 60%, regardless of spore population density, time of year, or crop. Viability sometimes rose at the time new spores were produced in late summer and fall, but not appreciably. In the absence of extreme treatment of soil, such as fumigation or steaming, about half of the spores present in surface soil may be considered viable in the soil studied here. Elsewhere, a few viability tests should be conducted to confirm this proportion.