Arbuscular mycorrhizal fungi (AMF) are vital to plant nutrition; however, factors affecting their presence are not fully understood. Soil conditions, plant species and hydrologic gradients are all factors that may affect the presence of AMF in South Florida soils. In this study, the distribution and diversity of AMF at field sites at the USDA/ARS Subtropical Horticulture Research Station (SHRS) were assessed. All field sites contained a Pennsuco Marl (Coarse-silty, carbonatic, hyperthermic Typic Fluvaquent) soil; however, each field site utilized a different management technique. The four field sites included: 1) banana grown on 20 cm raised beds from which water drains quickly after heavy rainfall; 2) Iris grown on 15 cm beds surrounded by berms to retain water. The iris is flooded daily at 9 A.M. and standing water normally is drained by 4 P.M.; 3) sugarcane grown in furrows between 10 cm beds. Standing water remains after rainfall and the field is intentionally flooded for 4 to 7 days each year; and 4) an unmanaged swale populated by grasses and containing standing water for up to 48 hours after rainfall. In January 2006, samples were extracted from each field site using a 4-inch auger and were immediately refrigerated. By employing the root-staining methods of Philips and Hayman (1970), AMF colonization was confirmed at the iris, sugarcane, and swale sites. Spores collected by the sucrose density/wet-sieving method of Daniels and Skipper (1982) were counted and identified by genus. Spore density varied greatly between the four sites, with the highest densities observed in the unmanaged swale and the lowest in the banana. Most spores collected from the non-banana sites were of the genus Glomus. How different management techniques at the SHRS affect spore diversity is uncertain; these preliminary findings suggest further research is needed.