Vesicular—Arbuscular Mycorrhizal Fungi Associated with Citrus in Florida and California and Notes on Their Distribution and Ecology

SUMMARY

Mycorrhizal fungi were associated with citrus roots or soils in 78 of 79 orchards and nurseries in California and in 64 of 66 citrus orchards and nurseries in Florida. Glomus fasciculatus, G. macrocarpus, G. etunicatus, G. constrictus, and Sclerocystis sinuosa were present in both states. In addition, G. microcarpus and G. monosporus were found in California. Gigaspora margarita and G. mosseae were associated with citrus in Florida but not in California. Glomus fasciculatus was consistently associated with young trees (0-30 yr), whereas G. constrictus was consistently associated with older trees (30-70 yr). Total numbers of mycorrhizal chlamydospores associated with citrus in California were negatively correlated with soil P and organic matter, but were positively correlated with soil Na and pH. Glomus macrocarpus was more frequently found in California citrus soils of high P content than was G. microcarpus, and G. monosporus appeared to inhabit soils of higher B, Ca + Mg, or salinity than several other mycorrhizal fungi. In California, chlamydospores of both G. fasciculatus and G. constrictus were most numerous from November to May and least numerous from June to September.