Rhododendron cultivars English Roseum and Nova Zembla were surveyed for the presence of ericoid mycorrhizae at various stages of propagation in four commercial nurseries in Rhode Island. Ericoid mycorrhizae developed in both cultivars in the rooting bench and were retained throughout all phases of commercial production in the nurseries surveyed. Significant differences in levels of mycorrhizal infection were observed among nurseries, among propagation stages (more in the rooting and field stages than in the transplant and container stages), and between cultivars (greater mycorrhizal infection occurred in 'English Roseum'). It is postulated that variability in nursery environments and plant production practices influences the mycorrhizal status of commercially grown Rhododendron spp.