Host ranges of Penicillium species causing blue mold of bulb crops in Washington State and Idaho

First reported from the Pacific Northwest of U.S.A. as causal agents of blue mold on edible and/or ornamental bulbs are Penicillium albocoremium (from Tulipa sp.; pathogenic on Allium sativum, A. cepa, A. stipitatum, Iris hollandica and Tulipa sp.), P. crustosum (from Narcissus; pathogenic on A. cepa and I. hollandica), P. paraherquei (from A. cepa; pathogenic on A. sativum and A. cepa), and P. radicicola (from Iris Casablanca; pathogenic on A. sativum, A. cepa and I. hollandica). Penicillium expansum and P. glabrum, from A. cepa, were verified as pathogens of A. sativum, A. cepa and Iris hollandica, and P. expansum was also pathogenic on Tulipa sp. Pronounced differences between Penicillium agents of blue mold in host range and in virulence have implications for crop rotation, postharvest storage and marketing. •New records are reported for Pencillium species causing blue mold of bulbs in the Pacific Northwest of USA.•Host ranges of these Pencillium species differ among the host species tested.•Management implications include crop rotation between bulb crops.•Virulence of these Penicillium species ranges from moderate to severe.