Submitted to: Crop Protection Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/14/2014
Publication Date: 7/7/2014
Citation: Dugan, F.M., Lupien, S.L., Armstrong, C.M., Chastagner, G.A., Schroeder, B.K. 2014. Host ranges of North American isolates of Penicillium causing blue mold of bulb crops. Crop Protection Journal. 64:129-136. Interpretive Summary: Blue mold of edible bulbs (onion and garlic) and bulbs of ornamental plants has long been a serious problem for consumers and growers. Blue mold is caused by fungi in the genus Penicillium, especially by fungi formerly classified as Penicillium corymbiferum. However, this species has been broken into several additional species, each of which may have overlapping but distinct host ranges and environmental preferences. This research is the first to use isolates in series Corymbifera (composed of species all formerly lumped into P. corymbiferum) recovered from North American sources to test the host range of each species. Bulbs, cloves or corms of onion, garlic, crocus, narcissus, iris, gladiolus, grass lily, tulip and an ornamental onion were inoculated with each of five species of Penicillium, four in series Corymbifera. Host ranges and virulence (aggressiveness) are compared, and management implications discussed.
Technical Abstract: Single isolates of four Penicillium species belonging to series Corymbifera (Penicillium allii, P. hirsutum, P. tulipae, P. venetum) plus an isolate of P. polonicum, all from North American sources, were inoculated individually into Crocus sativus, Allium sativum (garlic), A. cepa (onion), Iris hollandica,Ornithogalum umbellatum (grass lily), and varieties of Gladiolus, Tulipa and Narcissus. All isolates were pathogenic to garlic and onion, and all but P. polonicum to Tulipa, although virulence varied considerably. Additionally, P. hirsutum was pathogenic to Crocus, Gladiolus and Iris; P. tulipae to Narcissus, Crocus, Ornithogalum and Iris; P. venetum to Gladiolus, Ornithogalum and Iris; and P. polonicum to Iris. Nomenclature and taxonomy of series Corymbifera are summarized, the above results compared to similar investigations in Europe, and management implications provided.