Submitted to: Plant Health Progress
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/18/2013
Publication Date: 7/19/2013
Citation: Lupien, S.L., Hellier, B.C., Dugan, F.M., Skoglund, L., Ward, K. 2013. White rot of garlic and onion (Causal agent, Sclerotium cepivorum): A status report from the Pacific Northwest. Plant Health Progress. doi:10.1094/PHP-2013-0619-01-RV. Interpretive Summary: White rot of garlic and onion, caused by the fungus Sclerotium cepivorum, seems to be spreading in the Pacific Northwest of the USA and Canada. Previous reports are summarized for the region, and new instances are documented for Montana and specified counties in Washington and Idaho. The fungus is a regulated pest in state departments of agriculture regulations for Oregon, Washington and Idaho, as well as in Canadian plant health regulations. The regulations are summarized, and URLs for regulatory web sites are provided. Management recommendations are summarized and sources of literature provided. USDA-ARS Western Regional Plant Introduction Station (WRPIS) is immediately adjacent to Latah County, Idaho, in which white rot is recently reported. Strict phytosanitary measures are implemented at the WRPIS farm.
Technical Abstract: There is evidence from literature, state department of agriculture documents, and recent diagnoses that Sclerotium cepivorum, causal agent of white rot of garlic and onion, is spreading and/or becoming more established in the Pacific Northwest. Previously documented distributions are summarized, and the fungus is reported for the first time from Latah County, Idaho; Pend Oreille County, Washington; and Lake, Sanders and Missoula Counties, Montana. Although known from a tightly quarantined prior occurrence in the Idaho portion of Treasure Valley (southwest Idaho), the pathogen has not been formally reported from that state, nor from the state of Montana. Latah County has commercial production of seed garlic, and borders adjacent Whitman County, Washington, where the National Plant Germplasm System (NPGS) maintains North America’s largest non-commercial collection of garlic and wild/ornamental onion. Strict phytosanitary protocols have been implemented on the NPGS farm. Various areas within the Pacific Northwest have long been important for commercial Allium production, and a list of state departments of agriculture regulations addressing white rot is presented for Idaho, Oregon and Washington