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United States Department of Agriculture

Agricultural Research Service

Title: Leveillua Taurica: An Emerging Threat to Agriculture in the Pacific Northwest

Authors
item Gawe, D. - WASHINGTON STATE UNIV.
item Dugan, Frank
item Cerkauskas, R. - AGRI.& AGRI-FOOD CANADA
item Du Toit, L. - WASHINGTON STATE UNIV.
item Krishna, M. - UNIVERSITY OF IDAHO
item Liu, Y - UNIVERSITY OF WASHINGTON

Submitted to: Inoculum
Publication Type: Abstract Only
Publication Acceptance Date: June 1, 2005
Publication Date: July 1, 2005
Citation: Gawe, D.A., Dugan, F.M., Cerkauskas, R.F., Du Toit, L.J., Krishna, M.S., Liu, Y. 2005. Leveillua taurica: an emerging threat to agriculture in the pacific northwest. Inoculum V.56(4), P. 21.

Interpretive Summary: Leveillula taurica is a fungal plant pathogen belonging to a group of fungi known as the powdery mildews. The subject of various reports in the early to mid-1900s, it has since spread across the continent, apparently arriving in most areas of the Pacific Northwest (PNW) only in the past decade. It was reported from Idaho in 1989, and in 2003-2005 there have been reports from British Columbia, Idaho and Washington State. Because the fungus is apparently capable if infecting a broad range of plants, many of which are important to PNW agriculture, plant pathologists from several institutions and geographic locations have cooperated to produce a summary of reports from the PNW in order to alert regional plant pathologists to this pathogen and the diseases it causes.

Technical Abstract: Leveillula taurica occurs on numerous host plants representing more than seventy families, including both dicots and monocots. North American reports date to 1906. The fungus has been reported since then from Mexico and Ontario, as well as Florida, California, and Arizona. Within the Pacific Northwest (PNW), the conidial state first was reported from Idaho on cucumber (Cucumis sativus) and tomato (Lycopersicon esculentum) in 1989 and later on onion (Allium cepa) in 1995. It was reported from British Columbia on greenhouse pepper (Capsicum annuum) in 2003, and from central Washington State on onion and potato (Solanum tuberosum) in 2004. Both sexual and asexual states were found on greenhouse-grown seaside arrow grass (Triglochin maritima) in eastern Washington State in 2004. The ITS sequence obtained from the strain on T. maritima was identical to sequences from strains on pepper in Australia and Elaeagnus angustifolia in Iran. Given the confirmation of L. taurica on diverse hosts in the PNW, the recent discovery of the sexual state in the region, and the potential for economic losses to be caused by this pathogen, plant pathologists should be alert for impact of this pathogen on PNW agriculture. The possible epidemiologic role of alternative hosts in the region has the potential to complicate control of this pathogen.

Last Modified: 11/28/2014
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