Plant Disease (2019) 103, 1565-1576

Shan Xu, Michael J. Christensen, Rebecca Creamer and Yan Zhong Li (2019)
Identification, characterization, pathogenicity, and distribution of Verticillium alfalfae in alfalfa plants in China
Plant Disease 103 (7), 1565-1576
Abstract: Verticillium wilt caused by Verticillium alfalfae results in severe production losses in alfalfa crops and is a Class A quarantined disease in China. During 2015 to 2017, 365 alfalfa fields from 21 locations in six provinces were surveyed, and 45 fields from three closely located sites in Gansu, China were found to have alfalfa plants with symptoms typical of Verticillium wilt, with disease incidence of 12.6 to 53.6%. Isolates were identified to species using morphological characteristics and a maximum likelihood phylogeny of the concatenated partial sequences of actin, elongation factor, glyceraldehyde-3-phosphate dehydrogenase, and tryptophan synthase gene regions of Verticillium isolates. Isolation incidence was 93.9% from roots, 71.7% from stems, 66.1% from petioles, and 32.2% from leaves of field-infected plants, indicative of systemic disease and sporadic distribution of this pathogen. In greenhouse tests, the pathogen infected seedlings and colonized vascular tissues when inoculated on seeds, on root tips, in soil, or in injured, but not uninjured, aerial tissues, causing systemic symptoms like those in the field and significant losses. Pathogenicity testing also revealed that five locally grown perennial legumes (stylo, milkvetch, sainfoin, white clover, and red clover) could host V. alfalfae, with a high virulence to milkvetch, sainfoin, and stylo. This study confirmed that V. alfalfae has become established in some regions of Gansu, China and that is a risk to the alfalfa industry in China.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Michael J. Christensen, Rebecca Creamer, Yanzhong Li

Research topic(s) for pests/diseases/weeds:
surveys/sampling/distribution
quarantine treatments/regulations/aspects

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Verticillium alfalfae	Alfalfa/lucerne (Medicago sativa)	China (NW)