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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Sustainable Agricultural Systems Laboratory » Research » Publications at this Location » Publication #345516
Research Project: Biologically Based Technologies for Control of Soil-Borne Pathogens of Vegetables and Ornamentals

Location: Sustainable Agricultural Systems Laboratory

Title: First report of lily root rot caused by Thantephorus cucumeris AG 2-1 in the United States

Author
item Lakshman, Dilip
item Kamo, Kathryn

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/12/2017
Publication Date: 1/14/2018
Citation: Lakshman, D.K., Kamo, K.K. 2018. First report of lily root rot caused by Thantephorus cucumeris AG 2-1 in the United States. Plant Disease. https://doi.org/10.1094/PDIS-09-17-1497-PDN.

Interpretive Summary: Easter lilies are grown primarily in the Pacific Northwest for bulb production, and are susceptible to attack by multiple soilborne pahogens. Earlier, we demonstrated that isolates of Fusarium oxysporum, Fusarium tricinctum, Rhizoctonia AG-I, and the root lesion nematode, Pratylenchus penetrans, together or in various combinations cause root lesion and rots in lilies. In this communication, we have demonstrated that Thantephorus cucumeris (synonym: Rhizoctonia solani) AG 2-1 causes root rot in lily. This study adds to the list of a complex set of soil pathogens that cause disease in Easter lily, and the information will be useful in developing effective treatment and control of diseases in this important crop.

Technical Abstract: A disease survey was undertaken in April, 2016 to profile the soilborne fungal pathogens causing root rot and lesions on lily (Lilium longiflorum) cv. Nellie White in Brookings, Oregon, Curry County. Diseased root samples were either blackened or rotted. Several fungal isolates were cultured from infected roots and hyphal tip purified. Based on microscopic and ribosomal DNA sequence analysis, three fungal isolates were identified as a single haplotype of Thantephorus cucumeris (synonym: Rhizoctonia solani) AG 2-1 and numerated as ELRF 11. Upon inoculation on roots of in vitro grown Easter lily plants, ELRF 11 caused necrotic brown lesions on roots. Lactophenol staining and microsopy showed both inner and outer mycelia colonization on infected roots. Additionally, the ELRF 11 caused necrosis and rot upon inoculation to roots of diploid strawberry runners (Hawaii4 F7-3) and necrotic spots on detached leaves of Nicotiana glutinosa, N. benthamiana, and N. paniculata. This constitutes the first report of T. cucumeris AG2-1 infecting lilies in the U.S. As various AGs are known to differ in sensitivity to fungicides and biocontrol agents, a systematic survey of Rhizoctonia and other pathogens infecting lilies under field conditions is required for developing effective disease management strategies.