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Title: Stem versus leaflet inoculation of peanut with Sclerotinia minor

Author
item Melouk, Hassan
item BROWN, MICHAEL - Oklahoma State University

Submitted to: American Peanut Research and Education Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/2009
Publication Date: 2/1/2010
Citation: Melouk, H.A., Brown, M. 2010. Stem versus leaflet inoculation of peanut with Sclerotinia minor [abstract]. In: 2009 Proceedings of the American Peanut Research and Education Society (APRES), July 14-17, 2009, Raleigh, NC. 41:80-81. Available: http://www.apresinc.com/pdf/Proceedings/Volume%2041,%20Proceedings_2009.pdf.

Interpretive Summary:

Technical Abstract: Tamspan 90, a Spanish peanut cultivar, exhibits physiological resistance to Sclerotinia minor (S.M), as indicated by the low rate of lesion expansion (RLE) on inoculated stems. The purpose of this study was to determine the RLE on stems and leaflets of two peanut cultivars (Okrun, a susceptible cultivar to S.M., and Tamspan 90). Stems and distal leaflets of 6 week old plants were inoculated at midpoint with mycelial plugs from two-day-old S.M. cultures grown on potato dextrose agar containing 100 mg/L streptomycin sulfate. Inoculated plants were then placed in clear polyethylene humidity chambers (95-100%, relative humidity) for up to 7 days. Two days after inoculation visible lesions developed on stems and leaflets of both Okrun and Tamspan 90. Lesion length measurements were taken at 2, 3, 4, and 5 days after inoculation. The experiment was performed twice. In the two experimental runs, mean RLE (mm/24 hr) on stems of Okrun was 17.8 mm, which was significantly (P = 0.05) higher than that of Tamspan 90 which was 8.3 mm. In leaflet inoculation, in the first experimental run, mean RLE (mm/24 hr) on stems of Okrun was 6.1 mm, which was not significantly (P = 0.05) higher than that of Tamspan 90 with 6.0 mm. However, in leaflet inoculation, in the second experimental run, the RLE data for both Okrun and Tamspan 90 were highly variable where mean RLE on Okrun was 9.0 mm, which was significantly (P = 0.05) higher than that of Tamspan 90 with 3.7 mm. Therefore, more experiments with more genotypes need to be performed to determine the validity of using leaflet inoculation data as a measure to determine physiological resistance in peanut to S. minor.