Submitted to: American Peanut Research and Education Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: May 1, 2010
Publication Date: October 1, 2010
Citation: Melouk, H.A., Grichar, W.J., Chamberlin, K.D. 2010. Occurrence of Sclerotinia blight on peanut in Lee County, Texas. In: 2010 Proceedings of the American Peanut Research and Education Society, July 12-15, 2010, Clearwater Beach, FL. 42:73-74. Technical Abstract: A peanut field, north of Giddings in Lee County, TX, planted with the peanut cv. OLin in 2009 had about 5% incidence of Sclerotinia blight on October 29. Diseased stems of peanut plants were collected, and a culture of Sclerotinia minor (SM.TX1) was generated from a single sclerotium, and maintained at 25+2 C on Potato-Dextrose-Agar medium containing 100 ppm streptomycin sulfate. The pathogenicity of the SM.TX1 isolate along with an S. minor isolate from Oklahoma (SM.M6) was tested on two peanut cultivars, Okrun (OK) and Tamspan 90 (T-90). The pathogenicity tests were performed as described by Faske et al (Peanut Sci. 33:7-11, 2006). Starting three days after inoculation, lesion length measurements were recorded for the infected stems and continued on a 24 hour basis through day 7, after which time the rate of lesion expansion (RLE) in mm/day was calculated. The pathogenicity test was conducted twice. In the first experiment, mean RLE on cv. OK for SM.TX1 was 31, which was significantly (P > 0.001) higher than that of SM.M6 at 26. On cv.T-90, RLE for SM.TX1 was 22, which was significantly (P > 0.022) higher than that of SM.M6 at 19. In the second experiment, mean RLE on cv. OK for SM.TX1 was 19, which was significantly (P > 0.006) higher than that of SM.M6 at 10. On cv. T-90, RLE for SM.TX1 was 19, which was significantly (P > 0.005) higher than that of SM.M6 at 8. These findings demonstrate that the new S. minor isolate SM.TX1 is more virulent than that of the Oklahoma isolate SM.M6 under greenhouse test conditions, and the new S. minor isolate SM.TX1 has the potential to be more damaging under field conditions.