pnut pnut Peanut Science 0095-3679 0095-3679 American Peanut Research and Education Society 10.3146/i0095-3679-5-2-14 Articles A Method of Screening Peanut Genotypes for Resistance To Cercospora Leafspot1 H. A. Melouk and D. J. Banks 2 Research Plant Pathologist and Research Geneticist, respectively, Federal Research, Science and Education Administration, U. S. Department of Agriculture, Department of Plant Pathology and Department of Agronomy. Oklahoma State University, Stillwater, OK 74074

1Cooperative investigations of Fed. Res., Science and Ed. Admin., USDA, and Oklahoma State University, Journal Article No. 3471, Oklahoma Agricultural Experiment Station, Oklahoma State University, Stillwater, OK 74074.

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 7 1978 5 2 112 114 14 8 1978 American Peanut Research and Education Society 1978 American Peanut Research and Education Society Abstract

A detached leaf technique was developed for screening peanut genotypes for resistance to leafspot caused by Cercospora arachidicola. Compound leaves of four cultivars of peanut (Arachis hypogaea) and four wild peanut genotypes were used in this study. Individual leaf petioles, each supported by a foam plug, were immersed in Hoagland's solution in 1 × 14 cm test tubes. Leaves were inoculated with C. arachidicola by misting both surfaces with a conidial suspension (2 × 104 conidia/ml) using a DeVilbiss atomizer (No. 152). Test tubes with innoculated leaves were placed in racks in a clear polyethylene chamber on a greenhouse bench. Temperatures in the chamber averaged 26 ± 2 C and 31 ± 2 C during night and day, respectively. Relative humidity was maintained between 80 and 90% by hanging wicks of cheesecloth with their bases in water on both sides of the chamber. Lesions appeared on leaves of susceptible peanuts 8 to 10 days after inoculation and leaflet defoliation started 18 to 21 days after inoculation. This screening technique is reproducible, and requires a minimum of leaf tissue, space, and fungal inoculum.

 Key Words Disease resistance; , hypersensitive reaction; , peanut germplasm; , sporulation; , early leafspot