pnut pnut Peanut Science 0095-3679 0095-3679 American Peanut Research and Education Society 10.3146/i0095-3679-7-2-7 Articles Spore Production and Latent Period as Mechanisms of Resistance to Cercospora Arachidicola in Four Peanut Genotypes 1,3 D. J. Foster , M. K. Beute , and J. C. Wynne 2 Graduate Student, Crop Science Department, Professor of Plant Pathology and Associate Professor, Crop Science Department, North Carolina State University, Raleigh, respectively

1Paper No. 6408 of the Journal Series of North Carolina Agricultural Research Service, Raleigh, N. C.

3Use of trade names in this publication does not imply endorsement by the N. C. Agricultural Research Service of the products named, nor criticism of similar ones not mentioned.

 7 1980 7 2 88 90 16 9 1980 American Peanut Research and Education Society 1980 American Peanut Research and Education Society Abstract

Arachis batizocoi, A. monticola and two genotypes of A. hypogaea (‘Florigiant’ and PI 109839) chosen to represent differing levels of resistance to early leafspot (Cercospora arachidicola) were evaluated for their effects on production of conidia per lesion, conidia per unit area of lesion and latent period necessary for sporulation. The largest lesions and the most conidia per lesion and unit lesion area were produced on cultivar ‘Florigiant’. PI 109839 had smaller lesions than Florigiant. Fewer conidia per lesion and per unit lesion area were produced on PI 109839 than Florigiant C. arachidicola sporulated abundantly on lesions from both Florigiant and PI 109839 15 days after inoculation. Size of lesions and conidia per lesion did not differ between A. monticola and PI 109839 but conidia per unit lesion area were fewer on A. monticola. The smallest lesions and the fewest conidia per lesion and per unit lesion area were produced on A. batizocoi. C. arachidicola did not begin sporulating on A. monticola and A. batizocoi until 18 days after inoculation. Sporulation of C. arachidicola was observed on defoliated leaves of A. monticola and A. batazocoi 21 days after inoculation.

 Key Words Mechanism of resistance; , Arachis hypogaea; , Groundnut; , Epidemiology