Field screening of cowpeas for cercospora leaf spot resistance
AbstractDuring the spring and summer rainy season cercospora leaf spot (CLS) cause defoliation of susceptible cowpeas (Vigna unguiculata (L.) Walp.) in Puerto Rico. At least two Cercospora species C. cruenta Sacc. and C. canescens Ellis & Martin cause distinctively different leaf spot diseases in the field. Results of weighted lesion counts and visual disease rating method were significantly correlated (P<0·01), indicating that either method was effective in rating cowpea response to CLS in the field. Most of the 503 cowpea USDA Plant Introduction accession that were screened for CLS resistance were susceptible to both Cercospora species. Five of 11 accessions resistant to both species were released by the Agricultural Research service U.S. Department of Agriculture.