Abstract
Between 1970 and 1974 several plantings of the cowpea world germplasm collection were examined for incidence of mosaic virus symptoms at Ibadan. In 1974, 500 cowpea lines which had been consistently free from mosaic symptoms under natural infection were inoculated in the field with two isolate of the spherical, beetle -transmitted cowpea (yellow) mosaic virus. A great range of variability in reaction was observed, from rapid death of inoculated plants through various degree of mosaic, systemic necrosis and plant deformity, to complete freedom from symptoms. Fifty five line showed no symptoms, 38 lines were predominantly free from symptom with a few plants showing mild mosaic only 55 lines developed only mild mosaic or necrosis is 95 lines showed moderately severe symptoms, 231 lines developed severe symptom and 10 lines gave distinct differential reactions lo the two isolates. Sixteen of the resistant line were also resistant to anthracnose, rust, cercospora leaf spot and bacterial pustule.
