ANTHRACNOSE RESISTANCE OF THE CUCUMBER GERMPLASM COLLECTION IN NORTH-CAROLINA FIELD-TESTS

The resistance of the entire cucumber (Cucumis sativus L.) germplasm c ollection within the U.S. National Plant Germplasm System and of many available cultigens (improved cultivars, breeding lines, land races, f eral cucumbers, and plant introductions) to anthracnose [Colletotrichu m orbiculare (Berk, and Mont.) Arx] was tested under field conditions in North Carolina and compared with known resistant cultigens. Mean an thracnose leaf ratings for environments ranged from 5.5 to 7.7. Data w ithin an environment were standardized to a mean of 4.5 and a standard deviation of 1 to improve comparisons among cultigens by removing the main effect of environments. The most resistant 27 cultigens are ah o f U.S. origin and are improved cultivars or breeding Lines. The most r esistant cultigens, for which multiple environment data are available, were 'Dual', 'Regal', 'Slice', and Gy 3. The most susceptible cultige ns, for which multiple environment data are available, were PI 390248, PI 251028, and PI 277741. Thirty-one cultigens were classified resist ant, 100 moderately resistant, and 773 susceptible. No plant introduct ions were found to be more resistant than the most resistant named cul tivars or breeding lines tested. Cultigens found to be resistant in ot her studies were generally moderately resistant or resistant in this s tudy, except for PI 179676 and PI 183445, which were susceptible in th is test.