Resistance in Lactuca spp. to Microdochium panattoniana (lettuce anthracnose)

Four hundred and forty-nine lines of Lactuca spp. were screened for resistance to an isolate of Microdochium panattoniana. Eighty-seven lines were resistant. Forty-four lines were then screened for resistance to four isolates; twelve groups of lines were identified on the basis of their pattern of resistance. A differential set of lines was used to analyse nine further isolates; this revealed five races of M. panattoniana. Salad Bowl was the only cultivar found to be resistant to three races. A line of L. saligna, UC83US1, was the only line found to be resistant to all the isolates tested.