OCCURRENCE OF A RESISTANCE BREAKING PATHOTYPE OF MELOIDOGYNE-JAVANICAON TOMATOES IN CRETE, GREECE

The root galling and reproduction of five single egg mass lines of Mel oidogyne javanica originating from three different field sites of Cret e was assessed on fourteen resistant tomato hybrid cultivars (Scala, 7 352 Silco, Myrto, Menglo, Rakata, GC785, GC788 Alpado, Bermuda, 7353, 7358, W1964, W1967, W2913, 399) in a controlled environment where soil temperature was 22-24 degrees C. Two lines originating from a field w here the resistant cv. Menglo had been grown for two years were able t o infect the resistant cultivars and to reproduce on them as well as o n a susceptible cultivar (Carouso). One line isolated from cucumber in fected and reproduced only on the susceptible cultivars. Two lines fro m a field where the susceptible cultivar Carouso was grown showed eith er slight or no reproduction on resistant cultivars. Under greenhouse conditions (soil temperature 20-42 degrees C) Mi conferred resistance was nullified and all cultivars became hosts for an avirulent line.