RESPONSE OF MELOFON BREEDING LINES TO POWDERY MILDEW, DOWNY MILDEW, FUSARIUM-WILT, AND SUDDEN WILT

The responses of eight melofon (pickling melon, Cucumis melo) breeding lines to powdery mildew, downy mildew, Fusarium wilt, and sudden wilt were evaluated. No resistance to races 1 and 2 of Sphaerotheca fuliginea (powdery mildew) was found; however, all melofon lines tested except D17-5 were moderately susceptible compared with the highly susceptible melon cv. Ananas Yoqne'am and the cucumber cv. Bet Alfa. Two breeding lines, P22a and P6a-3, were relatively tolerant to Pseudoperonospora cubensis (downy mildew), exhibiting the lowest disease index in both experiments conducted. All melofon breeding lines were resistant to races 0 and 1 of Fusarium oxysporum f. sp. melonis. High susceptibility to F. o. f. sp. melonis race 2 was evident, while disease severity following inoculation with race 1,2 was moderate in most lines tested. There was a wide variation among melofon breeding lines in responses to sudden wilt: line D17 was very susceptible while P6a-1 did not collapse in field trials. Overall, breeding lines derived from cross P6 were the most promising with respect to disease resistance.