Evaluation location: South Carolina, United States
Year tested: 1989 Downy Mildew (Pseudoperonospora cubensis) reaction rated as reaction type expressed after artificial inoculation in field (Reference: HortScience 22:638-640, 1987). Cucumis melo var. reticulatus is susceptible to all five described pathotypes of P. cubensis (Thomas et.al., Phytopathology 77:1621-1624); therefore, pathotype 2 was used in the tests. Because all C. melo subspecies are susceptible to pathotype 2, it was considered that susceptibility to one pathotype was indicative of susceptibility to all in these evaluations. Those with RTs of 2, 3, or 4 were retested in artificial inoculations under greenhouse conditions. For the purpose of entry into GRIN, the RT listed for each PI represents the most resistant reation encountered within that PI. RTs standard 1-9 scale where 1 = RT4 = 1mm, circular, chlorotic lesions with necrotic centers and water-soaked margins beneath and extremely limited or no readily apparent sporulation; 3 = RT3 = 3-4mm, irregular to circular, chlorotic lesions with water-soaked margins beneath and sparse sporulation; 7 = RT2= Type "1" lesions, below, mixed with type "3" lesions, above; 9 = RT1 = 10-15mm irregular, chlorotic lesions with abundant sproulation that may extend beyond the apparent margins of the lesions.