Accessions of both domesticated and wild Cucurbita spp. were tested from Jan. to May 1996 in Isabela, Puerto Rico, for resistance to silverleaf and sweetpotato whitefly (Bemisia tabaci). None of the accessions tested were completely free of whiteflies, but some accessions were completely free of silverleaf. At 8 weeks, checks of `Soler' and `Butternut' had silverleaf ratings of 4.5 and 0.0, respectively (on a 0 to 5 scale, where 0 = no silverleaf). Both checks were highly infected with whiteflies. Wild Cucurbitas do not appear to be a good source of whitefly or silverleaf resistance. While no strong correlations were observed between number of whiteflies and degree of silvering, all plants that were highly silvered were also heavily infested with whiteflies. Some plants with little or no silverleaf had many fewer whiteflies. Plants from ≈40 accessions from a total of about 800 were selfed for further evaluation.
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