Abstract:
Carica papaya and other species of the genus Carica are hosts of numerous powdery
mildews belonging to various genera, including some records that are probably classifiable as
accidental infections. Using morphological and phylogenetic analyses, five different Erysiphe
species were identified on papaya, viz. Erysiphe caricae, E. caricae-papayae sp. nov., Erysiphe
diffusa (= Oidium caricae), E. fallax sp. nov., and E. necator. The history of the name Oidium
caricae and its misapplication to more than one species of powdery mildews is discussed under
Erysiphe diffusa, to which O. caricae is assigned as a heterotypic synonym. Sphaerotheca caricaepapayae is synonymized with Podosphaera xanthii. Podosphaera caricicola comb. nov and
additional powdery mildew species occurring on papaya are also described. A key to the papaya
powdery mildew species that are considered is provided.