Powdery mildew species on papaya - A story of confusion and hidden diversity

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 caricae-papayae 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.