Utricularia (Lentibulariaceae) – a New Host Plant Genus of Powdery Mildew (Sphaerotheca sp.)

Symptoms of powdery mildew infections were recorded on a group of 15 Utricularia species cultivated in a glasshouse. A white super®cial mycelium formed rings around the peduncles and also occurred on both sides of the leaves of several species. The microscopic examina- tion proved that the fungus belonged to the powdery mildews ± Erysiphales, only the anamorph was observed. Its morphological characters are typical for powdery mildews from the tribe Cystotheceae. Conidia were able to cause infections on cotyledons of suscept- ible Cucumis sativus cv. Stela F1. Based on all observa- tions, it is very probable that this fungus belongs to the genus Sphaerotheca. This is the ®rst report of a powdery mildew on Utricularia spp. and the family Lentibularia- ceae.