First report of downy mildew caused by Plasmopara halstedii on Gerbera jamesonii in Brazil.
African daisy (Gerbera jamesonii) is an important species for both the cut flower and potted plant industries worldwide. Since the winter of 2009, plants showing severe downy mildew symptoms have been observed in a greenhouse located in an experimental area of the Universidade Federal de Viçosa (Minas Gerais, Brazil). The disease appeared as ill-delimited adaxial chlorosis of lamina; tissues became yellow and then brown with age with intense blighting of leaves of entire plants, leading to their death, when untreated. Dense, whitish sporulation was observed on the lower surfaces since early stages. Based on morphological characteristics and sequence analysis of cytochrome-c oxidase subunit 2, the causal agent was identified as P. halstedii. Although P. halstedii has been commonly recorded on numerous hosts belonging to the Asteraceae worldwide, it has never been reported on G. jamesonii. This is thought to be the first report of P. halstedii on G. jamesonii in Brazil.