RHODODENDRON POWDERY MILDEWS
Powdery mildews (Erysiphales) are fungal parasites and the cause of debilitating and potentially very serious diseases of numerous angiosperms including many species, hybrids and cultivars of Rhododendron. If no appropriate control measures are taken to limit the spread and development of the disease, powdery mildew attacks can lead to complete defoliation and ultimately death of mature, otherwise healthy plants in a number of Rhododendron species and cultivars. A recent increase in the incidence of powdery mildew of rhododendrons in the British Isles as well as the apparent widening of the virulence spectrum of the fungi responsible has lead to a new research initiative in Scotland. To date at least three different taxa of Erysiphales have been found occurring on Rhododendron but their taxonomic identity and position is still unclear as characteristic cleistothecia are not normally produced. Data on the world distribution of rhododendron powdery mildews, their host range and climatic preference are presented as well as preliminary results of taxonomic studies and epidemiological experiments. Methods of the control of the diseases are discussed.
Helfer, S. (1994). RHODODENDRON POWDERY MILDEWS. Acta Hortic. 364, 155-160