Study of Ovulinia Azaleae, Weiss, in Scotland and an account of the petal blight it causes in rhododendrons

Abstract

A fungus similar to Ovulinia azaleae, Weiss causing a petal blight of hybrid rhododendrons in Scotland is recorded.The behaviour of the fungus in culture and in nature is described and a histological description of the perfect stage is included. The result of a number of infection experiments have established that the fungus is pathogenic to some rhododendrons.The Scottish fungus is compared with the American 0. azaleae and it is concluded that it is identifiable with this fungus.A number of fungi commonly associated with dying rhododendron petals are described: one of them Eotrytis cinerea occasionally forms sclerotia in peta but is not found to cause the petal blight disease.A culture received from America has not proved typical of 0. azaleae after being studied in culture and used for infection experiments.