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.