Disease Note.

First Report of Powdery Mildew on Nandina domestica (Berberi-daccae) in Edinburgh (UK). S. Heifer, Royal Botanic Garden Edinburgh EH3 5LR, UK. Plant Dis. 79:424. Accepted for publication 28 February 1995. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/PD-79-0424D.

Nandina domestica Thunb. is an ornamental plant mainly used in interior and exterior landscaping and is available in a number of cultivars. It is a member of the Berberidaceae. In one of the experimental glasshouses at the Royal Botanic Garden Edinburgh, Scotland, three plants of N., domestica of different cultivars (Wood's Dwarf, Firepower, and unnamed) recently developed red lesions that were shown to be caused by powdery mildew. Infected leaves showed extensive distortion and some shoots became defoliated. Initially only sterile mycelium could be discovered on the leaves, but later occasional conidiophores and germinating conidia were found. No cleistothecia have been located to dale. The epiphyllous mycelium branched regularly to form more or less circular colonies Mycelial appressoria were present at regular intervals, with globular haustoria forming in the underlying epidermal cells. Haustoria measured 8.1–12.0 μm in diameter. Conidiophores were straight, consisting of slender, cylindric foot-cells 13.5–21.5 x6–8 ?m and one additional cell 15.4–17.6 ? 6–8 μm. Conidia were single, measuring 26.1–33 0 x10.5–13.4 μm. Powdery mildews of other Berberidaceae are caused by Erysiphe epimedii, Microsphaera golovinii, M. ber-beridis, M. berberidicola, M. multappendicis, M. sichuanica, and Phyllac-tinia guttata (1). On account of its single conidia and conidial size, Microsphaera is the most likely genus to be the cause of this powdery mildew of Nandina.