Root and Basal Stem Rot of Scotch Broom Caused by Phytophthora citricola and P. drechsleri in Italy.

Scotch broom (Cytisus scoparius (L.) Link, Fabaceae), an evergreen shrub native to Europe, is cultivated as a garden plant. In 2003 and 2004, potted plants with symptoms of leaf chlorosis, defoliation, and eventual wilt and associated with root and collar rot were observed in ornamental nurseries in Sicily. As much as 10% of plants were affected in a single nursery. Two species of Phytophthora were consistently isolated alone or together from the same pot with the selective medium of Masago et al. (2). Pure cultures were obtained by single-hypha transfers and the species were identified as P. citricola Sawada (approximately 40% of isolations) and P. drechsleri Tucker (60% of isolations) on…