In 2000, chlorotic leaves with inconspicuous leaf spots were observed on several Vinca major L. and V. minor L. plants in a 0.8-ha area in Woodside, CA. In August 2001, 80 to 90% of the plants were symptomatic. Uredinia measuring 2 to 3 × 1 mm were present on the lower surface of leaves. Urediniospores were ellipsoidal to oblong, 27 to 36 × 17 to 27 μm, with cinnamon-brown walls 1 to 2 μm thick, echinulate, and with three or four equatorial or slightly supraequatorial germ pores. Telia were produced in the uredinia. Teliospores were 1-septate, ellipsoidal to clavate, slightly constricted at the septum, and 34 to 45 × 19 to 30 μm. Teliospore walls were chestnut brown, 1.5 to 2.5 μm thick, and verrucose, with the verrucae sometimes in longitudinal lines. One germ pore covered by a hyaline papilla was present in each cell, at the apex in the upper cell and adjacent to the short, hyaline pedicel in the lower cell. The rust was identified as Puccinia vincae Berk. (1). P. vincae is widespread in Europe on Vinca species and is common on V. major in the eastern United States, Washington, and Idaho (2). To our knowledge, this is the first report of P. vincae on V. major in California (vouchers BPI 841363, 841364) and on V. minor in the United States (voucher BPI 841365).
References: (1) J. C. Arthur. Page 324 in: Manual of Rusts in the United States and Canada. Purdue Research Foundation, Lafayette, IN, 1934. (2) D. F. Farr et al. Pages 35 and 916 in: Fungi on Plants and Plant Products in the United States. American Phytopathological Society, St. Paul, MN, 1989.