Digitalis Downy Mildew

Peronospora digitalis Gäumann

Introduction: Peronospora digitalis causes downy mildew on Digitalis spp.

Light to dark brown regions develop on the underside of leaves with erect hypophyllous conidiophores developing in dense groups within the lesion. Conidiophores hyaline, aseptate, 350-700 X 6-10 µm, branching dichotomously 2-7 times in the upper one-third. Ultimate branchlets attenuated, 3-15 X 1-2 µm, curved. Conidia hyaline to gray, ovoid to ellipsoid, 23-29 X 15-22 µm. Description partially taken from Hall (1994).

Host: Various species of Digitalis.

Geographic Distribution: Peronospora digitalis is known to occur in Asia and Europe. Recently it was identified on Digitalis purpurea from California, USA (Tjosvold 2002).

References:

Hall, G. 1994. Peronospora digitalidis. I.M.I. Descr. Fungi Bact. 1193: 1-2.

Tjosvold, S. A. 2002. First occurrence of downy mildew on Digitalis purpurea (common foxglove), caused by Peronospora digitalidis, in California and the United States. Pl. Dis. 86: 1176.

Nomenclature

Specimens in BPI

Additional distribution data

Suggested citation: Bischoff JF & McKemy JM. Systematic Mycology and Microbiology Laboratory, ARS, USDA. . Invasive Fungi. Digitalis Downy Mildew. Retrieved November 21, 2009, from http://nt.ars-grin.gov/sbmlweb/fungi/index.cfm .