Cladosporium herbarum Causes a Leaf Spot on Marshmarigold in Western North America

Abstract

Caltha leptosepala ssp. howellii and Caltha leptosepala ssp. leptosepala (marshmarigold, Ranunculaceae) inhabit stream banks and wet meadows in the northern Rocky and Cascade mountain ranges of North America. Cladosporium herbarum (anamorphic Davidiellaceae) is a cosmopolitan saprophytic fungus and epiphyte that can invade senescing tissues of many plants, induce disease in ripe fruits of some plant species, and occupy other diverse environments. Instances of biotypes of C. herbarum specialized to cause disease on a given host are rare. This study reports a biotype of C. herbarum that caused disease on C. leptosepala. The name Cladosporium leaf spot is proposed for this disease. Accepted for publication 14 September 2008. Published 21 November 2008.