Distribution and Host Range of a Powdery Mildew Fungus Infecting Garlic Mustard, Alliaria petiolata, in Southwestern Ohio

Abstract

Abstract Garlic mustard is an invasive Eurasian biennial that has rapidly spread throughout the United States. In Southwestern Ohio, many garlic mustard populations are infected with Erysiphe cruciferarum, a causal agent of powdery mildew disease in Brassicaceous plants. We examined the regional distribution of E. cruciferarum on garlic mustard and determined the potential host range of E. cruciferarum on several native Brassicaceous species and selected Brassicaceous crop varieties. A survey of 19 natural areas in western Ohio revealed that populations of garlic mustard with high incidences of powdery mildew were largely centered in Montgomery and Greene Counties in Ohio, with disease incidence decreasing away from Dayton, Ohio. Sampling locations that were on level or southeast facing slopes had significantly higher disease incidences than those on northwest or southwest facing slopes. Five native spring ephemeral species, including four Cardamine species and one Arabis species, showed no obvious signs ...