New host species for Chalara fraxinea

Abstract

During autumn 2009, several introduced ornamental ash (Fraxinus) species (~40 years old) showing ash dieback symptoms were investigated. These were located in three southeastern Estonian parks (Luua, Tartu and Jarvselja). Black ash (F. nigra) trees were badly affected with symptoms including wilting of leaves, dieback and necrotic lesions of shoots and twigs, and death of canopy. Green ash (F. pennsylvanica) trees were moderately affected (with symptoms similar to black ash, but with less evidence of dead shoots within the canopy). White (F. americana) and Manchurian (F. mandschurica) ash trees were least affected with symptoms including wilting of leaves, but only minor shoot and twig dieback and bark necrosis. C. fraxinea was consistently isolated from shoots with the above symptoms, as well as branches and petioles of all affected species. This is thought to be the first report of C. fraxinea infecting these ash species in the world.