Black spot of elm
Fig. 1. Stegophora ulmea, leaf spots
At first small yellow spots of about 1 mm diameter appear on the leaves in spring. They develop into dark spots of up to 5mm size (Fig. 1): on these stromata are produced. In early August premature shedding of leaves follows and sometimes also twig dieback and death of fruits occur.
Various species of elms, also European ones! Forests and urban sites.
Widespread in North America, only single cases reported from Europe; species with quarantine status in the European Union.
In North America mainly a problem in nurseries (defoliation and dieback).
Other leaf diseases of elms as for instance Phloeospora ulmi (Fig. 2).