Morphological measurements and ITS sequences show that the new alder rust in Europe is conspecific with Melampsoridium hiratsukanum in eastern Asia

Abstract

Three species of Melampsoridium have been reported to infect hosts in genus Alnus. An epidemic of foliar rust affecting A. glutinosa and A. incana began in Europe in the mid-1990s, and the associated pathogen was identified as Melampsoridium hiratsukanum based on morphology. In this investigation we analyzed the morphology and genetic variation of alder rusts from Europe and Japan and the host specificity of the European epidemic rust. Our results showed that two rusts occur on the leaves of alders native to northern Europe; in Scotland an endemic rust indistinguishable from M. betulinum occurs, whereas alders in areas of Europe affected by the current epidemic were infected by M. hiratsukanum. M. hiratsukanum from naturally infected alder in Finland produced aecia on all Larix species tested but did not infect Betula leaves.

• Alnus
• Betula
• Larix
• Melampsoridium alni
• Melampsoridium betulinum

We thank Ms Marja-Leena Santanen for skillful technical assistance. Drs Halvor Solheim, Adrian Bolay, Thomas Cech and Erhard Halmschlager as well as Mr. Masanobu Akimoto are thanked for their help in collecting material for this study. We thank Prof Veikko Hintikka for valuable discussions.