EVALUATION OF MORPHOLOGY OF INFECTION STRUCTURES IN DISTINGUISHING BETWEEN DIFFERENT ALLIUM RUST FUNGI

Fifteen isolates of rust fungi were collected in the United Kingdom and in the Netherlands from several Allium species. The samples represented three putative rust species. The morphology of the telia, teliospores and urediniospores was investigated. From urediniospores infection structures were induced on leek, and their morphology was described. Telia and teliospores were not available on every sample. Morphology of the infection structures clearly differentiated between ''leek' type and 'chive' type isolates. The morphology of infection structures of Puccinia mixta is very similar to that of Uromyces ambiguus, but clearly distinct from Puccinia allii sensu Jennings from leek. Quantitative differences in urediniospore characters differentiated between the putative species, but there was overlap between the taxa. We conclude that morphology of infection structures of urediniosporelings is a useful trait for identification of rust isolates from Allium. This is especially true where more than one rust species may occur on the same host species, as with Allium fistulosum.