RUST INFECTIONS OF SOME ALLIUM SPECIES - AN ASSESSMENT OF GERMPLASM FOR UTILIZABLE RUST RESISTANCE

Isolates of three species of rust (Puccinia allii, P. mixta and Uromyces ambiguus) were each inoculated onto a range of potential host plants, selected to include the major European crop Allium species together with the commoner wild species in the section Allium. Measurements of incubation period, lesion type, latent period and pustule quantity were made in a single environment. Each isolate was able to sporulate on a range of Allium species. There was evidence of specialisation to particular sections of the genus; all the leek isolates performed well on the majority of hosts in section Allium, whilst the chive isolate grew poorly on most members of that section. Exceptions to this are exemplified by A. fistulosum being attacked by all three rust species and A. sativum being attacked by both leek and chive isolates. A continuum of reaction types was found which, for the leek isolates, ranged from the low levels of quantitative resistance in leek cultivars, through higher quantitative levels within the A. ampeloprasum complex, to qualitative resistance in several interactions in non-host sections of Allium, where the pathogen was able to infect and form colonies of some size without sporulating. © 1990 Kluwer Academic Publishers.