The Development of the Sexual Stage, Pathogenic Specialization and a Potential Means of Controlling the Urediniophase of Sunflower Rust, 'Puccinia helianthi' schw.

Abstract

Sunflower rust has been present in Australia for over a century. The uredinial stage is common and is the cause of serious yield losses in commercial sunflower crops. The complete life cycle of this macrocyclic autoecious rust has only rarely been seen in Australia and has not been studied in detail. The importance of the sexual cycle in the epidemiology of sunflower rust in Australia is therefore uncertain. The role of the sexual cycle in the origin of new pathotypes of sunflower rust in Australia is also not known. The purpose of the studies reported in this thesis were to i) investigate and describe aspects of the sexual cycle of 'Puccinia helianthi' in Australia and ii) study a means of controlling the disease through the manipulation of host genes for resistance.