Cercospora beticola: The intoxicating lifestyle of the leaf spot pathogen of sugar beet

Cercospora leaf spot, caused by the fungal pathogenCercospora beticola, is the most destructive foliar disease of sugar beet worldwide. This review discussesC. beticolagenetics, genomics, and biology and summarizes our current understanding of the molecular interactions that occur betweenC. beticolaand its sugar beet host. We highlight the known virulence arsenal ofC. beticolaas well as its ability to overcome currently used disease management strategies. Finally, we discuss future prospects for the study and management ofC. beticolainfections in the context of newly employed molecular tools to uncover additional information regarding the biology of this pathogen. Taxonomy Cercospora beticolaSacc.; Kingdom Fungi, Phylum Ascomycota, Class Dothideomycetes, Order Capnodiales, Family Mycosphaerellaceae, GenusCercospora. Host range Well-known pathogen of sugar beet (Beta vulgarissubsp.vulgaris) and most species of theBetagenus. Reported as pathogenic on other members of the Chenopodiaceae (e.g., lamb's quarters, spinach) as well as members of the Acanthaceae (e.g., bear's breeches), Apiaceae (e.g.,Apium), Asteraceae (e.g., chrysanthemum, lettuce, safflower), Brassicaceae (e.g., wild mustard), Malvaceae (e.g.,Malva), Plumbaginaceae (e.g.,Limonium), and Polygonaceae (e.g., broad-leaved dock) families. Disease symptoms Leaves infected withC. beticolaexhibit circular lesions that are coloured tan to grey in the centre and are often delimited by tan-brown to reddish-purple rings. As disease progresses, spots can coalesce to form larger necrotic areas, causing severely infected leaves to wither and die. At the centre of these spots are black spore-bearing structures (pseudostromata). Older leaves often show symptoms first and younger leaves become infected as the disease progresses. Management Application of a mixture of fungicides with different modes of action is currently performed although elevated resistance has been documented in most employed fungicide classes. Breeding for high-yielding cultivars with improved host resistance is an ongoing effort and prudent cultural practices, such as crop rotation, weed host management, and cultivation to reduce infested residue levels, are widely used to manage disease. Useful website