Wild Beta species as a source of resistance to sugar-beet pests and diseases

This paper reviews previous studies on sources of resistance to pests and d iseases in wild Beta species and the attempts to introgress these into suga r beet. Preliminary results of the evaluations carried out on wild species since 1996 in the current GENRES CT95-42 collaborative programme are also r eported. Pests and diseases for which information is available include beet cyst nematode, Cercospora leaf spot, Rhizoctonia root rot, Rhizomania, Pow dery mildew (Erysiphe), Downy mildew (Peronospora), Beet yellowing viruses, Beet mosaic virus, Curly top virus and Aphanomyces and Pythium seedling di seases. Examples of resistance to all of these can be found in wild species , either in the sexually compatible Beta Section Beta (e.g. B. vulgaris ssp . maritima) or, more widely, in Sections Corollinae and/or Procumbentes. Th e prospects of utilizing these sources of resistance are discussed.