An In Vitro Screening System of Sunflower for Resistance to Sclerotinia Sclerotiorum (Lib.)

ABSTRACT

Sclerotinia sclerotiorum (Lib.) is one of the most important fungal pathogens of sunflower. The pathogen attacks all parts of the plant: roots, stalks, leaves, flower buttons and heads. There is no real possibility of chemical control of the disease that could be applied. During last several years S. sclerotiorum has been widely expanded in Bulgaria. There are no resistant cultivars of H. annuus between those grown in the country. Some resistant forms can be found between wild species of genera Helianthus. An in vitro testing system has been established for resistance to the disease. Culture filtrate of the pathogen was used as a selective agent. New sunflower lines, originating from interspecific hybridization between sunflower and wild Helianthus species were evaluated for their response to S. sclerotiorum during the seed germination stage of plant development. Conventional breeding methods for selecting the resistant sunflower forms to this disease can be completed using the described system.