A growth room inoculation method to detect different levels of sunflower susceptibility to Sclerotinia sclerotiorum - A seedling test for sunflower susceptibility to S-sclerotiorum

An indoor inoculation procedure to obtain reproducible infection of sunflower seedlings with Sclerotinia sclerotiorum was developed. Seedlings were sprayed with a S. sclerotiorum ascospore sus pension and, after 7 days incubation, leaves showed wilting symptoms. The insertion angle of the first pair of leaves was used for wilting quantification. When the susceptible inbred line 'HA89' was tested, highly significant differences in the values of the insertion angle between control and inoculated plants were detected In addition, Anova showed a significant decrease in the insertion angle in four inbred lines previously characterized as susceptible or rather tolerant in field trials. line 'HA89' showed the highest wilting index, whereas the tolerant line 'SD' was the less affected by the inoculation with S. sclerotiorum. As this result is consistent with their field responses, the possible uses of the procedure described here are discussed.