Phoma Macdonaldi on seed and its importance in etiology of Phoma black stem in sunflower

Phoma macdonaldi Boerema, teleomorph Leptosphaeria lindquistii Frezzi, is a widespread pathogen of sunflower. The aim of this research was to identify the presence of fungus P. macdonaldi in seed of different sunflower hybrids, as well as the correlation between seed and field infection. Phoma black stem assessment was performed on three hybrids grown in six localities in Serbia. Untreated and processed seeds of these hybrids were used in the seed health test. Severity of the disease did not differ between localities. Average disease index for hybrids H7, H9 and H19 was 14.01%, 13.25% and 11.83% respectively, and it shows that there are no significant differences in hybrid susceptibility. The index of disease indicates tolerance of these hybrids to Phoma black stem. Seed analysis showed the presence of fungi from the following genera: Phoma, Alternaria, Botrytis, Sclerotinia, Penicillium and Aspergillus. Seed infection with Phoma (of the untreated seeds) per hybrid ranged from 1.2-3.5%. There is no significant correlation between stem and seed infection