Investigations on the causal fungi (Fusarium spp.) of the dry rot of potato tubers in Slovenia
1994
Savor, J. | Macek, J. (Ljubljana (Slovenia). Biotechnische Fakultaet. Landwitschaftliche Abteilung)
In the last years the dry rot of potato tubers is becoming a more and more important storage disease in Slovenia. Up to the present the fungus Fusarium solani was considered the monocausal organism for this disease. In our investigations pure isolates of 12 fungi were obtained. Fusarium sambucinum was the most frequent species (41 per cent) followed by Fusarium graminearum, Fusarium solani, Fusarium avenaceum (up to 16 per cent) and Fusarium lateritium (8 per cent). The morphological and physiological properties of the fungi were investigated in vitro. Inoculation experiments were carried out on 'Resy', 'Jaerla', 'Desiree', 'Sirtema', 'Bintje' and 'Saskia' cultivars. The results show that F. avenaceum has the highest disease index (DI = 28) and F. solani the lowest pathogenicity, DI 3. The most resistant cultivar was 'Saskia' with DI 8, the most sensitive one was 'Bintje' with DI 29. All fungi were oxybionts under laboratory conditions. Different degrees of relative air humidity exerted no significant influence on the mycelial growth. F. lateritium was the only species that formed no spores under three different relative air humidity. This fungus on the other hand showed the best spore formation under normal conditions. Observations under climatic and laboratory conditions were in best agreement for F. solani and F. lateritium. The results indicate that the dry rot of potato tubers in Slovenia is more and more important, mostly because of mechanized production and because of the import of seed tubers.
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