Damping-off of sugar beet in Finland: I. Causal agents and some factors affecting the disease

Authors

• Mauritz Vestberg Department of Plant Pathology, University of Helsinki, SF-00710 Helsinki 71, Finland
• Risto Tahvonen Department of Plant Pathology, University of Helsinki, SF-00710 Helsinki 71, Finland
• Kyösti Raininko Sugar beet Research Centre, SF-25170 Kotalato, Finland

DOI: https://doi.org/10.23986/afsci.72102

Abstract

The fungus Pythium debaryanum auct. non Hesse is the main cause of damping-off on sugar beet in Finland. The fungus is found especially in diseased seedlings during the first two weeks after emergence. Later on, when the plants have one or two pairs of true leaves, Fusarium spp. can be isolated to a rather great extent. However, pathogenicity tests with three different Fusarium species have shown that this fungus is unble cause damping-off on sugar beet when inoculated into peat substrate. Among the fungi tried in this respect, only Pythium debaryanum and Phoma betae Frank showed clear pathogenicity. Sugar beet seedlings that outlive the disease grow slower, and their quality at harvest in the autumn is poorer than that of healthy beets.