Biological control of Alternaria radicina in seed production of carrots with Ulocladium atrum

Black rot of carrots is caused by seed-borne Alternaria radicina. Biological control of seed infestation by treatments applied to plants in flower during seed production with the fungal antagonist Ulocladium atrum was investigated in laboratory and field experiments resulting in a reduction of seed infestation by A. radicina. No negative side effects of the antagonist on seed quality were found. The application of U. atrum as a strong competitor during substrate colonisation of senescing tissues may also be promising in seed production of various other crops, e.g. of onion, cabbage or sugar beet, where necrotrophic seed pathogens enter necrotic flower parts before establishment on seeds.