Some observations on assessing Phoma betae infection of sugar-beet seed

Near-ultraviolet or ‘black’ light applied continuously from the start of incubation, facilitates tests for Phoma betae on sugar-beet seed by stimulating the production of pycnidia and restricting mycelial growth of P. betae and other fungi. Pretreatment of the seed with dilute sodium hypochlorite decreases the number of seeds with P. betae by removing superficial infection, but some of this is of significance in the field. Rubbing beet seed also decreased counts of P. betae in the laboratory and increased field emergence, primarily by removing the fungus. Griseofulvin sprayed on beet-seed plants either 2 wk or 2 days before harvest significantly decreased seed infection with P. betae, but not to a level at which further seed treatment could be omitted.