Phoma glomerata, P. herbarum, P. epicoccina, Myrothecium roridum, Pleospora herbarum, Colletotrichum sp., Alternaria sp., Diderma deplanatum and Didymium iridis were found on beet seed in addition to P. betae. Several of these fungi can be confused with P. betae in laboratory tests for seedborne infection, but only P. betae attacked sugar beet seedlings or caused a rapid rot of sugar beet root slices. The addition of 10 p.p.m. benomyl to potato dextrose agar eliminates some of the more troublesome contaminants. Incubating seed on this agar under continuous near ultraviolet light provides a rapid method of assessing seed-borne P. betae.