The host range of some English isolates of beet yellowing viruses

SUMMARY Of sixty herbaceous plant species, which were inoculated with beet mild yellowing virus (BMYV), fourteen species were susceptible to isolates of BMYV collected from sugar beet in eastern England. Three of these, Beta vulgaris L., Claytonia perfoliata Donn. and Capsella bursa‐pastoris (L.) Medic, had already been used as test plants for BMYV. The new hosts were six species in the genus Beta, Spinacea oleracea L., Senecio vulgaris L., Sinapis alba L., Spergula arvensis L. and Armaria leptoclados (Rchb.) Guss. Stellaria media L. (Vill.) is also probably a host of BMYV but results of susceptibility tests were inconclusive. Senecio vulgaris produced well‐defined symptoms when infected with BMYV and was a useful additional test plant. Similar experiments on the host range of beet yellows virus (BYV) generally confirmed the results of previous work. It seems likely that in recent years weeds have been important primary foci of BMYV infection, but probably not of BYV infection, in Great Britain. The host range studies have indicated that BMYV may be related to at least one part of the American beet western yellows virus (BWYV) complex.