OCCURRENCE OF BEAN GOLDEN MOSAIC-VIRUS IN FLORIDA

An epidemic of bean golden mosaic virus (BGMV-H) was observed in the winter of 1993 in South Florida. The disease was found in common bean, Phaseolus vulgaris, and lima beans, P. lunatus, in southwest Dade County and southeast Palm Beach County. In a survey of 125 fields in Dade County, there was an average disease incidence of 26%, with higher disease incidences in fields of cranberry beans and pole beans than in snap beans. Approximately 30% of the estimated 11,000 ha planted to snap beans in South Florida was affected. In snap bean fields where BGMV-H was most severe, growers reported yields of 26-87 hL/ha compared to expected yields of 175 hL/ha. In some cases, fields were completely abandoned or destroyed. The disease was not detected in the other winter bean production areas in South Florida. An isolate of the virus from Homestead (BGMV-H) was mechanically transmissible to P. vulgaris cv. Topcrop, and the whitefly Bemisia tabaci (also known as Bemisia argentifolii) was an efficient vector of the virus in transmission tests. Plants with bright golden mosaic symptoms tested positive for geminivirus infection when extracts were probed (dot blots) with A component DNA from a geminivirus infecting the weed Macroptilium lathyroides or from the recently identified tomato mottle geminivirus, both from Florida. The bean samples did not react with probes prepared to the B components for either of these viruses. Hybridization probes prepared to A and B components of BGMV-H gave strong reactions with extracts from beans infected with BGMV isolates from Guatemala and from the Dominican Republic. This is the first report of an epidemic of BGMV occurring in the continental United States.