Relationships Between the Sweetpotato Whitefly and the Squash Silverleaf Disorder

Squash silverleaf (SSL), a newly recognized disorder of many squash varieties in Florida, is of unknown etiology. Extracts from SSL-affected tissue did not react with antisera to several cucurbit and whitefly-transmitted viruses. Silverleaf was not graft or mechanically transmitted. Early SSL symptoms were induced in new foliar growth of squash (Cucurbita pepo Senator') after 3 days of feeding by nymphs of the sweetpotato whitefly (SPWF), Bemisia tabaci (average number = 25.4 nymphs per plant). The SPWF nymphs produced chlorotic spots on leaves at their feeding sites, which were clearly different from SSL symptoms (...)