Natural Occurrence of Sonchus Yellow Net Virus in Florida Lettuce. B. W. Falk, Everglades Research and Education Center, University of Florida, Belle Glade 33430. D. E. Purcifull and S. R. Christie, Department of Plant Pathology, University of Florida, Gainesville 32611. Plant Dis. 70:591-593. Accepted for publication 21 January 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-591.

The causal agent of a newly recognized disease of lettuce (Lactuca sativa) in Florida was investigated. A virus isolated from naturally infected lettuce was mechanically transmissible to Nicotiana × edwardsonii, N. clevelandii, N. debneyi, Sonchus oleraceus, and lettuce. Electron microscopic examination of extracts from infected N. × edwardsonii showed rhabdoviruslike particles present in infected plants. When virions were purified and examined by SDS-PAGE and serological analysis of “Western blots,” four major virion proteins that reacted with antisera to the type isolate of sonchus yellow net virus (SYNV) were identified. On the basis of host range and electron microscopic and serologic evidence, the causal agent of this Florida lettuce disease is identified as SYNV. This is the first report of natural infection of an economically important crop by SYNV.