A Severe Mosaic of Cucumbers in Lebanon Caused by Watermelon Mosaic Virus-1. K. M. Makkouk, Plant Virologist, National Council for Scientific Research/Faculty of Agricultural and Food Sciences, American University of Beirut, Beirut, Lebanon. D.-E. Lesemann, Plant Virologist, Institut für Viruskrankheiten der Pflanzen der Biologischen Bundesanstalt für Land- und Forstwirtschaft, Messeweg 11, 3300 Braunschweig, Federal Republic of Germany. Plant Dis. 64:799-801. Copyright 1980 American Phytopathological Society. DOI: 10.1094/PD-64-799.

Watermelon mosaic virus-1 (WMV-1) was isolated from cucumber leaves with severe mottling, blistering, and malformation. The virus was readily mechanically transmitted and induced local lesions without systemic spread on Chenopodium amaranticolor and C. quinoa and systemic infection in cucumber, squash, pumpkin, and watermelon. The virus was transmitted by the green peach aphid, Myzus persicae, in the stylet-borne manner. In SDS-immunodiffusion tests, the virus isolate reacted with WMV-1 but not WMV-2 antiserum. Electron microscopy of negatively stained extracts from infected pumpkin revealed flexuous particles 750–800 nm long. Using the Derrick technique of immune electron microscopy, we observed strong specific trapping when grids were coated with WMV-1 antiserum, but no trapping with WMV-2 or bean yellow mosaic virus antisera. Using the decoration technique of immune electron microscopy, we observed a strong effect with WMV-1 antiserum, a weak effect with bean yellow mosaic virus antiserum, and no effect with WMV-2 antiserum. Examination of ultrathin sections of infected pumpkin leaves revealed pinwheel and scroll inclusions similar to those reported for WMV-1.

Keyword(s): cucurbit virus, potyvirus.