During recent field surveys conducted in south and central Puerto Rico, 100% of cucurbit plants were observed with virus-like symptoms, and in 2006, losses of up to 100% were associated with a virus-like infection observed in watermelon fields in south of the island. The symptoms of this disease evolve from a pale green color on the foliage to die back of the terminal growing shoots and a complete collapse of the plants. Potential virus vectors like aphids, thrips and whiteflies are present in the areas during the entire year because of the weather and uninterrupted, overlapping crops. ELISA tests of symptomatic plants were negative for CMV, SqMV, ZYMV and PRSV, however they showed positive reactions to the Potyvirus group. Plants in the field growing under aphid and whitefly-proof screens were free of virus symptoms and negative with ELISA tests. Vector transmission assays conducted in greenhouse conditions demonstrated that the virus was transmitted by whitefly to watermelon and pumpkin.