First report of Squash vein yellowing virus affecting watermelon and bitter gourd in Puerto Rico.
In 2005, symptoms of watermelon vine decline (WVD) were observed on a 200-acre watermelon farm in Santa Isabel, on the south central coast of Puerto Rico. WVD symptoms included leaf curling, mosaics, and internode necrosis. At the early growth stages of WVD, reduced vigour and plant stunting occurred. At the flowering stage, symptoms progressed to necrosis and wilting of vines. By 2006, other watermelon fields were also affected. Field trials in 2007 and 2008 with insect-proof cages and insecticides suggested the role of whiteflies (Bemisia tabaci) in the transmission of the virus. Watermelon and pumpkin plants were successfully infected by mechanical inoculation and through B. tabaci transmission assays. Plants of Cucurbita moschata exhibited vein clearing symptoms typical of Squash vein yellowing virus (SqVYV) after mechanical inoculation with extracts from watermelon plants with WVD symptoms. In 2011, eight watermelon samples from plants exhibiting WVD syndrome were collected in Guánica, Santa Isabel, Juana Díaz, and Mayagüez, and two bitter gourd (Momordica charantia) samples were collected from Mayagüez. This is thought to be the first report of SqVYV in Puerto Rico associated with WVD syndrome in cucurbits.