Cacao swollen shoot virus

Cacao swollen shoot virus is a plant pathogenic virus in the genus Badnavirus within the family Caulimoviridae, carrying a double stranded circular DNA genome, first discovered in Ghana in 1936. It causes a severe disease of cacao trees marked by leaf discoloration, swelling of the stems and roots and dieback of branches, typically cutting a tree's yield by twenty five percent within the first year of infection and fifty percent within two years, with infected trees usually dying within three to four years. Although Theobroma cacao is its main host, the virus has also been found in other plants including species of Cola, the silk cotton tree and Sterculia tragacantha, and it spreads mainly through mealybug insects, chiefly Planococcoides njalensis and Planococcus citri, as well as occasionally through mechanical contact and seed. The disease is now endemic in Togo, Ghana and Nigeria, has destroyed more than two hundred million cacao trees, and is estimated to account for about fifteen percent of all cocoa crop losses worldwide, which is why Ghana has pursued costly tree eradication programs to contain it.