Plant Disease Clinic Diagnostician Causal Agent Bunchy Top Virus is one of the most important diseases of bananas. It is widespread in most of Southeast Asia, the Philippines, Taiwan, most of the South Pacific Islands, and parts of India and Africa. The first symptoms consist of darker green streaks on the lower portion of the midrib, and later on the secondary veins of the leaf. As infection progresses, streak symptoms become evident on the leaf blade. When fruit is produced, some of the hands may have distorted and twisted fruit.
Leaves are usually short, stiff, erect and more narrow than normal.
Leaves display marginal yellowing or chlorosis and necrosis or burning. These plants will not produce any fruit. The virus is spread by the banana aphid, which can acquire the virus after about an 18-hour feeding period and can retain the virus for about two weeks. During this time, an aphid can transmit the disease after feeding for about two hours on a healthy plant. Disease symptoms appear approximately one month after infection.