A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Source: Australian Broadcasting Corporation (ABC) Rural [edited]
Backyard banana growers in south east Queensland and northern New South Wales have been urged to stay alert for one of the world's most damaging banana diseases after dozens of outbreaks. The Australian Banana Growers' Council [ABGC] has responded to hundreds of reports of bunchy top, which almost wiped out the crop in northern NSW and southern Queensland last century.
The council runs the national detection and management program funded by grower levies. Inspectors have helped stop the aphid spreading outside a control area. But the virus has never been eradicated and remains a major threat to Australia's banana industry.
[ABGC's] David Peasley said, "The numbers of infections have been increasing in the backyards of southeast Queensland. 5 or 6 years ago it was under control, but it is getting away again." To stop spreading the virus, there is a prohibition on planting material being moved outside the bunchy top control zone.
[Byline: Jennifer Nichols]
[_Banana bunchy top virus_ (BBTV) is the type member of the genus _Babuvirus_ (family Nanoviridae) and only affects _Musa_ species. It causes one of the most serious diseases of banana with symptoms of chlorosis, stunting, and death of the host plant. The virus is spreading in Africa, Australasia, and the Pacific Islands.
BBTV is transmitted by the banana aphid _Pentalonia nigronervosa_ in a persistent manner. Infectious insects may be spread on plant material or by air currents. The virus is also spread with infected suckers but cannot be transmitted by mechanical means (such as cutting tools). Disease management is extremely difficult and may include vector control, removal of inoculum, use of clean planting material, and frequent scouting for new outbreaks. Eradication of established BBTV from a planting or natural cluster of plants is considered impossible, the only option is to kill off all plants in the group. Tolerant varieties can be used to enable some crop production in infected areas, but these cultivars may still support virus replication and thus serve as pathogen reservoirs.
There are 2 groups of BBTV isolates from different regions: the South Pacific group (including Australia, Burundi, Egypt, Fiji, India, Tonga, Western Samoa) and the Asian group (including Philippines, Taiwan, Viet Nam). The mean sequence difference between the 2 groups has been reported as approximately 10 percent (see link below). This is thought to suggest that the virus has spread after the initial movement of its hosts from the Indo-Malaysian region, where edible _Musa_ species originated, to Africa and the Americas.
BBTV is closely related to _Abaca bunchy top virus_ (ABTV) reported from some areas of SE Asia (ProMED post 20191215.6842101). ABTV and BBTV cause the same disease symptoms in both banana and abaca (_M. textilis).
Australia (with states):
BTD symptoms on banana:
BTD photo galleries:
http://www.ctahr.hawaii.edu/banana/leaves_bunchy.asp (whole plants),
http://www.ctahr.hawaii.edu/banana/deformed_fruits.asp (fruits), and
http://www.ctahr.hawaii.edu/banana/closeup_photos.asp (banana aphids)
Information on BBTV:
BBTV description and genetic groups:
ABTV description and characterisation:
Information on genus _Babuvirus_:
Virus taxonomy via:
Information on the banana aphid: