Global Plant Protection News

BANANA BUNCHY TOP VIRUS – UGANDA: ALERT

From PestNet

ProMED
http://www.promedmail.org

Source: New Vision [summ. Mod.DHA, edited]
https://www.newvision.co.ug/category/education/new-banana-virus-to-affect-entire-country—s-138365

The latest research by the National Agricultural Research Organisation (NARO) has revealed that banana bunchy top disease is set to affect the entire country. It was first reported in the Northern region and has now spread to the Western region. It is being speculated that the virus could have originated from the neighbouring Democratic Republic of Congo.

The Ministry of Agriculture, Animal Industry and Fisheries (MAAIF) is setting up surveillance systems to monitor the spread of the virus, so that management measures can be taken before it spreads further. MAAIF stressed the need to collaborate and support regional efforts toward emerging pests and diseases, since Uganda imports plants and plant products.

[Byline: Juliet Waiswa, Violet Nabatanzi]
—
Communicated by:
ProMED
[_Banana bunchy top virus_ (BBTV) is the type member of the genus _Babuvirus_ (family Nanoviridae). It affects only _Musa_ species and hybrids. BBTV causes one of the most serious diseases of these crops 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, as well as 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, and 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% (see link below). This is thought to suggest that the virus has spread after the initial movement of its hosts from the Indo-Malayan 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_).

In Africa, BBTV is thought to be present currently in around 16 countries (e.g. ProMED post 20211117.8699734). The virus is also endangering the diversity of banana varieties and landraces which are predominantly grown by farmers because they are well adapted to local conditions.

The Consultative Group for International Agricultural Research (CGIAR) through its International Institute of Tropical Agriculture (IITA), together with a number of international research institutions and stakeholders, have established an alliance to address the issue in the region and develop practical measures for BBTD control (see links below).

Undiagnosed diseases of banana have been reported recently several times from western Uganda (ProMED posts 20220511.8703185, 20210908.8655572, 20210601.8413562). It is feasible that some of these may have already been due to the spreading BBTV now confirmed by NARO above.

Maps
Uganda:
https://promedmail.org/promed-post?place=8704418,97,
http://www.nationsonline.org/maps/uganda-political-map.jpg, and
http://en.wikipedia.org/wiki/Districts_of_Uganda (regions & districts)
Africa (overview):
https://www.worldatlas.com/r/w960-q80/webimage/countrys/africa/maps/africa.jpg

Pictures
Bunchy top symptoms on banana:
https://feww.files.wordpress.com/2009/08/infected_plant.jpg?w=468&h=311,
http://www.iucngisd.org/gisd/image/ecology/infected_fruits5.jpg, and
http://callisto.ggsrv.com/imgsrv/FastFetch/UBER1/ZI-5YXF-2015-JAN00-IDSI-61-1
Bunchy top photo galleries:
http://www.ctahr.hawaii.edu/banana/leaves_bunchy.asp (whole plants),
http://www.ctahr.hawaii.edu/banana/morse_code.asp (leaves),
http://www.ctahr.hawaii.edu/banana/deformed_fruits.asp (fruits), and
http://www.ctahr.hawaii.edu/banana/closeup_photos.asp (banana aphids)

Links
Information on BBTV:
https://apps.lucidcentral.org/pppw_v10/text/web_full/entities/banana_bunchy_top_121.htm,
http://www.promusa.org/Bunchy+top,
https://www.cabi.org/isc/datasheet/8161, and
http://www.ctahr.hawaii.edu/banana/downloads/brochure1.pdf
BBTV description and genetic groups:
https://doi.org/10.1099/0022-1317-75-12-3541
ABTV description and characterisation:
https://doi.org/10.1007/s00705-007-1077-z
Information on genus _Babuvirus_:
https://viralzone.expasy.org/564
Virus taxonomy via:
https://talk.ictvonline.org/taxonomy/
Information on the banana aphid:
http://www.extento.hawaii.edu/kbase/crop/Type/pentalon.htm
BBTD Alliance:
https://www.iita.org/news-item/international-multi-stakeholder-alliance-continue-to-tackle-banana-bunchy-top-disease-in-africa/ and via
https://www.bbtvalliance.org/
NARO:
https://naro.go.ug/
– Mod.DHA]