Bunchy top

Have you seen bunchy top symptoms?

Be on the lookout for these symptoms and report them to the Banana Bunchy Top Hotline on 1800 068 371.

Do not cut or disturb plants or move plant material off your property - this can spread the disease. Plants should be treated only by a trained inspector.

Early detection and reporting of symptoms are the key elements in controlling the disease.

Call the Banana Bunchy Top Hotline on 1800 068 371.

  • Banana plant exhibiting symptoms of Bunchy top
    Banana plant exhibiting symptoms of Bunchy top

General information

Occurrin worldwide, banana bunchy top virus (BBTV), is characterised by the 'bunched' appearance of newly emerging leaves, and dot-dash flecking of leaves and stem sheaths. Affected plants do not produce fruit, which can cause significant loss of production on commercial farms.

BBTV is a regulated banana pest under quarantine control in Australia. It is currently present in the southern areas of Queensland and northern New South Wales.

Overview

What causes bunchy top?

Bunchy top is caused by Banana bunchy top virus (BBTV). 

What does it look like?

Key symptoms of bunchy top disease include:

  • dark green dot-dash flecks are along veins of leaves, most visible on the underside of leaves at the base of the leaf adjacent to the midrib
  • flecks in veins can form characteristic 'hooks' into the midrib from the leaf blade. Vein-flecking can also be seen on the petioles and in the leaf sheaths of stems
  • growth is reduced and emerging leaves become choked and 'bunched'
  • affected leaves are more upright with pale yellow margins, and may have more wavy leaf margins than normal.

If infected at an early stage, plants become very stunted and rarely produce bunches. If infected at a later stage, distorted bunches may be produced.

How is the disease spread?

BBTV is spread in infected planting material, including suckers or bits, or by the banana aphid (Pentalonia nigronervosa), when it feeds on diseased plants and moves to healthy ones. Banana aphids can retain the virus for several weeks and may cover large distances especially when blown by the wind. Tissue culture plants can also be infected without showing symptoms.

Where is BBTV now?

Bunchy top is currently present in the South East Queensland and northern New South Wales production areas of Australia. North Queensland, Western Australia and Northern Territory productions areas remain free of the disease.

How is the disease controlled?

Bunchy top cannot be cured and affected plants must be destroyed. Control depends on prompt detection and destruction of infected stools by a trained inspector. There are strict quarantine restrictions to prevent movement of contaminated planting material. Control also depends on the use of uninfected planting material and intensive eradication schemes.

Control programs

BBTV is currently the focus of a three year project funded by the Australian Banana Growers Council, the Banana Industry Advisory Committee and Horticulture Australia Limited to work towards eradication. Delimiting surveys to determine the spread and intensity of BBTV in southern Queensland and northern NSW are underway. Banana plants are inspected by the project team and infected plants are destroyed by injection.

Key strategies for bunchy top control are:

  • gradual eradication from South East Queensland and northern New South Wales by maintaining pressure on infested areas
  • use of tissue-cultured, uninfected planting material when possible
  • development of sensitive detection tests
  • contributions to international research on alternative hosts and strains of the virus
  • development of contingency plans for dealing with infection if bunchy top occurs in North Queensland.

Last updated 16 July 2012