Banana bunchy top virus

Primefact number Edition Published Author
1328 Second Jun 2017 Plant Biosecurity and Product Integrity

Banana plant with leaves that are very upright rather than horizontally fanned out

Close up of banana leaf showing dark green leaf streaks which form J shaped hooks at the midrib, typical of banana bunchy top

Bright green banana plant with many small round dark insects on the leaf sheath

Map of northern NSW showing the Banana bunchy top virus control zone

Banana bunchy top virus is a regulated plant pest in New South Wales. This virus is being actively controlled in NSW. Please report suspect symptoms to the National Bunchy Top Hotline 1800 068 371.

Banana bunchy top disease is caused by the banana bunchy top virus (BBTV).

Typical symptoms are the short, narrow and upright clustering of leaves which form at the top of an infected banana plant (Figure 1). Poor growing conditions such as cold weather and water logging can also cause leaf bunching in banana plants.

Suspect plants should be checked for additional disease symptoms to confirm the presence of BBTV.

Description

Banana leaves infected with BBTV have dark green streaks along the small veins on the underside of the leaf. The streaks consist of dots and dashes in a Morse code pattern which form J-shaped hooks where they join the midrib (Figure 2).

As BBTV progresses dark green streaks appear on the infected leaves, midribs and stalks. In older banana plants dark green streaks may be seen on flower bracts.

Banana plants which are mature when infected with BBTV may produce fruit but the bunches will be stunted and deformed.

Damage

Banana plants infected with BBTV rarely produce fruit. If fruit is produced it is small, deformed and unmarketable.

Hosts

Banana bunchy top virus infects cultivated and wild bananas in the Musaceae plant family.

Spread

Banana bunchy top virus is transmitted from plant to plant by the banana aphid (Pentalonia nigronervosa).

Long distance spread occurs through the movement of infected planting material.

Banana aphid

The banana aphid (Pentalonia nigronervosa) acquires the virus while feeding on the sap of infected plants (Figure 3). The virus can persist in the banana aphid for 13-20 days.

Banana aphids are small with reddish-brown, oval-shaped bodies. They have two characteristic projections at the rear of the abdomen.

Banana aphids may be found:

  • in the topsoil at the base of banana plants
  • underneath old banana leaves
  • on the unfurled leaves of young banana plants and suckers
  • beneath outer banana leaf sheaths
  • at the throat of the banana plant (Figure 3)

Banana aphids are all female. The aphids give birth to live young, which complete their lifecycle from nymphs to adults in 9-16 days.

Banana bunchy top virus is not transmitted from adult aphids to their offspring. Banana aphids must feed on an infected banana plant to acquire and spread the virus.

Distribution

Banana bunchy top virus is widespread in Southeast Asia, the Philippines, Taiwan, most South Pacific islands, Hawaii and parts of India and Africa.

The banana exporting countries of Latin America and the Caribbean region are free of BBTV.

Australian distribution

Banana bunchy top virus occurs in some areas of south-east Queensland south of Cooloolabin and in the Brunswick and Tweed River valleys of northern New South Wales.

Banana bunchy top virus does not occur in the Coffs Harbour area of New South Wales.

NSW Biosecurity (Banana Bunchy Top Virus) Control Order 2017

A Control Order is in place for the treatment and eradication of banana diseases and pests in the NSW Banana Bunchy Top Virus Control Zone PNG, 297.6 KB. This Control Order replaces the previous banana Order OR121.

The Control Order is called the Biosecurity (Banana Bunchy Top Virus) Control Order 2017 PDF, 299.29 KB. It covers the NSW Banana Bunchy Top Virus Control Zone. The Control Zone incorporates the local government areas of Ballina, Byron Bay, Lismore and Tweed on the north coast (Figure 4).

The Control Order will assist the NSW banana industry to achieve freedom from banana bunchy top virus.

The Control Order requires banana aphid infestations to be controlled and BBTV infected plants destroyed.

The Control Order also prohibits the movement and planting of banana plants (Musaceae plant family) without authorisation, to stop the spread of BBTV through infected planting material.

Control

Banana bunchy top virus and banana aphid are regulated pests which are being actively controlled in NSW.

BBTV can be controlled by promptly treating the banana aphid infestation and then destroying the infected banana plant.

Banana aphid infestations must be treated before destroying the infected banana plant. If the infected plant is destroyed first the banana aphids will simply fly to nearby healthy plants and spread the disease.

Banana aphid control

The Control Order requires that banana aphids on banana plants infected with BBTV are treated within 3 days of detection of the disease.

Banana aphids can be treated by either:

  • injecting the infested banana plant with imidacloprid (PER14850, expires 30 Sept 2024); or
  • spraying the entire infested banana plant with paraffinic oil. All banana plants within
    10 metres of the infested banana plant should also be sprayed with paraffinic oil (PER14850, expires 30 Sept 2024).

Bunchy top virus control

The Control Order requires that after the aphid treatment, the banana plants infected with BBTV are immediately destroyed.

Banana plants infected with BBTV can be treated by either:

  • injecting the infected banana plant with glyphosate . The whole banana plant, including the corm, attached suckers and pseudo stems, should be treated (PER14850, expires 30 Sept 2024); or
  • removing the entire infected banana plant from the ground. The pseudostems should be split and the corms cut into pieces no more than 5 centimetres in diameter.

Actions to minimise risks

Put in place biosecurity best practice actions to prevent entry, establishment and spread of pests and diseases:

  • practice “Come clean, Go clean”
  • ensure all staff and visitors are instructed in and adhere to your business management hygiene requirements
  • source propagation material of a known high health status from reputable suppliers
  • monitor your crop regularly
  • keep records
  • isolate banana plants or areas with suspect symptoms to prevent further spread