Bunchy top control

Bunchy top is a very serious disease of bananas which devastated the Queensland banana industry during the 1920s. It still lingers in the southern areas of Queensland and in the adjacent northern New South Wales.

What causes bunchy top?

Bunchy top is caused by a virus that is spread either on infected planting material or by the banana aphid, Pentalonia nigronervosa, when it feeds on diseased plants and moves to healthy ones.

Effects of bunchy top

Affected plants do not produce fruit. This causes significant loss of production on commercial farms.

What does it look like?

Bunchy top produces dark green, dot-dash flecks running along leaf veins and hooking down along the midrib, and dark green streaks running vertically down the leaf sheath into the pseudostem of the banana plant. New emerging leaves are progressively shorter, narrower and more erect. The stools fail to produce fruit.

Marking bunchy top infected plants

Note: If you live in Queensland and suspect you have bunchy top in your bananas, you should report to a plant health inspector (see Biosecurity contacts).

How is it controlled?

It cannot be cured, and affected plants must be destroyed. Control depends on prompt detection and destruction of infected stools. 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

Bunchy top has not been eradicated from southern Queensland and the banana industry and the Queensland Government are keen to ensure the disease is kept out of north Queensland. Bunchy top is kept in check by constant vigilance of inspectors and strict industry controls.

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 wherever 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 reviewed 23 August 2007