Banana freckle

Banana freckle on Cavendish bananas is caused by the fungus Phyllosticta cavendishii. Races of this species that affect Cavendish bananas are exotic to Australia.

There are other species of Phyllosticta that cause banana freckle overseas, for example Phyllosticta musarum. Phyllosticta musarum has also not been detected in Australia.

Some species of Phyllosticta that cause banana freckle are found in Australia, such as Phyllosticta maculata. Phyllosticta maculata does not affect Cavendish bananas.

Symptoms

• 'Sandpapery feeling' spots, predominantly on leaves and fruit.
• Spots can be very small to large (1–4mm) and dark brown to black in colour.
• The spots can run together to form streaks.
• Sometimes the centre of the larger spots are lighter in colour.
• Spots can also appear on the midrib of the leaf, bunch stalks and flower bracts.
• The spots have a sandpaper feel when touched because the fungal structures protrude through the plant surface.
• Severe infection results in yellowing of the leaf, which can wither and die.

Plant stage and plant parts affected

Banana freckle can affect a banana plant at all stages of the production cycle. It mainly affects leaves and fruit.

A closely related species, Phyllosticta maculata, causes similar symptoms on bananas, and is present in Australia. In Queensland, it can be found on islands in the Torres Strait, on Cape York Peninsula and Far North Queensland. Banana freckle caused by P. maculata is very uncommon in Queensland.

If you suspect banana freckle on any banana variety, don't hesitate to report it. Diagnostic testing is required tell them apart.

Banana freckle that can affect Cavendish bananas was previously eradicated from the Northern Territory in 2019. In May 2022, banana freckle was detected on dwarf Cavendish bananas in the Northern Territory and a new eradication program was started to eliminate it.

Banana freckle is known to occur in parts of Asia including Bangladesh, Bhutan, China, India, Indonesia, Malaysia, Myanmar, Nepal, Pakistan, Philippines, Sri Lanka, Taiwan, Thailand and Vietnam. The disease is also present in Fiji, Hawaii, New Zealand, Papua New Guinea, Samoa, Solomon Islands and Tonga.

Banana freckle is only known to cause disease in banana plants (Musa spp.) including sweet and cooking varieties.

The freckle spots contain fungal fruiting bodies (perithecia and pycnidia). When it rains or following heavy dew, fungal spores such as ascospores and conidia are released. Conidia in particular play an important part in the infection cycle. They can be spread by raindrops or water splash onto or across leaves and fruit. The spores germinate, penetrating the host and multiply within and between cells, creating new spots in the superficial layers of the host plant tissue.

The incubation period can be as little as 20 days in hot humid weather.

Banana freckle is a serious threat to the banana industry. The disease decreases plant health and productivity by reducing the amount of healthy leaf area, and affects fruit quality and appearance. Blemished fruit may not be marketable. Production costs may increase as a result of the additional costs of fungicide sprays and removal of infected leaves. Some of these increased costs might be passed onto consumers.

Home gardeners would also be affected as banana is a common backyard plant in Queensland.

Eating quality is not affected and there is no risk to human health from eating banana freckle infected bananas.

Banana freckle is a 'wet spore' organism. It generally moves short distances by water droplet splash and wind driven rain. The fungus is spread over larger distances by people moving infected fruit, leaves and suckers used for planting.

Inspect your banana plants regularly for the presence of exotic pests and diseases.

Look for small spots 1–4mm in diameter that have a sandpapery feel when you touch them. The spots may join together to form streaks.

If you suspect banana freckle on any banana variety, report it to Biosecurity Queensland immediately on 13 25 23.

Further information about banana crop monitoring can be found in the Farm Biosecurity Manual for the Banana Industry (PDF, 1.4MB).

Banana plants propagated from tissue culture under the Quality Banana Approved Nursery (QBAN) scheme are recommended as the preferred high health source of planting material to use.

• Protect your farm from emergency plant pests
• Understand good farm biosecurity
• Visit the farm biosecurity website

Banana freckle (other than Phyllosticta maculata) is prohibited matter under the Biosecurity Act 2014.

Report suspected banana freckle to Biosecurity Queensland immediately on 13 25 23 or contact the Exotic Plant Pest Hotline on 1800 084 881.

If you think you have found the disease, you must take all reasonable and practical steps under your control to minimise any associated risks. This is called a general biosecurity obligation (GBO).

To protect the Queensland banana industry from exotic pest threats, restrictions apply for moving plant material or related items such as soil and equipment into and within Queensland. A biosecurity certificate is required.