Panama disease tropical race 4 (Panama TR4)

Panama disease tropical race 4 (Panama TR4) is caused by the fungus Fusarium odoratissimum (syn: Fusarium oxysporum f. sp. cubense tropical race 4).

There are 4 races of Panama disease:

• Race 1 attacks Lady Finger, Sugar and Ducasse, but not Cavendish bananas.
• Race 2 attacks cooking bananas like Bluggoe and Blue Java bananas.
• Race 3 attacks only Heliconia species, not bananas.
• Race 4 attacks nearly all varieties of bananas, including the main commercial variety, Cavendish.

Panama TR4 is a soil borne fungal disease. There is currently no practical way to detect the disease in banana plants until external symptoms are showing.

Symptoms are more obvious at particular times of the year and crop stage. As bunch growth requires additional nutrients and water, this may promote the appearance of symptoms. For example, plants may look healthy until bunches emerge, then suddenly start to show leaf yellowing and wilt.

Environmental stress such as wet, dry or extremely hot conditions enhance disease development.

As the disease progresses, symptoms will become more obvious. Look for the following external symptoms:

• yellowing of leaf margins and at the base of older leaves
• entire leaves turning yellow and the leaf margins turning brown
• dead leaves collapsing along the leaf stalk or at the junction of the stalk and pseudostem, forming a skirt of dead leaves around the lower part of the plant
• younger leaves remaining green and upright giving the plant a spiky appearance
• stem splitting occasionally occurs at the base of the plant. Splitting is typically 2 or 3 layers thick, but can extend much higher and deeper in the stem in advanced stages.

Panama TR4 does not infect fruit.

In its early stages, the disease can be mistaken for:

• nutritional disorders
• drought
• waterlogging
• Erwinia or bacterial corm rot
• yellow Sigatoka or leaf spot
• banana weevil borer damage.

Panama TR4 has spread rapidly in Laos, Vietnam, Taiwan, Malaysia, Borneo, Indonesia, mainland China, Philippines, Jordan, Mozambique, Pakistan, Lebanon, Oman and India.

It was first detected in Australia near Darwin in 1997. It was detected in North Queensland in the Tully Valley in 2015.

Subtropical race 4 is also present in South East Queensland.

Both strains of race 4 are a serious risk to Queensland's banana industry. Quarantine and interstate plant movement restrictions aim to prevent disease spread.

Race 1, 2 and 4 are present in Queensland.

Nearly all varieties of bananas, including the main commercial variety, Cavendish are susceptible to Panama TR4.

Some weeds and grasses can also be infected with Panama TR4, though no disease symptoms are externally expressed.

The fungus produces 2 main types of asexual spores:

• conidia – which are produced in large numbers and result in rapid dispersal of the pathogen locally
• chlamydospores – which are long-lived, resulting in persistence of the fungal spores in soil over many years.

When the spores are in very close proximity with a banana plant, they germinate and produce threadlike hyphae that enter the roots through natural openings and wounds, such as those caused by nematodes and banana weevil.

The fungal hyphae grow through the corm into the vascular system within the pseudostem. The fungus blocks the plant’s vascular system preventing movement of water and nutrients.

The plant literally starves and eventually wilts and dies. As this happens, the fungus produces more spores that can spread the disease.

It takes only 1 microscopic spore to infect a new banana plant.

The time frame between initial infection and disease development may range from a few months to 1 or more years, depending on environmental conditions and the plants' age.

This means the fungus may have already spread to other banana growing areas by the time an infection is detected.

Panama TR4 is one of the greatest threats to worldwide banana production and in some countries, it has had devastating impacts.

Far North Queensland grows 95% of Australia's bananas, with the banana industry supporting many regional communities with income, jobs and produce.

If Panama TR4 is not managed, it could have a huge impact on the Australian banana industry, affecting production, people's livelihoods and the communities that rely upon it.

There is no cure for Panama TR4. Affected plants are unlikely to produce a marketable bunch of bananas, and the plants eventually die. As the fungus spreads throughout the crop, Panama TR4 significantly impacts crop yield.

Backyard plantings of bananas are common in Queensland and would be affected by Panama TR4.

Panama TR4 does not infect fruit, so the fruit is good to eat.

Anything that moves or harbours soil and water can spread Panama TR4.

It can be spread by:

• movement in infected planting material
• movement in contaminated soil and water
• people moving dirty vehicles, machinery, tools and footwear
• root-to-root contact
• parent banana plants to suckers
• insects such as the banana weevil borer
• potentially wildlife such as rats, bandicoots, feral pigs and wading birds.

Biosecurity Queensland's Panama TR4 Program has undertaken surveillance since the disease was first detected in the Tully Valley, Far North Queensland in 2015. The last round of Queensland Government surveillance for Panama TR4 took place during the 2022–2023 financial year.

The peak industry representative body, the Australian Banana Growers' Council (ABGC) has taken the lead to manage Panama TR4. ABGC conducts routine surveillance in accordance with its surveillance strategy. All information about Panama TR4 management through the TR4 Control Program can be found at panamatr4protect.com.au.

Growers should regularly check their plants for signs of Panama TR4. Surveillance for Panama TR4 outlines the best method to checking plants for signs of the disease. For a free copy of the disease identification guide, contact the ABGC on info@abgc.org.au.

Staff who access paddocks on a regular basis are best placed to check plants, which can be done at any time of year and crop stage.

All individuals and organisations have a responsibility to protect the banana industry from Panama TR4 and limit the spread of this disease. Suspect plants must be reported to Biosecurity Queensland within 24 hours on 13 25 23.

Good on-farm biosecurity measures are critical to protect banana farms from Panama TR4 and contain the disease if detected. Managing the movement of soil, water and plant material entering and exiting farms is the key to effective on-farm biosecurity.

The Panama TR4 Grower Kit brings together the latest information about the disease and on-farm biosecurity practices specifically for banana growers.

The Banana best management practices guide (PDF, 4MB) is designed to help banana growers implement effective on-farm biosecurity measures. For assistance in setting up biosecurity measures on your farm, contact the National Banana Development and Extension Team on (07) 4220 4152 or email betterbananas@daf.qld.gov.au.

Since the first detection of Panama TR4 in the Tully Valley in 2015, the Queensland Government has worked closely with ABGC to control and contain this disease. From 1 July 2023, industry took the lead in disease management through the TR4 Control Program. All information about the TR4 Control Program can be found at panamatr4protect.com.au.

For commercial banana farms where Panama TR4 has been detected, growers are required to follow the mandatory requirements of the Code of Practice for the management and control of Panama disease tropical race 4 on an infested property in Queensland. This industry initiative was adopted under legislation by the Queensland Government and came into effect 1 July 2023.

Panama TR4 is category 1 restricted matter under the Biosecurity Act 2014.

If you think you have seen Panama TR4, you must report it to Biosecurity Queensland on 13 25 23 within 24 hours.

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).

A biosecurity instrument permit is required to move banana plants (other than fruit), soil on which a banana plant has been growing, or machinery used in production of the plants out of any banana biosecurity zone into other parts of Queensland.

A biosecurity certificate may be required to move banana plants (other than fruit), soil on which a banana plant has been growing or machinery used in production of the plants:

• out of any banana biosecurity zone in Queensland
• into the northern banana biosecurity zone
• into Queensland from interstate.

Travellers arriving into Queensland are advised that there are movement restrictions on banana pest carriers into Queensland.

Visitors to Far North Queensland are asked to stay off banana farms and obtain permission from the grower before entering a banana farm. Do not enter any banana farm to take photographs in production areas of a farm.

All community members should purchase banana plants from accredited suppliers only.

If you are unsure about legal requirements, biosecurity zones, movement restrictions or certificates and permits contact Biosecurity Queensland on 13 25 23 or email qld.plantquarantine@daf.qld.gov.au.

Your cooperation in complying with these restrictions will help protect Queensland's banana industry from the spread of Panama TR4.