Yellow Sigatoka (leaf spot) General information

Yellow Sigatoka (leaf spot) Pseudocercospora musae

What is yellow Sigatoka and where does it occur?

Yellow Sigatoka is a fungal disease in bananas that causes leaf lesions and is commonly referred to as leaf spot. The fungal plant pathogen that causes the disease is Pseudocercospora musae.

Yellow Sigatoka occurs in all growing regions of Australia and is common in Far North Queensland, particularly during the wet season when conditions are warm and moist.

Figure 1 Advanced symptoms of yellow Sigatoka disease. It is important to remove leaves with visible spot prior to fungicide application, to reduce disease load and to ensure the longevity of fungicides used for management.

How does yellow Sigatoka impact banana production?

The lesions caused by the disease result in premature leaf death and reduces the plant’s ability to photosynthesize, impacting bunch size and delaying bunch filling. It also reduces the green life of fruit, causing mixed ripening which can restrict market access. 

If left uncontrolled or unmanaged (Figure 1), costs of deleafing and spraying increase and it can be difficult to identify other exotic leaf diseases such as black Sigatoka.

How does yellow Sigatoka spread?

The disease produces two types of spores, ascospores and conidia that spread by two main vectors, air and water.

Air movement within banana paddocks allows for easy dispersion of fungal spores (ascospores), allowing them to settle and infect new plants. These spores are most active in the wet season due to warm and moist conditions, causing tip spotting in younger leaves. Ascospores are responsible for the long distance spread of the disease due to dispersing in air currents.

Movement by water, such as rainfall or dew, moves conidia from higher leaves down the plant and onto suckers and causes line spotting on the leaf. Conidia infect new leaves of the same plant or neighbouring plants if the rain is wind driven.

What are the stages of yellow Sigatoka

Symptom development of yellow Sigatoka is broken up into five stages (Figure 2).

Stage 1: Yellowish green specks less than 1mm long. Generally, younger leaves are affected. Very hard to see with the naked eye.
Stage 2a: Specks develop into yellow streaks 3 to 4 mm long.
Stage 2b: Streaks darken to a rusty brown.
Stage 3: Streaks broaden to a spot, becoming wider with undefined margins.
Stage 4: Spots develop defined dark brown edges, the centre becomes sunken and occasionally has a yellow halo. Conidia are produced on stage 4 lesions. 
Stage 5: Sunken centre turns grey and is surrounded by dark brown/black border. Ascospores are produced on stage 5 lesions. 

Figure 2 Five stages of yellow Sigatoka symptom development.

How is yellow Sigatoka managed?

Yellow Sigatoka can be difficult to control in wet, moist conditions and should be managed with a combination of cultural and chemical controls.

Deleafing (Figure 3) is a major component of managing yellow Sigatoka that cannot be overlooked. Increased chemical application is unable to compensate for regular deleafing practices.

What cultural controls should I practice?

Controlling yellow Sigatoka is best managed through cultural control practices. Although labour intensive, they are necessary to keep fungal levels low within a canopy, especially during periods of high rainfall when the ability to aerial spray or mist is limited. 

Figure 3 Regular deleafing is critical for yellow Sigatoka control.

Deleafing is the most critical control method for managing yellow Sigatoka.

  • Deleafing removes infected leaves from the canopy and assists in keeping disease inoculum levels low. Deleafing is recommended once a single leaf on a plant has leaf spot lesions on more than 5% of the total leaf surface.

  • To prevent yellow Sigatoka infections, some growers practice intensive deleafing practices. This involves removing additional leaves, that are not yet showing visible signs of the disease, as the early stages can be difficult to detect with the naked eye. Bunched plants are an exception, as most growers only remove the minimum number of leaves. Tipping, which is only cutting out a proportion of the leaf with visible symptoms, is not recommended as the entire leaf would be infected.

  • Deleaf before spraying, as once yellow Sigatoka produces visible lesions (stage 3 onwards) neither systemic nor protectant fungicide applications are effective against those spots. Deleafing also assists in reducing the risk of fungicide resistance on your farm, and neighbouring farms.

  • Recent research suggests that the best deleafing practice is to go through frequently before the wet season to get inoculum levels low. This will improve spray efficiencies before the warm wet summer when yellow Sigatoka pressure is heaviest. In the wet season, deleafing can extend to every 6-8 weeks and during the dry season every 8-12 weeks, depending on disease pressure.

Other cultural practices

Other cultural practices, such as block design, are also important for managing the disease. Maximising airflow through a block will assist in creating conditions that minimise disease development. This includes the following considerations:

  • Avoid placing blocks close to waterbodies, such as dams, as it will only promote the disease due to the high humidity associated with them.

  • Lower density plantings are recommended to promote a drier microclimate.

  • Maintain good drainage to ensure water does not sit within interrows.

  • Reduce plant-to-plant contact by removing unnecessary suckers.

Download this information as a factsheet

More information

Videos

Overview of leaf spot diseases and their impact

Yellow Sigatoka – Life cycle and how it spreads

Yellow Sigatoka – Management tips for growers

For more information contact:

The Better Bananas team
Department of Agriculture and Fisheries
South Johnstone
13 25 23 or email betterbananas@daf.qld.gov.au

This information has been produced as part of the National Banana Development and Extension Program, funded by Hort Innovation, using the banana research and development levies and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture. The Queensland Government has also co-funded the project through the Department of Agriculture and Fisheries.
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Yellow Sigatoka (leaf spot) Fungicides and options to manage the development of resistance

Fungicides and options to manage the development of resistance

Fungicides help manage yellow Sigatoka in the tropics. We need to better manage their use or risk losing them forever.

Historical testing of yellow Sigatoka isolates in Far North Queensland has confirmed loss of sensitivity to strobilurin fungicides (e.g. Cabrio® and Flint®) and triazole fungicides1 (e.g. Folicur ®, Opus ® and Tilt ® are trade names).

There are relatively few new fungicides being registered, so it’s important to manage the usage of chemicals available today so they are effective in the future. Every grower needs to do their bit in protecting the industry. Here are several ways to manage fungicide resistance.

Deleaf spotted leaf, don't spray it!

The most critical part of managing Sigatoka disease in banana is deleafing (Figure 1). It can reduce ascospore production by up to 85%, significantly reducing the potential for disease resistance to develop on your farm and neighbouring farms. 

Fungicides are not effective on visible necrotic spots and applying products to infected leaf material encourages fungicide resistance. Therefore, leaf spot infected leaves should be removed before fungicides are applied.

Deleafing is important all-year-round, however, spring is the key period. Ensure all spotted leaves are removed to reduce the level of disease prior to summer. Warm and wet summer conditions favour yellow Sigatoka developing, making it more difficult to manage.

Figure 1 Regular deleafing is critical for managing yellow Sigatoka.

Know the fungicide groups

Both protectant and systemic fungicides are available for managing yellow Sigatoka. Each chemical group has a different mode of action and has an important role to play in a spray program. This influences when these products should be used. A complete list of fungicide groups registered for managing yellow Sigatoka in the banana industry is in Table 1.

Protectant fungicides help prevent yellow Sigatoka developing and should form the bulk of your applications throughout the year. Mancozeb should always be applied with paraffinic oil, while chlorothalonil should never be applied with oil. Therefore, growers cannot alternate between mancozeb and chlorothalonil. 

Systemic fungicides used in bananas are more accurately described as being ‘translaminar’, passing through the leaf tissue from one leaf surface to the other. This means the fungicide moves below the surface of the leaf but is not truly systemic because its movement is limited. The common misconception is that systemic fungicides used in bananas can ‘kill’ existing disease. While they are often referred to as ‘curatives’, their activity is limited to early stages (Figure 2) of the disease (Stages 1 to 2b). Once necrotic leaf spot symptoms are visible to the naked eye, fungicides will not arrest development. Fungicide application to lesion stages 3, 4 and 5 could encourage fungicide resistance to develop. Therefore, apply systemic fungicides when conditions are conducive to the disease developing in warm and wet weather conditions, and not when you can see symptoms.

Rotate fungicide groups

Chemicals, including fungicides, are grouped based on their mode of action and chemical structure.

There are nearly 200 trade names of fungicides registered to manage yellow Sigatoka in bananas. Know which groups the products belong to and ensure that systemic chemical groups are rotated.

It is important to rotate between the groups, not simply between products in these groups to avoid resistance. For example, switching between propiconazole and difenoconazole is not considered ‘rotating’ as both actives belong to Group 3.

Figure 2 Stage 2b lesions on banana leaf. Systemic fungicides have no effect on lesions beyond 2b.

Follow the product use recommendations

There are restrictions that apply, especially to the systemic fungicides, in relation to:

  • maximum number of applications per year
  • maximum number of consecutive sprays of the same fungicide group
  • restricted ‘no spray’ periods when some fungicide groups are not permitted for use

Table 2 is based on CropLife Australia’s Fungicide Resistance Management Strategy for the Far North Queensland banana industry. This resistance strategy came into effect on 25 June 2015 and as product labels are renewed they will refer to this strategy.

Group 7 and Group 11 products must only be applied in a mixture with another fungicide from a different activity group, registered for control of yellow Sigatoka, at the full registered rate. Each fungicide included in the mixture counts towards the maximum number of spray applications allowed for Group 3 or Group 9 fungicides.

A resistance strategy is also available for areas outside of Far North Queensland. Refer to CropLife’s website for details.

Table 1 Fungicides currently registered in banana crops for management of yellow Sigatoka as of October 2023. Always check registration status and product label prior to use, through the APVMA website.

* Trade names are used as an example only, other products may exist, and one name is chosen for simplicity and space.

Use the recommended label rate

Thorough spray coverage

The application rates listed on the product label have been proven through field efficacy trials. Therefore, halving or increasing the rate of a fungicide product can encourage the development of a resistant population of the yellow Sigatoka organism.

Always check the label for the correct application rate, as different trade names may have varying amounts of an active ingredient. For example, the active ingredient propiconazole (Group 3) appears in more than 50 products registered for yellow Sigatoka management in bananas, and among this list are four different concentrations of the active ingredient.

For the fungicide to have the best chance at protecting the leaf from further infections, thorough spray coverage is required. This is especially important for the protectants which only work on the leaf area they come into direct contact with, and as already mentioned, the systemics have limited ability to move within the leaf.

Table 2 CropLife Australia’s fungicide resistance strategy for the Far North Queensland banana industry (Valid 14 July 2023).

** IMPORTANT - Loss of sensitivity to yellow Sigatoka in banana among products in Groups 3 & 11 has been recorded in Far North Queensland production areas.
Reference:
1. Grice, K. (2009) Assessment of yellow Sigatoka populations in banana for loss of sensitivity to the fungicides trifloxystrobin and tebuconazole. 2009. Queensland Primary Industries and Fisheries.

Download this information as a factsheet

More information

New video available - Management tips for growers!

This video advises on the current best practice for managing yellow Sigatoka. Managing the disease requires a combination of timely deleafing and appropriate fungicide application. Tegan Cavallaro and David East from the Department of Agriculture and Fisheries discuss what’s involved.

For more information contact:

The Better Bananas team
Department of Agriculture and Fisheries
South Johnstone
13 25 23 or email betterbananas@daf.qld.gov.au

This factsheet has been produced as part of the National Banana Development and Extension Program which is funded by Hort Innovation, using the banana industry research and development levies and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture. The Queensland Government has also co-funded the project through the Department of Agriculture and Fisheries.
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Pests, diseases & disorders

Common pests, diseases & disorders of banana

Bananas can be impacted by a range of pests, diseases and disorders. Having appropriate management practices in place is essential for ensuring good quality fruit. Below is some general information on some of the major pests, diseases and disorders of banana. It also includes summaries of recent trial work undertaken by researchers from the Department of Agriculture and Fisheries.

If you are having problems identifying what is causing damage to your crop check out the Better Banana’s problem solver section here

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Bunch pests

Corm pests

Diseases

Physiological issues and disorders

For more information contact:

The Better Bananas team
Department of Agriculture and Fisheries
South Johnstone
13 25 23 or email betterbananas@daf.qld.gov.au  

This information has been developed as part of the National Banana Development and Extension Program (BA19004) which is funded by Hort Innovation, using the banana industry research and development levies and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture. The Queensland Government has also co-funded the project through the Department of Agriculture and Fisheries.
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South Johnstone field walk

Field day extension event held in FNQ

The project team in Far North Queensland (FNQ) facilitated a field day event on the 22 September 2023.  The half-day event was held in the paddock at the South Johnstone Research Facility and featured talks on the following  research topics:

A tour with Jeff Daniells and Katelyn Robertson through the current new selections of Cavendish with improved resistance to Panama disease tropical race 4 (TR4) to see the plant crop bunches. This was the first look in FNQ at selections developed by DAF using mutagenesis which were initially screened for TR4 resistance in the NT (BA21002).

An interactive display and discussion on latest bunch pest management research including the results from trials using current registered chemistries for bell injection and bunch spraying presented by Ingrid Jenkins and Tegan Cavallaro. This was complimented by information shared by Richard Piper and Daniel Farrell on the ‘biological’ bunch pest management research that is underway (BA21004).

An overview of the new fertiliser rate trial, funded by the Queensland Government’s Queensland Reef Water Quality Program, which will test the effect of varying rates of nitrogen and phosphorus fertiliser on banana productivity and profitability.  Also, the instruments that will be used to monitor the movement of nutrients, sediments and chemicals in overland flow and deep drainage in the trial.

Jeff Daniells giving a tour of the Cavendish variety trial block.
Richard Piper and Daniel Farrell presenting on the latest biological approaches being trialled to manage bunch pests.

Attendees were then offered the opportunity (optional) to take a tour through the plant crop bunches in the latest trial of the new Lady Finger-like varieties with improved resistance to Panama disease Race 1 and yellow Sigatoka.

Attendees of the field walk.
Variety field day sept 2023
Cavendish variety block.

Feedback from the event

The varieties, well we don’t have an answer yet but we may be getting closer, it is important work that needs to be happening – Grower

 

Good to see variety R&D progress and know that there is work happening in that space as TR4 spreads. It was good that we split into groups to make it more manageable and easier to talk and ask questions – Private consultant/agronomist

The presentations and effort put into it was fantastic. Bunch pest management is a complex thing and there is no single approach that will work across farms. Generally, I think there needs to be a bigger focus on biodiversity.  – Grower

Extension events are funded as part of the National Banana Development and Extension Program (BA19004). This project is funded by Hort Innovation, using the Hort Innovation banana research and development levy, co-investment from the Queensland Department of Agriculture and Fisheries and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture.
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Crop management

Crop management

Many crop management practices will have a direct influence on the yield and efficiency of your farming business. The following information and research relate to practices that may result in improved yield and/or efficiency gains. Crop management decisions can also be influenced by weather and climate. Advances in technology, including forecasting tools, help growers assess the risk and better prepare for severe weather events. This section also includes information and research related to mitigating the impact of adverse weather conditions.

Recent trial work has found that undertaking an additional early desuckering application in the plant crop of tissue-cultured plants can significantly improve yield and stability in the following ratoon crop. 

Click here for more information.

When preparing for a cyclone impact, some growers may decide to remove the canopy of their banana crop to reduce wind resistance and reduce plant loss. The following research looks at the effects of canopy removal and the subsequent impact on yield.

Click here for more information. 

Links to a series of interactive presentations, incorporating videos on important climate drivers and the Bureau of Meteorology (BOM) forecasting tools and outlooks.

Click here for more information.

Banana weevil borer – monitoring

Banana weevil borer Cosmopolites sordidus

Monitoring

Adult banana weevil borer activity increases during warm and/or wet weather and decreases during cold and/or dry conditions. Periods of greatest adult activity are in spring (September-October) and autumn (March-April). If blocks are suspected of infestation, trapping should concentrate on these times to determine whether chemical treatments are needed or not. In addition, it is advisable to set traps prior to a new planting or during the fallow period. This is to ensure that any banana plant material has decomposed entirely, eliminating the possibility of any remaining adult banana weevil borers being present in residues that might affect the new crop.

If infestations are suspected adult banana weevil borer monitoring should be carried out every month, except during the colder months when the time frame can be extended to six weeks. Banana weevil borer numbers at baits placed during adverse conditions may not accurately reflect actual adult population levels, as it has been shown that only 5-15% of the actual population will appear on baits under these conditions.

There are a few main methods of monitoring banana weevil borers, which are outlined below:

Bait trapping

Adult banana weevil borer numbers can be monitored by baiting (trapping). Baits are made by cutting a fresh pseudostem into slices about 10cm thick . The pseudostem material selected for making baits should ideally be taken from the lower portion of the stem of freshly harvested plants. One bait is placed close to the base of each plant, with one cut surface in full contact with the ground, and covered with leaves to prevent the bait from drying out. Twenty or more baits should be used in known hot spots to obtain a good indication of banana weevil borer numbers. The ground directly beneath the bait should be cleared of any weeds or plant material that can shelter adult banana weevil borers and hinder rapid checking of the baits. After three to four days, the baits are turned over and the adult banana weevil borers are counted (Hint! Look for banana weevil borers on the ground where the bait was resting as well as the base of the bait in contact with the ground).

Adult banana weevil borer numbers are recorded from each bait and, knowing the total number of baits set and banana weevil borers counted, the average number of adults per bait can be calculated by dividing the total number of banana weevil borers by the number of baits set.

Banana weevil borer BWB bait trapping
Banana pseudostem placed near the base of a banana plant to trap banana weevil borer.
Banana weevil borer BWB bait trapping
Banana pseudostem covered with a leaf to prevent drying out.
Traditional pitfall trap that is used with pheromones. Here the lid has been removed to count the number of banana weevil borer’s present.

Pheromone trapping

Another option for monitoring is the use of pheromone-baited traps, which contain a substance (sordidin) that specifically attracts adult banana weevil borers. These baits attract both male and female banana weevil borers and can attract individuals up to 20m away from the trap, however, this efficiency is reduced by rainfall. Baits need to be replaced every 30 days, as lures run out (depending on lure concentration – read labels for specifics). Different types of traps are commercially available for growers.

Corn damage assessment

Larval damage can be assessed by rating the percentage of tunnelling in the corm of harvested plants.

The larger the area affected the higher the pressure of banana weevil borers. This monitoring is destructive and requires the cutting of plants, and is more encouraged as a monitoring tool to see how known infestations are responding to treatment, rather than a diagnosis of infestations.

For more information contact:

The Better Bananas team
Department of Agriculture and Fisheries
South Johnstone
07 4220 4177 or email betterbananas@daf.qld.gov.au 

This information is adapted from: Pinese, B., Piper. R 1994, Bananas insect and mite management, Department of Primary Industries, Queensland and Treverrow, N., Pearley D., and Ireland, G 1992 Banana weevil borer : a pest management handbook for banana growers. : NSW Agriculture, North Coast Region; NSW Banana Industry Committee; Horticultural Research & Development Corporation.
This information has been updated as part of the National Banana Development and Extension Program (BA19004) which is funded by Hort Innovation, using the banana industry research and development levies and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture. The Queensland Government has also co-funded the project through the Department of Agriculture and Fisheries.
Hort innovation logo

Banana weevil borer – general information

Banana weevil borer Cosmopolites sordidus

General information 

Description and life cycle

The eggs of the banana weevil borer can be found in a pit that has been chewed into the side of the pseudostem. The site of egg laying is nearly impossible to find due to banana sap congealing and covering the hole. The larvae continuously feed within the corm producing distinctive tunnels until they are almost 2cm long when they move towards the outer edge to pupate.

The lifecycle of banana weevil borers (particularly egg and larval periods) is extremely temperature dependent and is shorter in warmer conditions. The total time from egg hatching to adult emergence can be as short as 12 weeks in ideal conditions in northern Queensland.

Banana weevil borer lifecycle
Lifecycle of the banana weevil borer (arrow indicating part of plant affected).
banana weevil borer egg
Banana weevil borer egg in banana tissue, egg circled in red.

Newly emerged adults are reddish brown but quickly assume their characteristic shiny black appearance as their exoskeleton hardens. The adults are sluggish and fake death if disturbed. However, it can be determined whether they are indeed alive, by gently blowing on them as live adults will wiggle their legs and snouts.

Banana weevil borers have functional wings, however, they rarely, if ever, fly. Instead, they can travel by walking up to 6-7 metres between plants at night, resulting in a very slow spread. Movement is reduced during dry weather, as adults remain in the corm to avoid desiccation. Dispersal of banana weevil borers over larger distances is primarily by the introduction of infested suckers and bits at planting.

Banana weevil borer
An adult banana weevil borer with scale.

Occurrence & seasonality

Banana weevil borer is found in all major banana growing areas throughout the world. Bananas and other species of the genus Musa are the only known hosts. First recorded at Mackay in 1896, the banana weevil borer has since spread to all major banana growing areas in Australia.

It has been observed that there are two distinct peaks in the emergence and activity of adults– the first in spring during September and October, and the second in autumn, during March and April. These peaks are particularly evident in subtropical regions where activity almost ceases during winter. In the Far North Queensland tropics, where winter temperatures are not as low, activity continues throughout the year although at a reduced rate in winter. In Far North Queensland, dry conditions greatly reduce adult activity, as adults remain in the corm to avoid desiccation, whereas rainfall may be a major factor in increasing adult activity.

 

Damage 

Most of the damage is done by the tunnelling of the larvae which occurs exclusively within the corm. Evidence of larval tunnelling is not noticeable since all the tunnelling is confined to the corm below the surface. In heavy infestations, tunnelling will extend for a short distance up the pseudostem; the presence of tunnels can be seen if the pseudostem is cut close to the soil surface. In plants that have fallen out or snapped off the pseudostem may decay more slowly and tunnelling may extend a greater distance up the pseudostem.

Newly planted blocks are more vulnerable to infestations of banana weevil borer as they don’t yet have a substantial corm (especially tissue-cultured plants), meaning tunnelling will cause proportionally more damage.

BWB larvae
Banana weevil borer larval stage (in red) on banana roots

Tunnelling in young plants can cause the death of the cigar leaf if banana weevil borers damage the primary meristem, which is especially likely if tunnelling has extended into the lower pseudostem. However, healthy, fast-growing plants can withstand considerable infestation without showing obvious signs of reduced vigour. 

Typical symptoms of a severe infestation are reduced plant growth, choking, yellow leaves and weak or dying suckers. Environmental stress has been shown to exacerbate the symptoms of banana weevil borer infestations. Plants under attack are also prone to falling out (particularly in windy weather) but the root system of fallouts must be inspected carefully to ascertain the cause. Fallouts can occur from both banana weevil borer and burrowing nematode damage. When banana weevil borer is the cause there is an obvious breakage with the lower part of the rhizome and roots are often retained in the ground (snapped off). Whereas if burrowing nematode is the cause the entire corm is exposed along with stubby roots (‘roll-out’).

Note: Banana weevil borers will be at higher pressure after weather events that cause serious plant damage, or in blocks that use cultural practices that encourage damage or breakages, such as desuckering, as they are attracted to fresh exposed plant volatiles.

For more information contact:

The Better Bananas team
Department of Agriculture and Fisheries
South Johnstone
07 4220 4177 or email betterbananas@daf.qld.gov.au 

This information is adapted from: Pinese, B., Piper. R 1994, Bananas insect and mite management, Department of Primary Industries, Queensland and Treverrow, N., Pearley D., and Ireland, G 1992 Banana weevil borer : a pest management handbook for banana growers. : NSW Agriculture, North Coast Region; NSW Banana Industry Committee; Horticultural Research & Development Corporation.
This information has been updated as part of the National Banana Development and Extension Program (BA19004) which is funded by Hort Innovation, using the banana industry research and development levies and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture. The Queensland Government has also co-funded the project through the Department of Agriculture and Fisheries.
Hort innovation logo

Banana weevil borer – management

Banana weevil borer Cosmopolites sordidus

Management

Cultural

The use of clean (banana weevil borer-free) planting material and maintenance of trash and weed-free areas near plants are two important factors in reducing the impact of this pest in bananas. Ideally, planting material should be obtained from an accredited QBAN nursery. If you are unable to use tissue culture the next best option is to use planting material from your own farm that is sourced from a block that is clean from pest and disease.

When planting into old banana land, allow at least six months of fallow after all old banana material has rotted down. This will help to prevent a carryover of weevil borer adults. Cut up all fallen and harvested pseudostems to prevent banana weevil borer breeding. This is particularly important in subtropical regions where drier, cooler conditions result in slow breakdown of plant material. Glyphosate injection for crop removal is encouraged to ensure adequate plant destruction to reduce weevil population levels.

Tissue culture plants
Banana planting material from clean sources, such as accredited plant nurseries, ensures that no banana weevil borers are present.
beauveria bassiana infected banana weevil borer adult BWB
Dead adult banana weevil borer infected with the fungus Beauveria bassiana.

Biological

A large range of general predators including flatworms, ants, beetles and cane toads assist in reducing banana weevil borer numbers. Research is being undertaken to determine the effectiveness of insect parasitic nematodes, which could prove suitable as biological control agents for banana weevil borer control.

Some international research, and research in NSW have shown some success using laboratory assays of entomopathogenic nematodes, Steinernema spp. and Heterorhabditis spp. However, to date, Queensland-based research has been unable to replicate positive results in the field, instead showing no difference between treated plants and untreated (control) plants, indicating that more in-field research is still needed.

Initial research in Australia shows that some insect diseases (entomopathogens) such as the fungus, Beauveria bassiana, have the capacity to reduce banana weevil borer populations, but more research is still needed.

Chemical

If the average banana weevil borer counts from bait trapping are more than two per trap (subtropics) or more than four per trap (tropics), registered chemical treatments should be applied according to label directions. If average counts are less than these, treatment is not considered necessary. Pheromone trapping doesn’t currently have a threshold value.

When choosing a chemical, it is essential to consider the life stage and behaviour of the banana weevil borer. The adults typically move around corms during spring and autumn to feed and lay eggs. To achieve optimal control, it is recommended to apply chemicals during these peak activity periods, using banded or butt spray applications that apply insecticides adjacent and/or onto the plants . By comparison, injection treatments aim to control larvae within the corm and therefore may have more flexibility in when they can be applied. However, some of these chemicals should not be applied during the dry season, as these chemicals have shown an increased incidence of mite flares. Always check the product label for guidance.

Chemical options are generally older chemistries that are disruptive to integrated pest management and/or other insects present throughout blocks. When trying to control banana weevil borer, certain chemicals have been known to cause mite flares. Therefore, it is crucial to only use spray treatments when the infestation has reached critical levels. Insecticide resistance is a threat with current options available, so chemical choices and modes of action should be rotated to reduce the risk of resistance. Always check the APVMA website for current chemical registrations before use. All chemical applications should be made according to the directions on the label. Resistance management plans should be followed to reduce insecticide resistance risk, see CropLife plans here.

Banana weevil borer BWB chemical options

For more information contact:

The Better Bananas team
Department of Agriculture and Fisheries
South Johnstone
07 4220 4177 or email betterbananas@daf.qld.gov.au 

 
This information is adapted from: Pinese, B., Piper. R 1994, Bananas insect and mite management, Department of Primary Industries, Queensland and Treverrow, N., Pearley D., and Ireland, G 1992 Banana weevil borer : a pest management handbook for banana growers. NSW Agriculture, North Coast Region; NSW Banana Industry Committee; Horticultural Research & Development Corporation.
This information has been updated as part of the National Banana Development and Extension Program (BA19004) which is funded by Hort Innovation, using the banana industry research and development levies and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture. The Queensland Government has also co-funded the project through the Department of Agriculture and Fisheries.
Hort innovation logo

Banana weevil borer Cosmopolites sordidus

Banana weevil borer

Banana weevil borer is found in all major banana growing areas throughout the world. Bananas and other species of the genus Musa are the only known hosts.

Often infestations of banana weevil borer will go unnoticed until the plant falls out, as most of the damage is done by the tunnelling of the larvae within the corm. In heavy infestations, tunnelling will extend for a short distance up the pseudostem, the presence of tunnels can be seen if the pseudostem is cut close to the soil surface. Other typical symptoms include reduced plant growth, choking, yellowing leaves, and weak or dying suckers. If infestations are detected, monitoring is essential to determine the levels present and appropriate management actions. 

Planting with clean material is essential to prevent banana weevil infestations. Plants from an accredited nursery are optimal, or the next best option is using clean planting material from your own farm.

Banana weevil borer
An adult banana weevil borer with scale.
Always use clean planting material to reduce the risk of a banana weevil borer infestation.

More information

For a general description for identification and detailed life cycle, seasonality and the damage that banana weevil borers can inflict on bananas click here

Monitoring should occur in peak times to determine whether chemical treatments are needed or not. To learn more about types of traps that are available for monitoring click here.

For information on how to manage banana weevil borer infestations and how to avoid infestations to begin with click here.

This information is adapted from: Pinese, B., Piper. R 1994, Bananas insect and mite management, Department of Primary Industries, Queensland and Treverrow, N., Pearley D., and Ireland, G 1992 Banana weevil borer : a pest management handbook for banana growers. : NSW Agriculture, North Coast Region; NSW Banana Industry Committee; Horticultural Research & Development Corporation.
This information has been updated as part of the National Banana Development and Extension Program (BA19004) which is funded by Hort Innovation, using the banana industry research and development levies and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture. The Queensland Government has also co-funded the project through the Department of Agriculture and Fisheries.
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Goldfinger mutagensis trial—screening activities—Top 5 selections

Goldfinger mutagenesis—screening activities

Further screening and consumer and sensory evaluation of top 5 performers

Plants of the top 20 selections were nurse-suckered in December 2020 and the first bunches began emerging in June 2021. Agronomic data has been collected from all variants, but only fruit from the top five performers was sent down for consumer and sensory evaluation at DAF’s Coopers Plains facility in Brisbane. Variants 144, 211, 521, 544 and 903 were the top five tasting selections chosen to be further assessed in the larger consumer surveys.

Here, a much larger tasting panel was engaged to assist in identifying which variants are the most well-received by consumers and have the best market prospects for the future. Planting material is also in the process of being sent to the Northern Territory, where field trials will confirm if the variants have retained Panama disease resistance before they are included in DAF supervised pre-commercialisation trials.

This phase of the project identified four selections which were liked by consumers as much as Cavendish and Lady Finger (more detail here, pg 12-13).

Goldfinger consumer testing
Just over 120 consumers were recruited to taste-test the new Goldfinger selections in a controlled sensory environment, rating the fruit on characteristics relating to appearance and taste. This work was overseen by the Consumer Intelligence team, Simoné Moller, Ishita Pramanik and Philippa Lyons.
Goldfinger consumer testing
Whole banana samples being prepared for consumer analysis at the Health and Food Sciences Precinct in Coopers Plains, Brisbane. This work was overseen by the Consumer Intelligence team, Simoné Miller, Ishita Pramanik and Philippa Lyons.

Bunches of top 5 selections compared to unirradiated Goldfinger bunch

Normal Goldfinger bunch (unirradiated)

Bunches of the five variants selected to progress into the next phase of the investigation

This Goldfinger work was initiated as part of the Fusarium Wilt Tropical Race 4 Research Program (BA14014). At the close of BA14014 funding has been provided through the project Improved Plant Protection for the Banana Industry (BA16001) for continuation of the evaluations.   This project has been funded by Hort Innovation, co-investment from the Queensland Department of Agriculture and Fisheries, and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture.