Pests, diseases & disorders

Posted on by Better Bananas

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. 

Pests

Banana flower thrips (Thrips hawaiiensis)

Banana rust thrips (Chaetanaphothrips signipennis) 

Banana scab moth (Nacoleia octasema) 

Banana weevil borer (Cosmopolites sordidus)

The banana spider mite (Tetranychus lambi) and the two-spotted mite (Tetranychus urticae) 

Adult female flower thrips measure 1 mm in length
Raised dark 'pimples' or ovipositions (eggs layed into skin) of flower thrips.
Corky scab damage from adult flower thrips feeding
Adult and larva of banana rust thrips
Banana rust thrips damage
Rust thrips damage on banana fruit
Banana rust thrips damage
Adult banana scab moth. Adults are approximately 22mm in width or wingspan.
Banana scab moth damage affecting multiple hands, progressing with intensity down the bunch.
Banana scab moth damage. Scarring on fruit makes it unsellable to market.
Adult banana weevil borer
Banana weevil borer larvae
Banana weevil borer tunnelling causing plants to come down
Adult spider mite with eggs
Adult spider mite with eggs

Diseases

Crown end rot (Several species including, Musicillium theobromae, Fusarium equiseti-incarnatum species complex, Colletotrichum musae and Thielaviopsis musarum)

Crown end rot trial work

Panama disease (Fusarium oxysporum f.sp cubense)

Panama disease trial work

Yellow Sigatoka (Pseudocercospora musae)

Panama disease tr4
Internal discolouration of pseudostem caused by Panama disease
Panama disease
Left: early stage of Panama disease symptom development showing the yellowing of leaves. Right: late stage after the leaves have dropped
Yellowing leaves in young plant infected with Panama disease TR4
Early stage symptoms of Crown end rot fungal infection
Symptoms of Chalara with damage extending from the neck of the fruit into the fingers
Alternative post-harvest product testing for treatment of crown end rot.
Yellow Sigatoka - New training materials now available
Yellow Sigatoka - New training materials now available
Stage 5 yellow Sigatoka symptom development

Physiological issues and disorders

Maturity bronzing

Maturity bronzing on top hand
Close up of maturing bronzing

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.
Hort innovation logo

South Johnstone field walk

Posted on by Better Bananas

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.
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.
Hort innovation logo

Crop management

Posted on by Better Bananas

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

Posted on by Better Bananas

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.

Download this information as a factsheet

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

Posted on by Better Bananas

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’).

Dark tunnelling pattern from banana weevil borer shown throughout corm cut close to the soil surface.
Dark tunnelling pattern from banana weevil borer shown throughout corm cut close to the soil surface.
Dark tunnelling pattern from banana weevil borer shown throughout corm cut close to the soil surface.
Dark tunnelling pattern from banana weevil borer shown throughout corm cut close to the soil surface.
Dark tunnelling pattern from banana weevil borer shown throughout corm cut close to the soil surface.

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.

Download this information as a fact sheet

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

Posted on by Better Bananas

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

Download this information as a factsheet

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

Posted on by Better Bananas

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.
Hort innovation logo

Goldfinger mutagensis trial—screening activities—Top 5 selections

Posted on by Better Bananas

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

Variant 903
Variant 544
Variant 144
Variant 211
Variant 521

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.

Goldfinger mutagensis trial—screening activities—Initial screening

Posted on by Better Bananas

Goldfinger mutagenesis trial—screening activities

Initial screening

630 irradiated Goldfinger plants were sent to South Johnstone Research Station, in two batches during June and August 2017 where they were held in the glasshouse prior to planting. 

They were planted in the field in September and November 2017 respectively. Goldfinger plants which hadn’t been irradiated were also planted as control plants to compare against.

Irradiated plants in the field showed considerable variation in vegetative characteristics. This variation is mostly related to degree of dwarfness/plant height, pigmentation of pseudostem/leaf stalk and midribs, leaf uprightness/droopiness and minor leaf deformities. Also some of the irradiated plants have gross plant/leaf deformities and extremely slow growth. About 13% of the irradiated plants were in this reject category.

Harvest of both the September and November 2017 plantings were completed by the end of 2018. The photos below show the very large range in bunch and fruit characteristics which have been obtained by irradiation. Yes they have all come out of Goldfinger!

Postharvest assessments also revealed diversity in the eating quality of the Goldfinger variants. Several had qualities considered to be ‘improved’ and ‘better’ than the standard Goldfinger, including increased sweetness and firmness. Taste-testing sessions held amongst the staff at the research station were used to gauge consumer acceptance of these variants.

Twenty better tasting Goldfinger variants, which rated highly in the agronomic and post-harvest assessments were selected for a second stage of testing.

Several variants had qualities considered to be improved than the standard Goldfinger
Taste test survey
Postharvest quality assessments use the Brix scale to measure the sugar content of fruit

Examples of variation

Normal Goldfinger bunch (unirradiated)
Goldfinger bunches (irradiated) - Variations as a result of mutagensis
Goldfinger bunches (irradiated) - Variations as a result of mutagensis
Goldfinger bunches (irradiated) - Variations as a result of mutagensis
Goldfinger bunches (irradiated) - Variations as a result of mutagensis
Goldfinger bunches (irradiated) - Variations as a result of mutagensis
Goldfinger bunches (irradiated) - Variations as a result of mutagensis
Goldfinger bunches (irradiated) - Variations as a result of mutagensis
Goldfinger bunches (irradiated) - Variations as a result of mutagensis
Goldfinger bunches (irradiated) - Variations as a result of mutagensis
Goldfinger bunches (irradiated) - Variations as a result of mutagensis
Goldfinger bunches (irradiated) - Variations as a result of mutagensis
Goldfinger bunches (irradiated) - Variations as a result of mutagensis
Goldfinger bunches (irradiated) - Variations as a result of mutagensis
Left is control that didn't undergo mutagenesis. Variant on the right has undergone mutagenesis and shows dwarfism and more upright leaves.
Left is control that didn't undergo mutagenesis. Variant on right shows changes to plant pigmentation as a result of mutagenesis.
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.

Goldfinger mutagenesis trial – screening activities-Top 20 selections

Posted on by Better Bananas

Goldfinger mutagensis—screening activities

Screening of the top 20 selections

Following the selection of the top 20 variants from the original 630 plants, sucker and bit material from the original trial was planted in September and October 2019.

Bunches of the 20 variants began to emerge from the more established plants in March 2020 and continued throughout the year; the final harvest was performed in January 2021. Data was again collected on both agronomic performance and eating characteristics to substantiate the findings from the first investigation.

The taste panelling occurred once a week, with a maximum of six variants tasted in one session (including a Goldfinger and a Lady Finger ‘Dwarf Rossi’ as control samples to compare against). Panellists included colleagues who volunteered to taste the fruit under ‘controlled’ conditions at the research station and the family members and friends of those who took fruit home.

Each variant was tasted 3—4 times over the six-month trial period, except for variant 423 (which was only tasted twice due to late bunch emergence). Taste preference was ranked on a hedonic scale, which included the following categories: 1 = dislike extremely, 2 = dislike very much, 3 = dislike moderately, 4 = dislike slightly, 5 = neither like nor dislike, 6 = like slightly, 7 = like moderately, 8 = like very much, and 9 = like extremely.

Dwarf Rossi, the Lady Finger comparison, scored the highest overall rating (at 6.8) of all the varieties included in the taste panelling (Figure 1), corresponding with 77% of respondents indicating they would purchase it if it were commercially available (Figure 2). This was closely followed by variant 521, which was the best performer out of all the Goldfinger variants with an average rating of 6.5.

Figure 1: The average overall rating given to the variants across several taste panels (where 1 = dislike extremely, 5 = neither like nor dislike, and 9 = like extremely). The bars represent the standard error of the mean. Dwarf Rossi is a Lady Finger-type control included in the panelling as a reference variety
Figure 2: The percentage of respondents in the taste panelling who answered ‘yes’ (green) or ‘no’ (red) to the question, 'If this product was commercially available, would you choose to purchase it?' The remaining category (blue) are the instances where the question was left unanswered

Several comments were made that this variant had similar eating characteristics to a Lady Finger. The Goldfinger control was rated poorly, 4.7 on average, with 255 the only variant below it at 3.7. Variants 211, 544, 144 and 903 joined 521 in making up the five selections given the highest overall eating experience rating, and which also had the greatest number of people answer ‘yes’ to the question: ‘if this fruit was commercially available, would you choose to purchase it?’

The plant heights of all the selected variants were not significantly different from the 3.1 m Goldfinger average. The total fruit yield was also comparable to the average Goldfinger bunch (27.3 kg) for three of the selected variants, while the other two were 15—20% lower.

There were a couple of variants with undesirable characteristics which had gone undetected in the original selection of top performers. For example, several plants from one variant had severely fused fingers – to the point where several hands in a bunch were unusable.

Another variant had fruit which retained a green-tinge upon ripening. The relatively tall (3.5 m) and thin pseudostem            (54 cm) of another contributed to two of the ten plants snapping before bunch maturity; its brittle pseudostem also made harvesting difficult. Such issues prevented these three variants from being pursued further. 

March 2023 saw the final bunches of the second ratoon crop harvested from these twenty selections at South Johnstone. The agronomic results from nineteen of these selections are summarised in the accompanying table. Variant 255 was excluded after the first ratoon due to its excessive height and slender pseudostem, which made harvesting very difficult. Its fruit was also rated poorly in the South Johnstone consumer surveys.

The trial block has been nurse suckered and prepared for rating the susceptibility of the variants to yellow Sigatoka in the coming months.

Key observations from second ratoon:

Seven out of the nineteen selections had plant heights shorter than standard Goldfinger, which stood at 4.2 m. In most cases the pseudostem circumference was also smaller, meaning these plants remained proportionally comparable to Goldfinger.

Most variants had shorter finger lengths than the original Goldfinger by an average of 3 – 4 cm. The consumer study found this was generally regarded as preferable, as Goldfinger was rated as ‘too big’ by 46% of panellists.

Although variant 521 averaged a smaller bunch size (15% less than Goldfinger), its slightly faster cycle time meant the cumulative yield was not significantly different to Goldfinger. This was also the case for selections 119 and 339 (which were also aided by having slightly heavier bunches in the first ratoon).

In contrast, variants 544 and 144, which had similar second ratoon bunch weights to Goldfinger, had lower cumulative yields by 16 and 17%, respectively, due to lower bunch weights in the first ratoon.

Goldfinger second ratoon agronomic yield data

Yellow Sigatoka screening results

Click here for more information on the yellow Sigatoka screening trials completed for the top 20 mutant selections. This trial assessed the selections’ resistance or susceptibility to the fungal leaf disease, yellow Sigatoka during the 2023 wet season. 

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.