Goldfinger mutagensis trial—screening activities—Top 5 selections

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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

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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

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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.

Banana flower thrips

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Flower thrips

Banana flower thrips (Thrips hawaiiensis) are a tiny pest frequently present in banana bunches. For most growers in Far North Queensland flower thrips are not the main bunch pest which leads to economic losses. However, large enough infestations can cause damage to fruit that does not meet market specifications. Damage caused by flower thrips is more significant in warm dry conditions with lower relative humidity, such as South East Queensland and northern New South Wales.

female Flower thrips to scale
Adult female flower thrips measure 1mm in length

Correct and timely bell injection is critical for the control of flower thrips. It must be performed when the bell is upright to ensure the insecticide solution provides protection to the entire bunch. Flower thrips are from the same family as Banana rust thrips (Chaetanaphothrips signipennis). Unlike banana rust thrips, flower thrips spend their entire life cycle on the banana plant, therefore, soil treatment does not provide control of flower thrips. 
 

Flower thrips cause damage to the peel of banana fruit from feeding and ovipositing (egg laying). These ovipositions resemble minute raised pimples on the young immature skin. These are readily seen because of a dark raised centre and can be confirmed by lightly touching the raised area with your fingertip. These oviposition marks almost disappear as the fruit matures. However, extensive damage from feeding from adult flower thrips can cause superficial scarring known as ‘corky scab’. This damage is usually confined to the lower hands (as flower thrips damage increases on lower hands as populations increase as they move down the bunch if it hasn’t been treated). Usually it is first noticeable on the outer whirl,  where the neck meets the cushion, but can extend to the outer curve of the fruit.  

Close up of flower thrips damageovipositions (pimples) on young banana fruit.
Severe flower thrips damage causing corky scab damage.

More information

This information has been prepared 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.

Agronomic evaluation of new varieties – South Johnstone screening trial (2020)

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Latest update...

Evaluation of the 2020 variety screening trial is now complete. Assessment of the plant and first ratoon crops is now complete and results are now available (see here). Trends which were observed in the plant crop (see here) continued in the first ratoon. Williams outproduced the TR4 resistant Cavendish varieties. All the Lady Finger selections performed well compared to the standard Lady Finger, with either improved plant or bunch characteristics and no yield reduction.

About the trial

This agronomic evaluation screening trial was planted at South Johnstone Research Facility in October 2020. Building on previous variety evaluation work, the trial is looking at new introductions that may have commercial potential for the Australian banana industry, forming part of the recently completed project ‘Improved plant protection for the banana industry (BA16001)’.  

Assessment of agronomic traits is being collected over a plant crop and first ratoon with leaf spot screening performed in a nurse-suckered third crop cycle.

Trial five months after planting in March 2021.

Below is a video of a field walk of the evaluation trial taken in September 2021.

About the varieties being evaluated

Three Cavendish selections, four CIRAD hybrids, and six Lady Finger selections were included in the evaluation trial, including two varieties with TR4 resistance.

Observations and results

Observations and results are now available.

What's next?

Currently, screening is underway to evaluate these selections for their tolerance to yellow Sigatoka. Plants will be assessed over three months during the wet season (March, April, and May 2023) and compared against control varieties with known resistance/susceptibility to this fungal leaf disease.

In December 2022, a new variety evaluation was planted as part of the project ‘New varieties for Australian banana growers (BA21002)’. This will again look at the agronomic traits as well as disease tolerance of recently imported varieties.

More information...

If you would like further information, feel free to contact the Better Bananas team via email at betterbananas@daf.qld.gov.au.

This research has been funded as part of the project Improved Plant Protection for the Banana Industry (BA16001), which is funded by Hort Innovation, using the banana research and development levy, co-investment from the 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.

Agronomic evaluation of new varieties South Johnstone (planted October 2020) Plant crop observations and results

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Plant crop results - agronomic evaluation trial (October 2020)

Two TR4 resistant selections were among the new varieties being assessed for agronomic performance at the South Johnstone Research Facility. Those who attended the September 2021 field walk saw the varieties as they were approaching harvest in the plant crop (available to watch online here). The results of the plant crop are presented below.

By Katie Robertson, Jeff Daniells and Ashley Balsom

The agronomic characteristics of the new varieties are being compared with industry standards over a plant crop and first ratoon. Three Cavendish selections, four CIRAD hybrids, and six Lady Finger selections were included in the evaluation. The trial was established in October 2020, and bunch harvest was spread from July to November 2021 for the different varieties.

Within the Cavendish varieties, Williams and the GCTCV 106 Selection had the fastest cycle times (planting to bunch harvest) of 8.9 and 9.0 months, resulting in yields of 31.5 and 28.9 kg/year, respectively. In contrast, Asia Pacific #1, a TR4 resistant selection from Taiwan, took 1.5 months longer to reach bunch harvest than Williams, resulting in a 21% yield reduction (24.9 kg/year). This longer cycle time has been a common feature of other TR4 resistant Cavendish varieties previously evaluated. Asia Pacific #1 was 24% shorter in stature than the other Cavendish varieties, standing at 2.2 metres. Fruit length was also shorter. Only 26% of its fruit was in the 22–26 cm finger size category compared to 64% for Williams.

The dwarf selections of Lady Finger (Dwarf Rossi, Dwarf Lady Finger, and Santa Catarina Prata) were 25–28% shorter in stature than standard Lady Finger at bunching. Pendulous Lady Finger (PLF) and Tall Rossi were also shorter than regular Lady Finger by 7 and 13%, respectively. Additionally, PLF had an 18% yield increase per year and displayed much better bunch conformation than Lady Finger’s typical sub-horizontal bunch angle.

The TR4 resistant Cavendish selection, Asia Pacific #1, was 24% shorter in stature than Williams but was 21% lower yielding in the plant crop and had much less fruit in the premium size grades.
The bunch conformation of Pendulous Lady Finger (L) compared to standard Lady Finger (R).

The French CIRAD hybrids were developed to have resistance to Sigatoka leaf diseases. One of them, CIRAD X17, has also demonstrated to be highly resistant to TR4 in the Northern Territory screening trials (Read here, pages 18 -19). Like other CIRAD hybrids we have evaluated previously (Read here,  pages 16 – 17), these four selections had long, narrow leaf petioles which are brittle and prone to breaking. Although the height of CIRAD 918 was comparable to Williams (average height of 2.9 m), its pseudostem snapped before harvest for 40% of the plants. There were no notable losses from snapping or rolling out in the other three hybrids. These varieties were bred and selected in a tropical region, and they do not seem to handle the relatively cooler winters and some other environmental stressors of north Queensland particularly well. There were also inconsistencies with the rate and capacity of fruit filling. The CIRAD hybrids took 14 – 21% longer to reach harvest maturity and had bunches that yielded 41 – 70% less than Williams per year.

CIRAD 918 was a similar height to Williams but experienced greater rates of snapping due to its more fragile pseudostem.

More information

This research has been funded as part of the project Improved Plant Protection for the Banana Industry (BA16001), which is funded by Hort Innovation, using the banana research and development levy, co-investment from the 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.

Maturity bronzing

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Maturity bronzing - stretching the limits on fruit quality

By Ingrid Jenkins and Jeff Daniells

Several growers have reported a higher incidence of fruit affected by maturity bronzing in early 2023. In response to grower enquiries regarding what causes maturity bronzing and how to reduce its impact, it seems timely to give an overview of past research and recap on the best management options available to growers.

Maturity bronzing has been a long-term problem for Australian commercial banana producers, with research into the disorder dating back to the early 1970s in Australia. Much of the research was undertaken in Far North Queensland over 30 years ago by Jeff Daniells and other state government researchers at the time and has provided some interesting insights into what has proved to be a complex disorder. 

What we know:

Maturity bronzing is not caused by a disease or insect but is a more complex physiological disorder due to certain environmental conditions.

Figure 1: Maturity bronzing damage seen on top and fifth hands of the bunch.
Figure 2: Severe banana rust thrips' damage on all hands throughout the bunch

The disorder blemishes the peel of banana fruit close to maturity and appears as bronze-red/brown streaks or blotches usually on the outer curved surface of the fruit and is more prominent in the top hands (Figure 1). The blemish can first appear when a bunch is three-quarters to full maturity stage and worsens as the fruit continues to fill. The damage is to the peel only and does not affect the yield and eating quality of the fruit. In severe cases, it can cause corking/cracking of the peel. Its appearance makes the fruit unmarketable and can account for significant losses for growers.

The disorder is associated with periods of heavy rainfall, high humidity and overcast weather conditions leading up to harvest and is therefore worse at certain times of the year. In Far North Queensland the disorder is usually more prevalent in the latter half of the wet season from March to June. Water stress at the time of bunch emergence has been shown to increase the severity of maturity bronzing.

Research by Dr Michelle Williams from the University of Sydney has shown that the high growth rates in the wet season lead to the stretching of the epidermis (outer surface of fruit peel) which exceeds its elastic limit, leading to cracks and cell disruption in the peel surface. Disruption of the cells causes the release of the enzyme called polyphenol oxidase. Oxidation of this enzyme leads to the production of melanin, which results in the bronze-red/brown markings within the peel. It is the same process in many fruits; for instance, when you cut open an apple and get brown discolouration of the cut surface.

Dr Williams’ research also found low levels of calcium in the fruit peel and low cell number in the peel epidermis have been linked to the disorder. They also found low calcium levels present in fruit suffering from water stress near bunch emergence. This stressed fruit had more severe maturity bronzing. Subsequent trials looking to increase calcium in the fruit peel to lessen maturity bronzing were unsuccessful.

There have been several trials looking into the effects of different agronomic practices on the disorder.

Trials looking into the effect of bunch covering found that normal bunch covering does not worsen the disorder but, the disorder is made worse by fruit from sealed bunch covers.

Both bunch trimming and de-belling (removal of the male bud) increase the severity of the disorder.

It is possible to reduce the severity of the disorder by reducing the leaf number to seven or less from bunch emergence. However, this is counterproductive as bunch weight and fruit green life are reduced at the same time.

How to manage and reduce the impact of maturity bronzing:

• Maintain good soil moisture levels, particularly in the period within 2 weeks of bunch emergence. The critical         period is October to January, special attention should be paid to irrigation during this time. A high moisture           level should be maintained during bunch emergence.

• Maintain even growth in the plant and the bunch, particularly from 2-3 weeks prior to bunch emergence up           to harvest.

• Depending on market specifications, bunches can be harvested early before the disorder becomes severe.             Blemished fruit losses are minimised but there is a trade-off with lower bunch weight. For every week that a           bunch is harvested earlier, 7–10 % in bunch weight is lost.

• Improve drainage and light within your paddock to ensure bunches don’t take so long to reach a harvestable         grade. Waterlogging can be minimised by mounding rows and the construction of deep drains on alluvial soils       and light penetration can be improved by planting at moderate densities.

• Ensure bunch covers are not too long and not prone to sealing at the bottom of the bunch. If this occurs                 maturity bronzing will worsen.

If you would like more detailed information on past research into maturity bronzing, please contact the Better Bananas team at betterbananas@daf.qld.gov.au.


This information has been compiled as part of the National Banana Development and Extension Program (BA19004). This project has been funded by Hort Innovation, using the banana research and development levy, co-investment from the 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.

Richard Piper

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Richard Piper

A career exploring the big world of tiny things

Richard is the man to talk to if you want information on insects in Bananas. Richard is a familiar face to many banana growers in Far North Queensland, having worked in the industry both in a private and government capacity for over 30 years. 

Over the past 5 years, Richard has worked as an entomologist with the Department of Agriculture and Fisheries (DAF) at South Johnstone. His work has encompassed screening of new chemistry for the control of bunch pests. These include synthetic as well as biological products such as fungi, bacteria and beneficial nematodes and botanical chemistries. Currently, he is continuing research on bunch pest management and spider mites, with a focus on integrated 

Meet a researcher
Richard Piper
Entomologist
Department of Agriculture and Fisheries
Centre for Wet Tropics Agriculture
South Johnstone

pest and disease management (IPDM) practices using a combination of existing chemistry with softer biological options.

Richard’s expertise is not only limited to bananas. He is often out in the field talking with growers about insect related problems in other crops grown in the wet tropics.

It’s not all about bugs though. The interaction between grower, industry and colleagues is what Richard enjoys most about his work. He is excited about the future in gaining a better understanding of the relationship between insects and plants. Richard considers finding biological options for control of banana bunch pests as an important part of his role, seeing an increasing need for softer alternatives for future management strategies.

Richard was born and raised at Manly on Moreton Bay and completed his early schooling there. He attended the University of Queensland, where he completed a science degree, majoring in entomology and botany and then completed his honours in entomology. He also completed a post graduate diploma at Gatton College in plant protection.

In 1984 he moved to Far North Queensland to take up a position working as a medical entomologist with Queensland Department of Health on the Dengue Program for four years, then took work with the Australian Army’s Malaria Research Unit for four years where he was based at Cowley Beach and employed as a mosquito collector. In 1990 he started work with the Department of Primary Industries on an integrated pest management (IPM) project which he did for four years before starting his own business, assisting growers to monitor and manage pest insects and other problems in the many crops in Far North Queensland. Twenty seven years later he returned to DAF at South Johnstone taking up the role of entomologist in 2017.

Richard’s favourite way of eating bananas is by mashing a banana, preferably lady finger, on toast and sprinkling it with brown sugar.

In his spare time, Richard likes to tend his extensive garden of tropical fruit and vegetables.

Sarah Williams

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Sarah Williams

Bringing passion to bananas

Sarah Williams is a recent addition to the National Banana Development and Extension team. Having moved to the Cairns region, Sarah has taken up the role with the Department of Agriculture & Fisheries and is based at South Johnstone. Sarah will be working to assist growers by shaping research to address their concerns. Currently, she is focusing on determining methods to improve bunch pest management practices to reduce fruit damage, waste, and raise the bottom line for growers.

Sarah Williams
Development Horticulturalist
Department of Agriculture and Fisheries
Centre for Wet Tropics Agriculture, South Johnstone, Qld

Completing her university degree in Environmental Science at the University of Technology Sydney, Sarah spent her final honours year focusing on using natural rooting hormones from plant extracts to improve planting establishment, to reduce dependencies on fertilisers. After finishing university, Sarah knew that she wanted to work to bring science to the people, equipping them to make decisions with the most recent research. Moving from NSW to Ayr, Sarah began her career in extension working at an independent agronomy firm with the sugar industry, working on projects that focused on precision agronomy, herbicide efficiency usage and alternative fallow cropping. Here, Sarah discovered her love for working with local growers and helping them get the best crop possible.

We asked Sarah what she’s most excited about in her new role ‘ I’m really excited to provide the industry with research that’s relevant, practical, and address’ growers’ concerns and limitations within the industry.’

Outside of work, Sarah enjoys hiking, camping and playing with her dog. Her favourite banana recipe is rum-soaked BBQed bananas.

Grower case study. Bagging technique improves fruit quality for Sellars Bananas

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Grower case study

Bagging technique improves fruit quality for Sellars Bananas

Experienced premium Cavendish grower Naomi Brownrigg is confident that their bagging technique which leaves a ‘flue’, has improved fruit quality by reducing fungal and mould issues.

Naomi continues to see the benefit of this technique, implementing it on their family farm over 20 years ago.

Naomi says the flue bagging technique has dramatically reduced fungal and mould issues. ‘From that moment on (leaving a flue in the bag) we haven’t really had an issue. It will only be if the flue closes up you might get a mouldy bunch, after that we were free of it,’ Naomi said.

‘We’ve adopted that technique on our family farm for 20 years now and it’s so easy to do.’

Tianara Takai and Naomi Brownrigg from Sellars Bananas

Sharing lessons learnt for the benefit of industry

Naomi is passionate about helping other growers improve their fruit quality and is willing to share her knowledge and experience of lessons learnt. 

Sellars Bananas transitioned from bunch dusting with chlorpyrifos and talc to using a bunch spray with chlorpyrifos. This was to eliminate the risk of fruit being rejected at market due to talc residue. When they made the switch Naomi said they experienced significant decline in fruit quality due to increased fungal and mould issues. ‘At first we weren’t leaving any air hole (flue) in the bag. The bags did have perforated holes in them and we were just tying them up like normal and putting the spray in,’ Naomi said. It was her husband Dave who first noticed they had an issue ‘he said we have a huge problem out there. He said I can see all the fruit sweating and the mould starting,’ Naomi said. 
Naomi said the type of bags they used at the time also contributed to the problem, as they didn’t hold their shape and instead closed around the fruit. Naomi explained it’s important for growers to ensure the bags they use don’t close up. 
With chlorpyrifos currently under review by the Australian Pesticides and Veterinary Medicines Authority (APVMA), the permit to apply chlorpyrifos mixed with talc may be cancelled or not renewed once the current permit expires. This will leave only spray application of registered insecticides to control banana bunch pests. 

Some growers have reported increased incidence of mould and fungal issues using a bunch spray compared to dusting. It’s suggested that bunch spraying increases the amount of moisture in the bag and combined with high temperatures, may lead to increased humidity and fungal issues. Market agents have also confirmed fruit continues to be rejected due to talc residues. Naomi hopes that sharing their bagging technique will help growers who are currently experiencing fungal issues affecting fruit quality, and those who are looking at transitioning from dusting to bunch spraying in the future.

In light of the APVMA review and continued market rejections due to talc residues, Naomi encourages growers to start trialling it. ‘Now is the time to be trialling these things. People are getting rejected at the supermarket level for talc at the moment and that pressure isn’t going to go away,’ Naomi said.

Flue bagging technique

The term ‘flue’, simply refers to an opening. Its use in this circumstance is designed to increase air flow through the bag and reduce humidity.

The key points to the bagging technique used by Sellars Bananas are:

  ⦁ A liner is applied first to emerged bells and tied tightly around the bunch stalk with no flue (Figure 1).
  ⦁ At pruning, bags are tied with a knot tightly around the stalk, not wrapped. The excess bag is left open (Figure 2).
  ⦁ The bag around the opening is folded down on itself to improve integrity and stop it from closing.
  ⦁ All bracts are removed to further reduce moisture within the bag.

Figure 1 Bells are bagged early with a liner which is tied tightly around the stalk with no flue
Figure 2 Bags are applied at pruning and are tied tightly around stalk leaving a flue to the side

Sellars Bananas achieve control of rust thrips

When the banana extension team discussed this technique with growers, some have raised concern  the flue may provide an avenue for rust thrips to enter the bunch.

Naomi said this has not been their experience and believes that the bag being tied tightly around the stalk, acts as a barrier preventing rust thrips from moving down the stalk. In addition, the use of a liner, also tied tightly around the bunch stalk (without a flue) may help limit movement of rust thrips into the bunch.

Of course it is never one single practice in isolation and other bunch protection practices are also important for control of rust thrips. ‘If it has been injected on time, bagged on time and sprayed properly, we haven’t had a drama. We throw very little fruit away to rust thrips,’ Naomi said.

Figure 3 Sellars Bananas achieve good control of bunch pests and supply premium grade fruit

Every farm has different management practices and pest pressure and it’s therefore recommended that growers trial this bagging technique to make their own assessment before implementing it as a standard practice. 

Watch the video below for a demonstration of the bagging technique

Thank you to Naomi Brownrigg and the team at Sellars Bananas who provided their time and gave permission to use this case study for the benefit of the wider industry.

Download this information as a fact sheet

If you would like further information or assistance with bunch pest practices, please contact the National Banana Development and Extension Team on email betterbananas@daf.qld.gov.au or phone 07 4220 4152.

This case study has been produced as part of project BA19004 the National Banana Development and Extension Program which is funded by Hort Innovation, using the banana industry research and development levies, co-investment from the 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.