Yellow Sigatoka (leaf spot) General information

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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

Yellow Sigatoka – General information

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

Posted on by Better Bananas

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

Fungicides and options to manage the development of resistance

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

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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.

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

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

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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
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)

Posted on by Better Bananas

Latest update...

Evaluation of the 2020 variety screening trial is progressing. Assessment of the plant crop is now complete and results are now available. Harvesting of the first ratoon was completed late in 2022 with data analysis underway. The new varieties are now being screened for yellow Sigatoka resistance.

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 for the plant crop and will soon be available for the first ratoon.

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.