Volume and timing trials for bunch protection

Posted on by Ingrid Jenkins

Volume and timing trials for bunch protection

About the trials

Volume and timing trials for bell injection and bunch spraying were conducted by the DPI extension team, after some growers expressed concern of not achieving adequate control of bunch pests. 

Several trials have been completed to confirm and compare efficacy of registered chemistries as well as gain a better understanding of the importance of volume, coverage and timing of application. 

The trials at the South Johnstone Research Facility in Far North Queensland looked at the effects of different treatments on the level of damage caused by the three main banana bunch pests treated via bell injection and bunch spraying. 

The main banana bunch pests treated via bell injection and bunch spraying.
Image showing banana scab moth damage on banana fruit.
Image showing banana rust thrips damage on banana fruit.

Key findings

Banana scab moth

  • Inject bells in the upright position. Bells injected late in the horizontal position had significantly more banana scab moth damage (nearly 25% of hands) compared to the best practice treatment that had no damage. See figure 1 below. The image carousel below shows the two timing treatments used in the trial. 
  • This trial also demonstrated that coverage is important. The best practice treatment of injecting bells in the upright position with full volume was the only treatment that was significantly less than the water control. 
Figure 1: Chart showing the mean percentage of hands with banana scab moth damage for the different treatments.
Best practice treatment. Bells injected in the upright position.
Best practice treatment. Bells injected in the upright position.
Late timing treatment. Bells injected in horizontal position.
Late timing treatment. Bells injected in horizontal position.

Banana flower thrips

  • Bell injecting with 60mL volume at permitted rates provided good control of banana flower thrips. Initial work found that bell injecting with acephate at 40mL volume @ label rate did not provide good control of banana flower thrips. Subsequent trials found good control was achieved by increasing the volume to 60mL @ label rate.
  • Bell injecting with 60mL of either acephate or spinetoram at permitted rates provided good control of banana flower thrips. Bells injected with spinetoram had significantly less damage compared to bells injected with acephate at label rates. However, acephate still provided acceptable control at the 60mL volume, below the mean damage threshold of 1. See Figure 2 below.
Fruit representative of the 60 mL volume trial. Minimal flower thrips damage recorded on treated bunches.
Figure 2: Chart showing performance of acephate and spinetoram for banana flower thrips control. Bells treated with spinetoram had significantly less damage compared to acephate and water control.

Banana rust thrips

  • Multiple trials using 50-60mL of spinetoram solution as a bunch spray has consistently achieved good control of banana rust thrips. Note, this is in combination with bell injecting with acephate solution.
  • Both air assisted and hydraulic systems have been effective in providing effective coverage required for control.
  • Trial assessments of banana rust thrips damage were undertaken on mature fruit at harvest.
  • In accordance with the label, bunches were sprayed with spinetoram solution after the bunch cover was applied.

Tips!

  • Always use registered products in accordance with the label and check rates and volumes before use.

  • Regularly check and calibrate equipment to ensure effective application and safety.

  • Good even coverage is important for effective control.

  • Mix insecticide solutions well and use spinetoram solution within 72 hours of being mixed.  

For more information on these trials contact the DPI extension team:
betterbananas@dpi.qld.gov.au 

This research has been undertaken 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 Primary Industries.
 Horticulture Innovation Australia (Hort Innovation) and the Queensland Government make no representations and expressly disclaim all warranties (to the extent permitted by law) about the accuracy, completeness, or currency of information in this factsheet. Reliance on any information provided by Hort Innovation and the Queensland Government is entirely at your own risk. Hort Innovation and the Queensland Government are not responsible for, and will not be liable for, any loss, damage, claim, expense, cost (including legal costs) or other liability arising in any way (including from Hort Innovation and the Queensland Government or any other person’s negligence or otherwise) from your use or non-use of this factsheet or from reliance on information contained in the material or that Hort Innovation and the Queensland Government provides to you by any other means. 
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Bunch spray technology

Posted on by Ingrid Jenkins

Bunch spray technology

About the trial

To support growers transition from bunch dusting to bunch spraying, the DPI extension team have investigated alternative bunch spray systems that deliver good coverage for controlling banana rust thrips.

The trial consisted of three different air assisted systems and three different hydraulic systems, comparing their effectiveness in controlling banana rust thrips. Also recorded, was the average time for each system to deliver 50-60mL of spinetoram solution to a bunch. In accordance with the product label, the solution was mixed at the specified label rate and was applied after the bunch cover had been placed on the bunch. All bunches were covered with a liner and 40 μm plastic bunch cover tied with flues (opening left in top of bag).

Assessments for banana rust thrips damage was undertaken at harvest, with all fingers in a bunch assessed for damage. 

Hydraulic systems - delivering 28psi with 12v pump

Treatment 1 – Spray wand from underneath the bag 

Teejet grey adjustable nozzle (38720-PPB-X8)

Spray applied via the flue at the top of the bunch cover for 2 seconds. Then applied underneath the bunch cover and liner from top hand to the bottom in a zig-zag motion for 3-4 seconds.

Treatment 2 – Spray wand from underneath and top of bag

Teejet grey adjustable nozzle (38720-PPB-X8) 

Spray applied from underneath the bunch cover and liner. Spraying from the top hand to the bottom in a zig-zag motion for 5-6 seconds.

Treatment 3 – Spray ring prototype    
                   

3 x 0.75 (BETE FF028-145) nozzles

Spray ring was slid underneath the liner and bunch cover and spray was applied from top hand to bottom hand for 3-3.5 seconds. *Note, the ring was difficult to get up underneath the liner and bunch cover and was not easy to place around the fruit in an efficient time.  

Air-assisted systems - delivering 28psi with 12v air compressor

Treatment 4 – Aeropro spray gun 

2.5mm nozzle opened half of a turn

Spray applied from reaching under the bunch cover and liner, spraying up at a 45-degree angle as far around the bunch and down to the bottom hands in a zig zag motion for 5-6 seconds.

Treatment 5 – Star S-770 spray gun 

1.2mm nozzle opened one and a half turns

Spray applied from reaching under the bunch cover and liner, spraying up at a 45-degree angle as far around the bunch and down to the bottom hands in a zig-zag motion for 4-5 seconds.

Treatment 6 – Prototype air sprayer

using 12v air compressor and 12v pump

Spray applied from just underneath the bunch cover and liner, spraying from the bottom of the bag pointing upwards for 3-3.5 seconds.

Key findings

  • All air-assist and hydraulic chemical spray treatments provided good control of banana rust thrips (Figure 1). 

  • Greater than 96% of all fingers in bunches across all treatments recorded no damage. This compared to 47% of fingers in the water control.

  • Positioning the spray ring (treatment 3) underneath the liner and bunch cover was difficult and the time taken would not make it commercially feasible.

  • Growers that have previously dusted can easily modify their current compressed air system to trial the air-assisted options.

Chart
Figure 1: All spray treatments provided good control of banana rust thrips, significantly greater than the water control

Air-pressurised spray gun system with Mark McAvoy

The DPI extension team in collaboration with banana grower Mark McAvoy put together a demonstration video of the spray gun system Mark uses on his farm for bunch spraying.

For more information on this trial contact the DPI extension team:
betterbananas@dpi.qld.gov.au 

This research has been undertaken 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 Primary Industries.
 Horticulture Innovation Australia (Hort Innovation) and the Queensland Government make no representations and expressly disclaim all warranties (to the extent permitted by law) about the accuracy, completeness, or currency of information in this factsheet. Reliance on any information provided by Hort Innovation and the Queensland Government is entirely at your own risk. Hort Innovation and the Queensland Government are not responsible for, and will not be liable for, any loss, damage, claim, expense, cost (including legal costs) or other liability arising in any way (including from Hort Innovation and the Queensland Government or any other person’s negligence or otherwise) from your use or non-use of this factsheet or from reliance on information contained in the material or that Hort Innovation and the Queensland Government provides to you by any other means. 

Timing of bunch cover application and its effect on bunch pests

Posted on by Ingrid Jenkins

Timing of bunch cover application and its effect on bunch pests

About the trial

Far North Queensland growers have reported that the biggest issues affecting their yield and quality are birds/bats and banana rust thrips. 

Bagging bunches is an important practice that protects developing fruit from leaf rubbing, banana rust thrips, and birds/bats.

This trial compared the effect of the timing of bunch cover application, comparing early bagging (applied to a newly emerged bell before hands are visible) to traditional bagging (at pruning) and examined the effect on damage caused by bunch pests.

Main banana bunch pests assessed in the trials
Timing of traditional bagging treatment used for the trial
Timing of traditional bagging treatment used for the trial
Timing of early bagging treatment used for the trial
Timing of early bagging treatment used for the trial

Key findings

Birds and bats

  • Bunches that were bagged ‘early’ had a significantly lower number of hands damaged by animal scratches (0.37%) compared to those that were bagged at ‘traditional’ timing (57%), refer to Figure 1 below.

Figure 1: Chart showing the percentage of hands with bird and/or bat damage for the two timing treatments for applying bunch covers. Bagging bells early (left column) had significantly less hands with damage compared to bunches bagged at pruning/traditional timing (See images above).
Image showing damage caused by birds and/or bats by puncturing and scratching the fruit.

Banana rust thrips

  • Bunches that were bagged early had a significantly lower number of fingers with banana rust thrips damage (3%) compared to traditional bagging (20%), refer to Figure 2 below.

  • Tying a bag and/or liner early provides a barrier to banana rust thrips moving down the stalk into the bunch (see image below).

Figure 2: Chart showing the mean percentage of assessed fingers with banana rust thrips damage for the two timing treatments for applying bunch covers. Bagging bells early (left column) had significantly less fingers with damage compared to bunches bagged at pruning/traditional timing.
Image shows demarcation of banana rust thrips feeding marks on bunch stalk. This is the point at which the liner was tied.

Banana flower thrips

  • As expected, early bagging had no significant effect on banana flower thrips damage, as control is mainly achieved through chemical application via bell injection. 

Banana scab moth

  • Not enough data was collected for banana scab moth damage. Only a few bunches had damage, indicating low pressure at the time of the trial. 

For more information on these trials contact the DPI extension team:
betterbananas@dpi.qld.gov.au 

This trial has been undertaken 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 Primary Industries. 

Horticulture Innovation Australia (Hort Innovation) and the Queensland Government make no representations and expressly disclaim all warranties (to the extent permitted by law) about the accuracy, completeness, or currency of information in this factsheet. Reliance on any information provided by Hort Innovation and the Queensland Government is entirely at your own risk. Hort Innovation and the Queensland Government are not responsible for, and will not be liable for, any loss, damage, claim, expense, cost (including legal costs) or other liability arising in any way (including from Hort Innovation and the Queensland Government or any other person’s negligence or otherwise) from your use or non-use of this factsheet or from reliance on information contained in the material or that Hort Innovation and the Queensland Government provides to you by any other means. 
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Yellow Sigatoka resistance – Goldfinger mutagenesis trial

Posted on by Ingrid Jenkins

Yellow Sigatoka screening - Goldfinger mutagenesis trial

Katie Robertson, Jeff Daniells, David East and Carole Wright, Queensland DAF (Dec 2023)

The screening trial assessing Goldfinger mutant selections’ resistance or susceptibility to the fungal leaf disease, yellow Sigatoka is now complete. Most of the selections had a similar reaction to yellow Sigatoka as the Goldfinger control, however GMS 766 was significantly more resistant, while four others were significantly more susceptible. This latter result demonstrates that mutagenesis can significantly change a plant’s level of yellow Sigatoka resistance.

An estimated $25-30 million per year is spent on controlling yellow Sigatoka leaf spot (Pseudocercospora musae) Identifying varieties with better resistance to the disease, provided they were otherwise commercially viable, would be of great benefit to the industry by reducing input costs and reliance on fungicides. 

Over the 2023 wet season, a yellow Sigatoka screening trial was conducted at the South Johnstone Research Facility on the top-twenty Goldfinger selections which had been developed through DAF’s mutagenesis project.

The block had been nurse suckered to standardise plant development stage. Leaf disease control ceased a few months prior to nurse suckering to build up inoculum levels and ensure adequate disease pressure. Plants were assessed for severity of leaf spot disease on 3 occasions, at monthly intervals leading up to bunching. The assessment consisted of determining the Youngest Leaf Spotted (10 or more mature necrotic lesions (YLS), and the Youngest Leaf with greater than 33% of the leaf lamina destroyed by disease (YL33). The Total number of Functional Leaves (TFL) was recorded if the disease was not present or had not progressed to the >33% necrosis severity level. For the purposes of this article, only the YLS and TFL data will be discussed.

While Goldfinger has resistance to black Sigatoka, this is not the case for yellow Sigatoka, to which it is better described as having an intermediate reaction.  Of particular interest was how the new selections compared to Goldfinger and the possible effect mutagenesis may have had on the plants ’ reaction to this disease.  Figure 1 below shows the average YLS of Goldfinger was 6.4, which was similar   to fifteen of the twenty mutant selections. ‘GMS 766’ was the only selection that demonstrated better resistance to leaf spot than Goldfinger, having an average YLS of 7.9.  

On the other end of the spectrum, ‘GMS 602’, ‘GMS 211’, ‘GMS 145’, and ‘GMS 255’ had average YLS values of between 5.4 and 4.4, demonstrating  they were significantly more susceptible to the disease. Although not the original objective of the project, these results demonstrate mutagenesis can significantly change a plant’s level of yellow Sigatoka resistance. The dwarf Lady Finger selection ‘Dwarf Rossi’ was planted as a single guard plant at the beginning of each row of Goldfinger. 

The level of disease was comparable to the ‘Dwarf Rossi’ plants in the variety evaluation, allowing comparisons to be made between the two trials. It was not significantly different to Goldfinger in its reaction to yellow Sigatoka. 

Figure 1: Youngest leaf with 10 or more necrotic lesions (YLS) for the 20 Goldfinger Mutant Selections, standard Goldfinger, and the Lady Finger variety ‘Dwarf Rossi’ (average of 3 rating occasions; error bars represent +/-1 standard error ). The different coloured bars indicate varieties that were statistically similar (yellow) or significantly different (red/green) to Goldfinger (patterned fill).
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. 
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Yellow Sigatoka resistance – agronomic evaluation trial (October 2020)

Posted on by Ingrid Jenkins

Yellow Sigatoka screening - agronomic evaluation trial (October 2020)

Katie Robertson, Jeff Daniells, David East, and Carole Wright, Queensland DAF (Dec 2023)

The screening trial assessing new varieties’ resistance or susceptibility to the fungal leaf disease, yellow Sigatoka is now complete. Varying degrees of leaf spot resistance were observed among the Cavendish (highly susceptible), Lady Finger (intermediate resistance) and CIRAD hybrids (resistant).

An estimated $25-30 million per year is spent on controlling yellow Sigatoka leaf spot (Pseudocercospora musae) in Australian banana plantations. Identifying varieties with better resistance to the disease, provided they were otherwise commercially viable, would be of great benefit to the industry, by reducing input costs and reliance on fungicides.

Over the 2023 wet season, a yellow Sigatoka screening trial was conducted at the South Johnstone Research Facility. This was after the agronomic assessments on 15 varieties had been completed in the 2020 Variety Evaluation and the block was nurse-suckered. 

Leaf disease control ceased a few months prior to nurse suckering to build up inoculum levels and ensure adequate disease pressure. Plants were assessed for severity of leaf spot disease on 3 occasions, at monthly intervals leading up to bunching. 

The assessment consisted of determining the Youngest Leaf Spotted (10 or more mature necrotic lesions) (YLS), and the Youngest Leaf with greater than 33% of the leaf lamina destroyed by disease (YL33). 

The Total number of Functional Leaves (TFL) was recorded if the disease was not present or had not progressed to the >33% necrosis severity level. For the purposes of this article, only the YLS and TFL data will be discussed.

Figure 1 shows four of the varieties had comparable disease severity to the very susceptible reference variety, ‘Williams’, which had an average YLS of 4.5. These included the TR4 resistant Cavendish ‘Asia Pacific #1’, along with the two tetraploid ‘High Noon’ selections (one with a ‘clean’ rachis [HNC] and one with a ‘dirty’ rachis [HND]) , and the Pendulous Lady Finger selection. 

The other four Lady Finger varieties demonstrated slightly better resistance and were statistically similar to ‘Pacific Plantain’ (YLS = 6.2), which has a documented intermediate level of resistance to leaf spot. Overseas, the hybrid ‘CIRAD 925’ has demonstrated both yellow and black Sigatoka (Pseudocercospora fijiensis) resistance (Risède et al. 2019). 

It was anticipated that the other three CIRAD hybrids may also possess this characteristic, which proved to be the case. Although no leaf spot was present, ‘CIRAD 925’ and ‘CIRAD 918’ only maintained around seven functional leaves throughout the assessments, with older leaves snapping due to petiole weakness, while ‘CIRAD L9’ and ‘CIRAD X17’ sustained over 10 functional leaves. 

The common leaf fungi, Cordana leaf spot (Neocordana musae) and banana leaf speckle (Mycosphaerella musae), were likely present on all varieties, but more obvious along the leaf margins of the CIRAD hybrids due to the absence of yellow Sigatoka. ‘Dwarf Ducasse’ was included as the resistant reference variety and supported an average of 13 functional leaves with no yellow Sigatoka present.

While the CRIAD hybrids remained unaffected by yellow Sigatoka (CIRAD X17 pitcured here), there were other common pathogenic fungi, primarily Cordana and banana leaf speckle present on some older leaves.
The TR4 resistant Cavendish 'Asia Paific #1', was as susceptible as Williams to yellow Sigatoka.
Figure 1 Youngest leaf with 10 or more necrotic lesions (YLS) for 15 varieties at South Johnstone (average of 3 rating occasions; error bars represent +/-1 standard error). If the YLS stage was not reached for a variety (i.e. the CIRAD hybrids and Dwarf Ducasse) the leaf number represents the total number of functional leaves present. Williams (very susceptible), Pacific Plantain (intermediate), and Dwarf Ducasse (highly resistant) were used as references to assess the disease reaction of the new varieties. The different coloured bars illustrate varieties that were statisically similar to the reference varieties (patterned fill).
References
Risède, J.-M., Achard, R., Brat, P., Chabrier, C., Damour, G., Guillermet, C., de Lapeyre., Lœillet, D., Lakhia, S., Meynard, P., Tixier, P., Tran Quoc, H., Salmon, F., Côte, F.-X. and Dorel, M. (2019). The agroecological transition of Cavendish banana cropping systems in the French West Indies. In The agroecological transition of agricultural systems in the Global South. Côte, F.-X., Poirier-Magona, E, Perret, S., Roudier, P., Rapidel, B., Thirion, M.-C, eds. (Agricultures et défis du monde collection, AFD, CIRAD, Éditions Quæ, Versailles). Pp. 107 – 126. https://agritrop.cirad.fr/592993/1/ID592993.pdf 

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.
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First ratoon observations and results (2020 agronomic trial)

Posted on by Ingrid Jenkins

First ratoon results - agronomic evaluation trial (October 2020)

By Katie Robertson & Jeff Daniells, Queensland Department of Primary Industries

Trends 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.

Productivity declined in the short statured TR4 resistant Cavendish Asia Pacific #1, while GCTCV 106 continued to perform comparably to Williams.

The yield reduction measured in the plant crop of the TR4 resistant Cavendish variety Asia Pacific #1 (AP#1) was further amplified by the end of the first ratoon. AP#1 yielded 33% less than Williams over the 2 crops (29.3 versus 44.1 kg/year). This was due to their longer cycle time and a lower average bunch weight (26.7 versus 37.9 kg). AP#1 pseudostem height only increased by 8% between the plant crop and first ratoon (2.2 to 2.4 m), remaining significantly shorter than the other Cavendish varieties. Most other TR4 resistant Cavendish selections from Taiwan are taller than Williams. Finger length also remained shorter, with only 17% of AP#1 fruit falling into the premium size grade (22 – 26cm), compared to 56% for Williams. The GCTCV 106 selection – which originated from a vigorous plant identified in the previous 2018 South Johnstone variety evaluation (BA16001) – again performed comparably to Williams with regards to cycle time and yield (see table). Unfortunately, this variety has not demonstrated TR4 resistance in the Coastal Plains (Northern Territory) screening trials (see here for more).

The TR4 resistant Cavendish selection, Asia Pacific #1, remained shorter than Williams with reduced bunch weights, a longer crop cycle and shorter fruit lengths.

There were no yield differences among the six Lady Finger varieties, with some selections displaying reduced pseudostem heights and better bunch conformation.

All Lady Finger selections, except Pendulous Lady Finger (PLF), remained significantly shorter in stature than standard Lady Finger in the first ratoon (11 – 30% shorter). In the plant crop, PLF had yielded 19% more than Lady Finger per 12-months, but by the end of the first ratoon the yields compared over the 2 crops was not different. The standard Lady Finger experienced a 33% increase in bunch weight between the plant crop and first ratoon, going from 12.2 to 18.5 kg, while PLF only had 15% heavier bunches in the first ratoon (17.7 to 20.9 kg). The fruit in PLF bunches took longer to fill (22.3 weeks) than standard Lady Finger (17.1 weeks), and had issues with premature ripening, likely influenced by the timing of bunch emergence and the environmental conditions during fruit filling. Nonetheless, the PLF plants lived up to their name and continued to produce bunches with a more desirable conformation. The four other Lady Finger varieties did not yield significantly differently to the industry standard.

The yield of 'Dwarf Lady Finger' was comparable to standard Lady Finger but was 30% (or 1.4 m) shorter in stature.

The novel hybrids from CIRAD continued to perform poorly in the first ratoon, in terms of bunch size and pseudostem height.

In the plant crop, 40% of the CIRAD hybrid 918 plants had snapped before harvest despite being similar height to Williams. The incidence of pseudostem snapping in this variety rose to 87% in the first ratoon, meaning there were not enough data plants to include in the analysis. The remaining three CIRAD hybrids had bunch weights 25 – 64% lower than Williams per 12-months for the 2 crops, and CIRAD 925 and X17 were taller by 10 and 17%, respectively. X17 has demonstrated a high level of resistance to TR4 in the NT (see here for more).

Where to next?

The trial block was nurse suckered at the beginning of the year to manage the cropping cycle, and the varieties were rated for yellow Sigatoka over the wet season. These results will be reported on later in the year.  

The TR4 resistant CIRAD hybrid X17 yielded 34% less than Williams per 12-months over the two crop cycles.

More information

This research has been funded as part of a project funded by Hort Innovation, using the banana research and development levy, co-investment from the Queensland Department of Primary Industries and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture.