Bunch pests

Posted on by Better Bananas

Bunch pest management

Managing bunch pests is important to producing good quality bananas. Control of bunch pests, including flower thrips, rust thrips and scab moth, by bell injecting, bunch spraying and/or dusting with registered insecticides is undertaken to ensure market specifications are met. 

The current focus of bunch pest research is on a range of chemical, biological and cultural controls that can be used as part of an Integrated Pest Management (IPM) approach. The aim of an IPM strategy is to reduce reliance on chemicals for pest control—which is important for two main reasons.

The first is that regular use of the same chemical can lead to resistance in pest populations, resulting in the chemical being no longer effective. The second is the risk of losing access to chemicals as a result of deregistration following review by the Australian Pesticides and Veterinary Medicines Authority (APVMA).

With this in mind, research is currently focused on evaluating the effectiveness of new chemistries as well as ‘softer’ biological and cultural pest control options. 

More info...

Banana bunch cover trial

Posted on by Better Bananas

The colour of your bunch covers may help control banana rust thrips

Banana rust thrips continue to be a significant pest for banana growers with levels of damage increasing in recent years. The thrips cause damage by feeding on the skin of immature banana fruit which causes reddish-brown marks. Growers are reporting that even fruit with low levels of damage are not meeting market specifications.

So what role does the colour of bunch covers play in rust thrips damage? Interest amongst researchers was sparked after previous work had shown that rust thrips respond differently to different coloured sticky traps. This prompted researchers to have a look into the effect that different coloured bunch covers have on thrips damage. The aim is to find non-chemical control methods as part of an Integrated Pest Management (IPM) strategy.

Bunch cover trial at South Johnstone Research Station. Orange and purple bunch covers seen in the photo had higher levels of thrips damage in the initial trial.
Severe damage caused by Banana rust thrips. In some cases splitting of the fruit skin can occur. This fruit would be rejected by the market place.
Banana rust thrips adult and nymph. Thrips cause damage to the skin of banana fruit but do not impact the eating quality of the fruit.

Initial trial results are encouraging and do show a difference in the level of damage caused by thrips depending on the colour of the bunch covers used. In this trial no chemical treatment was applied to the bunch after bell injection and the bunch cover was applied as per commercial timing. Orange, yellow and purple bunch covers showed damage above commercially acceptable levels in this scenario. The best performer was a paper bunch cover with a polyethylene ‘cloth’ liner. Light blue and white also produced similar low levels of damage compared with some other colours. 

Finger length, colour and bloom were also assessed with results indicating that bag colour has no significant effect on these fruit quality attributes. 

Based on the initial trial results growers should consider using bunch cover colours that have a low thrips damage rating. This coupled with standard insecticide treatments applied at bunch covering should provide the best level of control. Further work is underway to expand these results by testing new colour and liner combinations. Recommendations of the latest trial will be available to growers in the coming months. 

More information

More information on trial and initial results

This research is funded as part of the Improved Plant Protection for the Banana Industry Program (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.

Banana bunch cover trial information

Posted on by Better Bananas

Effects of using different coloured bunch covers on banana rust thrips damage

About the trial

The trial looked into the effect that different coloured bunch covers have on Banana rust thrips damage. The aim is to find non-chemical control methods as part of an Integrated Pest Management (IPM) strategy.

The only chemical treatment applied in the trial was omethoate injected at bell emergence to ensure researchers were only measuring the influence that bunch covers had on rust thrips damage. This meant that there was no damage to the fruit before the bunch covers were put on.

As per commercial practice, bunch covers were placed on bunches when all the bracts had fallen off, approximately a fortnight after bunch emergence. At the time of bagging, the bell and the false hand plus one were removed.

Rust thrips damage was assessed at harvest by examining the surface of 5 central fingers from the top, middle and bottom hands of the bunch.

The presence and extent of damage on the fingers assessed was recorded using a scale of 0 to 4. Rating 1 is defined by a faint halo and is considered the maximum rating for a commercially acceptable level of damage.

Black arrows show the position of fingers that were assessed from the inner whorl of fruit. These fingers were taken from the top, middle and bottom hands of the bunch.
Rating scale used to assess level of rust thrips damage. Rating 1 is regarded as the maximum damage level that would be commercially accepted.

Measuring the effect that bunch cover colours had on other fruit quality characteristics was also important to ensure they didn’t have a negative impact. The following fruit quality attributes were therefore assessed at harvest.

  • Finger length and diameter
  • Colour (Hue, chroma and lightness) of the peel at fruit colour stage 1 and 6
  • Bloom (the ‘lustre’ or ‘shine’ of the fruit) was assessed photographically to assess peel reflectance 

* Note – Omethoate was registered at the time the trial was conducted and has since been deregistered. Before using any chemicals always check the current registration status and read the product label. Label and permit details can be accessed via the APVMA website, www.apvma.gov.au. 

Results from the initial trial indicate that colours do play a role in level of rust thrips damage

The initial trial results showed a lot of variation in the damage caused by banana rust thrips with respect to different bunch cover colours.  

Orange, yellow and purple bunch covers had levels of damage above commercially acceptable levels. Statistically, orange had a significantly higher level of damage compared to all other covers. 

The best performer was a paper bunch cover with a polyethylene ‘cloth’ liner. This was the only bunch cover that had a liner in the initial trial. Therefore a new trial is looking at the impact of liners in combination with different bunch cover colours. Light blue and white produced similar low levels of damage as the paper bag.

Results also indicate that bunch cover colours have no statistically significant effect on finger length, diameter, colour and bloom.

Results from initial trial work. Orange and yellow bunch covers had the highest rust thrips damage rating, while paper bunch covers had the lowest rating.

Growers should consider using bunch cover colours with low thrips damage rating

Based on the initial trial results, growers should consider using bunch cover colours that scored a low thrips damage rating. Further work is underway to expand these results by testing new colour and liner combinations. Results of the latest trial will be available to growers in the coming months. 

Bunch cover colours being assessed in the new trial. The 'Kraft' colour on the far right of the photo is the paper bunch cover.

If you would like further information on this trial, contact the Better Bananas team.

This research is funded as part of the Improved Plant Protection for the Banana Industry Program (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.

Disinfectants

Posted on by Better Bananas

Disinfectants prove to be an integral part of on-farm biosecurity

Using disinfectants as part of your cleaning regime is vital to minimise the spread of Panama disease. Research shows that various disinfectant products are effective in killing fungal spores that cause Panama disease.

Products listed in the table below are examples of disinfectant products which were shown to be effective when applied at 1% solution. 

 
Disinfectants used in vehicle dip for low risk vehicles.
Example of disinfectant products registered to control Panama disease in bananas

Remember...

Before using any chemicals always check the current registration status and read the product label.  A minor use permit is available for banana growers to use these products off-label (PER 86485) http://permits.apvma.gov.au/PER86485.pdf. Label and permit details can be accessed via APVMA website: www.apvma.gov.au

It is important to note that soil reduces the effectiveness of disinfectants. Different soil types have varying impacts on the effectiveness of the products. However, research has shown that once the equivalent of 1g of soil is present in 20mL of solution (1% product) then the effectiveness of products is compromised or reduced. 

Investigations into DDAC products (e.g. Steri-maX®, Path-X™, Sporekill® made at 1% solution) has found that when there is no soil contamination, these products remain effective as a disinfectant after being exposed to sunlight, temperature and humidity for up to 12 months. 

Quaternary ammonium compound test strips have shown to be an effective tool that measures the concentration of the active ingredient DDAC or BZK in disinfectant products. These easy-to-use test strips do not require dilution of the sample and are used by comparing the colour development on the test strip to the colour scale.

In summary:

  • DDAC and BZK disinfectant products used at the correct concentration and as per label or permit specifications (contact times) do kill the fungal spores that cause Panama disease. 
  • It is important to remove all soil and organic matter before applying any disinfectant product and replace solutions if they become contaminated.
  • Easy-to-use test strips can be used to regularly test solutions in footbaths, spray shuttles and wash-down facilities.

More info...

Remember: Always follow and adhere to product label rates and instructions. Label and permit details can be accessed via APVMA website: www.apvma.gov.au 

This research was funded as part of project BA14013 Fusarium wilt Tropical Race 4 – Biosecurity and sustainable practices which was funded by Hort Innovation, using the 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.

How can I test my QA disinfecting products?

Posted on by Better Bananas

Test strips can help determine the effectiveness of your disinfecting solution

Disinfectant products that contain the active ingredient didecyl dimethyl ammonium chloride (DDAC – e.g. Sporekill®, Steri-max® and Path-X™) or benzalkonium chloride (BZK – e.g. Bactex, Agriquat) have shown to kill fungal spores that cause Panama disease. 

For these products to be effective, it is important they are mixed at a 1% solution. Our researchers have investigated a range of test strips to measure the concentration of the active ingredient of disinfectant products used in footbaths, spray shuttles and drive-through dips.  

High level (0 – 1500ppm) or extra high level (0 – 10,000ppm) quaternary ammonium compound test strips are an easy method of testing the active ingredient DDAC or BZK by comparing the colour development on the test strip to a colour scale.

For your information...

1% solution of 120g/L DDAC (e.g. Steri-max®) equates to 1200ppm
1% solution of 100g/L BZK (e.g. Bactex) equates to 1000ppm
1% of solution of 250g/L BZK (e.g. Agriquat) equates to 2500ppm *

*(either dilute and use high level test strips or use extra high level (0 – 10 000ppm) test strips)

For best results, make up a 1% standard solution of the DDAC or BZK disinfectant product you are using. This will allow you to directly compare the exact colour of a 1% solution to the colour of the disinfectant sample you want to test.

Keep this solution in a sealed container for future use.

It is recommended...

It’s recommended that you dip your test strip into the 1% standard solution and the disinfectant sample (e.g. footbath) simultaneously, that way you can compare colour instantly.

1. Dip

Dip test strips into the 1% standard solution and your disinfectant sample and remove immediately.

2. Compare

Immediately compare test strip to colour scale (maximum reading time of 5 seconds).

The colour of your disinfectant sample should be ≥ the 1% standard solution (as per image above with green tick).

In summary:

  • Use test strips to regularly check the disinfectant solutions in your footbaths, spray shuttles and wash-down facilities to ensure they are at an effective concentration (1% solution).
  • Ensure there is less than 5% soil in footbaths and wash-down facilities – that is equivalent to 1g of soil to 20mL of disinfectant solution (1% DDAC or BZK product).
  • Be aware that soil with a high clay content may have the potential to influence test strip results.
  • Different water sources do not appear to influence the test strip results.
  • With no soil present in your disinfecting solution, DDAC products prepared to a 1% solution are still effective at managing spores that cause Panama disease. 

For more information about this work or for details on where to purchase the test strips contact the better bananas team –betterbananas@daf.qld.gov.au or 13 25 23 

Please note...

There may be factors beyond the scope of the research that has been undertaken using the quaternary ammonium compound test strips which have the potential to influence results. 

This trial was funded as part of project BA14013 Fusarium wilt Tropical Race 4 – Biosecurity and sustainable practices which was funded by Hort Innovation, using the 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.

Are cleaning and disinfectant products corrosive?

Posted on by Better Bananas

Are cleaning and disinfectant products corrosive?

Infrastructure such as footbaths and wash-down facilities are important components of effective on-farm biosecurity. Demonstration trials have been conducted to investigate the potential corrosive ability of various cleaning and disinfectant products on different metal surfaces.

Two demonstration trials were conducted and the same treatments were used in both.  Products included a detergent (Farmcleanse (10%), three quaternary ammonium products made to a 1% solution (Sporekill®, Steri-max® and Path-X™), and water as a control. Both trials demonstrated the effects of the above products on five different metals; unpainted steel, painted steel, galvanised, aluminium and stainless steel (grade 304).

The first experiment consisted of the metals being completely submerged in solution for 8 weeks, whilst in the second experiment the metals were treated by being dipped in the solutions frequently (2-3 times a week) then exposed to field conditions (temperature and humidity) for a total of 12 weeks. 

Metals submerged in solution.
Metals being dipped.

Outcomes of this research

The demonstration trials showed that the detergent and disinfectant products caused low levels of surface rust development over the 8-12 week period for the majority of metals. Unpainted steel was the most susceptible to surface rust development, while galvanised steel, aluminium and stainless steel were the least susceptible.

When submerged in solution, the detergent and disinfectant products did not corrode the metals significantly more than water alone. The water treatment appeared to have similar corrosive abilities as the other products trialled in this experiment. 

When dipped frequently and exposed to field conditions, all three QA products appeared to be more corrosive on unpainted steel compared to the water and detergent treatments. Furthermore, the QA’s had shown to be more corrosive on unpainted steel when dipped frequently as opposed to the submerged in solution application method.

Remember...

Always follow label directions for cleaning and disinfectant products. After the appropriate exposure time you can rinse metal surfaces with clean water to minimise the risk of rusting. 

What did the corrosion demonstration trial show?

Unpainted steel

Submerged in solution
  • Water appeared to have similar corrosive abilities as the disinfectant and QA products.

Dipped frequently

  • The QA products appeared to be more corrosive than the detergent and water treatments with frequent dipping application.

Painted steel

Submerged in solution
  • The paint bubbled and peeled across most treatments, with water only having the least amount of damage to the paint.
  • Rust development was present on the cut edges for all treatments.

Dipped frequently

  • The paint remained in good condition for all treatments.
  • Minor rust development was present where there were chips in the paint.
  • Rust development was present on the cut edges for all treatments. 

Stainless steel (grade 304)

Submerged in solution
  • The stainless steel remained in good condition for the duration of the experiment against all treatments.
  • Rust development was present on the cut edges of most treatments with the detergent having the least amount of rust visible.

Dipped frequently

  • None of the treatments appeared to degrade the stainless steel for the duration of the experiment.
  • Rust was present on the cut edges of the stainless steel on most treatments but with the detergent treatment having the least amount of rust development.

Aluminium

Submerged in solution
  • All treatments oxidised the aluminium with the exception of Steri-max®. 
  • The oxidised aluminium plates changed colour and developed a chalky texture across the surface. 

Dipped frequently

  • The aluminium remained in good condition for the duration of the experiment across all treatments.

Galvanised steel

Submerged in solution
  • A white precipitate developed on the surface of the galvanised steel plates on most treatments, except the detergent.
  • Rust developed on the cut edges of the galvanised steel plates treated with water.

Dipped frequently

  • The galvanised steel remained in good condition for the duration of the experiment and across all treatments.

For more information about this work contact the better bananas team – betterbananas@daf.qld.gov.au or 13 25 23

This trial was funded as part of the Fusarium Wilt Tropical Race 4 – Biosecurity and Sustainable Practices project (BA14013). This project was funded by Hort Innovation using the banana research and development levy, co-investment from the 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.

How long are disinfectant products effective for?

Posted on by Better Bananas

How long are disinfectant products effective for?

Quaternary ammonium (QA) products have been shown to kill fungal spores that cause Panama disease. Our researchers have been investigating the longevity of three QA products that contain 120g/L of the active ingredient, didecyl dimethyl ammonium chloride. The QA products evaluated included Sporekill®, Steri-max® and Path-X™, at a 1% (1200ppm) solution.

So what did we do?

The QA products were placed in plastic storage containers outside (with the lids kept on) and exposed to field conditions (e.g. sunlight and temperature) for a period of 12 months. The high level (0-1500ppm) QA test strips were used as indicators to test the solutions on a regular basis, and at 4, 8 and 12 months intervals.  At these intervals, small samples of the solutions were collected and inoculated with fungal spores of Panama disease race 1.

QA disinfectant samples placed outdoors and exposed to field conditions.
Testing of QA disinfectants.

So what was the outcome?

The results showed that after 12 months exposure to sunlight, temperature and humidity, all three QA products were still effective at killing spores that cause Panama disease race 1. Testing at 12 months indicated a reduction in the concentration (using the test strips) for some of the QA products, particularly Path-X™. Despite the potential reduction, no colony growth was detected when samples of the three QA products were inoculated with spores of Panama disease race 1 in the lab. This result indicated that the products were stable, even after 12 months exposure to field conditions.

Test strips used to test concentration of disinfectants 12 months after exposure to outdoor conditions.
Image on left shows growth of 800+ fungal colonies recovered from control (water no disinfectant). No fungal growth was recovered from disinfectant solutions (image on right).

Good news for growers...

QA disinfectants used in infrastructure such as spray shuttles, that isn’t contaminated with soil and organic matter, will be effective for an extended period of time even when exposed to field conditions. However, always remember to schedule regular testing of your disinfectant solutions to ensure they are effective. This can be achieved by using easy-to-use test strips.

For more information about this work contact the better bananas team: betterbananas@daf.qld.gov.au or 13 25 23

This research is part of the Fusarium Wilt Tropical Race 4 – Biosecurity and Sustainable Practices project (BA14013). This project is funded by Hort Innovation, using the 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.

Alternative post-harvest product testing

Posted on by Better Bananas

Alternative post-harvest product testing

Research has shown that a range of farm management practices have some incremental influence on disease management of crown end rot (CER), from site selection to irrigation practices through to packaging and dispatch.  Specifically, good field and shed hygiene practices help reduce fungal spores making it easier and more effective for post-harvest fungicides to do their work. However, to reduce reliance on fungicide use and address issues associated with chemical resistance, research into potential alternative post-harvest treatments are being investigated. 

Twelve post-harvest treatments including disinfectants, biological/organic treatments and alternative fungicides have been screened using clusters of bananas and observing the natural development of CER symptoms. 

Crowns of each of the clusters were dipped in various treatments (for 30 seconds or 3 minutes), then ripened under standard ripening conditions. Once the fruit was ripened, the symptom development of CER was rated on a scale of 0-7 (7 being the most severe). 

 
Preparing to dip fruit
Preparing to dip fruit.
The crown of clusters being dipped in the various treatments
The crown of the clusters being dipped in the various treatments.

What are the results so far?

This initial screening has indicated that one fungicide (Fungicide B in the table below) appears to be better at managing some of the CER organisms than the currently registered fungicides.

The treatments that showed promise in this initial screening trial require further investigation on larger quantities of fruit and fruit from different production regions. This will help determine if they would be suitable candidates for post-harvest treatment in a commercial setting.
 
Some of the poorer performing treatments, including a biological product that caused severe fruit burn, will not be further investigated.
 
Severe burn was observed on one of the biological treatments
Severe burn was observed on one of the biological treatments.
Fungicide B treatment with no visible fungal growth on the crown surface
Fungicide B treatment with no visible fungal growth on the crown surface.
The water only treatment with obvious fungal growth on the crow
Water only treatment with obvious fungal growth on the crown.

The table below provides a summary of the performance rating of each of the post-harvest treatments tested. 

If you would like more information on this trial contact the better bananas team at betterbananas@daf.qld.gov.au or 13 25 23.

This work is funded as part of the Cause and management of crown rot of banana project (BA13011). This project is funded by Hort Innovation, using the 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.

Developing new resistant varieties CJ19 mutagenesis trial

Posted on by Better Bananas

Latest update...

CJ19 has been irradiated and is in the process of stabilisation. Plants will be sent to the Northern Territory later in 2018 for planting at the Coastal Plains Research Farm.

CJ19 irradiated tissue culture.

CJ19 overview

CJ19 is a Cavendish selection originally from Indonesia. It is shorter in stature than Williams and is prone to choking in sub-optimal growing conditions. Varietal screening trials in the Northern Territory have shown that it is resistant to Panama disease tropical race 4 (TR4). Agronomic assessments of the plant crop conducted at South Johnstone showed that it has a slightly slower cycling time of approximately 12 months from planting to harvest, compared to Williams 11.3 months. It also produced a smaller average bunch weight of 15.9 kg compared to Williams 16.5 kg. 

Trial progress

Mutagenesis, which is a breeding technique using gamma irradiation to increase  changes in tissue cultured plants has been applied to cultivar CJ19. The aim is to develop an improved variety which retains its tolerance to the disease and with improved agronomic characteristics. 
The first step in this process was to determine how much gamma irradiation to use on this variety. Too much irradiation can severely damage or kill the plant, and too little may not induce sufficient changes to the plants. 
Experiments, known as dose response trials, have been conducted at the Maroochy Research Station and the sufficient dosage for CJ19 was determined. 
CJ19 have been irradiated and are in the process of stabilisation. Plants will be sent to the Northern Territory later in 2018 for planting at the Coastal Plains Research Farm.

Preparing CJ19 tissue culture following gamma irradiation.
Gammacell chamber used to apply gamma irradiation to banana tissue culture.
CJ19 first ratoon in the variety screening trial in the Northern Territory.

Check back on this page for progress updates on this trial.

This trial is part of the Fusarium Wilt Tropical Race 4 Research Program (BA14014), which 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.

Developing new resistant varieties Dwarf Nathan mutagenesis trial

Posted on by Better Bananas

Latest update...

In December 2017, 309 plants were planted into the field inoculated with Panama disease tropical race 4. Cavendish and Dwarf Nathan plants which hadn’t been irradiated were also planted as control plants to compare against.

Dwarf Nathan mutagenesis trial at Coastal Plains Research Farm.

Dwarf Nathan overview

Dwarf Nathan is a naturally selected Extra Dwarf Cavendish originally from Israel. It was imported into Australia in the mid 1990s. The variety was included in the most recent Panama disease tropical race 4 (TR4) variety screening trial in the Northern Territory. While it showed relatively high resistance to TR4 in this trial, it did not possess commercially acceptable agronomic characteristics and as a result was selected for mutagenesis. 

Trial progress

Mutagenesis, which is a breeding technique using gamma irradiation to increase changes in tissue cultured plants, has been applied to cultivar Dwarf Nathan. The aim is to find an improved variety which retains its tolerance to the disease and has improved agronomic characteristics. 
The first step in this process was to determine how much gamma irradiation to use on this variety. Too much irradiation can severely damage or kill the plant, and too little may not induce sufficient changes to the plants. 
Experiments, known as dose response trials, have been conducted at the Maroochy Research Station and the sufficient dosage for Dwarf Nathan was determined. 

Dwarf Nathan were irradiated and sent to the Northern Territory, where they were held in the nursery prior to planting.
309 plants were planted into the field (inoculated with TR4) in December 2017. Cavendish and Dwarf Nathan plants which hadn’t been irradiated were also planted as control plants to compare against. 

Example of tissue culture that undergoes gamma irradiation treatment.
Gammacell chamber used to apply gamma irradiation to banana tissue culture.
Mutagenesis trial - irradiated Dwarf Nathan plants showing variation as a result of mutagenesis.
Variety screening trial - Dwarf Nathan plant crop.
Mutagenesis trial - control plants of Dwarf Nathan and Williams.

Check back on this page for progress updates on this trial.

This trial is part of the Fusarium Wilt Tropical Race 4 Research Program (BA14014) which 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.