News – Page 12 – Better Bananas

Meet a researcher — Jeff Daniells

Posted on 2018-12-13 by Better Bananas

Jeff Daniells

Jeff has been working with bananas for the past 37 years as a research horticulturist with the Queensland Department of Agriculture and Fisheries based at South Johnstone. He is passionate about bananas and currently works on a number of important industry projects looking at disease resistance and agronomics of alternative varieties — particularly those varieties which have some tolerance to Panama disease tropical race 4.

Growing up in Brisbane Jeff completed his Master’s degree at the University of Queensland and has always had a hands-on approach to learning about bananas. In fact, prior to starting his career, he meticulously kept harvest data (weights, hands and finger numbers) for a stool of Lady Fingers in parent’s backyard. Some call this destiny!

Jeff enjoys Saba (Pisang Gajih Merah) bananas boiled in the jacket served with meat and vegetables and in his spare time enjoys fishing and playing tennis with friends and family.

Principal Horticulturist
Department of Agriculture and Fisheries
Centre for Wet Tropics Agriculture, South Johnstone, Qld

Alternative post-harvest product testing

Posted on 2018-04-18 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).

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.

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 Goldfinger mutagenesis trial

Posted on 2018-04-17 by Better Bananas

Goldfinger overview

Goldfinger (FHIA-01) which was bred by the Honduran Foundation for Agricultural Research (FHIA) is a non-Cavendish dessert banana variety that is highly resistant to Panama disease tropical race 4.

Variety evaluation work previously conducted at South Johnstone has shown the agronomic performance of Goldfinger rates relatively well when compared to Williams. Average bunch weight of plant crop was heavier for Goldfinger at 34.3 kg compared to Williams 30.5 kg. However, the variety had a longer cycling time at 14.4 months from planting to harvest, compared to 12.4 months for Williams. Although it is a reasonably productive variety, improvements are sought in fruit quality characteristics.

Mutagenesis was the technique used to induce change to Goldfinger tissue culture material with the aim of improving fruit quality characteristics, whilst maintaining high resistance to TR4.

Mutagenesis

Mutagenesis, which is a breeding technique using gamma irradiation to promote changes in tissue cultured plants, has been applied to the cultivar Goldfinger. The aim is to develop an improved variety which retains its tolerance to the disease and has improved fruit quality 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 Goldfinger was determined.

Example of tissue culture that undergoes gamma irradiation treatment

Gammacell chamber used to apply gamma irradiation to banana tissue culture

Screening progress

This project has made selections from the original 630 irradiated Goldfinger plants based on agronomic and post-harvest characteristics. Further taste-testing identified five variants to include in a large-scale consumer and sensory evaluation. Click on the menu below for more information on the screening process.

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. Click here for more information.

Screening of the top 20 selections

Following the selection of the top 20 variants from the original 631 plants, sucker and bit material from the original trial was planted in September and October 2019. Click here for more information.

Top 5 selections and consumer taste testing

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. Click here for more information.

Goldfinger variety research features on ABC's Catalyst program

Check out ABC’s Catalyst story on banana production and the work that’s underway to find a new variety; a variety that can match our love for Cavendish while also having good pest and disease resistance. Paul West speaks with Cameron Mackay and banana researchers Jeff Daniells and Stewart Lindsay to find out more.

More information...

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.

Panama disease TR4 variety screening trial

Posted on 2018-04-16 by Better Bananas

TR4 variety screening trial

Panama disease tropical race 4 (TR4) is a major threat to the Australian banana industry. The availability of different varieties that are resistant to this soil borne disease is key to continuing to produce bananas in the presence of the disease.

Variety screening trials have been established to assess the resistance of different banana varieties to Panama TR4. These trials are an important first step in finding a commercially acceptable alternative to the industry’s main variety ‘Williams’ Cavendish, which is very susceptible to the disease.

The most recent variety screening trial conducted at the Coastal Plains Research Farm in the Northern Territory wrapped up in April 2018. This work was part of the research project, Banana Protection Program (BA10020) and results based on plant crop data are now available. Refer to the trial results below.

The new Improved Plant Protection for the Banana Industry (BA16001) project will continue this work with new trials at the site commencing in December 2018.

About the trial

Conducted at the Coastal Plains Research Farm the trial was established on a site infested with TR4. In summary, the trial included:

⦁ 27 varieties, planted in June 2016

⦁ plants artificially inoculated with Panama TR4

⦁ fortnightly disease ratings recorded

⦁ key agronomic characteristics of plant and first ratoon measured (time to bunching, bunch weight).

Williams — most plants did not survive the plant crop

Method of trial assessments

All plants were artificially inoculated with colonised millet at planting. Four varieties with known response to Panama TR4 were used as references in the trial. These included:

⦁ FHIA-25 (Highly resistant)

⦁ Goldfinger (Resistant)

⦁ Formosana (Intermediate)

⦁ Williams (Very susceptible)

Assessments for the appearance of internal and external symptoms of the disease were undertaken on a fortnightly basis as well as at plant death or harvest.

These assessments were undertaken on the plant crop as well as most of first ratoon plants. Unfortunately, in January 2018 a storm heavily impacted the trial three months prior to its intended finish. This meant that not all first ratoon information was able to be collected for all of the varieties.

The following categories were used to rank how susceptible or resistant varieties were to Panama TR4 in the plant crop.

Resistant (R): No disease symptoms were observed.

Intermediate (I): Majority of plants harvested with minimal plants showing symptoms or minor symptoms noted. With the appropriate crop management or environment to lower the inoculum levels these should be commercially viable.

Susceptible (S): Majority of plants harvested with most plants showing disease symptoms.

Very susceptible (VS): Plants showing severe symptoms and >50% killed due to TR4 infection.

Trial results

The following results of the plant crop have been reported by the project team as published in Australian Bananas Issue 52.

Disease resistance ranking of plant crop

R = Resistant, I = Intermediate, S = Susceptible, VS = Very susceptible
* No disease observed, no signs of bunch at 12 months.

Summary of results for plant crop

Where to from here?

The trial has produced some promising results, with four Cavendish varieties; CJ19, GCTCV 215, GCTCV 217 and Dwarf Nathan showing good resistance to Panama TR4 in the plant crop cycle. These varieties have been flagged as good candidates for mutagenesis. Mutagenesis is a breeding technique that uses gamma irradiation to promote changes in tissue cultured plants. The aim is to develop an improved variety that has commercially acceptable agronomic qualities, while maintaining its good resistance to Panama TR4.

This trial work has already begun with CJ19 and Dwarf Nathan already undergoing mutagenesis.

Future screening trials of new varieties will continue, with a new trial at Coastal Plains Research Farm due to commence in December 2018. This work will be delivered as part of The New Improved Plant Protection for the Banana Industry (BA16001) project.

Did you know...

In September 2017, several Far North Queensland growers visited the Northern Territory and saw the trial first hand.
The video below gives an overview of their visit and some of the grower’s impressions of the trial work being undertaken.

This trial was part of the Banana Plant Protection Program (BA10020). This project was funded by Hort Innovation, using the banana research and development levy, and contributions from the Australian Government, with in-kind contributions from the Queensland Department of Agriculture and Fisheries, the University of Queensland and the Northern Territory Department of Industry, Tourism and Trade. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture.

Host research using Panama disease race 1

Posted on 2018-03-20 by Better Bananas

Host research using Panama disease race 1

Understanding what species are capable of hosting the fungal organism that causes Panama disease will help inform how weeds and ground covers are managed in areas infested with the disease.

Work in Far North Queensland has used Panama disease race 1 as a surrogate for tropical race 4. Field surveys conducted in the region have identified plant species common to banana plantations that may act as potential alternative hosts. In this context, a host is defined as a plant in which the fungus can survive, often without obvious disease symptoms apparent.

Weed and ground cover species were collected from farms in Far North Queensland with a history of race 1 infection. In total 115 samples from 20 different plant species were analysed for the presence of the fungal organism (Fusarium oxysporum f.sp cubense) that causes Panama disease race 1.

Roots from each of the plant samples were washed to dislodge excess soil before being surface sterilised. Segments of roots were placed in Fusarium selective media, and incubated for 3-5 days to allow fungal growth. The recovered populations were sent to a specialist diagnostic lab in Brisbane for formal identification.

Race 1 was found living within four different species commonly found co-habiting Far North Queensland banana farms. These species were, spiny spider flower (Cleome aculeata), Youngia japonica, crowsfoot grass (Eleusine indica) and summer grass (Digitaria ciliaris).

Please note...

Panama disease race 1 (R1) was used as a surrogate for Panama disease tropical race 4 (TR4), as access to TR4 infested banana properties in Queensland is restricted.

This trial was funded as part 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 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.

Host research using Panama disease subtropical race 4

Posted on 2018-03-20 by Better Bananas

Host research using Panama disease subtropical race 4

Understanding what species are capable of hosting the fungal organism that causes Panama disease, will help inform how weeds and ground covers are managed in areas infested with the disease. Using Panama disease subtropical race 4 (SR4) as a surrogate for Panama disease tropical race 4 (TR4), a glasshouse experiment was conducted in Brisbane to investigate potential alternative hosts of the fungus. In this context, a host is defined as a plant in which the fungus can survive, often without obvious disease symptoms apparent.

The glasshouse experiment included 18 species identified as being the most common species co-habiting Far North Queensland banana farms, or were regarded as high risk due to their presence on TR4 infested farms in the Northern Territory and Far North Queensland. The plants were inoculated with SR4, and their roots were analysed for the presence of the fungus after a period of 3 months. The roots from each of the plant samples were washed to dislodge excess soil before being surface sterilised. Segments of roots were placed in Fusarium selective media, and incubated for 3-5 days to allow fungal growth. The recovered populations were sent to a specialist diagnostic lab in Brisbane for formal identification.

Panama disease subtropical race 4 was recovered from all 18 species. The fungal organism that causes the disease was recovered from more of the sample plants of some species than others. Although the experiment showed that all species had the potential to host SR4, the differences in the frequency in which it was recovered suggests that some species more readily host the fungus than others do.

Please note...

Panama disease subtropical race 4 (SR4) was used as a surrogate for tropical race 4 (TR4), as SR4 is more closely related to TR4 than other races of the disease.

As seen in the figure above, Mullumbimby Couch had the highest disease recovery, with SR4 recovered from 80% of samples. Whereas Pinto Peanut had the lowest recovery, with approximately 16% of samples recovering SR4.

This trial is 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 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 host research

Posted on 2018-03-20 by Better Bananas

Can weeds and ground covers host Panama disease?

The soil borne fungus Fusarium oxysporum f.sp. cubense (Foc) which causes Panama disease can survive and persist in the soil for years in the absence of banana plants. Weeds and ground covers that co-habit banana plantations can act as alternative ‘host’ plants. In this context, a host is defined as a plant in which the fungus can survive, often without obvious disease symptoms apparent.

By understanding what other species are capable of hosting Foc, it may change weed and ground cover management in areas infested with Panama disease. Keeping disease inoculum low is key to minimising spread to non-infected areas, and in the long term may play an important role in growing bananas in the presence of the disease.

So far, two complementary research efforts using Panama disease race 1 (R1) and subtropical race 4 (SR4) have begun to help our understanding of what weeds and ground cover species are capable of hosting Foc. This research has led to further trial work currently underway, including:

Understanding how Foc behaves within alternative hosts and whether it reproduces and has the ability to increase inoculum levels.
Publication of a guide that gives an overview of the plant species regularly observed in banana plantations and their ability to host Foc.
Investigation of weed and ground cover species in the Northern Territory using Panama disease tropical race 4 (TR4).

More information on trials...

This research 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 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.

Guide to crown end rot identification

Posted on 2018-03-05 by Better Bananas

Guide to crown end rot identification

Thielaviopsis musarum (commonly known as Chalara).

Rot extends beyond the crown and into the fruit (rapid development).
Usually limited to a few clusters.
Occurs randomly and mostly reported during winter and spring.

Fusarium equiseti-incarnatum species complex.

Gives a fuzzy/fluffy appearance on cut crown surface.

Usually causing cosmetic damage but incidence is often reported as high.

Reported to be worse during summer/spring.

Musicillium theobromae

Appearance not as fuzzy/fluffy as the above organism.
High incidence reported.
Reported to be worse during summer/spring.

Colletotrichum musae

Limited fungal growth apparent and sometimes orange spore masses are observed.
Rot can extend below the crown.
Low incidence reported.

Please note...

The above information is a guide only, as multiple organisms may be involved and simultaneously cause symptoms.

If you notice any crown end rot symptoms or want further information, 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.

Reducing inoculum – field trials

Posted on 2018-02-23 by Better Bananas

Field trials - reducing inoculum

The use of high rates of urea to reduce disease inoculum levels of plants infected with Panama disease has been investigated. Researchers have looked at the effect of applying urea to both the soil surface surrounding infected plants as well as infected pseudostems.

Two field trials conducted at Duranbah in New South Wales used a site infested with Panama disease race 1. In the first field trial, Dwarf Ducasse plants showing symptoms of Panama disease race 1 were cut off at ground level. The growing point was then gouged out and a 1 m² area was treated around each plant. All gouged corms were treated with 200 g of urea and the 1 m2 areas around the plants were treated with either:

urea (1 kg/m²) and covered with black plastic
urea (1 kg/m²), watered in (10 L) and covered with black plastic
urea (1 kg/m²), Basamid® (500 g/m²), watered in (10 L) and covered with black plastic
plastic only
untreated.

Soil samples were taken from the treatment areas 6 and 15 days after the treatments were applied. The soil was analysed to determine the ammonium content in surface (0-5 cm) and subsurface (5-15 cm) soil and the populations of Fusarium oxysporum in the subsurface samples (5-15 cm).

So what happened under these treatments?

As expected the ammonium levels were significantly greater in the soil treated with urea. As a result the number of Fusarium oxysporum spores in the soil (including the strain that causes Panama disease race 1) measured by the number of colony forming units (cfu) was significantly reduced.

The table below shows the levels of ammonium (ppm) in the soil 6 and 15 days after treatment application.

Means in each column with the same letter are not significantly different at 5% level (P<0.001). For example at 15 days after treatment at surface depth (0-5 cm) there was no significant difference between untreated and plastic. However, there was a significant difference between urea and all the other treatments (15 days at surface depth 0-5 cm).

The graph below shows the significant reduction in cfu under the urea treatments.

The second field trial investigated the method of cutting up infected pseudostem material and placing it into bags with urea. To test this technique Dwarf Ducasse plants infected with Panama disease race 1 were cut into 15 cm length and placed inside heavy duty plastic garbage bags. Some of the bags included 1 kg of urea and some bags contained no urea. After 6 weeks pieces of vascular tissue were plated out to determine the survival of the fungus. There was no recovery of the fungus that causes race 1 in any of the bags which were treated with urea. There was some reduction in survival of the fungus in the untreated bags, but the pathogen was still recovered.

So what does this all mean...

These field trials confirm that the current method for dealing with infected plants does significantly reduce the amount of inoculum in banana paddocks infested with Panama disease.

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 Biosecurity Queensland’s Panama TR4 Program and the Fusarium Wilt Tropical Race 4 – Biosecurity and Sustainable Practices project (BA14013). This project (BA14013) 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.

Reducing inoculum – Lab trials

Posted on 2018-02-22 by Better Bananas

Lab trials - reducing inoculum

To reduce disease inoculum levels, researchers have investigated the practice of using high rates of urea on the soil surface immediately surrounding infected plants.

Lab trials at South Johnstone used a soil bioassay with spores of Fusarium oxysporum f.sp. cubense (Foc), the fungus that causes Panama disease race 1. This was used as surrogate for tropical race 4. The inoculated soil was treated with one of the following treatments:

‘control’ – no urea or lime treatment
urea (rate equal to 0.5 kg/m²)
lime (rate equal to 0.5 kg/m²)
both lime and urea (rate equal to 0.5 kg/m²).

Interestingly, Foc was not recovered from soil that was treated with urea and the urea/lime combination. Foc was however recovered from soil treated with lime only, proving the application of lime on its own as ineffective at reducing inoculum levels.

Outcomes...

Lab trial results have shown that both urea and the combination of urea and lime at the specified rates are effective at killing the spores that cause Panama disease race 1.

Further lab investigations

Further trial work has evaluated the effectiveness of lower application rates of urea as well as chemical alternatives that are suggested to be toxic to Foc. The same bioassay using soil in jars was used to determine the effectiveness of the following treatments:

potassium chlorate @ 4, 8 and 16% (w/v)
sodium nitrite at 200, 400 and 800 ppm
nitrite at 200 and 400 ppm
lower rates of urea (rate equal to 0.031, 0.062, 0.125, 0.25 and 0.5 kg/m²).

These investigations showed that urea applied at 0.062 kg/m² or greater prevented Foc recovery from soil. All the other chemical alternatives were not effective at reducing the recovery rate of Foc.

Additional trials have investigated the effectiveness of different urea rates (between 0.031 and 0.062 kg/m²) and further explored alternative sources of ammonium. This time the effect of urea, ammonium nitrate + potassium hydroxide and aqueous ammonia were assessed. The trial showed that ammonia (NH₃) from any source that produces a concentration equal to or above 2500 ppm was effective at preventing Foc from being recovered from the soil.

So what does this all mean?

These lab trials show the current methods for dealing with infected plants using urea (1 kg per square metre) would significantly help in reducing the amount of inoculum in infested banana paddocks. The trials further show that ammonia, rather than other gasses produced during the breakdown of urea, is likely to be responsible for the toxic effect on the fungus.

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

This trial was funded as part the Fusarium Wilt Tropical Race 4 – Biosecurity and Sustainable Practices (BA14013) project, 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.