Banana Research – Page 5

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.

Resistance to current post-harvest chemical trials

Posted on 2018-02-03 by Better Bananas

Resistance to current post-harvest chemical trials

Lab testing used to indicate whether a fungal organism has developed resistance to a particular post-harvest fungicide is commonly termed ‘sensitivity testing’. Sensitivity testing has been carried out on the two registered post-harvest products (prochloraz – Protak® and thiabendazole – Tecto®), against each of the four fungi known to be responsible for causing crown end rot (Fusarium spp., Colletotrichum musae, Musicillium theobromae and Thielaviopsis musarum, commonly known as Chalara).

The fungal organisms listed above were collected from both Cavendish and Lady Finger fruit and from different growing regions including the coastal production area of Far North Queensland, the Atherton Tablelands and northern New South Wales. Where possible the fungi were also sourced from fruit that had not been exposed to commercial management practices (backyard production) in order to provide a suitable comparison.

These results show that it may be necessary to change your post-harvest treatment products, depending on the organism/s you are having issues with and the location of your farm.

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.

Time in supply chain studies

Posted on 2018-01-31 by Better Bananas

Time in supply chain studies

The length of time bananas spend in the supply chain can have a significant impact on the development of crown end rot (CER).
Researchers conducted a simulation experiment, where Cavendish (Williams) and Lady Finger clusters were held 1, 2, 3 and 4 weeks prior to being ripened. The fruit for the experiments was sourced from a commercial property and all fruit was treated with a post-harvest chemical (prochloraz). To ensure a fair comparison, fruit from different positions in the bunch (top, middle and bottom hands) were assessed in case this was also a contributing factor. Once the fruit was ripened, the symptom development of CER was rated on a scale of 0-7 (7 being the most severe).

As seen in the graph below, the experiment with Cavendish fruit revealed fruit held longer within the supply chain resulted in relatively more severe symptoms of CER than fruit that would generally move through quicker. However, the overall symptom development was low as you can see in the graph below.

As seen in the figure below, the simulation experiment using Lady Fingers showed similar results to Cavendish fruit in that fruit held for longer prior to ripening produced more severe symptoms of CER. However the overall symptom development was low as you can see in the graph below.

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.

Crown end rot

Posted on 2018-01-18 by Better Bananas

What is it?

Crown end rot (CER) of bananas is a serious cause of post-harvest quality loss for banana fruit. As the name suggests, the rot begins at the cut surface of the crown, and depending on the severity, can extend down the neck of the fruit and into the fingers. There are several fungi that can cause CER symptoms and the visual appearance of those symptoms may indicate what fungal organism is responsible. However, multiple fungi can simultaneously cause symptoms, so it can be difficult to distinguish the difference with the naked eye.

The following fungi can cause crown end rot in bananas:

Fusarium equiseti-incarnatum species complex

Musicillium theobromae

Colletotrichum musae

Thielaviopsis musarum (commonly known as Chalara).

More info...

Click here for more information and photos of the symptoms typically associated with each fungal organisms.

How do you manage crown end rot?

Currently, the most effective management strategy for CER is the application of post-harvest fungicides. Products containing thiabendazole (e.g. Tecto®) and prochloraz (e.g. Protak®) are registered for post-harvest use in bananas.

Recent research has indicated that some of the organisms that cause CER are less sensitive to thiabendazole based products, particularly in the coastal regions of Far North Queensland. These organisms remain more sensitive to products containing prochloraz. Simulation studies have also shown that the longer banana fruit is held in the supply chain before ripening, the greater the risk of developing more severe symptoms of CER. Research has also investigated alternative post-harvest products.

See below for more information on this research.

More info...

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 Department of Agriculture and Fisheries and contributions from the Australian Government. Hort Innovation is the grower-owned, non-for-profit research and development corporation for Australian horticulture.

Panama disease

Posted on 2018-01-15 by Better Bananas

Panama disease research and development

Panama disease is a soil borne disease caused by the fungus Fusarium oxysporum f.sp. cubense. Different strains of the disease are known as races. The most notable races that affect bananas include:

Race 1 – infects Lady Finger and Ducasse bananas but not Cavendish.
Subtropical race 4 – infects Lady Finger, Ducasse and Bluggoe, as well as Cavendish bananas in subtropical regions of Australia.
Tropical race 4 – is the most virulent race, affecting most varieties of bananas including Cavendish.

In March 2015, Panama disease tropical race 4 was detected in the main growing region in Far North Queensland. Over 95% of Australia’s bananas are Williams Cavendish. This variety is susceptible to the disease and therefore slowing the spread is vital to allow time to find solutions to protect our $600 million banana industry.

Our Australian researchers are focused on various aspects of the disease, and we will continually update this website with the latest Panama R&D outcomes as they become available.

More information...

For more information on how to protect your farm from Panama disease TR4, visit the Panama TR4 protect website panamatr4protect.com.au. The website provides information and practical advice for all banana growers and community members on how to protect our banana farms and our communities.

Biosecurity assistance is available

The National Banana Development and Extension Team are available to assist Australian banana growers who would like to start or make improvements to their biosecurity plan.
Contact our team today via email betterbananas@daf.qld.gov.au or phone 07 4220 4152.

Banana variety research

Posted on 2018-01-15 by Better Bananas

Banana variety research — the search for new resistant varieties

The search for new banana varieties that have both desirable agronomic characteristics and resistance to pests and diseases, especially Panama disease tropical race 4, is a current hot topic in the banana industry. This page gives you background into banana breeding techniques and links you to the latest progress updates from industry funded variety trials.

How do you 'breed' a new banana variety?

The development of new banana varieties is a slow and costly process, with high levels of infertility making it difficult to do conventional breeding from some commercially important varieties like Cavendish.

Banana breeding techniques fall into three broad categories:

Conventional breeding is when fertile male and female lines are crossed using pollen to produce seeds. The seeds are germinated and the seedlings are screened for the desired improved attributes. This method is extremely time consuming and labour intensive, however, there are many benefits by using and introducing the wider range of genetic diversity from wild banana cultivars. Improved banana cultivars are imported into Australia for evaluation.

Mutation breeding and somaclonal variation uses induced mutations in existing cultivars to produce plants with desirable attributes such as pest or disease resistance, improved plant stature and increased yield.
Selection of improved cultivars via somaclonal variation (off-types), induced by plant tissue culture, was pioneered by the Taiwan Banana Research Institute (TBRI) to develop Cavendish varieties with increased levels of resistance to Panama disease tropical race 4.

Mutagenesis applies chemical or gamma irradiation treatment to tissue cultured plants to fast track genetic changes, thereby causing a higher rate of off-type plants than somaclonal variation induced by tissue culture alone. Australian scientists were at the forefront of developing and using this method in banana in the 1990s. Both methods produce plants with potentially desirable characteristics, however, there are also many plants that have detrimental changes.

Genetic modification involves the manipulation of the banana DNA, by inserting identified genes for desirable characteristics from bananas or other organisms. Newer techniques include the manipulation of the plant’s own genes without the introduction of any external genetic material.

What types of 'breeding' is the banana industry investing in?

There are two key variety initiatives funded by the Australian banana industry. Currently through the project Improved Plant Protection for the Banana Industry (BA16001), which is part of the Hort Innovation Banana Fund, the industry is continuing to invest in variety importation and screening. This means that we import varieties – either from conventional breeding programs or somaclonal selection programs, ensure they are disease free and trial them under research agreements with each respective breeding program.

There are three field screening sites for these varieties.

The second key activity under way is the use of somaclonal selection to develop resistant varieties. As mentioned earlier, somaclonal selection relies on induced mutations in existing varieties, to produce plants with desirable attributes such as, pest or disease resistance, improved plant stature and increased yield. To increase the amount of variation of somaclonal selections, researchers are using mutagenesis to induce genetic mutations in selected cultivars by means of gamma irradiation. As part of this work, four varieties that have improved levels of resistance to Panama disease tropical race 4 have recently undergone mutagenesis to improve their agronomic characteristics.

Did you know...

Department of Agriculture and Fisheries scientists, used mutagenesis in the early 1990s to develop DPM25 as a Cavendish selection. DPM25 has acceptable resistance to Panama disease subtropical race 4 and similar yield as Williams. It was developed from the Extra Dwarf Cavendish, Dwarf Parfitt, using tissue culture and gamma irradiation.

Steering the direction for variety R&D

With the limited resources available and the high priority for identifying resistant varieties, it is essential that the research and development investment decisions, represent the best value for the Australian banana industry. A key part of this is the development of the Banana Variety Subcommittee (BVS). The BVS consists of banana growers, supply chain businesses and researchers, and focuses on the broad strategic issues associated with variety importation and development. If you have any questions please don’t hesitate to talk to one of the BVS members or contact the better bananas team via email betterbananas@daf.qld.gov.au or phone 13 25 23.

The mutagenesis trial work is part of the Fusarium Wilt Tropical Race 4 Research Program (BA14014), which is funded by Hort Innovation, with co-investment from the Queensland Department of Agriculture and Fisheries and contributions from the Australian Government.

The variety importation and screening activity is part of the Improved Plant Protection for the Banana Industry Program (BA16001). This project has been 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.