Global Plant Protection News

Saturday, 16 July 2022 17:42:00

Grahame Jackson posted a new submission ‘FRECKLE DISEASE, BANANA – AUSTRALIA (02): (NORTHERN TERRITORY)’

Submission

FRECKLE DISEASE, BANANA – AUSTRALIA (02): (NORTHERN TERRITORY)

ProMED
http://www.promedmail.org

Source: Mirage News, NT Government report [summ. Mod.DHA, edited]
https://www.miragenews.com/banana-freckle-detected-at-additional-sites-top-817527/

Banana freckle has now been detected at 13 sites in the Northern Territory’s northern regions. They include 12 infected premises, as well as a single plant in a secure area of a government research facility.

Additional testing is underway at the government facility, and all banana plants at the site will be destroyed and disposed of on site. Testing on 4 further properties is also underway.

Surveillance is continuing to determine the extent of the outbreak, with more than 130 properties examined so far. Survey officers are following strict biosecurity protocols to prevent the spreading of the disease.

—
Communicated by:
Dr G Jackson, PestNet
http://www.pestnet.org

[Banana freckle (BF) disease is caused by several fungi of the genus _Phyllosticta_. It affects the leaves and fruit of the _Musa_ species. Symptoms include dark spots resulting in a rough surface (“sandpaper feel” due to protruding fungal structures); leaf streaking and yellowing; as well as loss of plant vigour. Severe infections may lead to wilting and death of plants. Fruit yield and quality can be reduced significantly.

The fungi are spread on individual plants by spores moving in water on the leaf or fruit surface, or within plantings by wind blown water droplets over short distances. Long distance spread occurs mostly with infected plant material. Disease management may include fungicides and cultural techniques (such as bagging of fruit bunches). Antagonistic fungi in the genus _Trichoderma_ have been shown to be effective as biocontrol organisms to suppress various fungal pathogens including _Phyllosticta_. spp (see previous ProMED posts in the archives).

Previously, freckle disease on different banana cultivars was considered to be caused by strains of _P. maculata_ with different host specificities. However, these have recently been reclassified as different species (see link below). In Australia, freckle had previously been reported on lady finger and cooking varieties of banana, but the pathogen affecting Cavendish varieties (which include most of the commercial eating bananas; see link below) was reported for the 1st time from the NT in 2013 (ProMED post 20130829.1910083).

This fungus, now called _P. cavendishii_, was known to occur in several countries in South East Asia, but there were only unconfirmed reports of possible pre-2013 occurrences in Australia. During the post-2013 eradication programme, all banana plants in NT were destroyed; in 2019, Australia was declared free of banana freckle again (see links below). The initial detection of this new outbreak occurred on a single plant only a few weeks earlier (ProMED post 20220603.8703654) when surveillance for the extent of the infestation was started. Eradication of established crop diseases has hardly ever succeeded anywhere; hence it will be important to investigate the source of this new outbreak.

Other species in the genus cause, such as citrus black spot (_P. citricarpa_), as well as leaf spot of coffee (_P. coffeicola_) and ginger (_P. zingiberis_). For more information see previous ProMED posts in the archives.

Maps
Australia (with states):
https://www.nationsonline.org/maps/australia-political-map.jpg and
https://promedmail.org/promed-post?place=8704439,292

Pictures
BF fruit symptoms:
http://www.daff.qld.gov.au/__data/assets/image/0020/62147/varieties/thumb-500.jpg and
https://www.agric.wa.gov.au/sites/gateway/files/NTPDs%2021938%20%20by%20Jose%20Liberato%20IMG_4594.jpg
BF leaf symptoms:
http://www.daff.qld.gov.au/__data/assets/image/0009/56295/varieties/thumb-500.jpg,
https://www.dpi.nsw.gov.au/__data/assets/image/0015/800043/BananaFreckle2.jpg,
http://international-pest-control.com/wordpress/wp-content/uploads/2015/05/OPM_April_LOW-RES_page31_image2.jpg, and
https://www.agric.wa.gov.au/sites/gateway/files/styles/page_featured_image/public/NTPds%2022140%20%20by%20Jose%20Liberato%20IMG_4704.jpg
Close-up of BF leaf spots:
https://media.padil.gov.au/Species/136600/3867-large.jpg and
https://apps.lucidcentral.org/ppp_v9/images/entities/banana_freckle_124/earlyfreckle.jpg
BF symptoms & pathogen, photo gallery:
https://www.researchgate.net/profile/Cassie-Mcmaster/publication/336655866/figure/fig1/AS:835112132427777@1576117656201/Freckle-disease-Phyllosticta-cavendishii-on-Cavendish-banana-cultivar-a-Symptoms-on.png

Links
Information on banana freckle disease:
http://www.padil.gov.au/pests-and-diseases/Pest/Main/136600 (with pictures),
http://www.planthealthaustralia.com.au/wp-content/uploads/2013/01/Banana-freckle-FS.pdf,
http://www.planthealthaustralia.com.au/pests/banana-freckle/,
http://www.daff.qld.gov.au/plants/health-pests-diseases/a-z-significant/banana-freckle and via
http://www.farmbiosecurity.com.au/crops/fruit-nuts/fruit-nut-pests/banana-pests/
Previous BF outbreak in NT:
http://www.abc.net.au/news/2014-03-11/freckle-update/5313142,
http://www.abc.net.au/news/2014-01-09/freckle-update/5192754,
https://www.abc.net.au/news/rural/2014-10-16/timeline-banana-freckle-northern-territory/5808542,
https://www.abc.net.au/news/rural/2017-06-19/banana-freckle-restrictions-to-be-lifted-in-nt/8631086, and
https://www.abc.net.au/radio/programs/nt-country-hour/northern-territory-declared-free-of-banana-freckle/10771100
_Phyllosticta_ species and strains:
https://doi.org/10.1007/s13225-012-0182-9
_P. cavendishii_ taxonomy:
http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=564747
Genus _Phyllosticta_ taxonomy and species list via:
http://www.indexfungorum.org/Names/Names.asp
Cultivars and hybrids of banana and plantain:
http://www.plantnames.unimelb.edu.au/Sorting/Musa.html
– Mod.DHA]