Source: ABC News (Australian Broadcasting Corporation) [summ. Mod.DHA, edited]
Banana freckle has been found in the Northern Territory [NT] again, 3 years after it was officially declared to be eradicated [see links below]. The disease has been confirmed south of Darwin. It is too early to determine the source or the potential spread of the disease.
The outbreak has been detected on dwarf cavendish bananas and surveillance for the extent of the infestation has started. It may be limited to a few properties in the area or may be widespread. Restrictions were placed so far only on the affected property. It is too early to say if more restrictions or an eradication program will follow.
The 2013 outbreak cost AUD 26 million [about USD 18.8 Million]. Thousands of banana plants were removed and the NT commercial banana industry was essentially wiped out. Authorities are asking NT residents to be vigilant and report any freckle symptoms.
[Byline: Matt Brann]
[Banana freckle disease is caused by several fungi of the genus _Phyllosticta_. It affects the leaves and fruit of _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 windblown water droplets over short distances. Long distance spread occurs mostly with infected plant material. Disease management may include fungicide 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). 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, e.g., 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.
Australia (with states):
Banana freckle, fruit symptoms:
Banana freckle, leaf symptoms:
Information on banana freckle disease:
http://www.padil.gov.au/pests-and-diseases/Pest/Main/136600 (with pictures),
http://www.daff.qld.gov.au/plants/health-pests-diseases/a-z-significant/banana-freckle, and via
Previous banana freckle outbreak in NT:
_Phyllosticta_ species and strains:
_P. cavendishii_ taxonomy:
Genus _Phyllosticta_ taxonomy and species list via:
Cultivars and hybrids of banana and plantain: