Have you seen banana freckle?
A suspected case of banana freckle has been detected on Cavendish bananas in the Northern Territory.
If you suspect banana freckle on your plants, report symptoms to Biosecurity Queensland on 13 25 23.
Three closely related species have been found to cause freckle disease of banana: Phyllosticta maculata, Phyllosticta cavendishii and Phyllosticta musarum. Phyllosticta maculata is endemic to Australia and the Torres Straits Islands and causes minor disease. Phyllosticta cavendishii and Phyllosticta musarum are both exotic to Australia. Phyllosticta cavendishii is capable of infecting Cavendish and is the pathogen which has recently been found in the Northern Territory.
Severe infection results in yellowing of the leaf, which withers and dies. The disease may also cause blemishes on fruit.
Large and small spots are found on leaves and also on fruit. The most characteristic symptom of both types of spot is a sandpaper feel to the leaf and fruit. This is caused by the fungal structures protruding through the surface of the leaf.
Both the large and small spots are dark brown to black in colour. The small spots are less than 1mm in diameter and appear sooty. They can run together to form streaks. The larger spots are up to 4mm in diameter and can also appear as streaks. Sometimes the centre of these larger spots are lighter in colour. Spots can also appear on the midrib of the leaf and on the petioles.
|Where is it now?|
A suspected case of banana freckle has been detected on Cavendish bananas near Darwin in the Northern Territory. It was detected on a residential property and has not been detected on any commercial banana farm.
There have been two suspected detections of banana freckle on Cavendish bananas in Western Australia at Kununurra in 1979 and Kalumburu in 2001. In both instances, the incursions were small and all infected plants were destroyed.
In Queensland, a form of freckle disease has been found on islands in Torres Strait and on Cape York Peninsula, but not in banana production areas. It has been seen on cooking bananas such as Bluggoe, but not on dessert bananas such as Cavendish and Lady Finger. Freckle also occurs on cooking bananas in Papua New Guinea, other areas of south-east Asia, and possibly India, the Caribbean and central Africa.
However in the Philippines and Taiwan (and possibly India, Borneo and Java), a form of freckle disease is also found on Cavendish bananas.
|How is the disease spread?|
Banana freckle is a 'wet spore' organism. It generally moves short distances through droplet splash. Banana freckle may also be spread through the movement of infected plant material and fruit.
Some chemical treatments, which are used to control yellow Sigatoka, may provide control of freckle. Mineral oil alone is thought to be ineffective. The use of a plastic bag cover over the bunch may in the long run be the most economical control for freckle.