Banana freckle

Banana freckle (Phyllosticta cavendishii) is an exotic plant pest on Cavendish bananas. This disease is a serious threat to Australia’s banana industry.

Banana freckle causes spotting on banana leaves and fruit. Spotting may extend to the flower bracts, leaf midrib and bunch stalks under conditions which favour infection. The blemishes on fruit reduce their commercial value. Eating qualities are not affected and there is no risk to human health from eating banana freckle infected bananas.

In Australia banana freckle is an established plant pest on Lady Finger bananas but not on Cavendish bananas. Please report suspect symptoms on Cavendish bananas.

Notifiable status

Banana freckle (Phyllosticta cavendishii) is a notifiable plant disease in NSW.

All notifiable plant pests and diseases must be reported within 1 working day.  You can report notifiable plant pests and diseases by one of the following methods:

• Call the Exotic Plant Pest Hotline 1800 084 881
• Email biosecurity@dpi.nsw.gov.au with a clear photo and your contact details
• Complete an online form

A full list of notifiable plant pests and diseases can be found in Schedule 2 of the NSW Biosecurity Act 2015.

Description

Fungal infection and disease symptoms can occur on both young and old leaves. Two types of leaf spot symptoms have been described.

One type of leaf spot consists of very small (less than 1 mm) dark brown to black spots mainly on the upper surface of the leaf giving the leaf a sooty appearance (Figure 1). Spores develop from these spots and protrude slightly making the surface of the leaf feel rough.

Spots can cluster in streaks that may run diagonally or horizontally across the leaf. In other cases these streaks run along the leaf veins from the midrib to the edge of the leaf. Yellowing of the leaf occurs where spotting is severe (Figure 2).

The second type of spotting is characterised by larger (up to 4 mm in diameter) individual dark brown to black spots. These spots may have grey centres and can aggregate to form large blackened areas or streaks with yellowish green haloes.

The spots give the leaves a rough feel. Severely affected leaves turn yellow, wither and die prematurely. When the leaf collapses as a result of infection it provides an abundant source of inoculum for the pathogen to spread to lower leaves and the developing fruit.

Fruit is susceptible to infection from the time of bunch emergence until maturity. On very young fruit individual spots first appear as small red brown flecks surrounded by a halo of dark green water-soaked tissue.

Secondary infections increase disease severity as fruit matures (Figure 3).

Hosts

The principal hosts of banana freckle are Musa species, including a range of edible banana and plantain cultivars.

Spread

Short distance spread of banana freckle occurs as fungal spores are dispersed from infected banana plants and debris by rain splash and wind-blown rain. Moisture is essential for spore dispersal.

Long distance spread occurs through the movement of infected fruit and infected leaves.

Distribution

Banana freckle has been recorded in 27 countries across South-east Asia, Oceania and India.

The fungus Phyllosticta maculata which infects Lady Finger and Bluggoe bananas occurs in Australia.

The fungus Phyllosticta cavendishii which infects Cavendish bananas is not considered established in Australia. The Northern Territory is currently responding to an outbreak of banana freckle in Cavendish bananas.

Actions to minimise risks

Put in place biosecurity best practice actions to prevent entry, establishment and spread of pests and diseases:

• practice “Come clean, Go clean”
• ensure all staff and visitors are instructed in and adhere to your business management hygiene requirements
• source propagation material of a known high health status from reputable suppliers
• monitor your banana plants and fruit regularly
• keep records
• isolate banana plants or areas where suspect symptoms are observed