Outbreak of freckle disease (Phyllosticta cavendishii) on Cavendish bananas in Australia and the initial biosecurity response

Abstract

Phyllosticta cavendishii has been recorded in the Northern Territory (NT) of Australia occurring on non‐Cavendish bananas since 1991. The race of P. cavendishii that infects Cavendish bananas is considered exotic to Australia and classified as an emergency plant pest. In July 2013, P. cavendishii was detected on Cavendish bananas near Darwin, NT. Here, the diagnoses and field observations carried out during the Incident Definition Phase of the national biosecurity response, from July 2013 to October 2014, are reported. Of 1395 banana samples collected from 676 properties, 480 were positive for freckle disease, including 463 samples with P. cavendishii and 17 samples with P. maculata. Phyllosticta cavendishii was detected in 256 properties, including 62 properties where it was detected on Cavendish banana plants, within six distinct geographical zones across the NT. Phyllosticta cavendishii was detected on two cultivars within the Cavendish subgroup and six non‐Cavendish cultivars. Multigene characterization of Phyllosticta cultures showed that P. cavendishii was isolated from both Cavendish and non‐Cavendish cultivars. Multilocus phylogeny analyses also revealed that the P. cavendishii strain in the outbreak had identical sequence similarity to the holotype (CBS H‐20918) clade 2 P. cavendishii isolates that infect both Cavendish and non‐Cavendish cultivars in Southeast Asia and Oceania. The genetic data in this study showed that there was one P. cavendishii strain infecting both Cavendish and non‐Cavendish cultivars in the outbreak. However, historical data and field observations provided anecdotal evidence for the existence of two races of P. cavendishii, including one that does not infect Cavendish bananas.

Dissipation and Distribution of Prochloraz in Bananas and a Risk Assessment of Its Dietary Intake

“…However, many diseases may affect the quality of the banana before it is harvested [9][10][11]. Banana freckle is an economically significant disease on banana plantations; the disease causes pinhead-sized black spots on affected leaves and fruits [12]. For countries such as India which produce bananas for export, the infectious freckle disease makes the fruit less desirable [13].…”

Evaluation of NGS DNA barcoding for biosecurity diagnostic applications: case study from banana freckle incursion in Australia

“…P. cavendishii is classified as a high priority pest of banana in Australia. It was detected on Cavendish bananas in the Northern Territory, Australia in 2013 and was eradicated in 2019 (McMaster et al 2020).…”

First report of Phyllosticta spp. associated with banana freckle disease in southern Lao PDR

“…Banana freckle disease is caused by species of Phyllosticta, including P. musarum (reported from Malaysia, India and Thailand), P. maculata (American Samoa, Australia, Indonesia, Malaysia and Papua New Guinea), and P. cavendishii (Taiwan, Indonesia, Vietnam, Timor Leste, Malaysia, United States of America, Federated States of Micronesia, Tonga and Australia) (Wong et al 2012;McMaster et al 2020). There is some evidence of host specificity of Phyllosticta species on banana, with P. cavendishii, thus far the only Phyllosticta species associated with disease symptoms on 'Cavendish' banana (Wong et al 2012).…”