Following outbreaks in Jordan and Mozambique just over a year ago and reports in Queensland, Australia in March this year, the Tropical Race 4 strain (TR4) of Fusarium oxysporum – the cause of Panama disease in Cavendish bananas – has now spread to Pakistan and Lebanon.
According to Wageningen University, these outbreaks have underlined the extent of the threat TR4 poses to global banana production.
Wageningen UR (University & Research centre) has joined forces with Asim Agriculture Farm in Pakistan and Debbane Agri Group in Lebanon to analyse samples from symptomatic plants, with the results published in the journal Plant Disease.
Pakistan and Lebanon
Hadi Bux Laghari from Asim Agriculture Farm in Tando Allahyar, Sindh, Pakistan, detected suspicious symptoms of wilt on banana plants and made an appeal on an online forum.
The Wageningen UR scientist Gert Kema offered to analyse samples of the plant. After several experimental steps, including DNA diagnosis, isolation of the fungus and infection of healthy banana plants in a contained greenhouse at Wageningen UR, Kema’s team concluded that TR had indeed reached Pakistan.
Further dissemination of the disease in the country is a grave concern: the pathogen was detected in an area which is prone to flooding and neighbours India, the world’s largest banana producer, with an annual production of nearly 30m tonnes.
A similar request reached Wageningen UR via Debbane Frères in Lebanon. Despite the small affected area of just a few hectares, alert growers raised the alarm and samples were dispatched and analysed at Wageningen. Once again, the diagnosis was TR4.
“It is unclear how the disease got in Pakistan, but we do know that it spreads very quickly," said Kema. "While the initial infected area was only six hectares, we have reports that over 100 hectares are now affected.
"This is more than a local issue – it is a threat to the entire region," he continued. "The appearance of the pathogen in Lebanon is most likely due to local transportation of infected plants, possibly from Jordan, which underscores the need for quarantine and awareness campaigns.”
Kema and his team are currently screening large numbers of bananas for resistance to Panama disease.
“There are many local banana varieties in addition to Cavendish,” Kema explained. “Our goal is to find fruits resistant to TR4 and to identify the responsible genes. Armed with this knowledge, we can start developing resistant bananas together with our partners.”