Early last century, the Fusarium fungus, causative agent of Panama disease, eliminated the Gros Michel banana variety. Farmers then opted for the resistant Cavendish banana, but now a new Fusarium strain, TR4, is threatening this very popular banana variety too. Colombian and Wageningen researchers may have found a solution. Treatment with a non-virulent Fusarium strain stops the disease symptoms, they write in PLOS ONE.

Using a non-virulent, i.e. non-pathogenic, variant of a pathogen to combat plant diseases is a well-known strategy. This led PhD student Fernando García-Bastidas and his supervisor Gert Kema of Wageningen University to the idea of testing this approach in bananas as well. They combined several non-virulent Fusarium strains with the pathogenic TR4 strain (Tropical Race 4). ‘And for the combination Race 1 and TR4, the results were fantastic,’ says García-Bastidas. Cavendish banana plants first treated with the non-pathogenic Race 1 strain showed much less disease symptoms after infection with TR4 than untreated plants.

Gene transfer

‘Unfortunately, Race 1 is also still a pathogen,’ says García-Bastidas. This strain does affect many other banana varieties and so cannot be used without restriction. ‘In addition, we know from