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A banana killer fungus that has been destroying crops in Asia and Australia for decades is now in the Americas, which produce the majority of world banana exports.
Colombia declared a national emergency on August 8th after laboratory results confirmed the presence of the fungus, known as Fusarium wilt tropical race 4 (TR4), within its borders. This marks the first confirmation of TR4 in the Americas. The Agricultural Institute of Colombia (ICA), a federal agency responsible for monitoring agricultural health in the country, says about 175 hectares have been affected so far.
Authorities quarantined four farms on the Guajira Peninsula in the north of the country in June, when they suspected for the first time that TR4 was killing banana trees in the region. But scientists now fear that the fungus has spread beyond the containment zone and could threaten banana production in the Americas for decades to come.
TR4 infects several varieties of bananas and plantains, but is particularly harmful for Cavendish, the main variety sold in grocery stores and accounting for the largest share of international exports.
"These epidemics are developing slowly, so the [spread] It will take time, "says Randy Ploetz, phytopathologist at the University of Florida at Homestead. "But ultimately, it will not be possible to produce Cavendish for international trade."
The TR4 strain, which began destroying Cavendish cultures in Asia in the 1990s, then spread to Australia and then to Africa, infects the banana through the roots and spreads throughout the vascular system, depriving the plant of its water and nutrients. The fungus can be transmitted by moving infected plants from one place to another, or in the water and soil.
It can not be controlled with fungicides. The main way to combat TR4 is to try to prevent its spread (see "In the Americas"). ACI claims to have removed most of the plants from the infected fields, but TR4 can remain in the soil for about 30 years.
"The soil is very hard to contain," says Fernando García-Bastidas, phytopathologist at KeyGene in Wageningen, The Netherlands, who led the TR4 trials on Colombian specimens. "Who knows how many cars and people have entered this farm and have [the fungus] Containment efforts can slow the spread of the fungus, and Colombia is doing everything in its power, says García-Bastidas, but once TR4 arrives somewhere, it's almost impossible to eradicate it.
This article is reproduced with permission and was published for the first time on August 19, 2019.
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