A banana-killing fungus that has killed crops in Asia and Australia for decades has now reached the shores of America for the first time triggering Colombia to declare a national emergency.
The fungus, known as Fusarium wilt tropical race 4 (TR4), is likely to hit the crop not this year alone but for decades. Scientists from the Colombia Agricultural Institute estimate that TR4 has spread beyond a quarantine zone in the north of Colombia in about 175 hectares.
Officials quarantined four farms on the Guajira Peninsula in June, when they first suspected that TR4 was killing banana plants in the region. But now they fear that the fungus has spread beyond the containment zone.
TR4 infects all varieties of banana, especially the Cavendish, which is the main variety sold in departmental stores and exported internationally. "These epidemics develop slowly, so (it) will take some time (to spread)," says Randy Ploetz, a plant pathologist at the University of Florida in Homestead. "But eventually, it will not be possible to produce Cavendish for international trade."
The fungus TR4 was found destroying Cavendish crops in Asia in the 1990s, then spread to Australia and, later, Africa. It infects banana plants through the roots and spreads throughout the vascular system, starving the plant of water and nutrients. The fungus also spreads when infected plants are shifted from one area to another, or through water and soil.
However, it can be controlled using fungicides and stop its spread first. The ICA in Colombia said that it has eradicated most of the plants from infected fields, but TR4 strain remains in the soil for roughly 30 years.
"Soil is very difficult to contain," says Fernando García-Bastidas, a plant pathologist at KeyGene in Wageningen, the Netherlands, who led the TR4 testing effort. "Who knows how many cars and people have entered that farm and carried it elsewhere?" Containment can slow its spread but once TR4 arrives somewhere, it's almost impossible to eradicate, added García-Bastidas.
