Vandermeer suspects that the shift to sun coffee may be contributing to the severity of the latest coffee rust outbreak. The move to sun coffee results in a gradual breakdown of the complex ecological web found on shade plantations. One element of that web is the white halo fungus, which attacks insects and also helps keep coffee rust fungus in check.
Both the widespread use of pesticides and fungicides and the low level of biodiversity found at sun-coffee plantations have likely contributed to the decline of white halo fungus in recent years, Vandermeer said. Without white halo fungus to restrain it, coffee rust, also known as roya, has been able to ravage coffee plantations from Colombia to Mexico, he said.
"What we feel has been happening is that gradually the integrity of this once-complicated ecosystem has been slowly breaking down, which is what happens when you try to grow coffee like corn," Vandermeer said.
"And this year it seems to have hit a tipping point, where the various things that are antagonistic to the roya in a complex ecosystem have declined to the point where the disease can escape from them and go crazy."
The big unanswered question is whether the current outbreak is a freak one-time event or the first look at a new normal for the region.
"It could be that this disease is just going to run itself out this year and will then return to previous levels," he said. "Or it could be that it now becomes a relatively permanent fixture in the region. The path this disease takes will have huge implications for the region's coffee producers."
Coffee rust is the most important disease of coffee worldwide. It was first discovered in the vicinity of Lake Victoria in East Africa in 1861 and was later iden
|Contact: Jim Erickson|
University of Michigan