Coffee rust is coming for your morning brew, Guelph prof says

The price of your morning coffee could be on the rise thanks to a crop-destroying disease exacerbated by climate change, according to a Guelph academic. 

It's called "coffee leaf rust," caused by a brown fungus that infects the leaves of the prized coffea arabica species. The rust limits the plants' yield, often for multiple growing seasons.

"One British botanist described these fungi as 'vampires of the vegetable world," said Stuart McCook, a professor of history at the University of Guelph, and author of Coffee is Not Forever: A Global History of the Coffee Leaf Rust.

McCook's book chronicles the history of the disease and its journey along trade routes through the world's coffee growing regions.


One outbreak in Ceylon — modern day Sri Lanka — devastated the coffee crop in the 1860s and caused the island to abandon coffee for tea, a product it is now world famous for. 

In recent years, outbreaks have been especially severe in Latin America, from the Andes through to Central America.

Worsened by climate, economic change  

Climate change can make outbreaks more frequent and more severe. 

"The fungus life cycle is very, very sensitive to changes in environmental conditions," he said.

"If rainfall patterns change or there are, perhaps, slight increases in temperature, it can have really significant impacts on how devastating this disease is."

He said, added economic factors, like the removal of protective trade agreements, have contributed to a volatile situation for farmers.  

'Farmers not paid enough'

"In Latin America, the rust has definitely had an impact on farmers," said Bill Barrett, founder of Planet Bean Coffee in Guelph.

He buys his coffee through the fair trade certification system — so he's already paying higher prices than he would through the conventional market. Even so, he said his suppliers aren't immune to coffee rust. 


Barrett said he works with one Peruvian producer who recently lost between 70 and 80 per cent of its coffee plants to the fungus. 

With farmers so close to the margins, said Barrett, we should consider why industry pays so little for something we consume so much of. 

"Farmers are not paid enough," he said. "Big, mainstream coffee companies have to belly up and pay a fair price."