Coffee rust fungus is threatening farmers and driving up prices

What is Coffee Rust?

The Coffee Rust is an obligate parasitic fungus, which means it is a microorganism that must take energy and nutrients from a specific live host (coffee) and reproduces differently than either plants or animals. Coffea arabica is the most susceptible species to this fungus, but C. canephora (Robusta) can also be affected. The fungal life cycle is a complex and ingenious one, where organisms asexually produce thousands of tiny spores (reproductive bodies) that can travel in water, rain, or air and remain viable for long distances (Kushalappa and Eskes 1989; Gouveia and others 2005). Once a spore lands on a leaf, it can sit until conditions are right. At that point, it germinates and enters the leaves through stomata, the pore-like openings utilized for plant gas-exchange (Muller and others 2009). The coffee rust is an obligate parasite to coffee, meaning that it must find a coffee host in order to complete its life cycle. Most scientists believe that it once had or still has alternative host, but one is yet to be identified. Despite the importance of this destructive organism there is still much to be learned on the biology of coffee rust.

Many blame climate change for this outbreak.  Yet there have been significant outbreaks in the past, including the collapse of the coffee industry in Ceylon in the 1870s (and since then the island shifted to tea production).  Climate may be a factor (as well as weather), but planting practices, natural cycles, and other variables all play a roll.