How to Treat Coffee Leaf Rust: Colombian Coffee Researchers Discover New Variant of Coffee Leaf Rust

New Aggressive Coffee Leaf Rust Variants Discovered in Colombia

Colombia's coffee growing organizations are urging farmers to switch to rust-resistant varieties after the discovery of more aggressive new variants of Coffee Leaf Rust (CLR).

The alarming findings come from Colombia's National Federation of Coffee Growers (FNC) and its research arm, Cenicafé. According to the organization, researchers have identified six new subspecies of leaf rust within the country, along with nine new destructive variants of the fungus.

By FNC estimates, roughly 84% of Colombia's coffee planting area is now occupied by trees carrying rust-resistant genes. The organization is quick to caution, however, that resistance to leaf rust is not the same as immunity.

"Like other microorganisms that survive in adverse and diverse environments, the coffee leaf rust fungus can change and mutate within its only host — both susceptible and rust-resistant coffee varieties," said plant pathology researcher Carlos Ariel Ángel in a statement from the organization. "This selection pressure and response is a normal biological dynamic by which the fungus attempts to adapt and survive. More than 50 of its mutant subspecies have already been identified worldwide, and new variants continue to be discovered in different countries."

Recommended Rust-Resistant Varieties

Given the spread of these new variants and subspecies, the FNC encourages growers to plant proven rust-resistant varieties such as Castillo, Cenicafé 1, Castillo zonales, or Tabi — varieties developed and promoted by the FNC and Cenicafé at different times.

The organization regards varietal selection as the first line of defense against the further spread of leaf rust, ahead of any fungicide program. This approach has been crucial ever since the 2012 leaf rust epidemic devastated crops across Colombia and much of Latin America.

According to FNC estimates, if left unmanaged, the disease can destroy anywhere from 30% to 80% of a coffee crop.

Impact on Global Coffee Production

Coffee leaf rust has been present in most coffee-producing countries for at least 150 years. Despite significant advances in variety research over the past decade, rust pathogens keep emerging, posing a direct threat to coffee farmers' livelihoods and to the global supply of Arabica beans.

Recently, coffee leaf rust was detected in Hawaii for the first time — a sobering reminder that no origin is immune.

FrontStreet Coffee Recommendation

Colombia's battle against leaf rust is also a story of remarkable cup quality preserved through decades of variety breeding. To taste what Colombian coffee is all about, try FrontStreet Coffee's Washed Huila. Huila, in the southern reaches of Colombia's central mountain range, is the country's most celebrated specialty region — rolling hills above 1,500 meters, watered by the confluence of the country's major rivers.

Roasted medium-dark, this washed Huila highlights dark chocolate, nutty sweetness, moderate body, and a smooth, rich mouthfeel. It works beautifully as pour-over or French press, and it also extracts superbly in a moka pot or espresso machine for Americanos and lattes.