New study links COVID-19’s socioeconomic disruptions to disease threat in coffee industry

Study: Reduced crop care and investment in coffee farms brought on by economic impacts of COVID-19 pandemic will likely cause a spike in coffee leaf rust, a disease with the potential to decimate the global coffee industry. Coffee leaf rust was found in Hawai‘i for the first time last fall.

Two photos, one showing rust spots under the leaves of a coffee plant, the other showing rust spots on the top of the leaves.
Left, coffee leaf rust on the upper leaf surface. Right, CLR on the lower leaf surface. Photo: Cooperative Extension Service.

By Susan Enright

Chris Knudson
Chris Knudson

In a perspective just published, a geographer at the University of Hawai‘i at Hilo links the socioeconomic disruptions of the COVID-19 pandemic to a worsening epidemic of coffee leaf rust (CLR), a devastating plant disease threatening the global coffee industry.

In the study, Assistant Professor of Geography Chris Knudson and colleagues address how the COVID-19 pandemic is likely to worsen the global CLR epidemic. He is the co-author of the perspective, “Epidemics and the future of coffee production,” focusing on coffee leaf rust, the most significant coffee plant disease in the world. The researchers explore how the socioeconomic impacts from COVID-19 could lead to the re-emergence of another CLR epidemic.

“We describe how past CLR outbreaks have been linked to reduced crop care and investment in coffee farms, as evidenced in the years following the 2008 global financial crisis,” says Knudson.

In the perspective, the researchers discuss relationships between CLR incidence, agricultural practices, global economics, and local effects. “We contextualize how current COVID-19 impacts on labor, unemployment, stay-at-home orders, and international border policies could affect farmer investments in coffee plants and in turn create conditions favorable for future shocks,” states the study’s abstract.

Unfortunately, the disease was confirmed on Maui, Lāna‘i, and Hawai‘i Island late last year, a time when the local agricultural community was already struggling with systemic socioeconomic disruptions brought on by the pandemic.

“CLR was found in Hawai‘i for the first time last October,” says Knudson. “Until then, Hawai‘i was the only major coffee-growing region without CLR.”

Hawai‘i-grown coffee is the second most valuable commodity produced in the state, with annual production over $48 million. There are approximately 900 coffee farms throughout the islands.

According to the Cooperative Extension Service at UH Mānoa, coffee leaf rust is one of the most devastating pests of coffee plants and is established in all major coffee growing areas of the world. The first observable symptoms are yellow-orange rust spots, appearing on the upper surface of leaves. On the underside of the leaves, infectious spores appear resembling a patch of yellow- to dark orange-colored powder.

Rust colored spots on a coffee leaf.
A coffee leaf infected by coffee leaf rust (Hemileia vastatrix). Some small insects are also visible. Photographed in NW Rwanda, July 2011. Wikimedia.

The damage caused by coffee leaf rust is the result of reduced photosynthesis of infected leaves and premature defoliation or leaf drop associated with high infection levels. Vegetative growth and berry growth and size are reduced and is generally related to the amount of rust in the current year.

In the perspective, Knudson and colleagues draw on recent scientific research on the coffee leaf rust epidemic that severely impacted several countries across Latin America and the Caribbean over the last decade.

“We conclude by arguing that COVID-19’s socio-economic disruptions are likely to drive the coffee industry into another severe production crisis,” he explains.

Chart shows covid health policies and depressed local economy lead to increase coffee leaf rust.
Chart shows how the drivers of covid health policies coupled with a depressed global economy lead to increases in coffee leaf rust. Graphic from study.

Looking to the future, Knudson adds, “By increasing investments in coffee institutions and paying smallholders more, we can create a fairer and healthier system that is more resilient to future social-ecological shocks.”

The perspective is co-written by Kevon Rhiney (Rutgers University), Zack Guido (University of Arizona), Jacques Avelino (CIRAD, UMR PHIM, Turrialba, Costa Rica), Christopher M. Bacon (Santa Clara University), Grégoire Leclerc (CIRAD, UMR SENS, Montpellier, France), M. Catherine Aime (Purdue University), and Daniel P. Bebber (University of Exeter).

See also: Socioeconomic Fallout of COVID-19 Threatens Global Coffee Industry (June 28, 2021, University of Arizona News).

UH Hilo media release.


Story by Susan Enright, a public information specialist for the Office of the Chancellor and editor of UH Hilo Stories. She received her bachelor of arts in English and certificate in women’s studies from UH Hilo.