Coffee-Leaf Rust: Problems with Rust-Resistant Varieties

Editor’s note: We got an overwhelming response from the article by Chad Trewick, “Rust on the Rampage,” in the April+May issue of Barista Magazine. The topic of coffee-leaf rust and the devastation it’s causing in Central America is one we are all just starting to talk about because unfortunately, coffee-leaf rust will continue to plague the coffee industry ”specialty in particular ”for many years to come. We at Barista Magazine intend to continue covering coffee-leaf rust, the research that is being done to combat it, and the effects it will have on our industry in both the short and long term. Recently, Patrick Hughes of Union MicroFinanza, a non-profit that works with farmers in La Union, Honduras, contacted me to discuss points not yet addressed in recent coffee-leaf rust news, and I welcomed his input. Below is the second of two articles from Patrick. The first appeared on Saturday, June 22, and is viewable on the blog.

Problems with Rust-Resistant Varieties
By Patrick Hughes

Lempira. I’ve heard the name of this coffee variety more in the past three months than I had in the three years previous. Until the coffee-leaf rust (CLR) attack of this past year, the Lempira coffee plant was used in Honduras mainly for its high-yield characteristics. However, the massive damage to plantations caused by CLR has led Honduran farmers to uproot old plants and switch to rust-resistant plant varieties.   Because Lempira is the most preferred of the area’s common rust-resistant varieties,farmers are planting it almost exclusively following the CLR outbreak.   But, this creates a huge problem.

I estimate that La Unión had a 50% decrease in harvest this year compared to last harvest. This loss was concentrated on older varieties such as Bourbon, Tipica, and Catuai, while resistant-varietals saw no losses. For this reason, farmers are getting rid of these older varieties in an attempt to prevent losses in coming years.

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Susceptibility to disease

By planting a single coffee variety instead of various different ones, farmers are risking even greater losses than they experienced this year.   CLR is not the only disease with the potential to attack coffee plants and devastate harvest. Diseases such as Ojo de Gallo and Coffee Berry Borer have the potential to cause losses as great as CLR; and rust-resistant varieties are susceptible these diseases. If there were an outbreak of one of these, the impact on the coffee harvest could be closer to 100% loss. In a town that depends completely on coffee production, this would be a big enough disaster to put the entire town back years in its growth and development.

And it could even be coffee leaf rust itself that attacks rust-resistant varietals like Lempira. In her report Some Insights on Coffee Leaf Rust, Emma Bladyka, SCAA Coffee Science Manager, says the following:

Kent was perhaps the first variety to show good resistance to coffee rust in India. However, this resistance was lost after about 10 years of exposure. This phenomenon of gradually losing resistance has also been noticed in some  C. iberica  and  C. canephora  varieties.

Not only is it possible for coffee leaf rust to break down resistance, it is a documented occurrence. As a higher percentage of a single variety is planted, the mono-cropping issue of rapid disease mutation becomes exaggerated from its already high potential. According to Arnold Pineda, Director of IHCAFE’s Santa Barbara Regional Training and Experimentation Center, 12% of Lempira variety leaves on the center’s test plots were affected in this past harvest, suggesting that CLR has already started to bypass the variety’s resistance. Pineda estimates that this variety will lose all resistance within the next 10 years, and that this will be accelerated by the mass-adoption that is currently happening.

Other concerns

Additionally, most rust-resistant varieties were created to have higher than normal coffee production, meaning these varieties require significantly more nutrients than do other varieties. Lempira variety needs 15% more nutrients than lower producing varieties, and other rust-resistant varieties need as much as 33% more nutrients or they will become weakened and more susceptible to disease attacks. Many farmers had severely reduced incomes this past year and will face limited access to credit in the coming year. This leaves them without the resources that they need to nourish high-yield plants, making it likely that plants will be more susceptible to both CLR mutation and other diseases.

And finally, there is the issue of quality. Rust-resistance is created by cross-breeding Arabica and Robusta coffee, since Robusta is not susceptible to CLR. This means that their quality is inherently inferior to pure Arabica varieties. Mass adoption of these rust-resistant varieties will make it more and more difficult to find amazing coffees in CLR-affected areas.

I don’t pretend to have the answer. The logic of most farmers is sound in the short term ”they are planting Lempira because they can trust that it will not be attacked by coffee leaf rust in the coming harvest. After the losses that they faced with plants of non-resistant varieties, I can hardly blame them. Without the proper training and resources to control rust, planting resistant varieties is the surest short-term way for farmers to avoid the catastrophic losses they faced this past harvest. But in the long term,the mass adoption of rust-resistant varieties is setting farmers all over Latin America up for long-term harvest and quality losses that could have an even greater economic impact than what we saw this past year.


Patrick Hughes, center, with coffee farmers in Honduras.
Patrick Hughes, center, with coffee farmers in Honduras.

ABOUT THE AUTHOR: Patrick Hughes cofounded Union MicroFinanza, a non-profit working with farmers in La Union, Honduras, in 2009. Unión MicroFinanza’s mission is to improve the economic capacities of impoverished rural communities by developing and applying the most advanced procedures and technology in microfinance. You can follow Patrick and Unión MicroFinanza online on Patrick’s blog.

About Sarah 934 Articles
Sarah Allen (she/her) is co-founder and editor of Barista Magazine, the international trade magazine for coffee professionals. A passionate advocate for baristas, quality, and the coffee community, Sarah has traveled widely to research stories, interact with readers, and present on a variety of topics affecting specialty coffee. She also loves animals, swimming, ice cream, and living in Portland, Oregon.