A Cup of Coffee, Hold the Rust

Rust on the underside of a coffee leaf.

Rust on the underside of a coffee leaf. Image used courtesy of Wikipedia.

While at my desk early in the day last week, one headline struck me as particularly troubling: “Coffee Rust Regains Foothold”.

Reports from the Institute of Coffee of Costa Rica estimate that the latest coffee outbreak may cut by 50% the 2013-14 coffee harvest in that country. Coffee specialists in the U.S. are calling it the worst outbreak of rust in Mexico and Central America since rust arrived in the region, 40-some years ago.

And in Kenya, Africa, coffee rust has been described as causing ever-greater problems, even with Kenyan coffee varieties resistant to rust being grown.

Several Central American governments are enacting special legislation to fund projects against spread of the fungus.

It’s early February and in this little corner of the world, times seem tough. We are suddenly (although typically, for southern Wisconsin, USA) getting regular snowfalls: 3” this day, 6” a day later. It adds up to a lot of shoveling.  There is nothing like a fresh snowfall and 30 minutes of shoveling to slow the morning commute.

It’s been cold as well. When the indoor temperature is around 60°F, getting started in the morning is a bit more challenging.

But these issues can all be handled, with a little coffee. It is the jet fuel solution to morning ignition problems; a companion on a long slow drive on icy roads. It’s possibly even a cofactor for better listening to Morning Edition on National Public Radio.

Thus the news of the recent spread of coffee rust struck a nerve. Could this affect coffee prices? Availability?

National Geographic  shows a map of coffee-growing regions around the world, along with some interesting facts on who grows what type of coffee, how much and a brief history of coffee in that region.

In Science magazine online,  January 29, 2012, Daniel Cressey wrote about the long struggle between coffee and coffee rust, Hemileia vastatrix, and how the rust is currently winning. 

Coffee rust is a fungal disease that was first identified in 19th century Ceylon (now known as Sri Lanka). The wet climate in parts of Ceylon was perfect for coffee rust. As much as 90% of coffee plants were lost in those wet areas. In fact, coffee rust caused Ceylon to abandon coffee for tea, a crop that the region is well-known for today.
In the 1970s coffee rust was discovered in Brazil, and from there spread to Central America. Severe outbreaks were seen in Costa Rica in 1989 and Nicaragua in 1995.

Fungal diseases like coffee rust are tough to eradicate. One of the greatest difficulties with spore-forming diseases is the ability of spores to survive in a wide range of conditions, from extreme heat to extreme cold. In addition, fungal diseases can be spread by winds. Rain can also traffic a fungal disease, albeit over short distances.

There are coffee growing regions that have successfully thwarted coffee rust. In addition to rust-resistant coffees in Kenya, Columbia has been held up as possibly closest to a solution to coffee rust. As with Kenya, the Columbian government has supported research into development of rust resistant coffee strains through inbreeding. While treatment with copper-containing fungicides is possible, growers have learned to better monitor weather during the growing season. This helps in predicting fungal outbreaks and has allowed Columbian coffee growers to cut the use of anti-rust fungicide by as much as 50%. Columbian researchers are also studying the genetics of the rust fungus and the coffee plant.

No doubt coffee rust research has paid attention to other important plant blights and research approaches to control or end those infections. The U.S. lost almost all of it’s American Chestnut trees during the 20th century due to a blight (also a rust) that was first seen in New York in 1904. Fifty years later nearly all American chestnuts were gone.

Researchers have approached bringing the chestnut tree back with a multi-branched attack, consisting of identifying viruses that the chestnut blight is susceptible to, by developing hybrid chestnut species, crossing the American species with a Chinese variety and even by developing transgenic chestnut trees. A new chestnut tree variety has been developed that expresses a wheat gene for the enzyme oxalate oxidase, which can block the blight fungus.

Of course transgenic chestnut trees are one things, transgenic (genetically-modified) coffee quite another.  But beating coffee rust with a generation of coffee developed in the laboratory?

On a snowy February morning in Wisconsin this coffee fan might take GM coffee over no coffee at all.

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Kari Kenefick

Kari has been a science writer/editor for Promega since 1996. Prior to that she enjoyed working in veterinary microbiology/immunology, and has an M.S. in Bacteriology, U of WI-Madison. Favorite topics include infectious disease, inflammation, aging, exercise, nutrition and personality traits. When not writing, she enjoys training her dogs in agility and obedience. About the practice of writing, as we say in DNA purification, spin, rinse and repeat.

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