Central American coffees have an astounding reputation when it comes to coffee quality. Guatemala, Costa Rica, Panama, El Salvador and its neighboring countries have been providing the world with excellent green beans for decades. But this year, these countries are having some copper-colored concerns. A disease called coffee rust – or Roya in Spanish – is making a fundamental impact on today’s crops, raising a whole range of questions. We went ahead and answered them for you. (Part 1/2)

The Roya Virus: What is it?

The root of the problem is the Hemileia Vastatrix fungus. When accelerated by a combination of water, heat and the plant’s tissue, this fungus can develop into a Roya infection. This coffee rust can be identified through the appearance of yellow spots and orange spores on the leaves. Eventually, the fungus causes the leaves to decay and to fall of the (Arabica) coffee plant, impairing the plant’s ability to photosynthesize. This results in the production of fewer coffee berries, ergo fewer coffee beans. Other effects of the disease are: unripe cherries, lighter cherries (in weight) and ripening in different stages. To add insult to injury, Roya can also affect two crops in a row (or worse), although it rarely fully kills a plant.

The disease first occurred in Sri Lanka in 1869, where it wiped out 90% of the coffee crops in some regions, after which the entire country switched to the production of tea. After this dramatic occurrence, the fungus first spread to Africa, then to Asia, and around 1970 it finally reached South and Central America. Because the Hemileia Vastatrix fungus travels to other plants in its vicinity through wind, rain or insects, it can spread very easily. Therefore, Roya is now known as the most “economically important” coffee disease in the world, and is considered to be so universal, that it has become impossible to eradicate.

Where does it occur?

Originally, coffee rust only occurred in lower coffee producing areas (below 1000 meters). Due to the global climate change however, the disease is able to creep higher and higher, even endangering the High Grown (1400m) and Strictly High Grown crops (1700m). Some trees are more sensitive to the disease than others, like old trees, trees in soils with bad nutrition, and trees that have not been pruned (correctly).

How can it be treated?

However, every (fumigation) cloud has a silver lining. The coffee rust can be treated by fertilizing the soil, administering plague control and applying fungicide (containing Potassium, Phosphorus, Calcium, Boron and Zinc). Although the treatment measures are largely effective, they do confront the farmer with a serious investment.

How can it be prevented?

But as Benjamin Franklin said: “An ounce of prevention is worth a pound of cure.” These prevention measures can for example consist of the correct pruning of the coffee tree. A more long-term approach to combatting the pest is to cross-breed the indigenous coffee plants with strains that are resistant to Roya. The challenge here is to guarantee the quality of the cup and the specific flavor of an origin, but the new generations of crossbreeds are said to be better than the first experiments. A great example of this method is Kenya, that almost entirely consists of rust-resistant coffee plants of excellent quality! In Central America, a new variety called Lempira has had some satisfying results already, and may be an option to consider.

Learn more in the second part of our Q&A here!

Sofie Nys Sofie Nys

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