Coffee Rust


March 15, 2013 by Beans Ahoy

What is it?
Hemileia vastatrix is a coffee fugus that attacks coffee bush leaves causing them to yellow, rot, and eventually fall off the bush. It is indiscriminate attacking both Arabica and Robusta plants and is now spread across almost every coffee growing country in the world.

It is thought that the disease stems from central and eastern Africa in the area of Ethiopia and Kenya in about 1861. Evidence of the disease was also found on dried coffee leaves in 1869 sent from Ceylon (now Sri Lanka). Over the last 150 years the disease has spread throughout the coffee growing countries with the exception of Hawaii, most likely due to its isolated location in the middle of the Pacific.

How it spreads
Part of the reason for the diseases rapid and vast spread has come from the atmospheric conditions necessary for it to survive and propagate. The spores thrive in temperatures of between 22°C and 28°C where there is large amounts of water. For propagation to occur requires 24 to 48 hours of continuous moisture so most of the infection takes place during the rainy season. Once a plant is infected however the spore wastes no time in going to work. It takes about two weeks for a spore to develop into an uredinia (yellowing spot) which continue to grow for several weeks. With the infection fully developed roughly 300,000 spores will be released making it highly infectious to other plants.

Impact on coffee growers and drinkers
The most obvious concern for coffee drinkers and growers is the dwindling supply that this infection could cause. 2.25 billion cups of coffee are now consumed every day which requires the steady and substantial flow of coffee to continue. The first possible impact is going to be the price. If this disease takes hold and wipes out any more of the coffee crop (which is likely) then we can expect to see coffee prices increase. More than that though, the impact will eventually hit the farmers the hardest. If infection cannot be controlled this disease will likely wipe out close to an entire coffee crop.

Governments of coffee growing nations are becoming increasingly concerned about the impact of coffee rust and are trying to find ways of tackling it, however it is very likely that we will see continued damage cause before we see any improvement in the short run.

Something can be done though, and that is the most important point. It is important that people in the coffee industry don’t panic and instead continue to work towards a solution.
The governments of coffee growing countries are aware of the issue with some countries such as Guatemala declaring a state of agricultural emergency. However, as we are well aware the government is unlikely to be able to fix the problem by themselves. It is also important for growers to have plans on how to deal with coffee rust.

One of the key areas of any contamination is containment. Coffee farmers must keep a close eye on coffee crops, continuously checking them for any signs of coffee rust and take appropriate action in disposing of a bush if rust is found. Other simple techniques are also important to stop trans-country contamination. If you are an international coffee buyer don’t wear the same clothes and shoes in an infected zone as you wear in a non-infected zone.

There have been a number of genetic issues that also need to be taken into account. Amazingly, when coffee rust was first discovered in Brazil, almost all of the trees could trace their DNA lineage back to a single tree that was planted in King Louis XIV’s conservatory in 1713. It is thought that 90% of coffee available now springs from this one bush. As a result the DNA in coffee bushes is surprisingly uniform, so if one bush is infected, it is likely that all the other bushes will be susceptible to infection and may answer why coffee rust has been able to spread with such ease. Coffee cultivators have also managed to combine some of the rust resistant genes into coffee plants, however the trick remains whether this can be done with minimal impact on the taste of the coffee. Another concern is also the disappearing species of wild coffee available for cross breeding caused by deforestation.

There are also a growing number of people who are arguing that growing techniques can make a big difference. Most coffee is grown in direct sunlight in densely planted areas making the spread of the rust easier between plants, and the forcing of plants to produce high yields harms their health and ability to resist the fungus. It is also thought that because these coffee bushes are exposed to the full force of rain that they provide a perfect wet environment for the fungus to spread. One argument is that shade grown coffee does not suffer the same problems as trees block a lot of the water falling to the ground avoiding the ultra wet conditions necessary for the fungus to spread.

There is unlikely to be a silver bullet in the quest to hold back coffee rust. The answer is likely to lie in a combination of the factors above. Clever coffee crop management, proper hygiene to avoid contamination, and a continued push to diversify the gene pool of coffee are all likely to help. What is certain however is that we cannot continue to abuse the production of coffee and squeeze every last bean out of every last square meter. Large scale commercial coffee production is weakening plants and making it easier for coffee rust to spread, and if this means that the price of coffee has to increase, so be it, because the alternative is a continued decline the production of coffee and an ultimately higher price in any event.



One thought on “Coffee Rust

  1. […] Commercial coffee is genetically very weak and farming practices have sought maximum yield at the expense of coffee health. One such problem hitting coffee was that of rust which I wrote about earlier this year. ( […]

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