Coffee Pests, (not-so) Fungi and Diseases

By Fairtrade’s reckoning, 125 million people depend on coffee for their livelihoods. 41% of Ethiopia’s exports are in coffee, with Burundi at 27% and between 2-10% for most Latin American countries. With coffee making up such an important part of developing country’s economies, coffee pests, fungi and diseases can cause great damage to many. A farmer’s crop can be devastated, workers will lose their seasonal employment and coffee organisations and governments suffer from losses relating to trade. This article covers the common pests, the environments in which they thrive and efforts to cope with them.

Picture Source - Pestnet.org

Coffee Borer Beetle

This not-quite 2mm long beetle is native to Africa, though it has colonised the Americas all the way to Hawaii. A female bores into the berry and lays eggs in the endosperm, or bean. With up to five generations living on a coffee plant, they can fully colonise a plant and destroy the fruit.

Efforts to control this pest include more careful inspection of coffee seeds transported for agriculture. Predators like birds and wasps will feed on the beetle when they are in transit. Parasites and fungi will also kill the beetles. Pruning will help rid of stem boring beetles, as well as a clean environment and effective management. Insecticides are ineffective on female beetles and can be harmful to the environment.

The Coffee Borer Beetle needs a moist climate to spread. Global Warming has increased the rainfall and temperature required by the beetle to colonise further away from the equator, resulting in the continuing spread of this resilient pest.

Coffee Borer Beetle - Picture source - Pestnet.org

Other Pests

There are many other pests resistant to caffeine which bore into the fruit, stems or roots of the coffee plant, either outright killing the plant or reducing the quality of its harvest. These include the cicada, stem borers (most devastating in Asia), mealybugs and virus transmitting red flat mites. Hotter weather can increase the damage and colonisation rates of these pests.

Coffee Leaf Rust (CLR), La Roya

This devastating fungus, latin name Hemileia vastatrix, reveals itself as a yellow, powdery, rusty-looking mark on coffee leaves. This is a death sign for many farmers and where it was apparently isolated to East Africa in the 1860s, it is now a global epidemic. Its destructive potential can be seen from the case of Sri Lanka. Once a great producer of coffee, in the 1890s the entire country’s production pretty much came to an end.

Infection is complete in only 2 full days. The leaves are covered in a rust, blocking the sunlight required for photosynthesis. The yield is significantly reduced, as is its quality. When losses in infected areas can be as high as 75%, it’s no wonder farmers switch to less damage susceptible crops. In Sri Lanka, the country switched to producing tea. In 2013, the Guatemalan government went as far as to declare a state of emergency in relation to CLR.

A fact which makes it so hard to control is its adaptability to new climates and speed of mutation. Many of the world’s coffee research bases have developed Coffee Leaf Rust resistant Arabica strains, only for La Roya to later mutate and start infecting them, too. These mutations can also make them more resistant to fungicides, too. Colombia’s Fedecafe is one of the organisations leading the charge against CLR. Greater shade coverage, high-altitude planting, copper sprays and varieties such as Catimor offer preventative measures to the spread of the fungus. Global Warming has increased its range.

La Roya or Coffee Leaf Rust - Picture source - Anacafe

Coffee Berry Disease (CBD)

There are a number of coffee plant diseases affecting the leaves, fruit and tree but the Coffee Berry Disease is one of the more common in Africa. Another fungus induced disease, coffee berries show small black scabs and can be completely hollowed out in a number of days. Green berries will fall off the branch before ripening. Losses in yield have been recorded up to 80%. Thankfully, CBD has not spread to other continents.

Fungicides are used to control the spread and certain varieties are more resistant (Timor hybrids). Quarantine, pruning and placement of competing microorganisms are used to manage the fungus, Colletotrichum kahawae. Shading coffee trees also helps prevent infestation as taller trees reduce the spread of spores dispersed by rainfall falling on the berries.

Other diseases

These include Brown-Eye Leaf Spot, Anthracnose or Brown-Blight and Berry Blotch. These cause leaves and berries to curl up and turn brown or black. Once again, shading and good fertilisation of the land are preventative measures.

Coffee Berry Disease - Picture Source - Cirad

What does the future hold?

Coffee is a fragile crop and as our global consumption increases, the pressures are too. Costa Rica offers an example of the issues at hand, with coffee production having dropped by as much as 40% since the year 2000. This is an example of the damage done to crops induced by a warming climate, although in Costa Rica urbanisation is also a factor.

As fewer regions are able to support coffee-growing, evident in Ethiopia, we can expect coffee prices to increase as costs rise and availability is squeezed. There will also be increased hardships for those already in poverty, yet rely on coffee for their living. If we are unable to change the way in which the planet warms and the associated spread of pests and diseases, some forecasts predict that by 2050 most production will have ceased. We could dismiss this as exaggerated scaremongering but the problems are real and current efforts to combat them inadequate. It is also to damn the lives of coffee farmers and pickers through negligence.

The answer for coffee might be in cultivating new varieties or even species. New research and practices can also improve the lives of producers. However, this does not address the need for us to change our behaviour relating to our polluting and damaging of the planet.

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