The Coffee Tree
This section deals only with the most interesting of the coffee species, Coffea arabica. At first glance, all Arabica trees look similar: a thin trunk with numerous branches coming off it, supporting foliage and fruit. However, if you look closer there are many differences between trees, determined by the variety of Arabica being grown. Different varieties yield different amounts of fruit, in different colours, and some carry the fruit in clusters, while others have fruit evenly spaced down the branch.
There are also big differences between the leaves of plants of different varieties, but more importantly between the cup characteristics when the seeds of these varieties are harvested and brewed.
Different varieties have different qualities of flavour, and may also have different mouthfeels.
It is always important to remember that for the bulk of coffee producers, flavour is not the main reason they have selected a certain variety to grow. The yield of the tree and its resistance to disease are usually of great value to those who depend on growing coffee for their livelihood. That is not to say that all producers choose their varieties this way, but one should bear in mind the impact of these choices on the profitability and income of the producer.
From Seed to Tree
Most established coffee farms have a nursery in which to raise seedlings before planting them out on the farm for production. The coffee beans are first planted in rich soil, and will soon germinate. The bean itself is then lifted out of the ground by the developing shoot, and at this stage they are often called ‘soldiers’. They look strangely like a roasted coffee bean has been attached to the top of a thin green stem. Not long after this, the bean bursts open to reveal the first leaves. Coffee plants grow quickly and after 6–12 months they can be moved from the nursery into production.
Coffee growing requires the investment of not only money, but also time. A coffee farmer will usually have to wait three years for a newly planted tree to fruit properly.
Pests and Diseases
The coffee tree is susceptible to a variety of pests and diseases. Two of the most common are coffee leaf rust and the coffee berry borer.
Coffee Leaf Rust
Known as roya in many countries, this is a fungus (Hemileia vastatrix) that causes orange lesions on the leaves. It impairs photosynthesis, then causes the leaves to drop and eventually can kill the tree. It was first documented in East Africa in 1861, although it was not not studied until it began to affect plants in Sri Lanka in 1869 where it pretty much destroyed the coffee plantations over the following ten years. It spread to Brazil in 1970, perhaps brought over from Africa with a shipment of cacao seeds, and quickly spread into Central America.
It is now found in every coffee-producing country in the world and the higher temperatures brought about through climate change are exacerbating the situation. In 2013 several Central American countries declared a state of emergency due to the damage caused by rust.
Coffee Berry Borer
Also known widely as broca, this is a small beetle (Hypothenemus hampei) that lays its eggs inside coffee cherries. The hatching young eat the cherries, thereby reducing the quantity and quality of the crop. The beetle is native to Africa, although it is now the most harmful pest to coffee crops across the world. Research is being done into different methods of control, including chemical pesticides, traps and biological controls.
Making the decision to begin growing coffee is a serious one, and this also means that if a producer abandons coffee it will be difficult to encourage him to return to the crop in the future.
Blossom and Fruit
Most coffee trees have one main harvest per year, though the trees in some countries have a second harvest, which is usually smaller and often of a slightly lower quality.
The cycle is first triggered by a prolonged period of rainfall. This causes the trees to bloom, producing lots of white blossom flowers with a strong scent that is reminiscent of jasmine.
Insects such as bees pollinate the flowers, although Arabica is able to self pollinate, meaning that unless they are knocked off the tree by adverse weather, the flowers will always yield fruit.
It takes up to nine months until the fruits are ready to harvest. Unfortunately, coffee cherries do not ripen uniformly. The coffee producer has a difficult choice between harvesting all the fruits from each tree at the same time and having a certain quantity of unripe or overripe coffee cherries in the harvest, or paying pickers to do multiple passes of the same trees so each cherry is harvested when it is perfectly ripe.
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The World Atlas of Coffee excerpted with permission from Firefly Books / Text Copyright © 2018 James Hoffmann / Images Copyright © 2018 Dreamstime.com