The coffee tree: Interesting facts about this exotic crop
Since when people have been using the coffee plant and the coffee fruit is not known. However, the plant’s region of origin can be determined: tropical to subtropical Africa as well as Madagascar and the chain of islands in the Mascarenes. The Latin name for the genus of coffee plants is Coffea. It belongs to the red plants (Rubiaceae). Of the approximately 120 species within the plant genus, only nine are cultivated to produce beans for coffee consumption. The best-known varieties are Arabica and Robusta.
From seed to tree
In order to thrive, the coffee tree needs a humid and hot climate. It prefers average temperatures between 18 and 22 °C without significant temperature fluctuations. Nutrient-rich, slightly acidic, soils are best suited for cultivation. The evergreen plants can be grown at home under suitable conditions, but rarely produce a significant amount of fruit.
The coffee seed develops in the form of beans inside the coffee fruit, the so-called cherry. As a rule, each fruit contains two seeds. Under suitable conditions, they germinate within a few days. After four to five months, the young plants are about 20 to 40 cm high. It takes three years until the first flowering. From the 4th year, onwards, fruits can develop. It takes a total of five to seven years before the yield of a tree is worthwhile for commercial production. A coffee tree can reach a height of 8 m. Smaller species are no larger than shrubs.
Pests and diseases
The coffee borer or coffee cherry beetle (Hypothenemus hampei) is a widespread pest that causes considerable damage to coffee trees. It belongs to the bark beetles and originates from Africa. The beetle bores into the coffee bean and nests there. It uses it as a food supply. The females can lay up to 120 eggs and move on when the substance of the bean is used up. Another coffee plant pest is the butterfly species Leucoptera coffeella. Its caterpillars weaken the plants by eating leaves.
The coffee rust (Hemileia vastatrix) is particularly widespread among the diseases. This is a fungal disease in which orange-colored fungal cultures form on the leaves of the coffee plant. This leads to leaf shedding and weakened plants. The coffee rust can infest entire plantations and lead to considerable harvest losses.
Some Coffea species use caffeine to protect themselves. However, this substance is not found in every coffee plant. For commercial cultivation in monocultures, natural pest control is not sufficient. Coffee farmers try to contain the infestation with chemical and biological pesticides. Another method is to breed more resistant species that are more resilient.
Blossom and fruit
The white flowers of the coffee plant are star-shaped, five-lobed, and grow in clusters of four to five flowers. A large coffee tree can produce up to 40,000 flowers. They smell pleasant and relatively strong. Pollination of the flowers is necessary for the coffee fruit and beans to develop. Most Coffea species are pollinated by wind or insects. Only Coffea Arabica is self-pollinating. Coffea plants only flower briefly and must be pollinated quickly.
Subsequently, drupes with two seeds are formed. First, the fruits are green, later yellow, and then red. The strong red coloring has led to the name coffee cherry. In some species, the fully ripe fruits remain yellow. It takes several months from pollination until the coffee fruit ripens. Some Coffea species need eight or nine months, others more than a year.