Coffee berry disease: a century-old anthracnose of green berries of Arabica coffee (Coffea arabica L.) in Africa

Coffee berry disease (CBD), anthracnose of green berries of Arabica coffee, chronicles 100 years in 2022. The disease was detected for the first time in Kenya in 1922, and its causal pathogen was designated Colletotrichum coffeanum Noack (renamed C. kahawae). CBD has been causing substantial yield losses (ca. 80%) in susceptible varieties, and there has not been a coffee disease with a remarkable economic impact as CBD resulting in a sharp decline in total Arabica exports from Africa. During the past 100 years, a considerable amount of scientific knowledge on the biology, epidemiology, and management of coffee berry disease has been documented. The use of resistant varieties is the most empirical and effective CBD management practices in East Africa. The disease is still of great concern to Arabica producers and exporters around the world. There are unresolved issues that require the due attention of scientists and coffee communities. The nomenclature and taxonomic position of the fungus (C. coffeanum, C. kahawae, C. kahawae subsp. kahawae, and C. kahawae subsp. cigarro) confuse pathologists in identifying the actual cause of anthracnose in coffee berries and other hosts. The host resistance is consistently long-lasting. However, the nature of resistance and its inheritance mechanisms remained a major point of debate (oligogenic vs. polygenic), implicating that genetics of CBD resistance needs further in-depth analysis. This comprehensive review examines published information during the past 100 years that shows success stories; pinpoint contrasting research gaps that motivate scientists and sensitize coffee industries to the impact of coffee berry disease in Africa and beyond.