Barat describes anthracnose under the name Glomerella cingulata, whose asexual form is called Colletotrichum coffeanum. The fungus spares no organ: leaves, twigs, flowers, fruits. It ends in die-back, that is, the descending death of twigs, which starts at the tip and moves toward the trunk. One form attacks mainly the berries, and it is this one that bears a proper name, coffee berry disease (CBD).

Rayner's discovery in Kenya changes how the disease is read. The fungus is already settled in a latent state in the bark of trees that look healthy. It only waits for the plant to weaken before declaring itself.

The list of triggering factors then becomes legible, because none of them is the fungus itself: lack of shade and exhausting overproduction, erosion, weeds, wind, and, in arabica, defoliation by rust. Caring for the tree is here a sanitary measure, on a par with a treatment.

In 1955, then, the mechanism was held correctly with a wrong identification. The agent of CBD is not Colletotrichum coffeanum but a distinct species, Colletotrichum kahawae, described only in 1993.

Coste 1955, p. 220-222 (Barat); Waller et al., Mycological Research 97 (1993); LC ch. 15

CBD is reported in 1922 on young plantations on the slopes of Mount Elgon, at Sotik, in western Kenya. It crosses the Rift Valley, from the east, only in 1939. In 1951, it covers all the Kenyan coffee zones.

From Kenya, it then spreads to the rest of the continent.

• 1930Angola
• 1937Congo
• 1955-57Cameroon
• 1959Uganda
• 1964Tanzania
• 1971Ethiopia
• 1985Malawi

CBD has remained confined to Africa. That is the reason for the strict quarantine imposed on African plant material headed for the Americas. American coffee plants have never met this fungus. Nobody wants to be the one who brought it there.

The Kenyan epidemic of 1967-68 triggers the genetic response. The Coffee Research Foundation launches a breeding program in 1971. The resistance then available came down to three genes of distinct origins. The T gene comes from the Timor Hybrid. The R gene comes from Rume Sudan, a wild accession from the Boma Plateau collected in 1941. The k gene comes from K7.

Silva et al. 2022; Agronomy Journals 2019; Current Agriculture Research Journal 2021

Berry anthracnose (CBD)

Coste 1955, p. 220-222; J. Plant Dis. Prot. 2023; WCR 2025

The three are assembled in Ruiru 11 (1985). It is a composite F1 hybrid: the mother is a Catimor, the father a multicross of SL28, SL34, Rume Sudan, N39 and K7. The price to pay is manual pollination, on which the variety depends, because the seeds of an F1 do not give the same tree again.

Batian (2010) lifts this constraint: a tall variety, propagated by seed, it also aims at the SL cup. The WCR catalog rates Ruiru 11 highly resistant to rust and resistant to CBD, Batian resistant to CBD.

Elsewhere, tolerance was sought in the Ethiopian stock rather than in crossing. Java and Geisha were retained in Cameroon and Tanzania for their tolerance to CBD. Chemical control has not changed: copper and systemic fungicides in the rainy season, on the green berries, that is, at the moment and on the organ where the fungus strikes.

Journal of Plant Diseases and Protection (2023), “Coffee berry disease: a century-old anthracnose”; Current Agriculture Research Journal 9 (2021); WCR 2025, Ruiru 11 and Batian sheets; site/data.js