tags: [] - coffee/varieties - coffee/varieties/breeding aliases: - CBD resistance breeding - Colletotrichum kahawae resistance

Coffee Berry Disease Resistance¶

Tags: #coffee/varieties #coffee/varieties/breeding Aliases: CBD resistance breeding, Colletotrichum kahawae resistance Related: Coffee Breeding and Genetics MOC | Coffee Leaf Rust Resistance Breeding | Ruiru 11 | Multi-Disease Resistance | Kenya Status: ✅ Complete

Overview¶

Coffee berry disease (CBD) resistance breeding refers to the development of Coffea arabica varieties with genetic resistance to Colletotrichum kahawae subsp. kahawae — the fungal pathogen responsible for coffee berry disease, one of the most economically significant coffee diseases in sub-Saharan Africa. CBD causes the infection and rotting of developing coffee cherries (anthracnose of green cherry), resulting in yield losses of 50–80% in susceptible varieties during epidemic years. Unlike coffee leaf rust, which has spread globally, CBD is primarily confined to Arabica-growing regions of Africa — particularly East Africa (Kenya, Ethiopia, Uganda, Tanzania) and parts of West and Central Africa — where the pathogen is endemic and susceptible varieties are highly vulnerable.

The Pathogen: Colletotrichum kahawae¶

Colletotrichum kahawae is a specialised host-specific pathogen of C. arabica; it is distinct from other Colletotrichum species that cause anthracnose on other crops and is not widely present outside Africa. The pathogen infects green cherry (between pin-head and mature stages), causing a rapidly spreading dark rot that destroys the developing bean. The disease is favoured by cool, wet conditions — common in the East African highland growing zones where the best-quality Arabica is produced.

Impact¶

CBD was first formally described in Kenya in 1922 and is estimated to have caused cumulative losses of billions of dollars in affected East African coffee industries over the 20^th century. Kenya established the Coffee Research Foundation at Ruiru specifically as a response to CBD, and CBD resistance was the primary motivation for the development of Kenya's Ruiru 11 variety (released 1985).

Resistance Sources¶

Timor Hybrid¶

The Timor Hybrid carries partial CBD resistance derived from its C. canephora background, in addition to its well-characterised leaf rust resistance. However, the CBD resistance in Timor Hybrid-derived varieties (Catimor, Sarchimor) is incomplete and does not provide the full resistance needed for reliable crop protection in high-disease-pressure environments.

Rume Sudan and Other Ethiopian Accessions¶

Ethiopian wild and cultivated C. arabica accessions, particularly Rume Sudan (from the Sudan-Ethiopia border region), carry higher levels of CBD resistance than most commercial Arabica varieties. JARC has screened Ethiopian germplasm collections for CBD resistance and identified accessions with stronger resistance for use as breeding parents.

Hibrido de Timor Lines with Enhanced CBD Resistance¶

Some Timor Hybrid accessions carry better CBD resistance than others; CIFC and CRF (Kenya) evaluated multiple Timor Hybrid lines and selected those with the best combined rust and CBD resistance for use in Ruiru 11's complex multi-parent crossing scheme.

Ruiru 11: Dual Rust + CBD Resistance¶

The development of Ruiru 11 by the Coffee Research Foundation at Ruiru, Kenya (released 1985) represents the most sophisticated deployment of CBD resistance to date. Its breeding strategy used multiple crossing steps to incorporate:

Leaf rust resistance from Timor Hybrid-derived sources
CBD resistance from both Timor Hybrid lines and Rume Sudan
SL28/SL34 background for Kenyan cup quality

No other commercially released variety achieves Ruiru 11's dual resistance to both rust and CBD at the same time, which explains Ruiru 11's dominant position in Kenyan smallholder plantings despite cup quality concerns relative to SL28 and SL34.

Genetic Basis of CBD Resistance¶

CBD resistance in coffee is poorly understood compared to leaf rust resistance: - Unlike leaf rust, where specific SH resistance genes are well characterised, the genetics of CBD resistance involves both qualitative (major gene) and quantitative (polygenic partial) components - Some studies have identified QTL (quantitative trait loci) associated with CBD resistance in crosses between resistant and susceptible parents, but the specific genes are not yet characterised to the same degree as rust resistance genes - Durability of CBD resistance is less well studied; no major race breakdown of CBD resistance has been reported in deployed varieties, though some pathogenic variation in C. kahawae populations has been documented

Key Facts¶

Coffee berry disease (CBD) is caused by Colletotrichum kahawae and infects developing green cherry in East African Arabica growing regions; yield losses of 50–80% in susceptible varieties during epidemics
CBD resistance breeding uses Timor Hybrid-derived resistance (partial) and Ethiopian accessions including Rume Sudan (stronger resistance) as resistance sources
Ruiru 11 (Kenya, released 1985) is the only commercially deployed variety combining both leaf rust resistance and CBD resistance; its complex multi-parent cross incorporated multiple resistance sources
The genetics of CBD resistance is less well characterised than leaf rust resistance; involves both major-gene and quantitative polygenic components
CBD is primarily confined to African Arabica production regions; not currently a significant threat outside Africa but represents a risk if the pathogen were to spread

References¶

Changelog¶

Date	Change
2026-04-28	Note created

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