A hybrid of Bourbon and heirloom Ethiopian varietals developed by the Scottish Labs (during colonial years) which did lots work on varietals in the 1930's. Very typical of Kenya where it was introduced although there have been lots of experimental plantings in central South America, by those wanting to experiment.
- Varietal: SL-28
- Related to: Bourbon
- Origin: Kenya
- Grows best at: 1,000 meters or above
- Type: Bourbon hybrid
- Prevalent in: Kenya
- Predominant Colour: Red
- Fruit size: Medium
- Leaf Characteristics: Large
- Botany: Heirloom
A hybrid of Bourbon and heirloom Ethiopian varietals developed by the Scottish Labs (during colonial years) which did lots work on varietals in the 1930's. Very typical of Kenya where it was introduced although there have been lots of experimental plantings in central South America, by those wanting to experiment.
Fairly open to leaf rust and pest, it's not a high yielding plant. But the quality of the cup is often high, and some of the most treasured cups.
SL28 is among the most well-known and well-regarded varieties from Africa. It has consequently spread from Kenya, where it was originally selected in the 1930s, to other parts of Africa (it is important in Arabica-growing regions of Uganda, in particular) and now to the Americas. The varietal is suited for medium-to-high altitudes and shows resistance to drought, but it's susceptible to the major diseases of coffee plants. SL28 is notable for its rusticity. This means that it can be left untended for years or even decades at a time, and then return to successful production. There are SL28 trees that are 60–80 years old and still productive in many parts of Kenya.
SL28 was selected at the former Scott Agricultural Laboratories (now the National Agricultural Laboratories, NARL, situated at Kabete). Individual tree selections made at the Scott Laboratories during the 1935–1939 period were prefixed 'SL'.
Forty-two trees of various origins were selected and studied for yield, quality, and drought and disease resistance. SL28 was selected in 1935 from a single tree in a population called Tanganyika Drought Resistant.
In 1931, the senior coffee officer of Scott Labs, A.D. Trench, conducted a tour of Tanganyika (now Tanzania). According to historical documents, he noticed a variety growing in the Moduli district that appeared to be tolerant to drought, diseases and pests. Seed was collected and brought back to Scott Laboratories, where its drought resistance was confirmed. It was widely distributed until superseded by its progeny, SL28.