Scott Laboratories was a research organisation based in Kenya that developed multiple cultivars under contract between 1934 and 1963. Scott Labs developed various SL varieties, mostly based on Moka and Bourbon types brought by the Scotch and French missions to Kenya to cultivate.
Some of the more successful SL (Scott Labs…get it?) varieties are still widely grown in Kenya today, however, SL 28 and SL 34 are the ones that are most relevant for speciality coffee.
SL 28 – Bred in 1931 from Tanganyika D.R, SL 28 has become ubiquitous throughout Kenya and is recognised as a variety of exceptional cup quality. It has wide leaves with coppery tips. Beans are wide and productivity relatively low. Though it is not substantiated that we can find, some sources claim that Scott Labs crossed mutations of French Mission, Mocha and Yemen Typica to produce the SL 28 variety. No matter the exact genetic composition, almost certainly their original goal was to create a plant with high quality, high productivity and great resistance towards diseases. SL 28 hits the first objective squarely on the head.
SL 34 – A mutation of French Mission, originating from the plantation of Loresho in Kabete, SL 34 has wide leaves with bronzy tips. It is widely grown throughout Kenya. SL 34 is valued for its high productivity in different climate conditions and great height ranges. It is also claimed to be resistant towards draught and strong rainfall.