Last year the Coffee Research Foundation (CRF) in Ruiru, Kenya released a new disease-resistant arabica varietal that has been in development for more than an decade. Named after the highest peak on Mt. Kenya, Batian is resistant to coffee berry disease and coffee leaf rust, the two common fungal diseases affecting coffee in Kenya and much of Africa.
The parentage of Batian is predominantly arabica, and it is closer genetically to the well-regarded SL28 and SL34 varieties than Ruiru 11, the rust-resistant varietal introduced in 1985. Varieties used in the development of Batian include SL4, N39, N30, Hibrido de Timor, Rume Sudan, and K7. They were repeatedly backcrossed with SL28 and SL34. The Hibrido de Timor is the naturally-occurring hybrid of arabica and robusta, and is often used in disease-resistant breeding due to its robusta heritage.
Of course, it is the robusta lurking in the background that tends to lower cup quality. According to the CRF, however, Batian cups far better than Ruiru 11 and even the parental SL varietals. Here’s a slide from a presentation by Dr. Joseph Kimemia of the CRF (click to enlarge):Should we take that with a grain of salt (so to speak)? A tasting of these four varietals by the guys from Tim Wendelboe at the CRF did find Bastian rising to the top, but the cupping was a little suspect (e.g., poor examples of the SL28, for instance).
Why a new varietal?
Kenyan coffee production has been declining since at least 2001. There are a number of reasons for this, but in recent years part of the problem has been instability in the weather. Drought and heavy rain disrupt flowering and fruiting, and wet conditions also cause an increase in fungal diseases. Thus, a varietal that has more resistance to these diseases is welcomed by farmers.
In the case of Batian, it also matures faster than other varieties — in two years versus three. It is high yield, but Batian’s ability to boost production is in large part due to the fact it can be planted at twice the density of other typical varietals in Kenya, up to 2500 trees per ha. The end result is a yield of up to 5 tons per ha under optimal management, versus an average of 2 tons/ha. Batian also has a large bean size, which must also contribute to yield estimates.
What does this mean for the environment?
On the plus side, if Batian does show good resistance to fungal diseases (one news piece implies Batian has complete resistance), it may reduce the use of copper fungicides. While often considered allowable under many organic standards, their extensive and prolonged use on coffee in Kenya has resulted in soil contamination. Copper fungicides are already applied many times a year on Kenyan coffee. If rain is frequent, it must be reapplied more often because it is washed off (and fungal diseases are worse in wet conditions). If dependence on fungicides can be reduced or eliminated, this would be a huge accomplishment, and very positive for the environment.
There is a growing movement in Kenya, where most coffee is grown in the sun, to plant shade trees and also reforest many areas. I am not sure it is possible to grow many shade trees and also grow Batian at the recommended density, which is essentially a coffee tree every 2 m. But, (as pointed out in the comment section below and amended here) if farmers don’t have to worry about fungal diseases they may be more apt to plant shade trees. (I will do a post on coffee berry disease and shade similar to the one on coffee leaf rust some time this fall.)
The CRF and government is also encouraging the planting of Batian in areas where it is currently not being grown, particularly in western Kenya. Bungoma, Kasii, and Nyanza are current western coffee regions and I have not found details on whether these are the areas being targeted, or some other districts. It’s my understanding that west Kenya gets more rain than the central region where most coffee is grown, and that may be why Batian is being pushed there — coffee planted at high densities usually requires more moisture. Unfortunately, densely planted coffee often also requires heavy fertilization and the trees need to be replaced more often.
Combating diseases, declining yield, and climate change while maintaining quality in a sustainable manner is a challenge to coffee growers worldwide. One can hardly fault farmers for wanting to sustain or improve their livelihoods, or governmental agencies for working to stabilize or increase the production of a primary export crop. Is another potentially sun-grown, high-input varietal the answer, or environmentally sustainable? We will have to wait and see.