Dar es Salaam (IITA) – The push to increase the production of cassava in Tanzania has received a major boost with the recent official release of four new varieties that are tolerant to the deadly rot disease of the crop, the Cassava Brown Streak Disease (CBSD) and resistant to the equally devastating Cassava Mosaic Disease (CMD).
The two diseases have been rapidly spreading through the Great Lakes countries of eastern Africa from war-torn Democratic Republic of Congo to Rwanda, Burundi, Kenya, Uganda, Tanzania, Mozambique and Malawi, nearly reaching epidemic proportions as all the varieties grown by the farmers were susceptible.
They represent the greatest threat to the production of Africa’s, and Tanzania’s, second most important food crop after maize and which provides more than half of the dietary calories for over half of the total rural and urban population in sub-Saharan Africa and which also has great potential as an industrial crop.
The varieties, code-named Pwani, Mkumba, Makutupora and Dodoma, can easily double cassava production in the country with their potentially high yields ranging from 23-51t/ha against the current average yield of 10t/ha.
They are a result of eight years of collaborative work between researchers from Tanzanian Agricultural Research Institutes (ARIs), the International Institute of Tropical Agriculture (IITA) and the International Centre for Tropical Agriculture (CIAT).
They were developed through conventional breeding supported by advanced biotechnology tools, molecular marker-assisted breeding, to speed up the process.
Two of the varieties, Pwani and Mkumba, are targeted to the coastal belt and the other two, Makutupora and Dodoma, to the semi arid areas of Central Tanzania. Pwani has the highest potential yield of 51t/ha while Mkumba -which farmers liked due to its high dry matter and sweet taste- the lowest at 23.1t/ha.
According to Dr. Geoffrey Mkamilo, the Team Leader of Cassava Research in Tanzania, the farmers will be very relieved and happy as they have been eagerly awaiting these varieties as the two diseases have devastated the crop’s production for many years.
He points out the cassava brown streak disease as being especially devastating and causing a lot of heartbreak to farmers.
“CBSD has been very devastating because its symptoms are not always clear. Farmers looking forward to a good harvest get a rude shock when they harvest and discover the useless rotten roots,” he explained. “As a result, many of them had abandoned this hardy crop that performs relatively well even under harsh conditions such as poor soils and little rainfall.”
The project was funded by the Rockefeller Foundation (RF) and the Alliance for a Green Revolution in Africa (AGRA). The Generation Challenge Program of the Consultative Group on International Agricultural Research Centers (CGIAR) contributed funds for farmer participatory trials to test for resistance and productivity under actual farm conditions and to complete tests required by the National Variety Release Committee before the new varieties could be officially released to farmers.
Dr. Edward Kanju, a cassava breeder with IITA-Tanzania, who was also involved in the research, says that the varieties were developed by crossing local varieties with those introduced from Latin America from CIAT in Colombia and are the result of eight years of research.
“We used local varieties from Tanzania as sources of resistance to CBSD and for local adaptation and those from CIAT as sources of high yield and resistance to CMD and cassava green mites,” he said.
CBSD that causes a dry rot in cassava has been around in eastern and central Africa since the 1930’s but confined to the low altitude coastal lowlands. However in 2004, a deadlier form of the disease was reported in Uganda, spreading to the mid-altitude areas of neighbouring countries that are just recovering from bouts with CMD.
The disease which can cause up to 80 percent yield reduction as it affects the roots and leaves, the most useful parts of the crop, has drastically affected cassava production in North Western Tanzania and in the coastal belt. Its devastation has been the greatest around the lake zone in districts such as Ukerewe, Mara, Musoma and Bunda.
The next challenge will be to get adequate planting material for farmers. At the moment, farmers mainly get their planting material from neighbours, Non-Governmental Organizations (NGOs) and the government, and supplies are sometimes erratic.
To address this, cassava stakeholders are seeking to develop systems to enhance production, sale and marketing of clean cassava planting material to supply meet the demand both from small-scale as well as commercial cassava growers.
The combination of these new varieties coupled with improved systems for delivering planting material offers huge promise for a brighter future for cassava in Tanzania.