image: Diseased tuber of the cassava. view more
Credit: Stella Kihara/AGRA
Nairobi, Kenya (18 October, 2007)—A meeting of Africa’s leading cassava breeders zeroed in on actions needed to stop the rapid spread of cassava brown streak disease (CBSD). The resurgent crop disease has already caused a low-grade famine in northern Mozambique, and led farmers in Zanzibar to largely abandon cultivation of the critical food crop. Breeders from Uganda, Kenya, Tanzania, Malawi and Mozambique all noted the rising threat of the disease to small-scale farmers in their areas.
Cassava breeders at the meeting in Zanzibar 3-5 October 2007 said that the disease has recently spiked, for reasons that are unclear. Yet, breeders have already developed a number of disease-resistant varieties, and others are in the pipeline. Breeders noted that the problem lies in getting these varieties to farmers and that many African governments have stringent variety release rules that seriously delay getting the new varieties into farmers’ fields.
“Joint action by cassava breeders, farmers and government agencies can contain this disease,” said cassava breeder Dr. Edward Kanju of the International Institute for Tropical Agriculture in Tanzania. “Isolated action or inaction will worsen hunger. Unless cassava scientists and policy makers understand that there is this menace, farmers and their families will suffer as a result.”
The African Cassava Breeders Network meeting brought together nearly 50 people from eight countries: Kenya, Uganda, Tanzania, Mozambique, Nigeria, Ghana, Malawi and Rwanda. Present were crop breeders, seed producers, and representatives of agriculture-related businesses and non-governmental organizations. The meeting was jointly convened by the Alliance for a Green Revolution in Africa (AGRA) and the Ministry of Agriculture of Tanzania. AGRA, whose board is chaired by former United Nations Secretary-General Kofi A. Annan, has recently awarded a total three grants, totalling US$553,692 to cassava breeders at national agricultural research organizations in Kenya, Malawi, and Tanzania. AGRA has also made a grant for $157,500 to support rapid distribution of four cassava varieties that are resistant to CBSD on the islands of Zanzibar and Pemba.
If CBSD continues to spread unabated, the damage would be considerable, breeders said, and would compound the losses already being caused by a second disease, the African cassava mosaic virus. CBSD causes the normally edible cassava roots to become corky and inedible, and may also streak and destroy leaf tissue. Once introduced into a field, the virus can spread rapidly, and yield losses of up to 100 percent have been registered. However, Tanzania’s cassava breeders have developed tolerant materials that could be critical to arresting the epidemic. The key will be getting this genetic material to other breeding programmes in the region for use in local breeding programmes.
Across Africa, cassava is a staple food for some 250 million Africans, and its tuberous root is the second most important crop in terms of calories consumed. It has served as a reserve against famine and is tolerant to water stress and poor soils, making it important to African farmers facing longer and more frequent droughts. Its leaves are used as a vegetable and provide a cheap but rich source of proteins, vitamins A, B and C, and other minerals. Cassava’s importance to Africa has even been recognized by the African Union’s New Partnership for Africa’s Development (NEPAD), which has developed a Pan African Cassava Initiative. Nonetheless, cassava remains susceptible to a number of crop diseases and pests, and most varieties grown by small-scale farmers are low yielding, limiting the crop’s potential to alleviate hunger and malnutrition.
Breeders and Farmers Working Together to Increase Yield and Tackle Disease
The breeders noted that while curbing the spread of cassava brown streak disease is a top priority, breeding strategies also need to increase cassava yield and to target specific traits that farmers are looking for, otherwise farmers are unlikely to use the new varieties.
Yield increases will not only stem hunger, but are also essential to conserve African environments, which are being converted to agriculture, according to Dr. Ibrahim Benesi, a cassava breeder with the Chitedze Agricultural Research Station in Lilongwe, Malawi. The conversion of natural landscapes to farm fields is a major cause of deforestation in Africa.
Benesi noted that cassava production in Africa has grown from 90 to 145 million tons in the last forty years and, at that production is expected to double in the next twenty years. “However, more than 75% of this increase in cassava production has come from increases in land area rather than increases in productivity. Farmers need to harvest more on less land if African environments are to be spared,” Benesi said.
Network breeders recommended a new breeding strategy, known as “farmer participatory selection” as key to the development of varieties that are disease resistant, high yielding, and appeal to farmers. Using this approach, crop breeders involve local farmers directly in their work to identify farmer preferences, which may involve a range of qualities, including taste, good cooking ability, early maturity, good storage in the ground, more roots per plant, and leaves suitable as a good vegetable. The approach ensures that qualities for disease resistance and yield are coupled with qualities important to local farmers and communities.
“This farmer-participatory approach to plant breeding is a genuine and fairly recent breakthrough in crop breeding,” said George Bigirwa of AGRA. “Only a decade ago, such methods were considered by many to be ‘less scientific’ than selecting for maximum yields in trials grown on isolated research stations using high applications of fertilizers and chemical pesticides.”
At the meeting, cassava breeders from eight countries reported on the farmer participatory breeding work of their national research institutions. In many cases, the reports represented the first time that the breeders were testing their own locally-bred varieties, rather than varieties developed by others at distant research stations.
Building Farmer Entrepreneurs and Strengthening Private-Sector Involvement
Some network participants also stressed the urgent need to increase private-sector involvement in supporting small-scale cassava farmers and building markets.
Zanzibar is developing one approach to the problem. The government has not only approved four new CBSD-tolerant varieties, but is working across the region to spur farmer entrepreneurial efforts.
On Zanzibar’s two islands, cassava had been the most important crop after rice—until a severe outbreak of cassava brown streak disease practically wiped it off the map. With the support of a grant from AGRA, the government, breeders and farmers are taking an innovative approach to restoring the crop. The government has already approved several CBSD-resistant varieties, and it has initiated a farmer-led variety distribution program. Instead of centrally distributing cuttings from the Ministry of Agriculture, each village will designate its own farmer responsible for growing the disease-resistant varieties and distributing them, at a low set cost, to local farmers.
“With the support of AGRA, we will train farmers themselves to multiply and disseminate cassava planting materials to other farmers rather than relying on companies,” said Mr. Haji Saleh of the Ministry of Agriculture of Zanzibar. “This system will make sure farmers are able to access these new varieties of cassava while at the same time empowering them with entrepreneurial skills.”
About the Alliance for a Green Revolution in Africa (AGRA)
AGRA is a dynamic partnership working across the African continent to help millions of small-scale farmers and their families lift themselves out of poverty and hunger. AGRA programs develop practical solutions to significantly boost farm productivity and incomes for the poor while safeguarding the environment. AGRA advocates for policies that support its work across all key aspects of the African agricultural “value chain”—from seeds, soil health, and water to markets and agricultural education.
AGRA is chaired by Kofi A. Annan, the former Secretary-General of the United Nations. AGRA, with initial support from the Rockefeller Foundation and the Bill & Melinda Gates Foundation, maintains offices in Nairobi, Kenya and Accra, Ghana.
For more information, go to www.agra-alliance.org .