Cassava Pests and Diseases
From Biosecwiki
New cassava homepage | Importance of cassava | Sector development | Building a resilient cassava production system
Cassava-related diseases
Cassava production in the Great Lakes region is being seriously threatened by pests and diseases. The two major diseases are the Uganda variant of the East African cassava mosaic virus (EACMV-Ug) and cassava brown streak virus (CBSV). These are just the latest in a long line of disease strains affecting cassava (1983, 1993, 1997, 2004). Although timing is not regular, depending on biological events and conditions such as area under cultivation and climatic factors, major new diseases or strains of cassava disease tend to appear every 7–10 years.
These two diseases, spread by a whitefly vector (Bemisia tabaci) and the movement of planting materials, pose a severe threat to cassava production in many areas in the region. According to researchers, there has been a significant increase in the density of whitefly populations in recent years, to the extent that the whitefly itself has become a pest to the crop (causing damage to cassava leaves) as well as being a disease vector.
In 2009, FAO conducted a regional review of current efforts to combat cassava diseases. The review identified a number of underlying causes in the spread of cassava diseases in the area, including: weakness in farmer education and information; lack of institutional capacity on the part of government plant health and extension services; and challenges in the research, release and multiplication of new varieties [link to programme review page].
Responding to cassava-related diseases
Given the severity of the current cassava disease outbreaks and the threat it poses to the food security of millions of people, a number of donor-funded cassava disease programmes have been operational within disease-affected areas of Burundi, the Democratic Republic of the Congo, Kenya, Rwanda, Tanzania and Uganda (see below - current cassava disease programmes).
Until now, the replacement of susceptible varieties with tolerant or resistant varieties has been the preferred strategy for responding to cassava-related diseases. However, large-scale distribution of planting materials tends to reduce the diversity of varieties grown in large areas, and this in turn can render the cassava production system more susceptible – sooner or later – to pests and diseases. A combination of short- and long-term options is therefore required to address the immediate needs of rural populations as well as to ensure long-term sustainability of the crop and preserve biodiversity.
Current cassava disease programmes
a) The FAO Regional Cassava Initiative, sponsored by the Humanitarian Aid department of the European Commission (ECHO), involves: (i) the multiplication and distribution of CMV‑resistant planting material in five worst-affected countries; (ii) support to country and regional data and information management; and (iii) the basis for improved consensus and coordination mechanisms. The project, implemented in two phases between 2006–2009, works by multiplying and distributing material to primary beneficiaries and then relies on subsequent farmer-to-farmer re-distribution. It is estimated that a minimum of 500,000 households have received improved vegetative material from nurseries in this programme. Furthermore, it is estimated that some 2,000 farmers, individually contracted or engaged in some form of Farmer Field School activity, now have the skills and knowledge to generateplanting material.
b) The Great Lakes Cassava Initiative (GLCI), funded by the Bill and Melinda Gates Foundation and implemented by the Catholic Relief Services (CRS), addresses cassava disease in six countries. This programme (2008–2012) covers cooperative research into new varieties, surveillance in partnership with the IITA and also involves multiplication and distribution of materials, together with communication and farmer awareness activities. By 2012, the programme aims to have provided resistant planting material to over 1.1 million households and transferred skills on disease identification.
c) The United States Agency for International Development is sponsoring a cassava project, implemented by the Association for Strengthening Agricultural Research in Eastern and Central Africa (ASARECA). This project (2008–2012) focuses on: (i) developing knowledge on CMV and CBSV diseases; (ii) developing multiplication system for generating quality material of improved varieties; (iii) building capacity on cassava production; (iv) supporting the development of policies and standards for cassava; and (v) scaling-up processing technologies.
d) An International Institute of Tropical Agriculture (IITA) project entitled “Integrated protection of cassava from emerging pests and diseases that threaten rural livelihoods”, is meant to increase and sustain cassava productivity and improve livelihoods of farmers through the reduction of crop losses due to pests and diseases in sub-Saharan Africa (2007–2010). This project is sponsored by the International Fund for Agricultural Development.
e) The Common Market for Eastern and Southern Africa (COMESA) is also implementing a programme entitled Cassava Transformation in Southern Africa (CATISA). It aims to analyse and help accelerate cassava commercialization in southern Africa in order to help improve food security in the region. CATISA focuses on the rapidly growing commercialization of cassava – an integrated food staple market-shed in which cassava commercialization offers significant potential for improving food security in drought prone areas in five countries, the Democratic Republic of the Congo, Malawi, Mozambique, Tanzania and Zambia. The programme budget of USD 2 million was complemented with start-up funds provided by the Swedish International Development Cooperation Agency.
There are several other local and international non-governmental organizations (NGOs) with varied range and scope of operations ranging from research to development and across districts of the same country to across countries.
