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Tanzania losing millions from cassava virus diseases

18th February 2013
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The officer in charge of Mikocheni Agricultural Research Institute, Dr. Joseph Ndunguru (centre) shows research scientists, cassava leaves affected by cassava mosaic disease (CMD) and cassava brown streak disease (CBSD) at Zinga village in Bagamoyo district, Coast Region over the weekend. (Photo by Gerald Kitabu)

From Feb 14 to 16, 2013, Tanzania hosted the launch of Disease Diagnostics for Sustainable Cassava Productivity in Africa project. The event brought together 70 scientists and stakeholders from eight countries in Africa namely: the host Tanzania, Kenya, Uganda, Burundi, Rwanda, Malawi, Mozambique and Zambia with partners from the United States of America (USA) and the United Kingdom (UK). Our reporter Gerald Kitabu who attended the meeting sheds light on the measures being taken to address the problem and increase cassava productivity. Read on …

Cassava, a widely known and grown staple food in many parts of Tanzania, Africa and other parts of the world, has come under severe attack. This time around, it is not about climate change, but rather several biotic and abiotic factors, among which cassava mosaic disease (CMD) and cassava brown streak disease (CBSD) constitute the main threat to cassava productivity. CMD is caused by cassava mosaic begomoviruses (CMBGs) where as CBSD is caused by cassava brown streak virus (CBSV). 

In Tanzania for example, cassava is an important crop for both food security and income generation for low income people. In coast region, cassava is one of the main food crops.  According to the Ministry of Agriculture, Food Security and Cooperatives, the annual production of fresh cassava is seven million metric tonnes. In sub-Saharan Africa, and Asia cassava is a staple food and is eaten by over seven hundred million people. However, two thirds of more than 18 million ha, of cassava cultivated worldwide are produced in Africa. Cassava has potential for industrial use in production of starch and bio fuel. The cassava leaves are also used for food in many communities in Africa including Tanzania. 

Despite its potential benefits, cassava is faced by the two diseases namely cassava mosaic disease (CMD) and cassava brown streak disease (CBSD). The rate at which the viruses of the two diseases multiply is shocking, especially given the fact that the farmers are ignorant of the diseases, as such they would leave the already infected plant to spread the viruses without taking appropriate measures. 

According to Dr. Joseph Ndunguru, the officer in charge-Mikocheni Agricultural Research Institute (MARI) which is under the Ministry of Agriculture, food security and cooperatives, CMD and CBSD have become a serious constraint to sustainable production of food and fibre crops in Sub-Saharan Africa including cassava. During the last decade, these plant pathogens have increased in number, distribution and importance and in some places, they have forced farmers to abandon their fields. 

Dr. Ndunguru who is a molecular plant virologist says at the moment, the diseases have no cure, however, efforts are undergoing by different scientists to research on the diseases which threaten the existence of the cassava crop. He says, meanwhile the farmers can only uproot the infected plants at its infant stage before it spreads the viruses to other plants. He also says, the farmers can also stop using the already infected plants as seeds for the next planting season to fight the infection.

For his part, the Chairman, Department of horticulture, Jomo Kenyatta University of Agriculture and Technology (JKUAT) Dr. Elija Ateka says a recent quantitative survey conducted in four major cassava growing areas in Kenya to determine the status of cassava shows a presence of the CDD and CBSD. He named the four provinces as Eastern, Nyanza, Western, and the coast.

Dr. Ateka says the diseases have caused difficulties to sustain production and development of cassava in Kenya.

He says as a result, when people venture into cassava related industries, they don’t last longer as they quickly close their industries because of poor quality or lack of raw materials to sustainably run their factories.

“Even those who had just started, when they see their fellows closing their industries, they feel insecure or are simply discouraged. So, they can’t continue any more,” he says.

It is from this background that last week from 14th to 16th Feb this year, a total of 70 scientists and stakeholders from 11 countries in Africa launched this project of disease diagnostics for sustainable cassava productivity which is building on phase one. The regional initiative is funded at a tune of 9,487,448/-m by the Bill and Melinda Gates Foundation (BMGF) and the Department for International Development (DFID) and it is led by national agricultural research scientists from Tanzania, Kenya, Uganda, Rwanda, Malawi, Mozambique and Zambia working together with a common goal and vision to manage virus diseases affecting cassava in collaboration with partners from centres and universities in the USA and UK.

When officiating at the launch of phase two of this project for diagnosing and managing important cassava viral diseases in Africa, the Deputy Minister for the  Ministry of Agriculture, Food Security and Cooperatives, Adam Malima said under  normal circumstances, cassava yields could be as high as between 25 to 40 tons per hectare. In Sub-Saharan Africa, however, yields are very low and sometimes less than 5 tons per hectare due to the diseases. The Deputy Minister says, in 2005 for example, CMD alone caused crop losses of 4 M metric tons per year in Tanzania, Uganda, Rwanda and Burundi. On the other hand, CBSD caused estimated crop losses in Tanzania of between 35 and 70 million USD per year calculated at a price of 100 USD per metric tons of fresh cassava.

Conservative loss estimates based upon the minimum average prices of high quality cassava flour in Dar es Salaam would make this at least 70-140 million USD at wholesale, and 175-350 million USD  at retail.

He said that for sustainable management of cassava virus diseases, we need to build the capacity of the national research institutions in terms of human and infrastructure as well as establishing and strengthening regional networks.

“This project addresses key aspects of improving cassava productivity and food security including: understanding the threat from evolving viruses and vectors, support clean seed systems for farmers and building sustainable regional capacity. It also aims to minimize the persistent occurrence of cassava viruses and their associated vectors. It is anticipated that project will benefit cassava farmers, commercial planting materials production, trade and the future development of a cassava-based industry in Africa” he said.

Phase one of this project, successfully established and strengthened capacity for local scientists and infrastructure to conduct virus disease diagnostics. In phase two, the project aims to further enhance the capacity of national cassava programs in the partner countries to use diagnostic tools developed in phase one, for effective implementation of CMD and CBSD management strategies. It will address the threat of increasingly virulent cassava viruses and their associated whitefly vectors, which together cause CMD and CBSD in Sub-Saharan Africa. Support clean seeds systems for farmers and build sustainable regional capacity. The beneficiaries of the project include farmers, breeders, scientists, governments, other stakeholders and donors. The beneficiaries will benefit through increased access and use of cassava virus resistant materials, acquiring increased knowledge of virus types and breeding hotspots, screening materials more efficiently with infectious clones, acquiring new virus resistant clones, and saving time and resources by knowing the status of initial parent material.  

SOURCE: THE GUARDIAN