Cassava is an important source of food and income for small-holder farmers in Africa, because it grows well in conditions of drought and low soil fertility. However, plant viral diseases can destroy up to 100 percent of a cassava crop causing many farming families to go hungry and threatening their livelihoods. According to published reports, healthy cassava harvests could increase incomes for more than half of the households in cassava-growing regions of Uganda and Kenya.

Our partnership – the Virus Resistant Cassava for Africa (VIRCA) project – was established in 2006 and includes African and international organizations working together to develop effective solutions for the control of cassava viral diseases. Supported by this partnership, VIRCA researchers are using genetic modification techniques to improve resistance to cassava brown streak disease (CBSD) in familiar and well-liked varieties, to help cassava farmers have an abundant harvest so they can provide for their families and share the surplus with their communities.

Over the past few years, the VIRCA team has conducted several confined field trials in both Uganda and Kenya. These trials have been done with the approval and cooperation of government regulators, and under their oversight. We have observed very effective resistance to CBSD in our improved cassava plants. In collaboration with experienced cassava breeders in the region, the VIRCA project is now employing familiar techniques of conventional plant breeding to combine transgenic CBSD resistance with non-transgenic CMD resistance to develop new varieties that will provide broad-spectrum virus control.

As with all cassava research and crop improvement projects, it will take some time to fully develop the improved cassava varieties for release to farmers. Researchers will assess the improved cassava in field trials over several years for disease resistance, root yield, and other desirable root and plant characteristics. Since cassava is a long-lived crop, this work takes time. National government regulators will review all the data as part of the standard review process that all new cassava varieties undergo before becoming available to farmers.

For VIRCA cassava, the process will also include a thorough assessment of food, feed, and environmental safety of the improved cassava. The improved cassava varieties developed by the VIRCA project will be available to farmers in a similar manner and at a similar cost as conventionally bred cassava varieties currently available from national research organizations.

We understand the serious threat that viral diseases pose to farmers in Africa and are encouraged that our research efforts over the past several years have yielded fundamental new understandings of how these viruses work and how cassava plants can be protected from them.

The VIRCA project is a collaborative effort involving the Donald Danforth Plant Science Center in St. Louis, Missouri, USA, the National Crops Resources Research Institute (NACRRI) in Namulonge, Uganda, and the Kenya Agricultural and Livestock Research Organization (KALRO) in Nairobi, Kenya.

The VIRCA project is funded by the Bill & Melinda Gates Foundation, the Unites States Agency for International Development from the American People (USAID), and the Monsanto Fund.


Nigel Taylor, Ph.D.
Member and Dorothy J. King Distinguished Investigator
975 N. Warson Road
St. Louis, MO 63132, U.S.A.
Tel: 314-587-1257
Fax: 314-587-1357
Email: ntaylor@danforthcenter.org 


Ann Kruse
(314) 587-1443