Cassava is mostly grown by subsistence farmers on fields of less than 1 ha. Cultivation of cassava is hampered by several biotic constraints, of which cassava mosaic disease (CMD) is currently the most important factor limiting cassava production in Zambia. CMD occurs in all the cassava-growing provinces and accounts for 50% to 70% of yield losses countrywide. Strategies to counter CMD were initiated in the early 1990s and included the release of CMD-resistant cassava cultivars. However, efforts to control CMD are limited because few growers plant these cultivars. More recently, to address the CMD problem, regular disease monitoring and diagnostic capabilities have been strengthened, and there is increased support for screening breeders materials. CMD is a rising threat to cassava production in Zambia. This review of CMD research on disease surveillance, CMD spread, yield losses, awareness campaigns and control options in Zambia over the past 25 years informs future control efforts and management strategies.
Figure1: Symptoms of cassava mosaic disease (CMD). a A healthy cassava plant (left) and a plant infected with CMD (right); plants are same cultivar, Manyopola. b A healthy cassava leaf. c A cassava leaf showing severe CMD symptoms including leaf curling and chlorosis. d A cassava plant (cultivar Katobamputa) with a single infection of African cassava mosaic virus (ACMV) and e a plant of the same cultivar with a dual infection of ACMV and East African cassava mosaic virus (EACMV).