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Fig. 15.2.
(Left) Cassava plant infected with African cassava mosaic virus (ACMV), in Ghana, showing mosaic,
chlorosis, and distorted leaves. (Right) Cassava plant infected with ACMV and East African cassava mosaic Cameroon
virus (EACMCV), in Ghana, showing a synergistic effect of the two viruses with extreme “candle stick” symptoms. For
a color version of this figure, please refer to the color plate.
infection diminishes with altitude. Disease is
much less prevalent in altitudes greater than 1000
m above sea level (Storey 1936; Cours-Darne
1968). Virus incidence increases where cassava
is grown intensively (Fargette et al. 1994), and
thus plant density impacts the spread of the virus,
with low density fields encouraging faster dis-
ease propagation than high density fields (Fau-
quet and Fargette 1990). High CMD infection
leads to high chlorosis and distorted leaf patterns
that severely affect plant growth (Figure 15.2)
ther epidemics in Uganda and Madagascar in the
1930s and 1940s (Cours 1951). Records associ-
ated with the “first encounter” epidemics were
from Sierra Leone, Ivory Coast, Ghana, Nige-
ria, Madagascar, and Uganda. It was apparent
that by the 1930s, CMD had spread to virtually
all cassava-growing environments of the African
mainlands and its islands (Cours 1951). In sec-
ond encounter epidemics, the detailed descrip-
tion of symptoms provided by Cours (1951)
highlighted the intense chlorosis, reduction in
leaf size, and stunted architecture of plants
infected by the severe CMD associated with
the epidemic. There were no further reports
of epidemics in East Africa until the 1990s,
when severe CMD epidemic resurged in Uganda
(Gibson et al., 1996; Otim-Nape et al. 1997).
However, we have brief descriptions of epi-
demics in Cameroon (Fondong et al. 2000),
Ghana (Fauquet pers. com.), Ivory Coast (Pita
et al. 2001), Nigeria, and the Cape Verde Islands
(Calvert and Thresh 2002), but none of these
CMD Epidemic
The first report of cassava mosaic disease
(CMD) was from East Africa in 1894 (War-
burg 1894; Zimmerman 1906). Since then, epi-
demics have occurred throughout the African
continent, resulting in great economic loss and
devastating famine (Legg and Fauquet 2004).
The first reported epidemics occurred in many
parts of Africa in the 1920s, followed by fur-
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