Agriculture Reference
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severe outbreak of CMD, which hitherto had been relatively unimportant (Otim-
Nape et al., 2000). Affected plants developed severe leaf mosaic symptoms and
chlorosis. There was much leaf distortion and abscission and little or no yield of
tuberous roots, except from the plants recently infected. Plants grown from infected
cuttings were the most severely affected and grew so badly that whole plantings
were abandoned or removed and replaced by other crops.
Uganda at the time was emerging from a prolonged period of political instability
and insecurity. Access to many parts of the country had been impossible or severely
curtailed and the work of the National Cassava Programme had been seriously
disrupted following the enforced evacuation of all senior staff from the Serere
Research Station in Soroti District and their relocation at Namulonge Agricultural
Research Institute, near Kampala in 1987. This explains the limited information on
the background and emergence of the Luwero epidemic. It soon became apparent
from observations in northern Luwero that the affected area was expanding and the
progress of the epidemic was monitored by regular assessments of farmers'
plantings along the main north-south road through Luwero and on into Mpigi district
and Kampala. Each year from 1988, the epidemic moved progressively southwards
along a broad front towards Kampala at a rate of c. 20-30 km per year (Fig. 20.2).
Within the epidemic area, CMD-affected plants developed very severe symptoms
(Gibson et al., 1996), and produced such low yields that serious food shortages
ensued (Otim-Nape et al., 2000).
Figure 20.2. The overall incidence of CMD in successive years in representative farmers'
plantings along a south-north transect from Kampala into northern Luwero district,
illustrating the southward movement of the epidemic front between 1988 and 1994.
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