Agriculture Reference
In-Depth Information
A later survey of Kumi district in April 1992 revealed that the overall disease
situation had deteriorated further and the symptoms were very severe. There was a
high incidence of infection throughout the whole district, including the southern
areas where CMD incidence and severity were relatively low in 1991. Much of the
infection in the southern areas had occurred soon after planting and was due to
whiteflies, as recorded to the north around Kumi township in 1991. The situation
was different there in 1992 as, in the absence of healthy planting material, farmers
had collected cuttings from plants that had been infected late the previous year and
consequently virtually all plants showed severe symptoms from the outset. Growth
was very stunted; many plantings were soon abandoned and became completely
overgrown by weeds.
Some use was being made of cuttings obtained from less severely affected
districts immediately to the south of Kumi, but movement was restricted and the
traffic in planting material was much less than in Luwero district. Consequently,
there was a rapid decline in the area of cassava as farmers abandoned the crop after
realizing the futility of planting infected cuttings. This had very severe consequences
in 1994, when there were widespread food shortages and famine-related deaths were
reported to a later Presidential Commission of Inquiry into the causes of the crisis.
The areas worst affected were those where the second rains of 1993 had failed and
there was little or no cassava available to sustain populations until the 1994 crops of
sweet potato, sorghum and other grain crops were harvested.
Various attempts were made to restore cassava production in Kumi using the
most appropriate varieties available. In the initial 1991 OXFAM resettlement
project, cuttings of the Ugandan varieties Bao and Aladu were obtained from Apac
district to the west. However, these varieties were not very resistant to infection and,
as in Luwero and West Nile, they were introduced at the height of the epidemic
when whiteflies were numerous and CMD was prevalent. Rapid spread occurred to
the new plantings and many were soon almost totally infected. This occurred
whether or not farmers had heeded the advice to combine the small individual
family allocation of cuttings so as to establish larger blocks and to provide these
with at least some degree of isolation.
Later rehabilitation projects were much more successful, although some of the
varieties used were even more susceptible than those distributed in 1991. This can
be explained by the reduction in infection pressure that occurred as a consequence
of the big decrease in the area of cassava grown, following earlier losses and the
switch to other crops. A particularly successful project was operated by the
Ugandan charity Vision Terudo, which introduced Nase 3 (TMS 30572). This and
other improved CMD-resistant varieties were also distributed in an Agricultural
Development Project in 1995 that had a particularly big impact. A survey in 2003
established that CMD-resistant varieties were being widely grown and they
predominated in 88% of the fields assessed. This explains why the overall
incidence of infection in Kumi was only 14%, symptoms were generally
inconspicuous and there has been a full recovery in cassava production (Bua
et al
.,
2005).
