Agriculture Reference
In-Depth Information
Attempts were made to restore production in the areas of Luwero that were first
affected by providing farmers with uninfected cuttings of Ugandan varieties
obtained from districts to the south, where CMD was not a problem at the time.
Almost total infection occurred within a few months of planting, even in locations
where farmers had followed the official advice to remove all diseased plants from
the neighbourhood before the uninfected cuttings were planted. This emphasizes the
high 'infection pressure' prevailing at the time, the mobility of the whitefly vector
and the vulnerability of the introduced varieties. There was an obvious need for
varieties that were resistant to infection, but these were not available in quantity for
distribution to farmers. This led to virus screening and on-farm trials of potential
new varieties for release in the area.
While these studies were in progress, farmers in Luwero responded in various
ways to the great scarcity of CMD-free cuttings for new plantings. Some farmers
sought to maintain production by collecting cuttings from plants in the locality that
had escaped infection, or that developed inconspicuous symptoms and continued to
produce at least some yield. There was a rapid turnover in varieties as those that
were vulnerable soon succumbed and were discarded, whereas relatively tolerant
varieties became increasingly prevalent. Nevertheless, many farmers were so badly
affected that they ceased to grow cassava and increased the area of other food crops
including maize, sorghum, sweet potato and finger millet. There was also continued
use of cuttings obtained from relatively unaffected areas to the south and from other
districts to the west bordering Lake Albert. This traffic was facilitated by the good
communications and the ready availability of transport along main and feeder roads.
Cassava production was sustained, although many of the varieties used were
susceptible to CMD. They eventually succumbed to the disease, which created the
need for further replacement material and CMD-resistant varieties were adopted
when they became available.
Initially, the main rehabilitation project in Luwero and also in five other districts
of Uganda was funded by the UK Gatsby Charitable Foundation (GCF) (Otim-Nape
et al.,
1994, 1997). This supported the activities of the National Cassava
Programme, extension staff and local government collaborators in multiplying and
distributing the improved CMD-resistant varieties that had been shown to be
successful in on-farm trials and were sought by farmers. Funds were also provided
for on-farm trials and to train farmers and extension staff on CMD and its control.
The initial emphasis was on providing cuttings of three improved virus-resistant
varieties that originated from IITA, Nigeria, in the 1970s. These and other officially
released varieties now account for a substantial proportion of the area grown in
Luwero district and predominated in 46% of the fields assessed there in 2003 (Bua
et al.,
2005). Additional CMD-resistant varieties are being developed to extend the
range of genotypes available (Otim-Nape
et al
., 2000).
20.4.2 Arua, Nebbi and Moyo districts (West Nile region)
Cassava has long been the main staple food in Arua, Nebbi and Moyo districts of the
West Nile region of north-west Uganda, near the border with eastern DRC. A severe
