Incidence, Distribution and Characteristics of Major Tomato Leaf ...

Incidence, distribution and characteristics of major tomato leaf curl and mosaic virus diseases
virus diseases in Uganda. Where more detailed and correct viral diseases information is
available, tomato leaf curl viruses alone are reported to cause 100% crop yield loss
(Czosnek and Laterrot, 1997). This devastating situation could also be possible for
Uganda.
Major tomato growing areas in Uganda have dry and wet seasons alternating in a year
(Mukiibi, 2001; Ministry of Agriculture Zoning Report, 2005 unpublished, Annex 1).
The dry seasons are between June to August and January to February, while wet seasons
are between March to Mid-June and Mid-August to December. Elsewhere, seasonality is
known to affect tomato virus diseases incidence and distribution (Moustafa, 1991).
Therefore, our objective is to survey for incidence and distribution, and to identify
viruses infecting tomato in Uganda, as was done elsewhere (Czosnek and Laterrot, 1997;
Green et al., 1991; Bock, 1982; Martyn, 1968). We assume that viruses occurring on
tomato in neighbouring countries also infect tomato in Uganda. Knowledge of these
viruses would provide a sound basis for future resistant tomato variety introduction and
breeding programmes.
3.2 Materials and Methods
3.2.1 Field Survey
During the first rainy season (March-June of 1997), second rainy season (August-
November 1997, the dry season (January-February 1998), and the first rainy season
(March to July 1998), a survey was conducted to cover major tomato growing districts in
Uganda, i.e., Iganga, Kasese, Kabale, Mbale, Mbarara, Mpigi, Mukono, and Rakai
(Figure 3.1). According to the Ministry of Agriculture, Animal Industry and Fisheries
(MAAIF) and the National Agricultural Research Organization (NARO), these districts
are located in five agro-climatic zones (Table 3.1 and Annex 1), which are among the ten
zones into which Uganda is divided (Annex 1).
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