Incidence, Distribution and Characteristics of Major Tomato Leaf ...
Incidence, Distribution and Characteristics of Major Tomato Leaf ...
Incidence, Distribution and Characteristics of Major Tomato Leaf ...
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
<strong>Incidence</strong>, distribution <strong>and</strong> characteristics <strong>of</strong> major tomato leaf curl <strong>and</strong> mosaic virus diseases<br />
3 CHAPTER 3<br />
A Survey <strong>of</strong> <strong>Tomato</strong> Viruses In Ug<strong>and</strong>a: <strong>Incidence</strong>,<br />
<strong>Distribution</strong>, <strong>and</strong> Identification<br />
3.1 Introduction<br />
It is known that 146 tomato viruses exist worldwide ¹ . According to available reports,<br />
some <strong>of</strong> these viruses occur in East Africa. As early as the 1960s, reports from<br />
neighbouring Tanzania indicated occurrence <strong>of</strong> <strong>Tomato</strong> spotted wilt virus (TSWV) (CMI,<br />
1969), <strong>Tomato</strong> yellow leaf curl virus (sensu stricto) <strong>and</strong> <strong>Tomato</strong> leaf curl virus (ToLCV-<br />
TZ), <strong>Tomato</strong> mosaic virus (ToMV), Cucumber mosaic virus (CMV), <strong>and</strong> Potato Virus Y<br />
(PVY) (Nono-Womdim et al., 1996; Chiang et al., 1996). <strong>Tomato</strong> yellow leaf curl virus<br />
(TYLCV) (sensu stricto) <strong>and</strong> <strong>Tomato</strong> leaf curl virus (TLCV-SD) (Yassin, 1989; Brunt et<br />
al., 1990) have also been reported from Sudan. However, Potato Virus X (PVX) <strong>and</strong> Chili<br />
veinal mottle virus (ChiVMV) have not been reported on tomato from the East African<br />
region, <strong>and</strong> the report available to me about viruses occurring worldwide (Brunt et al.,<br />
1990) has nothing about PVX or ChiVMV occurrence on tomato in this region.<br />
In Ug<strong>and</strong>a, there is lack <strong>of</strong> information on prevailing tomato viruses. However, the<br />
occurrence <strong>of</strong> some tomato viruses in neighbouring countries, together with poor<br />
quarantine measures, <strong>and</strong> the ability <strong>of</strong> vectors to move across borders, implies a high<br />
probability <strong>of</strong> Ug<strong>and</strong>a having similar tomato viruses. The actual information gap on<br />
tomato viruses occurring in Ug<strong>and</strong>a is basically due to attribution <strong>of</strong> tomato crop losses<br />
caused by viral diseases to other production constraints (Akemo <strong>and</strong> Ssekyewa, 1996<br />
unpublished work on general tomato agronomy in report submitted to IPM-CRSP<br />
Project). As such, <strong>and</strong> apart from the general survey on horticultural crop viruses<br />
conducted by Hansen (1990), during which mosaic, curl <strong>and</strong> mottle symptoms were<br />
observed in tomato farmers’ fields, there was no other more specific report on tomato<br />
¹ http://image.fs.uidaho.edu/vide/descr002.htm<br />
47
Change language