Diversity and economic importance of viral diseases of pepper (Capsicum spp.) in Eastern Africa

Pepper (Capsicum spp.) is an important vegetable crop in the Eastern Africa region where it is grown mainly by small-scale farmers. However, productivity of the crop is limited by many abiotic and biotic constraints. The abiotic constraints include high cost of seeds and inputs, shortage of improved varieties, drought, low soil fertility and lack of technical knowhow among others, while biotic constraints are dominated by diseases and insect pests. Numerous diseases especially those that are caused by viruses pose serious threats in pepper production. Currently, over 68 viruses are known to affect pepper on a worldwide scale and have serious impact on the quantity and quality of pepper produced. Out of the 68 viruses, 12 belonging to seven genera namely Potyvirus, Cucumovirus, Tobamovirus, Polerovirus, Tospovirus, Alfamovirus and Potexvirus have been reported in Eastern Africa. Pepper veinal mottle virus, Potato virus Y and Cucumber mosaic virus are the most widespread and damaging viruses in the region. Yield losses ranging from 10 to 100% in pepper production have been reported for various viruses namely; Pepper veinal mottle virus, Potato virus Y, Chilli veinal mottle virus, Ethiopian pepper mottle virus, Cucumber mosaic virus, Pepper mild mottle virus, Tobacco mosaic virus, Pepper vein yellows virus, Tomato spotted wilt virus, Alfaalfa mosaic virus and Potato virus X. This article provides an overview of the important pepper viruses occurring in Eastern Africa with reference to their geographic distribution, yield-losses, symptoms, transimission, management methods and research gaps that need to be addressed. It can be concluded that viruses are a major constraint to pepper production in the target region.