This article describes the incidence and etiology of a viral disease of passion fruit in Uganda. Symptoms, including those characteristic of passion fruit woodiness disease (PWD), were observed on 32% of plants in producing areas. Electron microscopic observations of infected tissues revealed flexuous filaments of ca. 780 nm. Enzymelinked immunosorbent assays indicated a serological relationship with Cowpea aphid-borne mosaic virus (CABMV) and Passion fruit ringspot virus (PFRSV). In host range studies, only species in the families Solanaceae and Chenopodiaceae were susceptible, and neither Vigna unguiculata nor Phaseolus vulgaris became infected. Coat protein (CP) gene sequences of eight isolates exhibited features typical of potyviruses and were highly similar (88 to 100% identity). However, the sequences had limited sequence identity with CP genes of two of the three potyviruses reported to cause PWD: East Asian Passiflora virus and Passion fruit woodiness virus (PWV). Deduced amino acid sequences for the CP of isolates from Uganda had highest identity with Bean common mosaic necrosis virus (BCMNV) (72 to 79%, with evolutionary divergence values between 0.17 and 0.19) and CABMV (73 to 76%, with divergence values between 0.21 and 0.25). Based on these results and in accordance with International Committee for Taxonomy of Viruses criteria for species demarcation in the family Potyviridae, we conclude that a previously unreported virus causes viral diseases on passion fruit in Uganda. The name “Ugandan Passiflora virus” is proposed for this virus.
The presence of inocula all year round poses a daunting challenge to the management of late blight [causal agent Phytophthora infestans (Mont.) De Bary] of Solanum potato in the highlands of eastern Africa. Commercial production depends heavily on use of fungicides and, to some extent, host resistance. In this study, integration of host resistance and fungicide application reduced late blight severity by more than 50% and resulted in yield gains of more than 30% when compared with the untreated control. The study demonstrated that susceptible varieties can be successfully grown in the region if well‐timed fungicide sprays are administered. Under high late blight pressure, fungicide application was necessary but integration of resistant cultivars in late blight management assisted in reducing the amount and frequency of fungicide applications. However, integration of timely planting (early planting) is difficult due to limitations in weather monitoring and the subsistence nature of the farming system in the eastern African highlands.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.