Browsing by Author "Owusu, G.K."
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Item Detection Of Viruses And The Spatial And Temporal Spread Patterns Of Viral Diseases Of Cucurbits (Cucurbitaceae Spp.) In The Coastal Savannah Zone Of Ghana(University of Ghana, 2013-07) Gyamena, E.A.; Amoatey, H.M.; Owusu, G.K.; University of Ghana, College of Basic and Applied Sciences, Biotechnology CentreCucurbits are susceptible to over 35 plant viruses; each of these viruses is capable of causing total crop failure in a poorly managed virus pathosystem. The objectives of this study were to detect the viruses that infect six cucurbit species in the coastal savannah zone of Ghana and to describe the spatial and temporal spread patterns of virus epidemics in zucchini squash (Cucurbita pepo L.) by the use of mathematical and geostatistical models. Cucumber (Cucumis sativus L.), watermelon (Citrullus lanatus Thunb.), zucchini squash (Cucurbita pepo L.), butternut squash (Cucurbita moschata Duchesne), egushi (Citrullus colocynthis L. Schrad.) and melon (Cucumis melo L.) were grown on an experimental field in the coastal savannah zone of Ghana and were monitored for the expression of virus and virus-like symptoms. The observed symptoms were further confirmed by Double Antibody Sandwich Enzyme-Linked Immunosorbent Assay (DAS ELISA) and mechanical inoculation of indicator plants. The temporal spread patterns of virus disease in zucchini squash were analyzed by exponential, logistic, monomolecular and gompertz mechanistic models. The spatial patterns of virus disease spread in zucchini squash field were analyzed by semivariograms and inverse distance weighting (IDW) methods. Cucumber, zucchini squash, melon and butternut squash were infected by both Cucumber mosaic virus (CMV) and Papaya ringspot virus (PRSV-W). Egushi was infected by CMV but not PRSV-W. None of the six cucurbit species were infected by Watermelon mosaic virus (WMV) or Zucchini yellow mosaic virus (ZYMV). The temporal pattern of disease incidence in the zucchini squash field followed the gompertz function with an average apparent infection rate of 0.026 per day. The temporal pattern of disease severity was best described by the exponential model with coefficient of determination of 94.38 % and rate of progress of disease severity of 0.114 per day. As at 49 days after planting (DAP), disease incidence and severity factor had reached 11.82 % and 1.09 respectively. The spatial pattern of disease spread in the zucchini squash field was best described by the Gaussian model with range of spatial dependence of 0.63 m.Item Incidence of sweet potato viruses in the coastal savannah agro-ecological zone of Ghana(Journal of Plant Pathology, 2015-05) Sossah, F.L.; Appiah, A.S.; Oduro, V.; Amoatey, H.M.; Owusu, G.K.; Oppong, A.; Lamptey, J.N.L.; Carey, E.E.; Fuentes, S.An experiment was conducted under field conditions to assess the incidence of viral diseases in 20 accessions of sweet potato [Ipomoea batatas (L.) Lam.]. Using symptomatology, biological indexing, nitrocellulose membrane ELISA (NCM-ELISA) and PCR, the accessions were assessed for disease incidence and symptom severity. Symptom expression varied among the accessions with severity index ranging from 2.24 in UK/BNARI at eight weeks after planting (wap) to 3.63 in US029 at 12 wap. Mean disease incidence varied significantly among the accessions, ranging from 43.2% to 96.3%. Using NCM-ELISA, 85% of the sweet potato plants tested positive to Sweet potato feathery mottle virus (SPFMV), Sweet potato mild speckling virus (SPMSV, 55%), Sweet potato collusive virus (SPCV, 45%), Sweet potato chlorotic fleck virus (SPCFV, 30%), Sweet potato virus G (SPVG, 20%), Sweet potato mild mottle virus (SPMMV, 5%), Sweet potato chlorotic stunt virus (SPCSV, 1.67%) and Cucumber mosaic virus (CMV, 1.67%). PCR detected Sweet potato leaf curl virus (SPLCV) in accessions UK/BNARI and CRI054. Biological indexing resulted in characteristic symptoms, commonly vein-clearing with eventual death of plants grafted with scions mix-infected with SPCSV and SPFMV. This work provides the first detailed report on sweet potato virus diseases in Ghana correlating symptoms, grafting, serology as well as PCR. It emphasizes the importance of selecting resistant cultivars as planting materials and the enforcement of quarantine measures to minimise the introduction of viruses into Ghana and their subsequent spread. © 2015, Journal of Plant Pathology. All rights reserved.Item Non-Destructive Determination of Photosynthetic Rates of Eight Varieties of Cassava (Manihot Esculenta, Crantz(University of Ghana, 2015-07) Amadu, A.A.; Danso, K.E.; Owusu, G.K.; University of Ghana; University of Ghana, College of Basic and Applied Sciences,Department of Nuclear Agriculture and Radiation Processing