Feyissa, Tileye (PhD)Tesfaye, Tewodros2018-07-122023-11-082018-07-122023-11-082010-06http://etd.aau.edu.et/handle/123456789/8325The current study was conducted to assess the recent magnitude of virus diseases attacking sweet potato in the chief production areas of country. Thus, a total of 235 symptomatic and 735 asymptomatic sweet potato vines were collected. Samples from farmers’ fields were established in an insect-proof screen house and were tested for viruses by nitrocellulose membrane enzyme-linked immunosorbent assay (NCM-ELISA) together with 624 imported in vitro plantlets. During the field survey it was observed that incidences of virus and virus-like symptom were high in Sidama, Wolayita, Awassa and Hadiya and very low in Gamo-Gofa and Kembata-Tembaro. The viruses detected were sweet potato feathery mottle virus (SPFMV), sweet potato chlorotic stunt virus (SPCSV) and sweet potato virus G (SPVG). The most prevalent virus detected was SPFMV. The second most frequent virus was SPCSV and SPVG being the third yet, low frequent virus. From imported in vitro plantlets 19.2% was reacted positive for Anti-SPFMV and only 0.2% sero- positive for Anti-SPCSV. SPVD was the most common co-infection observed followed by SPVG+SPCSV yet, less frequent. None of the samples obtained from Eastern and Western Hrarge was any virus infection detected. TAS-ELISA was performed for weakly reacted samples and 35.7% was reacted positive for mAb of SPFMV. However, none of the samples obtained from East and West Hararge was sero-positive for mAb of SPFMV. This study has provided a quantitative assessment of both single and co-infection of viruses in sweet potato plants in Ethiopia, and elucidated the importance of developing resistant varieties particularly against the detected sweet potato viruses, production of virus free materials and quarantine measures not to be overlooked specially in high SPVD incident areas. Key words/Phrases: Sweet Potato, NCM-ELISA, TAS-ELISA, Incidence, Virus, Mixed Infection, Single InfectionenSweet PotatoNCM-ELISATAS-ELISAIncidenceVirusMixed Infection, Single InfectionThesis