James KoskeJohn MuriukiNgare, Innocent Osoro2022-09-192022-09-192022http://ir-library.ku.ac.ke/handle/123456789/24252A Research Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy (Sustainable Urban Development) in the School of Environmental Studies of Kenyatta University, September 2021Dodders are annual parasitic plants that reproduce by seeds and do not have leaves that parasitize different plant species across the globe. These holoparasites forage on a variety of plant hosts by sucking nutrients through vascular bundle interaction of haustorium activity. Dodders threaten the survival of plant hosts in Kenya, ranging from trees, shrubs and herbaceous that some are grown as ornamentals. This study was carried in Mombasa to assess the effects of dodder on urban ornamental plants in the coastal urban region. The following objectives guided the study: to identify dodder morphological and anatomical characteristics; to determine the effect of temperature and rainfall on dodder infestation; to assess the effects of dodder on urban ornamental plants and to examine the perceptions of urban household heads on the spread and control of dodder in Mombasa County. This study used a mixed-method research design where both qualitative and quantitative data were collected. In the study, different sampling techniques were used; snowballing, purposive sampling, stratified sampling, and random in the study. A total of 382 respondents were sampled. Questionnaires were used to obtain primary data attaining Cronbach’s Alpha reliability index of 0.72%. Secondary data was obtained from the Kenya Metrological Department and relevant published peer-reviewed articles. Data analysis and interpretation was done by the Statistical Package of Social Sciences, analysis of variance, laboratory microscopic pictorial and micrograph observations, and thematic content analysis. Dodders are androgynous angiosperms with both pistil and stamen reproductive structures. Observational microscopic and anatomical dodder demonstrate numerous productions of seed capsules, each containing a single seed, with hairy stems that are environmentally sensitive to wind direction to identify the immediate host through the haustorium. Dodder undergoes three haustorium phases to establish host vascular bundle interaction – the adhesive, intrusive and conductive phase. When dodders intertwine, they parasitize their own stems, revealing an intraspecific trait. Mombasa (1989–2019) experienced climate variability, with a maximum temperature of t=-5.628, =23, P:0.000 and a minimum temperature of t=-5.401, df:23, P:0.000, and total rainfall of t= 2.025, df=23, P:0.275.The linear regression analysis shows rainfall variation y =-9.588x + 1217.1 and temperature variation y =0.0258x + 29.888 with an increase of +0.4°C. Dodder had ravaged ornamentals where 82.7% of respondents asserted it was attacking and foraging on trees, herbaceous and shrub 𝜒2: 40.73, P:0.000. Cuscuta was fast spreading and the majority (73%) of respondents preferred a mechanical method through cutting of stems 𝜒2 : 1.645, P: 0.026 to control dodder infestation. A majority of respondents (97.1%) knew about dodder across all constituencies, with a mean significant difference of F (5,361) =5, P: 0.000. This study discovered dodder, a generic weed parasite that is rapidly spreading and attacking a diverse community of ornamentals in Mombasa County. Dodder laurel (Cassytha filiformis) species are hemiparasites as they photosynthesize, unlike field dodder (Cuscuta campestris) species that are primary holoparasites. The study recommends fast mitigating measures to be undertaken through biotechnological control methods that are effective with limited environmental impacts.enEffectCuscuta Species (Dodder)Urban Ornamental PlantsMombasa CountyKenyaThesis