Spatial Ramifications of Dodder Infestation on Urban Ornamentals in Mombasa, Kenya

Dodders are cosmopolitan generalist holoparasites that forage on a community of plant species ranging from shrubs, trees and herbaceous. In this study, we employ mixed method research design that involved use of questionnaires and dodder host sampling matrix. Host identification and naming was car-ried out by ecological Android PlantNet Plant App version 3.0.5. Respondents sample size was determined by Krejcie and Morgan sampling formula. Results show that dodder was fast spreading through spatial retrospective satellite Landsat imagery analysis. Dodder was known by the majority of respondents (97.1%) where the exploratory analysis score shows that respon-dents’ constituency of residence influenced their understanding of dodder (F(5, 361) = 5.329, P = 0.000). The mode of parasitism between dodder & the hosts varied as some ornamental trees, shrubs and herbaceous plants were either affected moderately or extremely. The study recommends use of biotechnological dodder control approaches through transgenic plants biotechnology and plant breeding to develop resistance towards dodder plant parasites.

534 Current Urban Studies The current phylogenetic studies by Stefanovic et al. 2003 andNeyland, 2001, suggest that their genus is nested in monophyletic Convolvulaceae terming Cuscuta, a member of this family. Morphologically, Cuscuta is leafless, obligating with twinning flexibility, with yellowish or orange haustoria stems (having specialized stems with sucking roots). These artificial roots aid dodder ability to penetrate their hosts and extract nutrients (Dawson et al., 1994;Zhuang et al., 2018). Dodder produces small flowers (approximately 7 mm in length or less) that have waxy textures with whitish corollas. Sherman et al. 2008 indicate that, dodder seeds germinate in the soil before their rudimentary roots (swollen root-like small structures) parasitize host plant, twinning itself with its roots falling or dying within a few days. This death of roots is known as haustoria. Dodders are cosmopolitan obligate parasites that are purely weedy and causing damage to host plant species (Lanini & Kogan, 2005;Flores-Sánchez & Garza-Ortiz, 2019). The authors add that they obtain all of their growth requirements (water, minerals, and carbohydrates) by attaching to host plants. Dodder category of hosts includes; ornamental plants, plants grown for agricultural purposes, and rangeland plants (Hegenauer et al., 2018).

Research Design
This study used a mixed method research design that involved use of questionnaires and dodder sampling matrix to obtain primary data through an explora-  Krejcie and Morgan (1970) formula determined the sample size of a finite population through the equation;

Sample Size
where: 2 χ = table value of Chi-Square @ 1 DF at a desired confidence level of (3.84), N = population size, in this case 268,700, P = population proportion (assumed to be 0.5 since this would provide the maximum sample size), d = the degree of accuracy expressed as a proportion (0.05).
Therefore, giving 384 as the least sample size from a given finite population (P) thus sample size was in the range of plus or minus 0.05 of the population proportion with a 95% level of confidence.

Study Area
This study was conducted in Mombasa County, Kenya. The county lies in latitude of −4˚S and longitude of 39˚E ( Figure 2). The county is among the for-

Knowledge on Dodder in Constituencies
The study wanted to establish if the respondents knew what the dodder weed was and hence, they were shown a pictorial dodder sample (Figure 3), then asked questions to confirm if they were familiar with the weed.  Nearly all the respondents (97.1%) claimed to have known the weed with a small portion (2.7%) acknowledging that they do not know the plant. To examine further their knowledge about the dodder, Likert scale was applied to collect opinions from the respondents to ascertain their understanding on dodder weed. Afterwards, a Likert scale was developed, which measured the understanding score of dodders, and a one-way ANOVA performed to test for any significant variations. After performing some exploratory analysis on the data, it emerged the constituency that a respondent came from had an influence on the score (Table 1).
The results in Table 1 are from a one-way ANOVA analysis that was performed to check if there was any significant difference in the mean score of the understanding of dodder weed between respondents of the six constituencies that took in this survey. The output shows that there is a significant difference in the mean scores of the understanding of dodder weed for at least one constituency at 0.05 level of significance; F(5, 361) = 5.329, P = 0.000. This is an indication that some constituents have a better understanding of the weed compared to others. In order to establish the constituency(s) that significantly differed from the rest, a Least Significant Difference (LSD) test was performed on the data and the output is as shown in Table 2.
The multiple comparison table shows that the mean understanding score of

Geographical Spread of Dodder in Mombasa
The spatial Landsat imagery in Figure 4,

Identified Dodder Ornamental Hosts
The extent dodder foraged on different plant species is shown in  (Koch et al., 2004;Runyon et al., 2006) dodders have a range of different hosts it attacks. However, the degree of parasitism depends on the interaction that is determined by the flow of nutrients from the hosts vascular bundles, the xylem and phloem (Těšitel, 2016).

Research Limitations
This study was conducted in Mombasa County and it was anchored by both fieldwork and laboratory work to identify dodders species and hosts samples.
The noted limiting factors from the study included: 1) The unrelated nature of dodders and their morphological features that have evolved overtime within their genera. Distinguishing dodders by phenotype appear similar however genotype could give a clear taxonomical identity.
2) Some dodder hosts could not be parasitized even within their sampling scope. Therefore, allelopathy defense mechanisms shown by some hosts like acacia could enhance further interior sampling to obtain ravaged samples.

Conclusion
The spatial retrospective analysis shows fast proliferating spread of dodder in Mombasa foraging on different plant hosts grown as urban ornamentals that are both exotic and indigenous. Predominant dodders in the area were C. competris and C. florimis that were fast spread. These common dodder species in Mombasa are generalist holoparasites infesting shrubs, trees and herbaceous plant species. The residents within the coastal town suburbs across the county's constituencies were familiar with dodder parasite and its existence. Therefore, the presence of dodder was felt, ravaging existing ornamentals different ornamental plant species moderately or extremely affecting their growth.

Recommended Control Measures
• Use of biotechnological dodder control approaches. This involves; transgenic plants biotechnology and plant breeding to develop resistance towards dodder plant parasites. • Persistent application of herbicides to eradicate notorious ramifications of dodder parasitism on hosts.
• Use of mechanical control measures but with high level of caution to avoid probable spread of the weed parasite.
• Capacity building to the community in high dodder ravaged areas to enhance monitoring and control of dodder spread.