Effects of Climate Variability on Dodder Invasion, Distribution and Management in Belgut Area of Kericho County, Kenya
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Date
2020
Authors
Chepkirui, Winny
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University
Abstract
Parasitic weeds are plants that have evolutionarily lost autotrophic way of life during their
development stages. Dodder, a plant of the Cuscuta species, is one such invasive parasitic
weed with a wide range of world geographic distribution and host diversity. In Kenya,
dodder is common in counties at the Coast, Central, Nyanza, Western and Rift valley. The
plant is alleged to parasitize on a variety of perennial crops, wild and domesticated trees
and shrubs thus affecting host vigor quality and quantities of crop yields, in particular the
socio-economic reliance on crops infested by the weeds is in jeopardy as measures to curb
the spread and control it are being sought urgently. Moreover, there are relatively less local
research reports on socio-economic, biological and physical factors enhancing its spread,
host association and effective control methods. This survey therefore sought to find out
implications of climate variability on dodder invasion, association, distribution and
management in Belgut area of Kericho County, Kenya. Specifically, the study examined
climate variability in the study area between 1988 and 2017 in relation to dodder
occurrence and distribution. Historical climate data, consisting of rainfall and temperature,
was obtained from the Kericho Meteorological Department for the period 1988 to 2017.
The study also identified socio-economically valued plant hosts, impacts and cultural
management methods of the dodder control. The Survey of Kenya Topographic Sheet No.
117/3 was used to sample 399 households as the sample size for the study. This was done
by first sampling the land segments. The study area covered an area of 200km² and was
divided into 1 km² land segments. Yamane’s formula was used to determine the sample
size and 133 of these land segments were obtained as the sample size. Within each 1 km²
land segment, three farm households were purposively selected for acquisition of data
based on field accessibility. A questionnaire consisting of items on such variables as socioeconomic profiles, historical dodder invasion, hosts and its management, was administered
to the heads of the selected households. An observation sheet was used to record GPS
locations of dodder occurrence, broad ecological characteristics, host species associations
and related characteristics. The data were classified and statistically analyzed (p≤0.05).
Linear regression model revealed that rainfall has been decreasing while temperature has
been increasing. The Shannon-Weiner Diversity Index of dodder hosts was 1.89, this
implies diversity was on average since the index normally lies between 1.5 and 3.5 for most
communities. Simpson Diversity Index was 0.2, This index lies between 0 and 1 and
approaches 1 in cases of monoculture. The number of parasitized species were 43 in total,
tea was the most parasitized host with 2391 individuals parasitized. Analyzed data map
indicate that Waldai and Sigowet wards had the highest relative occurrence and densities
of dodder. Six local methods were used for management of dodder and their applications
differed significantly by gender of the household head (χ2 = 24.72, df = 10, N = 124, p =
0.006) and non-significantly with education level of the household head (χ2 = 39.79, df =
40, N = 124, p = 0.48). Killing of host was reported to be the most effective dodder
management method. There is rapid spread of dodder primarily because of the wide host
range (Shannon Weiner Index 1.89) and no economical and effective management method.
Further research in a multi-disciplinary approach needs to be undertaken urgently to
understand the local environment in relation to proliferation as well as determination of the
most effective management methods. Prevention of dodder spread is the best way to
manage dodder, where infestation has occurred treatment should be done immediately.
Description
A Research Project Report Submitted in Partial Fulfillment of the Requirement for the
Award of the Degree of Master of Environmental Studies (Climate Change and
Sustainability) in the School of Environmental Studies of Kenyatta University
Keywords
Climate Variability, Dodder Invasion, Belgut Area, Kericho County, Kenya