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.
