Browsing by Author "Githae, E. W."

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Antimicrobial activities of Tithonia diversifolia and Kigelia africana against Fusarium oxysporum in tomatoes
(Chuka University (Journal of Environmental Sustainability Advancement Research), 2021) Awere, C. A.; Githae, E. W.; Gichumbi, J. M.
Fusarium wilt disease caused by the soil-borne fungus Fusarium oxysporum Schlechtthe is a serious threat to tomato production worldwide. Chemical and cultural methods of management used are either ineffective or toxic to the environment. Plant secondary metabolites; therefore, pose a possible alternative because they are environmentally friendly and have minimal effect on non-target organisms. This study screened phytochemical compounds of two plants; Tithonia diversifolia and Kigelia africana and assessed their potency in controlling plant fungal pathogen F. oxysporum, the causative agent of Fusarium wilt disease in tomatoes. Leaf extracts of T. diversifolia and fruit extract of K. africana were used in this study becauses they are readly available and the plnts have been used in the treatment of varius diseases in humanbeings. The plant etract were concentrated in water and screened for phytochemical contents using standard procedures. Concentrations used were 25 g/L, 50 g/L and 100 g/L to sock the disc. Fusarium oxysporum was isolated from infected soil using potato dextrose agar media while the antifungal activity was evaluated by measuring the zone of inhibition against the test organism. In determining the antimicrobial properties of each of the plant extract, a 3×3 randomised complete block design was used, replication was done 3 times. The results showed that the mean inhibitory zones were highest at 100g/l in both plants, although K. africana fruit extract portrayed the higher inhibitory activity compared to Tithonia africana. The effect of the plant extracts and the positive control were statistically significant (pα0.05). This study indicates that K. africana and T. diversifolia possess the antifungal activity and can be used as a broad-spectrum fungicide against F. oxysporum. The effect of the plant extract was statistically significant (p<0.05). The Mean of inhibition ranged from 23.67 to 7.78 mm for Tithonia diversifolia and 23.67 to 11.75 for Kigelia africana. While for the combined extract the The Mean of inhibition ranged from 22.78 to 7.93 . The minimum reduction in sporulation was recorded in the positive control, which was significantly lower than the rest of the treatments.These plant extracts may provide an effective measure for the management of Fusarium wilt of tomatoes that may form an integral part of integrated pest management and become a prospect alternative to conventional fungicides.
Biological Control of Desert Locust (Schistocerca Gregaria Forskål)
(2021) Githae, E. W.; Kuria, E. K.
Desert locust (Schistocerca gregaria Forskål) is one of the most serious agricultural pests in the world due to its voracity, speed of reproduction, and range of flight.We discuss the current state of knowledge on its biological control using microorganisms and botanical extracts. Metarhizium flavoviride was among the first fungus to be recognized as a bio-control agent against desert locust in the laboratory and field conditions. Nevertheless, its oil formulation adversely affected non- target organisms, hence led to further research on other microorganisms. Metarhizium anisopliae var. acridum (syn. Metarhizium acridum) is an environmentally safer bio-pesticide that has no measurable impact on non-target organisms. However, there are various shortcomings associated with its use in desert locust control as highlighted in this review. Bacterial pathogens studied were from species of Bacillus, Pseudomonas, and Serratia. Botanical extracts of 27 plant species were tested against the locust but showed varied results. Azadirachta indica and Melia volkensii were the most studied plant species, both belonging to family Meliaceae, which is known to have biologically active limonoids. Out of the 20 plant families identified, Apiaceae was the most represented with a frequency of 21%. However, only crude botanical extracts were used and therefore, the active ingredients against desert locust were not identified. Through a comprehensive research, an integrated pest management strategy that incorporates these bio-controls would be a realistic option to control desert locust infestations.
Climate-Smart Agro-Pastoral Practices: A Case Study of Narok County, Kenya
(Chuka University, 2015) Githae, E. W.
Pastoralism is described by a high reliance on livestock production systems for socio-economic wellbeing. In Kenya it is the dominant form of livelihood in the arid and semi-arid lands, which constitute more than 80% of the total land area, host about 10 m people and 70% of the national livestock herd. Despite these areas being the major meat producers in the country, production is threatened by climate related hazards as witnessed by livestock deaths, reduced daily yields and prices, degraded natural resources, and high incidences of livestock pests and diseases. The traditional coping strategies applied in terms of nomadic pastoralism, has been reduced due to fragmentation of rangelands, forcing them to transform towards sedentary lifestyles. Thus, what can be done to improve this sedentary lifestyle and how can it be sustained within the ASALs? What are the on-the-ground coping strategies that enhance environmental conservation? This study assessed the coping mechanisms applied to the changed lifestyle within the pastoral communities of Narok County that not only improve livelihoods through climate change adaptation but also contribute towards climate change mitigation. This was done using key informant and focus group discussions. Policy guidelines are provided on building capacity through participatory approaches to enhance long-term sustainable systems that will ensure food security to these vulnerable communities, while at the same time contributing to natural resource conservation and ecosystem services
Ecological restoration of pastoral landscapes in the drylands of East Africa
(Journal of Dryland Agriculture, 2021-01-26) Githae, E. W.; Mutiga, I. M.
The East African drylands cover about 47% of the land surface and host about 20 million people. Rural people living in the drylands are mainly pastoralists who depend on livestock for both economic and social well-being. During the dry season, pastoralists apply strategic mobility to access grazing resources efficiently. However, this strategy has experienced change and constraints due to various demographic- and climate-related challenges. Pastoral lands have been cleared for large-scale agriculture while pastoralists have shifted towards agro-pastoralism. This has eroded many dryland trees and forests leading to environmental degradation. This review discusses important indigenous trees that can be utilized in ecological restoration of drylands as well as providing ecosystem goods and services. These include trees for gums and resins (Acacia, Commiphora and Boswellia), indigenous fruit trees (IFTs) (Adansonia digitata, Tamarindus indica and Balanites aegyptiaca), trees for wood (Melia volkensii and Terminalia brownie) and fodder (Acacia tortilis and Faidherbia albida). They are not only drought-tolerant but also have minimal disruption to the ecosystem. Various dryland restoration strategies and constraints are also discussed. For successful establishment, seedling planting should be integrated with other appropriate practices such as natural regeneration, silviculture and enrichment planting for sustainable dryland management.
Effects of Agricultural Nutrients Influx on Water Quality in Thiba River basin, a sub-catchment of Tana River Basin in Kirinyaga County, Kenya.
(EAST AFRICAN NATURE & SCIENCE ORGANIZATION, 2022) Njue, J. M.; Githae, E. W.; Magana, A. M.
ABSTRACT Excessive enrichment of waters with nutrients and the associated adverse biological effects leads to eutrophication, which is one of the major environmental problems across the world. Various studies have revealed the overuse of inorganic fertilizers to increase agricultural productivity in Kenya contributes to pollution of water bodies. In order to meet increasing demand for clean water, sustainable use and conservation of available water resources is therefore paramount. This study was done to find out effects of agricultural nutrient pollution in Thiba River, a sub-catchment of Tana River Basin, located in Kirinyaga County, Kenya. The study area was divided into four distinct agro- ecological zones based on different anthropogenic activities. Ecological survey design was used in the study. Sampling was done during the wet and dry season. Water samples were analysed for temperature, transparency, pH, electrical conductivity (EC), salinity, total dissolved solids (TDS), dissolved oxygen (DO), biological oxygen demand (BOD), phosphates, nitrates, nitrites, ammonia, and toxic microalgae. All parameters showed both spatial and temporal variations with statistically significant differences (p˂0.01). Temperature of the river ranged from 14.57 0C to 28.08 0C due to climatic changes along the agro- ecological zones. The pH ranged from 7.02 to 8.51. The DO values decreased from the highlands to lowland within the range of 9.00 mg/l at the reference site to 5.43 mg/l at the most polluted site. EC ranged from 20.54 µScm-1 at the reference site during the wet season to 251.2 µScm-1 at the rice irrigation scheme site during dry season. The TDS ranged from 16.9 ppm at the reference site to 167.05 ppm at the most polluted site. Salinity also had a high variation with a range of 0.01 ppt at the reference site to 0.07 ppt at the most polluted site. The highest values of BOD (3.49 mg/l) were recorded at the rice irrigation scheme during the wet season and the lowest (0.22 mg/l) at the forest edge reference site.The lowest levels of NH4, P, NO2 and NO3 were recorded at the forest edge reference site at 1.088 µg/l, 1.177 µg/l, 0.217 µg/l and 0.148 µg/l respectively during the dry season while the highest values for the same nutrients were recorded at the rice irrigation site at 11.439 µg/l, 4.933 µg/l, 1.518 µg/l and 2.721 µg/l in the same order. There was a high peak of all nutrient levels at the rice irrigation scheme zone which was attributed to the extensive use of inorganic fertilizers. Dam water samples were analysed for members of Cyanobacteria group of microalgae which are bio-indicators of eutrophic waters. Out of the seven members of this group that were identified four were toxic genera. These were Nostoc, Oscillatoria, Anabaena and Microcystis. During the wet season Nostoc had the highest population followed by Oscillatoria and Anabaena. No Microcystis was observed during the wet season. There was a steady increase of all the genera during the dry season with Microcystis making appearance. Microcystis and Oscillatoria had a very high correlation. This study concludes that various anthropogenic activities especially agriculture along the study site are the main factors of Thiba River pollution hence a major threat to human, livestock and aquatic organisms. Environmental protection laws should be enforced by the government.
Ethnobotanical and vegetation survey of Kiango’mbe and Kianjiru Hill Forests in Embu County, Kenya
(International Scholars Journals, 2015-11-10) Waiganjo, B. W.; Githae, E. W.; Warui, C. M.; Opiyo, E. A.
Ethnobotanical study and vegetation survey was carried out in Kiang’ombe and Kianjiru hill forests of Embu County to evaluate the indigenous knowledge relevant to malaria cause, diagnosis, treatment and prevention as well as to establish the hills’ medicinal plants species diversity. Semi-structured questionnaires were used to gather ethnobotanical information while trees with diameter at breast height ≥5 cm, shrubs and herbs were sampled by use of 20×20, 5×5 and 1×1 m plots respectively. Malaria symptoms mentioned in this study were in concurrent with the widely acceptable ones and they included: headache, vomiting, loss of appetite, joint pains and fever. Mosquito was recognized as the main malaria vector. Fifty six species belonging to 31 families were documented from the ethnobotanical study. Achyrothalamus marginatus, Dombeya rotundifolia, Monanthotaxis schweinfurthii and Premna resinosa were documented for the first time in this study indicating high endemism. Barks, roots, trees and shrubs were the most commonly harvested parts and growth forms respectively. Charcoal burning, timber harvesting, grazing and forest fires were observed. Kianjiru had significantly (P≤0.001) higher diversity index (H’=2.92) than Kiango’mbe (H’=2.63). The two hill forests are major sources of medicinal plants and therefore the need to conserve them.
EVALUATION OF ANTIMICROBIAL ACTIVITIES OF Tithoniadiversifolia AND Kigeliaafricana AGAINST TOMATO FUSARIUM WILT PATHOGEN (FusariumoxysporumLycopersci)
(Chuka University, 2021) Awere, C. A.; Githae, E. W.; Gichumbi, J. M.
Fusarium wilt disease caused by the soil-borne fungusFusariumoxysporum Schlechttheisaserious threat to tomato production worldwide. Chemical and cultural methods of management used are either ineffective or toxic to the environment. Plant secondary metabolites; therefore, pose a possible alternative because they are environmentally friendly and have minimal effect on non-target organisms. This study screened phytochemical compounds of two plants; Tithonia diversifolia (Hemsl.) A. Gray and Kigelia africana (Lam.) Benth and assessed their potency in controlling plant fungal pathogen F. oxysporum, a causal agent of Fusarium wilt disease in tomatoes. Leaf extractsof T. diversifolia and fruit extract of K. africana were concentrated in water and screened for phytochemical contents using standard procedures. Concentrations used were25g/L,50g/Land100g/Ltosockthedisc. Fusarium oxysporum was isolated from infected soil using potato dextrose media, Antifungal activity was evaluated by measuring the zone of inhibition against the test organism. The results showed that the mean inhibitory zones were highest at 100g/l in both plants, although K. africana fruit extract portrayed the highest inhibitoryactivity compared to Tithonia africana. The effect of the plant extracts and the negative control was statistically significant (p<0.05). This study indicates that K. africana and T. diversifolia possess the antifungal activity and can be used as a broad- spectrum fungicide against F. oxysporum. These plant extracts may provide an effective measure for the management of Fusarium wilt of tomatoes that may form an integral part of integrated management and it also has prospect as an alternative to reliance only on fungicides.
Prevalence and distribution of plant parasitic nematodes associated with sweet potato: A case study of Kirinyaga County in Kenya
(African Scholars Publishing / journal editorial platform based in Africa (Kenya)., 2023-05) Onchari, N. M.; Githae, E. W.; Muraya, M. M.; Nyabuga, F.
A survey of plant parasitic nematodes (PPNs) associated with sweet potato (Ipomoea batatas) was carried out in three agro-ecological zones of Kirinyaga County in Kenya. Samples of rhizosphere soil and sweet potato tubers were collected for PPN extraction and morphometric characterization. Seven genera were morphologically identified (Meloidogyne, Pratylenchus, Helicotylenchulus, Scutellonema, Rotylenchulus, Heterodera and Aporcelaimellus). There were differences in the shapes and sizes of the mature PPN females and the diameter ranged from 204.3 μm to 437.3 μm. Meloidogyne had the highest prevalence (25%) and distribution (0.161), followed by Pratylenchus with a prevalence and distribution of 23% and 0.151, respectively. Farmers’ perceptions were captured using a semi-structured questionnaire. Overall, sweet potato farming was mainly practiced under mixed cropping (70.11%), small-scale (60.11%) and subsistence (55.17%). A higher proportion of the respondents (49.43%) sourced sweet potato vines from their own farms. The main control strategies applied for PPN were insecticides (55.59%), nematicides (11.49%) and concoctions (5.75%). Of all the respondents, 29.89% could not recognize symptoms of nematode infection. The distribution was significantly (p < 0.05) different among agro-ecological zones, with UM3 (upper midlands) showing the highest prevalence of 31. In conclusion, the differences in shapes and sizes of the mature females extracted from PPNs reveal a high level of morphological diversity. However, morphological characterization should be integrated with molecular methods for proper identification of PPNs. Awareness-raising among farmers about the best practices for proper management of PPN is necessary.