Browsing by Author "Githae, E. W"

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Phytochemical analysis and antifungal activity of Tithonia diversifolia and Kigelia africana extracts against Fusarium oxysporum in tomato
(African Journal of Agricultural Research, 2020-08-11) Awere, C. A; Githae, E. W; Gichumbi, J. M.
Fusarium wilt can cause severe losses in many vegetables and flowers, field crops and plantation crops. The main method for controlling Fusarium wilt is through chemical methods which have the disadvantage of polluting the environment and are expensive. Thus, there is a need for more environmentally friendly and cheaper techniques for controlling Fusarium Wilt. This study screened the phytochemical compounds of two plant extracts; Tithonia diversifolia and Kigelia africana and assessed their potency in controlling plant fungal pathogen F. oxysporum, which causes fusarium wilt in tomatoes. The phytochemical analysis revealed that the two plant extracts contained saponins, tannins, terpenoids, flavonoids, glycosides and phenolics except alkaloids and steroids which were only found in T. diversifolia. The mean inhibitory zones ranged from 7.93 to 10.44 mm for T. diversifolia at 25 to 100 g/l. The mean inhibitory zones for K. Africana ranged from 12.07 to 15.56 mm at 25 to 100 g/l. K. Africana extracts had the highest inhibitory (antimicrobial) activity. Combining both extracts was more effective compared to the single extract. The effect of the combined plant extract and positive control was statistically significant (p < 0.05). This study provides scientific evidence that K. africana and T. diversifolia extract possess antifungal activity and can be used as a broad-spectrum in managing microbial diseases.
PREVALENCE AND DISTRIBUTION OF PARASITIC ROOT KNOT NEMATODES IN SWEET POTATO FARMS OF KIRINYAGA COUNTY
(Chuka university, 2022) Onchari, N.M; Githae, E. W; Nyabuga, I; Muraya, M
Sweet potato production is constrained by many biotic factors which include parasitic root knot nematodes. Root knot nematodes (RKN) pose a significant threat to a wide range of agricultural crops. The effect of RKN on sweet potatoes include reduced yields and poor quality of the tubers, high costs of production and hence loss of income. Moreover, development of resistance by RKN has partly rendered various pest management strategies ineffective, therefore risking food security. It is likely more losses may be experienced in future due to ongoing withdrawal of nematocides from the market. Information on distribution and management of root knot nematodes is limited. This study aimed in the isolation and characterization of root knot nematodes from soils and root tubers of sweet potato farms in different agro ecological zones of Kirinyaga County. From the undertaken study, prevalence and distribution of root knot nematodes was analyzed based on early cropping of sweet potatoes between one to two months and post harvested farms. Across all sweet potato farms, identification through microscopy revealed parasitic RKNs that were Meloidogyne species, Pratylenchus species, Trichodorus species among other spiral nematodes (Helicotyllenchus species and Scutellonema species) that are also categorized as parasitic nematodes. Reniformis (Rotylenchus species) were also identified as well as predatory nematodes which were singled out too under microscope observations. Root tubers that were stained pink with phloxine B showed large galls with mature female root knot nematodes under microscopy. Based on the questionnaire answers from farmers, they were familiar with nematode symptoms on sweet potatoes however, awareness of nematodes was low.