Browsing by Author "Ogolla, Fredrick O."

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BACTERIOLOGICAL QUALITY ASSESSMENT OF DOMESTIC BOREHOLES IN THARAKA NITHI COUNTY, KENYA
(Chuka University, 2021) Kithaka, Samson Chabari; Ogolla, Fredrick O.; Karimi, Jedida
Water shortage that is caused by long droughts and higher cost of accessing piped water have forced many households in Kenya to opt for wells and borehole water. Where they are used, boreholes are exposed to contaminationbypathogenic microorganismsfrom nearbytoilets,defecationfromdomesticatedanimalsand surface runoff.Despiteofknown healthconcernsofconsumingcontaminated water manyruralresidentsconsumeborehole water whose portability is not determined and may not meet WHO standards. Thus, this study was conducted in Tharaka Nithi County to determine bacterial safety of selected wells and boreholes in Maara, IgambaNgombe and Tharaka Constituencies between March to September 2019. A total of 108 water samples were collected from 36 boreholes. The samples were analyzed at Chuka University using most probable number methods, Plate count and bacteria species identified using selected biochemical methods. Data (MPN) for different locations of study and boreholes were compared using general linear method in SAS. Significance means were separated using least significant difference post hoc test in SAS version 9.4. Number of bacteria isolated from water samples were also compared using general linear model. Feacal coliform values exceeding WHO recommendation of (0 CFU/ 100 ml was observed in all borehole surveyed. Mean MPN value of 17.5/ 100 ml CFU was observed in Kawangware in tharakasouth.ColiformbacteriaE.coli,Bacillusspp,Klebsiellasppwereisolated inallthewatersampled.However, E. coli followed by Bacillus sppwere higher compared to the rest of isolates.Occurrence of these bacteria in borehole water put the health of depended consumers at risk of infection
In-vitro Evaluation of Fungicide Sensitivity of Tomato Leaf Blight Pathogens
(Jurnal Pertanian Tropik (JPT), 2021) Ogolla, Fredrick O.; Nyakinywa, Ruth; Chabari, Samson K.; Onyango, B.; ; ;
Tomato early and late blight diseases caused by Alternaria solani and Phytophthora infestans respectively, are constraints to tomato production globally. Conventional use of commercial synthetic fungicides in management of tomato blight disease has become a key input for tomato production among farmers in Tharaka Nithi County, Kenya. Indiscriminate use and application of sub-lethal doses of fungicides negate disease management efforts, and may lead to gradual fungicide resistance. Yet, local tomato farmers have continued to use the fungicides without periodic evaluation of their effectiveness. This study was carried out in-vitro to evaluate the efficacy of six synthetic commercial fungicides used by farmers around River Ruguti, against two tomato leaf blight pathogens; Alternaria solani and Phytophthora infestans. The poison food method was used to evaluate fungicides known by trade names and application levels; Mancozeb (640 g kg-1) + Metalaxyl (40 g kg-1), Mancozeb 640 g/kg + Metalaxyl 80 g/kg, Mancozeb, Propineb700 g/kg + Cymoxanil 60 g/kg, Carbendazim and Triticonazole at different concentration (25%, 50% and 75%). The in-vitro plate experiment was laid out in a Complete Randomized Design with 3 replicates, and data on mycelia growth inhibition analyzed through General Linear Model (α=.05) and significant means separated using Least significant difference (LSD) using Scientific Analysis System version 9.4. All the tested fungicides significantly (p≤ 0.05) inhibited mycelial growth of tested pathogen. Percentage inhibition for early blight pathogen (Alternaria solani) was 80.42% compared to late blight pathogen Phytophthora infestans at 69.51%. Mancozeb (640 g kg-1) + Metalaxyl (40 g kg-1) and Propineb700 g/kg + Cymoxanil 60 g/kg recorded higher per cent inhibition of mycelia growth of 92.4% and 89.71% respectively. Carbendazim recorded lower per cent inhibition of 39.15%. Mycelia growth inhibition increased with an increase in fungicide concentration. Lower inhibition of 71.78% was observed at 25% concentration as compared to 50% and 75% with 76.77% and 76.36% respectively. Fungicides screened varied in mycelia inhibition against P. infestans and A. solani isolates with Mancozeb (640 g kg-1) + Metalaxyl (40 g kg-1) and Propineb700g/kg +Cymoxanil 60g/kg giving significantly (p≤ 0.05) better inhibition while Carbendazim had the lowest inhibition effect. Increased fungicide concentration effectively inhibited mycelia growth. Thus higher concentration of fungicide application is recommended in cases where there is low efficacy of fungicides.
IN-VITROEVALUATION OF FUNGICIDES SENSITIVITY OF TOMATO LEAF BLIGHT PATHOGENS ISOLATES Alternariasolani and Phytophthorainfestans
(Chuka University, 2021) Nyakinywa, Ruth; Ogolla, Fredrick O.; Chabari, Kithaka Samson
Tomato early and late blight diseases caused by Alternaria solani(Ellis & Martin) Sorauer and Phytophthora infestansrespectively hinder tomato production globally. Use of fungicides in management of blight diseases has become a priority among farmers. However, indiscriminate or use of sub lethal doses negate disease management efforts. Despites the knowledge of possible occurrence of fungicide insensitive phyto-pathogens, farmers has continued using fungicides without periodic evaluation of their effectiveness. This study was carried out to evaluate an in-vitro sensitivity of tomato leaf blight pathogens (Alternaria solaniand Phytophthora infestans) against selected fungicides mostly used by tomato farmers along River Ruguti in Tharaka Nithi County in Kenya.Fungicides evaluated included, Mancozeb (640 g kg-1 ) + Metalaxyl (40 g kg-1 ), mancozeb 640 g/kg + metalaxyl 80 g/kg, Mancozeb, Propineb700 g/kg + Cymoxanil 60g/kg, Carbendazim and Triticonazole at different concentration (25%, 50% and 75%). Poison food method was used for evaluation. Complete Randomise design was used for the experiment. Per cent data on mycelia growth inhibition by various fungicides at different concentration were analysed using General Linear Model (α=.05) and significant means separated using Least significant difference (LSD) in Scientific Analysis System version 9.4. All the tested fungicides significantly (P≤ 0.05) inhibited the mycelial growth of tested pathogen. However, among tested fungicides, Carbendazim (89.83%) and Propineb700g/kg +Cymoxanil 60g/kg were superior over other fungicides with Carbendazim being the least. Mycelia growth inhibition increased with an increase in fungicide concentration. Mycelia growth inhibition of Alternaria solaniwas 81.78% as compared to Phytophthora infestans at 69.78%.