Browsing by Author "Onyango, B."

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    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.
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    Tomato Cultivation and Farmers’ Knowledge on Selected Foliar Fungal Diseases in Agro- Ecological Zones of Kirinyaga County, Kenya
    (Asian Journal of Agricultural and Horticultural Research, 2022) Ogolla, F. O.; Onyango, B.; Muraya, M. M.
    Diseases are hindrance to tomato production in Kirinyaga County, Kenya. However, information on farmer’s knowledge about tomato diseases to warrant pesticide usage is scanty. Further, there is information gap on disease predisposing factor such as varietal choice and seed source. This study assessed the tomato farmers’ socio characteristic, varieties grown, seed source and knowledge of selected foliar fungal disease among tomato farmers in agro-ecological zones (AEZs) of Kirinyaga County. A cross sectional survey design that in cooperated purposive sampling and snowballing approaches was adopted in the study. Data were collected from 120 tomato farmers using structured questionnaires. A chi square (Ӽ2) test was used to examine the association between different variables at α= 0.05 using SAS version 9.4. No significant association (p > 0.05) was observed between gender of farmers and AEZ. Nonetheless, there were more men (83.33%) than women (16.67%). Terminator F1 variety was popular among farmers (25%). No significance (p > 0.05) association was observed between source of tomato planting material and AEZs. However, Agrovet was a popular seed source among farmers (40%). The reasons for choosing a particular tomato variety was significantly (p < 0.05) associated with the AEZ with 40.83% of farmers preferring tomato varieties with good marketability traits such as fruit size. Farmers’ knowledge of causative agent of early blight, late blight and Septoria leaf spot was significantly (p < 0.05) associated with AEZs. The source of farmer’s knowledge on tomato foliar fungal diseases was not significantly (p > 0.05) associated with AEZ. However, farming experiences was a popular source of knowledge (51.67%) among farmers. Inability of some farmers to identify tomato diseases negates the efforts on disease management in tomato production in Kirinyaga County. Therefore, measures such as coordinated education on tomato diseases is necessary to empower farmers on disease causes and identification to enhance disease management and improve tomato yields in Kirinyaga County in Kenya.