Browsing by Author "Nyongesa, M.W."
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Item Assessment of Pesticide Multiplicity in Potato Production and Storage in Bomet, Kenya(East African Agricultural and Forestry Journal, 2022-06-02) Oyoo, J.I.; Abong, G.O.; Okoth, M.W.; Nyongesa, M.W.; Kenya Agricultural and Livestock Research Organization ; University of NairobiPotato (Solanum tuberosum L.) crisps are among the most appealing potato products to middle and high income households including women, youth and children and are produced from potatoes mainly grown in Bomet County. A cross-sectional survey was done in 305 potato growing households in Bomet County to establish categories of pesticides used in potato production and storage, level of awareness of pesticide residues and perceptions of risks associated with pesticide contamination at ingestion of potato and its products. Questionnaires were administered through simple random sampling of potato farmers, disaggregated according to their gender, level of education and age. The parameters of interest were type of pesticides applied, knowledge of banned or restricted pesticides and knowledge of presence of pesticide residues in potatoes and risks involved. Data was collected using open data kit (ODK) and analysis done using Statistical Package for Social Science (SPSS) software version 21. Descriptive statistics were used to generate socio-demographic characteristics (gender, age, education levels) and analysis of variance (ANOVA) was performed on the data about knowledge of pesticides. Results are presented as percentages, means and frequency distribution. Differences between the means were calculated at 95% level of significance using Fischer’s test. The study showed that 72% of the respondents were male and 28% female. Most of the potato farmers aged between 20- 59 years (87.2%). A majority of the sampled farmers (26.9%) had up to tertiary level education while 31% attended primary school only. About 95% of the respondents used fungicides to control late blight while 14% used insecticides for pest control. It is worth noting that only 0.6% of the respondents used dimethoate and Diazinon, restricted/banned chemical compounds in Kenya. A significant number of fungicides (47%) used were classification class II which are moderately hazardous. Most respondents (79%) could not tell which pesticides had high residues. However, majority (84%) perceived that potatoes in the markets or those cooked at home, restaurants or hotels contained pesticide residues which could harm consumers. The study demonstrated the need for more awareness creation on appropriate pesticide use and sensitization on pesticide residues in potato production.Item Enhancing the Efficacy of Biocontrols and Fungicide Application for Improved Late Blight Management and Yield of Potato(East African Agricultural and Forestry Journal, 2023) Kilonzi, J.M.; Mafurah, J.J.; Nyongesa, M.W.; Egerton university ; Kenya Agricultural Livestock and Research Organization (KALRO) TigoniLate blight (Phytophthora infestans), whose history dates back to 1840s, still remains a major constrain in potato production. Management of the disease solely depend on extensive use of fungicides that has been implicated, not only on their efficacy, but also has recently raised human health and biodiversity concern globally. Unexpectedly, proposed non-chemical disease management strategies including, use of biocontrols, are yet to yield substantive results that reflect effectiveness and cost saving. Therefore, field trial was conducted to optimize antifungal activities of Trichoderma asperellum and T. harzianum and Ridomil application in managing potato blight. Seed was pre-treated with T. asperellum and T. harzianum suspensions at concentrations of 3 × 106, 7 × 106 and 1 × 107 CFU/mL and Ridomil® applied at spray intervals of 21, 14 and 7 days. Results revealed that, weather conditions contributed to late blight epidemics development and efficacy of the biocontrols and spray intervals. T. asperellum suppressed late blight more than T. harzianum. Concentration of the biocontrols had significant effect on late blight epidemics, growth and yield. Weekly fungicide application provided higher disease subdual and tuber yield than 14 and 21 days spray intervals. Use of biocontrols at concentration of 7 × 106 and 1 × 107 CFU mL-1 in combination with application of Ridomil® weekly and fortnightly, repressed blight effectively, contributed to higher yield and net farm income than any other combination. The results suggest that, integrated disease management using biocontrols and fungicide could delay late blight epidemics resulting in reduced fungicide application frequencies.Item Relative Yield Loss of Potato in Fields Infested with Potato Cyst Nematodes and the Efficacy of Selected Control Products in Nyandarua County, Kenya(East African Agricultural and Forestry Journal, 2022-12-15) Mbiyu, M.W.; Kimenju, J.W.; Muiru, W.M.; Nyongesa, M.W.; Haukeland, S.; University of Nairobi ; Kenya Agricultural Livestock Research Organization ; International Centre of Insect Physiology and Ecology (icipe) ; The Norwegian Institute of Bioeconomy Research (NIBIO)Despite the rapid spread of potato cyst nematodes (PCN) in Kenya, data on associated yield loss is limited. The objective of this study was to determine the efficacy of four nematicides and relative yield loss associated with PCN damage. Three on-farm sites with varying PCN densities (low; 1-9, moderate; 10-39, and high; 40-80 cysts in 100 g/soil) were selected for the study in Nyandarua County during the 2021 long and short rains seasons. Treatments consisted of three potato cultivars namely Desiree and Shangi (susceptible) and Manitou, which is partially resistant. The four PCN control products tested were, fluopyram, oxamyl, azandirachtin (commercial neem extract) and Paecilomyces lilacinus. The experiments were set up in a randomized complete block design, in a split plot arrangement, with varieties as the main plots, and PCN control products including the control as the sub-plots. Treatments were replicated three times. The reproductive index of the nematodes ranged from 0.17 to 2.39 during the long rains and from 0 to 4.13 during the short rains season. Relative yield loss attributed to PCN infection varied from 6.3% to 80.5% during the long rain season and from 5.5% to 73.3% during the short rain season. The magnitude of yield losses was dependent on susceptibility of the variety and the initial PCN population density. This study has demonstrated that PCN are already causing substantial yield losses especially in heavily and moderately infested fields. The study demonstrated that oxamyl was the most effective nematicide in reducing PCN numbers and yield losses. Farmers are advised to take appropriate measures to prevent spread and buildup of the nematodes.
