Bio

Publications

2021

Makinya, KJ, Wagacha JM, Odhiambo JA, Likhayo P, Edoh-Ognakossan K, Tefera T, Abass A, Mutungi C.  2021.  The importance of store hygiene for reducing post-harvest losses in smallholder farmers’ stores: Evidence from a maize-based farming system in Kenya. Journal of Stored Products Research. 90(DOI:10.1016/j.jspr.2020.101757):101757.
application/pdf iconjesse_makinya_et_al_store_hygiene_paper.pdf

2019

Njeru, NK, Muthomi JW, Khan ZR.  2019.  Influence of socio‐economic and agronomic factors on aflatoxin and fumonisin contamination of maize in western Kenya. Food Science & Nutrition.

2017

Nyaboga, E, Wagacha JM, Mwaura FB.  2017.  Silicon induces resistance to bacterial blight by altering the physiology and antioxidant enzyme activities in cassava. World J. Agric. Res. 5:42-51.
Waithaka, PN, Mwaura FB, Wagacha JM, Gathuru EM.  2017.  Isolation of Actinomycetes from Geothermal Vents of Menengai Crater in Kenya. Int J Mol Biol Open Access. 2(5):00031.
Udomkun, P, Wiredu AN, Mutegi C, Atehnkeng J, Nagle M, Nielsen F, Müller J, Vanlauwe B, Bandyopadhyay R.  2017.  Aflatoxin distribution in crop products from Burundi and Eastern Democratic Republic of Congo. :1.
Ondieki, DK, Nyaboga EN, Wagacha JM, Mwaura FB.  2017.  Morphological and Genetic Diversity of Rhizobia Nodulating Cowpea (Vigna unguiculata L.) from Agricultural Soils of Lower Eastern Kenya. International journal of microbiology. 2017
Bayissa, W, Ekesi S, Mohamed SA, KAAYA GP, Wagacha JM, R Hanna, Maniania NK.  2017.  Selection of fungal isolates for virulence against three aphid pest species of crucifers and okra. Journal of pest science. 90(1):355-368.
Muthomi, JW, Lengai GMW, Wagacha MJ, Narla RD.  2017.  In'vitro'activity of plant extracts against some important plant pathogenic fungi of tomato. Australian Journal of Crop Science. 11(6):683.
Muthomi, J, Fulano AM, Wagacha JM, Mwang’ombe AW.  2017.  Management of Snap Bean Insect Pests and Diseases by Use of Antagonistic Fungi and Plant Extracts. Sustainable Agriculture Research. 6(3):52.
Waithaka, PN, Mwaura FB, Wagacha JM, Gathuru EM, Githaiga BM.  2017.  Antimicrobial Properties of Actinomycetes Isolated from Menengai Crater in Kenya. CellBio. 06(2):13.
and Gakuubi, MWAWJM 4.  2017.  Antifungal activity of essential oil of Eucalyptus camaldulensis Dehnh. against selected Fusarium spp. Abstracthttps://profiles.uonbi.ac.ke/mainawagacha/

The objective of this study was to evaluate the antifungal activity of essential oil (EO) of
Eucalyptus camaldulensis Dehnh. against five Fusarium spp. commonly associated with
maize. The essential oil had been extracted by steam distillation in a modified Clevenger-
type apparatus from leaves of E. camaldulensis and their chemical composition
characterized by gas chromatography mass spectrometry. Poisoned food technique was
used to determine the percentage inhibition of mycelial growth, minimum inhibitory …

2016

Angeline W Maina, John M Wagacha, FBMJMCWWP.  2016.  Assessment of Farmers Maize Production Practices and Effect of Triple-Layer Hermetic Storage on the Population of Fusarium Spp. and Fumonisin Contamination. AbstractWebsite

Fumonisin contamination of maize by Fusarium spp. is a major risk in food security, human
and animal health. A study was carried out in Kaiti District, Makueni County in Kenya, to
assess the effectiveness of triple-layer hermetic (PICS™) bags in the management of
Fusarium spp. and fumonisin contamination of stored maize grains. Maize production
practices including scale of production, methods of land preparation, variety grown and
storage methods were obtained with a questionnaire. Fusarium spp. in soil and maize …
Angeline W Maina, John M Wagacha, FMJMCWBWP.  2016.  Postharvest Practices of Maize Farmers in Kaiti District, Kenya and the Impact of Hermetic Storage on Populations of Aspergillus Spp. and Aflatoxin Contamination. Abstracthttps://profiles.uonbi.ac.ke/mainawagacha/

Aflatoxin contamination in maize by Aspergillus spp. is a major problem causing
food, income and health concerns. A study was carried out in Kaiti District in Lower Eastern
Kenya to evaluate the effect of three months storage of maize in triple-layer hermetic
(PICS™) bags on the population of Aspergillus spp. and levels of aflatoxin. Postharvest
practices by maize farmers including time of harvesting, drying and storage methods were
obtained with a questionnaire. Aspergillus spp. in soil and maize were isolated by serial …
Oliver O Okumu, James W Muthomi, CMJWKM.  2016.  Resistance of Kenyan wheat germplasm to Fusarium head blight and deoxynivalenol contamination. Abstracthttps://profiles.uonbi.ac.ke/mainawagacha/

Fusarium head blight (FHB) of wheat causes quantitative and qualitative reduction in yield.
Cultivar resistance is the most effective method of managing the disease. This study
evaluated the resistance of wheat germplasm currently available in Kenya to Fusarium head
blight and deoxynivalenol (DON) contamination. Nine wheat varieties and four CIMMYT
lines were evaluated for susceptibility to FHB under two diverse agro-ecologies in Nakuru
and Narok Counties, Kenya during the 2013 cropping season and in the greenhouse …
John Maina Wagacha, Nancy Karimi Njeru, OOOJWMCKM.  2016.  Occurrence of Fusarium head blight of wheat and associated mycotoxins in Narok and Nakuru Counties, Kenya. Abstracthttps://profiles.uonbi.ac.ke/mainawagacha/

Fusarium head blight (FHB) is an important disease of small grain cereals. This study
assessed the incidence and severity of FHB of wheat at hard dough stage, and levels of
deoxynivalenol and T2-toxin at harvest by direct competitive enzyme linked immuno-sorbent
assay. Wheat ears were randomly sampled from 51 farms in Narok County and 51 farms in
Nakuru County at hard dough stage while wheat kernels were sampled at harvest.
Prevalence of FHB in both Counties was 100%. The mean incidence of FHB was 28.4 …

2014

O Okumu, J Muthomi, WNMMRC.  2014.  Role of agronomic practices on the occurrence of Fusarium head blight of wheat. Abstracthttps://profiles.uonbi.ac.ke/mainawagacha/

Fusarium head blight is a disease of small grain cereals that reduces yield and
causes mycotoxin contamination. The role of agronomic practices on the occurrence of
wheat agronomic practices was studied. In the experiment, a survey to determine wheat
production practices was conducted in four agro-ecological zones in 2013 cropping season.
Fusarium head blight incidence and severity was determined in four 1m2 quadrants by
counting infected heads and the proportion of diseased head respectively. Fungal

2013

Wagacha, JM, Mutegi CK, Christie ME, Karanja LW, Kimani J.  2013.  Changes in Fungal Population and Aflatoxin Levels and Assessment of Major Aflatoxin Types in Stored Peanuts (Arachis hypogaea Linnaeus). Journal of Food Research. 2(5):10-23.
Ndung'u, JW, Makokha AO, Onyango CA, Mutegi CK, Wagacha JM, Christie ME, Wanjoya AK.  2013.  Prevalence and potential for aflatoxin contamination in groundnuts and peanut butter from farmers and traders in Nairobi and Nyanza provinces of Kenya. Journal of Applied Biosciences . 65:4922–4934.
Mutegi, CK, Wagacha JM, Christie ME, Kimani J, Karanja L.  2013.  Effect of storage conditions on quality and aflatoxin contamination of peanuts (Arachis hypogaea L.). International Journal of AgriScience. 3:746-758.
Wagacha, JM, Mutegi C, Karanja L, Kimani J, Christie ME.  2013.  Fungal species isolated from peanuts in major Kenyan markets: Emphasis on Aspergillus section Flavi. Crop Protection. 52:1-9. Abstract

Abstract
A survey was conducted in Nairobi, Nyanza and Western provinces in Kenya between March and July 2009 with 1263 peanut products sampled out of which 705 samples underwent microbial analysis. The study aimed at determining the incidence of fungal species - emphasis on Aspergillus section Flavi - associated with peanut products. A 0.5kg representative sample was obtained from each surveyed vendor and the colony forming units (CFU) of fungal species determined. The samples were also analyzed for total aflatoxin level while isolates of A. flavus and A. parasiticus were screened for production of aflatoxin B1, B2, G1 and G2. Eight fungal species were detected in the samples and were in decreasing order of CFU/g of sample: A. flavus S-strain (467), A. flavus L-strain (341), Penicillium spp. (326), A. niger (156), A. tamari (27), A. alliaceus (21), A. parasiticus (10), and A. caelatus (5). The overall incidence of A. flavus S-strain in samples from Nairobi was 92 and 1425% higher than samples from Nyanza and Western regions, respectively. The combined incidence of A. flavus and A. parasiticus was varied significantly (p ≤ 0.05) with peanut product: peanut flour (69%), shelled raw peanuts (53%), spoilt peanuts (49%), boiled podded peanuts (45%), podded peanuts (39%), peanut butter (31%), fried peanuts (22%) and roasted peanuts (20%). Seventy three percent of A. flavus and A. parasiticus isolates produced at least one of the aflatoxin types, with 66% producing aflatoxin B1. The total aflatoxin level among peanut products ranged from 0 – 1629 µg/g; and there was a positive correlation (r = 0.2711) between the incidence of A. flavus and A. parasiticus, and total aflatoxin level. The high incidence of aflatoxin producing fungi in peanuts traded in Kenyan markets implies a risk of aflatoxin contamination, highlighting the need for stakeholders to promote sound practices at all stages of the peanut value chain in order to minimize market access by non-complying products.

Keywords: Aflatoxin; Aspergillus section Flavi; fungal species; peanuts.

Nyirahakizimana, H, Mwamburi L, Wakhisi J, Mutegi CK, Christie ME, Wagacha JM.  2013.  Occurrence of Aspergillus Species and Aflatoxin Contamination in Raw and Roasted Peanuts from Formal and Informal Markets in Eldoret and Kericho Towns, Kenya . Advances in Microbiology. Abstract

Abstract:
The population and diversity of fungal species and levels of aflatoxin contamination were investigated in 228 marketed peanut samples; 140 from formal and 88 from informal markets, in Kericho and Eldoret towns of Kenya. Ground peanut samples were cultured on Modified Dichloran Rose Bengal (MDRB) agar while aflatoxin level was quantified based on indirect competitive ELISA. Correlation between the incidence of major aflatoxin-producing fungal species and aflatoxin levels was also established. Fungal species commonly isolated from the peanut samples included Aspergillus flavus L strain, A. flavus S strain, A. parasiticus, A. tamarii, A. caelatus, A. alliaceus (all of Aspergillus section Flavi) and A. niger. Fungi isolated in low frequency included Fusarium spp., Penicillium spp., Mucor spp. and Rhizopus spp. Aflatoxin levels in peanut products ranged from 0 to 2345 μg/kg in raw peanuts, 0 to 382 μg/kg in roasted coated peanuts, and 0 to 201 μg/kg in roasted de-coated peanuts. Overall, levels of total aflatoxin were higher in samples from informal (mean = 97.1 μg/kg) than formal (mean = 55.5 μg/kg) market outlets. There was a positive and significant correlation (R2 = 0.63; p ≤ 0.05) between aflatoxin levels and the major aflatoxin producing fungi in raw peanuts from formal markets in Eldoret town. Additionally, total aflatoxin in raw peanut samples from informal markets in Kericho was positively and significantly correlated (R2 = 0.81; p ≤ 0.05) to the population of A. flavus (L and S strains). In roasted coated peanuts sampled from formal market outlets in Eldoret, aflatoxin levels correlated positively and significantly (R2 = 0.37; p ≤ 0.05) with A. flavus S strain. There is need to create awareness among peanut traders and consumers on proper handling of peanuts and health risks associated with consumption of unsafe peanut products.
Mutegi, C, Wagacha JM, Kimani J, Otieno G, Wanyama R, Hell K, Christie ME.  2013.  Incidence of aflatoxin in peanuts (Arachis hypogaea Linnaeus) from markets in Western, Nyanza and Nairobi Provinces of Kenya and related market traits. Journal of Stored Products Research. 52:118-127.

2012

Musyimi, SL, Muthomi JW, Narla RD, Wagacha JM.  2012.  Efficacy of biological control and cultivar resistance on Fusarium Head Blight and T-2 Toxin contamination in Wheat. American Journal of Plant Sciences . 2:393-402.
Wagacha, JM, Oerke E-C, Dehne H-W, Steiner U.  2012.  Interactions of Fusarium species during prepenetration development. Fungal Biology. 5:581–590.
Wagacha, JM, Oerke E-C, Dehne H-W, Steiner U.  2012.  Colonization of wheat seedling leaves by Fusarium species as observed in growth chambers: a role as inoculum for head blight infection? Fungal Ecology. 116:836–847.
Gachu, SM, Muthomi JW, Narla RD, Nderitu JH, Olubayo FM, Wagacha JM.  2012.  Management of thrips (Thrips tabaci) in bulb onion by use of vegetable intercrops. 2:599-607.
Muthomi, JW, Musyimi SL, Wagacha JM, Narla RD.  2012.  Occurrence of Fusarium species and associated T2-toxin in Kenyan wheat. Agricultural Sciences. 3:24-34.

2010

Wagacha, JM, Steiner U, Dehne H-W, Zuehlke S, Spiteller M, Muthomi J, Oerke E-C.  2010.  Diversity in Mycotoxins and fungal species infecting wheat in Nakuru District, Kenya. Journal of Phytopathology. 157:527–535.: Journal of Phytopathology 157: 527 Website

2008

Muthomi, JW, Otieno PE, Cheminingw’a GN, Nderitu JH, Wagacha JM.  2008.  Effect of chemical spray on insect pests and yield quality of food grain legumes. Journal of Entomology. 5:156–163.
Muthomi, JW, Ndungú JK, Gathumbi JK, Mutitu EW, Wagacha JM.  2008.  The occurrence of Fusarium species and mycotoxins in Kenyan wheat. Crop Protection. 27:1215–1219.
Mutitu, EW, Wagacha JM, M MJ, B. MF.  2008.  Control of bean rust on snap beans (Phaseolus vulgaris L.) using antibiotic metabolites produced by Bacillus and Streptomyces species. Botswana Journal of Agriculture and Applied Sciences. 4:62-69.
Riungu, GM, Muthomi JW, Narla RD, Wagacha JM, Gathumbi JK.  2008.  Management of Fusarium head blight of wheat and deoxynivalenol accumulation using antagonistic microorganisms. Plant Pathology Journal. 7:13-19.
Muthomi, JW, Riungu GM, Ndungú JK, Narla RD, Gathumbi JK, Wagacha JM.  2008.  Head blight of wheat in Kenya and contamination of grain with mycotoxin producing Fusarium species. Journal of Plant Sciences . 3:52-60.: Journal of Plant Sciences 3: 52 - 60Website
Wagacha, JM, Muthomi JW.  2008.  Mycotoxin problem in Africa: Current status, implications to food safety and health and possible management strategies. Journal of Food Microbiology . 124:1-12.: International Journal of Food Microbiology 124: 1-12Website

2007

Muthomi, JW, Ndungú JK, Chemining´wa GN, Wagacha JM.  2007.  Reaction of some Kenyan wheat cultivars to head blight after inoculation with Fusarium graminearum. Asian Journal of Plant Sciences . 6:585-591.
Wagacha, JM, Muthomi JW, Mutitu EW, Mwaura FB.  2007.  . Control of bean rust using antibiotics produced by Bacillus and Streptomyces species - Translocation and persistence in snap beans. Journal of Applied Sciences and Environmental Management . 11:165–168.
Muthomi, JW, Otieno PE, Chemining´wa GN, Nderitu JH, Wagacha JM.  2007.  Effect of root rot pathogens and fungicide seed treatment on nodulation and biomass accumulation. Journal of Biological Sciences. 7:1163-1170.
Wagacha, JM, Muthomi JW.  2007.  Fusarium culmorum: Infection process, mechanisms of mycotoxins production and their role in pathogenesis in wheat. Crop Protection . 26:877-885.: Crop Protection 26: 877-885Website

2003

Wagacha, JM, Mutitu EW, Muthomi JW, Mwaura FB.  2003.  Translocation and persistence of antibiotics produced by Bacillus and Streptomyces spp. in the bean plant. African Crop Science Conference Proceedings.

1983

Maina, JW, Gaciri SJ.  1983.  Contributions to the hydrogeochemistry of the area to the immediate north of Nairobi Conservation Area, Kenya. Website

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