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Publications


2013

Muthomi, JW;, Nderitu JH;, Olubayo FM;, Kabira JN;, Cheminin’wa GN;, Kiretai SM;, Aura JA;, Muindi EM.  2013.  Management Of Potato Viruses In Seed Potato Production Using Border Crops. Abstract

Field experiments were conducted over two croppi ng seasons to investigate the effectiveness of border crops in managing potato aphids and the associated viruses in seed potato production. Potato plots were surrounded with maize, sorghum and wheat borde rs. Aphid population was monitored on leaves and on yellow sticky traps. Other data collected included virus disease incidence and tuber yield. The border crops reduced aphid popula tion on leaves compared to non-bordered potato plots. More alate aphids we re caught on yellow sticky traps placed inside potato plots than on traps placed inside the border crops. In addition, virus disease incidence was reduced in all plots surrounded by the border cr ops. However, plots surrounded by border crops had reduced tuber yield, although the yield of s eed grade was increased. The results indicated that use of border crops would be beneficial in the management of virus diseases in small-holder seed potato production.

Muthomi, JW;, Otieno PE;, Chemining’wa GN;, Nderitu JH.  2013.  Effect Of Root Rot Pathogens And Fungicide Seed Treatment On Nodulation In Food Grain Legumes. Abstract

Greenhouse experiments were conducted over 2 cropping cycles to investigate the effect of fungicide seed treatment and fungal root rot pathogens on nodulation and dry matter accumulation of selected food legumes. The legumes were common bean (Phaseolus vulgaris L.var GLP 2), green gram (Vigna radiata L., variety M66) and lablab (Lablab purpureus L.). Treatments included, inoculation of legumes with pathogen alone (Fusarium oxysporum f.sp. phaseoli or Macrophomina phaseolina or Sclerotinia sclerotiorum or Rhizoctonia solani), or with appropriate rhizobia alone or application of fungicide (copper oxychloride) or their combinations. Results of the study indicated that fungicide seed treatment reduced disease incidence on Sclerotinia and Rhizoctonia inoculated plants. However, fungicide treatment significantly (p=0.05) depressed nodulation of the legumes but its effect on nodulation was significantly suppressed when applied together with rhizobia on infected seeds. Fungicide application significantly reduced seedlings mortality (pre-emergence damping off) and number of nodules per plant but had no effect on dry matter accumulation. Combination of fungicide and rhizobia inoculation improved nodulation as well as reducing disease incidence. It is therefore concluded that this combination yields better results if the aim is to reduce root rot incidence while improving nodulation concurrently.

WAHOME, SW, Kimani PM, Muthomi JW, Narla RD.  2013.  Quality and yield of snap bean lines locally developed in Kenya. International Journal of Agronomy and Agricultural Research (IJAAR). 3(7):1-10.analysis_of_iris_yellow_spot_virus_replication_in_vector_and_non.pdf
Bigirimana, J, Njoroge K, Muthomi JW, Walyaro DJ, Phiri NA, Gichuru EK, Gahakwa D.  2013.  Resistance of Arabica coffee genotypes (Coffea arabica L.) to coffee berry disease and coffee leaf rust in Rwanda. International Journal of Farming and Allied Sciences (IJFAS). Accepted
Karanja, LW, Wachira PM, Muthomi JW, Phiri NA, Mutegi CK, Nzioki HS, Gikaru AK, Kanampiu F, J.M W.  2013.  Use of geographical information system to determine incidence of Aspergillus section flavi in different soils in Kaiti, Kenya. East African Agricultural and Forestry Journal. Accepted
Muthomi, JW, Weru RW, Chemining'wa GN, Mutitu EW.  2013.  Resistance of maize varieties to infection by Aspergillus flavus and aflatoxin accumulation. East African Agricultural and Forestry Journal. Accepted
Muriithi, BK, Muthomi JW, Chemining'wa GN, Mutitu EW.  2013.  Identification of predisposing factors to aflatoxin contamination of maize value chain in eastern Kenya. East African Agricultural and Forestry Journal. accepted
R.Birithia, S.Subramanian, H.R.Pappu, Muthomi J, R.D.NARLA.  2013.  Analysis of Iris yellow spot virus (IYSV, genus Tospovirus) replication in vector and non-vector thrips species. Plant Pathology . (12057)
Kitonyo, OM, Chemining'wa GN, Muthomi JW.  2013.  Productivity of farmer-preferred maize varieties intercropped with beans in semi-arid Kenya. International Journal of Agronomy and Agricultural Research (IJAAR). 3(1):6-16.kitonyo_ijaar-v3no1-p6-16.pdf

2012

Subramanian, S, Pappu HR, Birithia R, Muthomi JW, Sseruwagi P, Narla RD.  2012.  Diversity and distribution of Iris yellow spot virus infecting onion in Eastern Africa, 17-20 May 2012. 4th Conference of the International Working Group on Legume and Vegetable Viruses (IWGLVV). , Antequera, Málaga, Spain
Kwach, JK, Onyango MA, Muthomi JW, Nderitu JH.  2012.  Baseline survey for status of Banana Xanthomonas Wilt in Kenya, 22 - 26 Oct 2012. 13th KARI Biennial Scientific Conference. , KARI Headquarters
Tom, FK, Muthomi JW, Olubayo FM, Chemining'wa GN.  2012.  Susceptibility of locally grown maize varieties to infestation by maize weevil (Sitophilus zeamais Motsch.)., 22 - 26 Oct 2012. 13th KARI Biennial Scientific Conference. , KARI Headquarters
Muthomi, JW, Musyimi SL, Wagacha JM, Narla RD.  2012.  Occurrence of Fusarium species and associated T2-toxin in Kenyan wheat. Agricultural Sciences. 3(1):24-34.
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. International Journal of AgriScience . 2(5):393-402.
Chemining’wa, N, Ngeno J, Muthomi JW, Shibairo SI.  2012.  Effectiveness of indigenous pea rhizobia (Rhizobium leguminosarum bv. viciae) in cultivated soils of central Kenya. Journal of Applied Biosciences. 57:4177-4185.effectiveness_of_indigenous_pea_rhizobia.pdf
Birithia, R, Subramanian S, Villinger J, Muthomi J, Narla RD, Pappu HR.  2012.  2012. First report of tomato yellow ring virus (Tospovirus, Bunyaviridae) Infecting tomatoes in Kenya. Plant Disease. 96:1384.: The American Phytopathological SocietyWebsite
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. International Journal of AgriScience 2(5): 393-402. International Journal of AgriScience. 2(5):393-402.: International Academic Journalsgachu_thrips_paper.pdfWebsite
W, DRMUTHOMIJAMES.  2012.  Muthomi J. W., Mureithi B. K., Chemining. International Journal of AgriScience. : International Academic Journals
Muthomi, JW, Musyimi SL, Wagacha JM, Narla RD.  2012.  Occurrence of Fusarium species and associated T2-toxin in Kenyan wheat. Agricultural Sciences. 3(1): 24-34.(1):24-34.: Scientific Research Publishing Inc. Abstractfusarium_t-2_toxin_paper_agricultural_sciences.pdfWebsite

Malaria is a serious cause of mortality globally. The disease is of regional concern in Africa and of national interest in Kenya due to its high morbidity and mortality as a result of development of resistant strains of Plasmodium falciparum to many existing drugs such as chloroquine. Alternative medicine using herbal remedies are commonly used to treat malaria in Kenya. However, plants used in some rural areas in Kenya are not documented. Many antimalarial drugs have been derived from plants. This study was conducted to document medicinal plants that are traditionally used by the Msambweni community of Kenyan South Coast to treat malaria, where the disease is endemic. Herbalists were interviewed by administration of semistructured questionnaires in order to obtain information on medicinal plants traditionally used for the treatment of malaria. Focused group discussions held with the herbalists supplemented the interview and questionnaire survey. Twenty-seven species of plants in 24 genera distributed in 20 families were reported to be used in this region for the treatment of malaria. Labiatae, Rutaceae and Liliaceae families had each eleven percent of the plant species reported and represented th species that are most commonly used. Thirteen plant species, namely; Aloe deserti Berger (Liliaceae), Launea cornuta (Oliv and Hiern) C. Jeffrey (Compositae), Ocimum bacilicum L. (Labiatae), Teclea simplicifolia (Eng) Verdoon (Rutaceae), Gerranthus lobatus(Cogn.) Jeffrey (Cucurbitaceae), Grewia hexaminta Burret.(Tiliaceae), Canthium glaucum Hiern. (Rubiaceae), Amaranthus hybridus L.(Amaranthaceae), Combretum padoides Engl and Diels. (Combretaceae), Seneciosyringitolius O.Hoffman. (Compositae), OcimumsuaveWilld(Labiatae), Aloe macrosiphon Bak. (Liliaceae) and Laudolphia buchananii (Hall.f) Stapf. (Apocynaceae) are documented from this region forthefirst time for the treatment of malaria. These results become a basis for selection of plants for further pharmacological, toxicological and phytochemical studies in developing new plant based antimalarial drugs.

2011

Birithia, R;, Subramanian S;, Pappu HR;, Sseruwagi P;, Muthomi JW;, Narla RD.  2011.  First Report of Iris yellow spot virus Infecting Onion in Kenya and Uganda. Abstract

Onion (Allium cepa L.) is one of the key vegetables produced by small-holder farmers for the domestic markets in Sub-Saharan Africa. Biotic factors, including infestation by thrips pests such as Thrips tabaci Lindeman, can inflict as much as 60% yield loss. Iris yellow spot virus (IYSV; family Bunyaviridae, genus Tospovirus) transmitted by T. tabaci is an economically important viral pathogen of bulb and seed onion crops in many onion-growing areas of the world (2,4). In Africa, IYSV has been reported in Reunion (1) and South Africa (3). In September 2009, symptoms suspected to be caused by IYSV were observed on onions and leeks cultivated in Nairobi, Kenya. Symptoms consisted of spindle-shaped, straw-colored, irregular chlorotic lesions with occasional green islands on the leaves. The presence of the virus was confirmed with IYSV-specific Agdia Flash kits (Agdia Inc., Elkart, IN). Subsequently, surveys were undertaken in small-holder farms in onion production areas of Makueni (January 2010) and Mwea (August 2010) in Kenya and Kasese (January 2010) and Rwimi (January 2010) in Uganda. The incidence of disease in these locations ranged between 27 and 72%. Onion leaves showing symptoms of IYSV infection collected from both locations tested positive for the virus by double-antibody sandwich-ELISA with IYSV-specific antiserum (Agdia Inc). IYSV infection was confirmed by reverse transcription-PCR with primers IYSV-465c: 5′-AGCAAAGTGAGAGGACCACC-3′ and IYSV-239f: 5′-TGAGCCCCAATCAAGACG3′ (3) as forward and reverse primers, respectively. Amplicons of approximately 240 bp were obtained from all symptomatic test samples but not from healthy and water controls. The amplicons were cloned and sequenced from each of the sampled regions. Consensus sequence for each isolate was derived from at least three clones. The IYSV-Kenya isolate (GenBank Accession No. HQ711616) had the highest nucleotide sequence identity of 97% with the corresponding region of IYSV isolates from Sri Lanka (GenBank Accession No. GU901211), followed by the isolates from India (GenBank Accession Nos. EU310287 and EU310290). The IYSV-Uganda isolate (GenBank Accession No. HQ711615) showed the highest nucleotide sequence identity of 95% with the corresponding region of IYSV isolates from Sri Lanka (GenBank Accession No. GU901211) and India (95% with GenBank Accession Nos. EU310274 and EU310297). To our knowledge, this is the first report of IYSV infecting onion in Kenya and Uganda. Further surveys and monitoring of IYSV incidence and distribution in the region, along with its impact on the yield, are under investigation.

Kwach, JK;, Onyango MA;, Muthomi JW;, Nderitu JH.  2011.  Baseline survey for status of Banana Xanthomonas Wilt in Kenya.
Muthomi, JW, Kinyungu TN, Nderitu JH, Olubayo FM, Kabira JN.  2011.  Spatial Arrangement Of Maize As Border Crop To Manage Aphids And Aphid-Transmitted Viruses In Potato. Abstract

Field experiments were conducted over two growing seasons to determine the effect of spatial arrangement of maize as border crop to manage aphid infestation and aphid-transmitted virus diseases in potato (Solanum tuberosum L.). Maize was planted at a distance of 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 m from the potato crop. Aphid infestation and incidence of virus infection was monitored over the growth period of potato. Aphids were recorded on potato leaves and in water pan traps while virus infection was determined by visual symptoms on the potato plant. At harvest, potato tubers were graded into ware, seed, and chatts and weighed. The results show that placement of maize border up to 0.5 m and 1.0 m reduced aphid population and virus disease incidence by up to 48%. The maize borders had no effect on the yield of seed potato grade but only on the ware. Placing maize border at 0.5m had the greatest reduction of ware potato yield by 48%. Maize borders placed up to 1m from the potato crop would be effective in the management of potato aphids and aphid-transmitted virus diseases. This study shows that the technology would be ideal for propagation plots in small scale seed potato production.

Nderitu, JH, Muthomi JW.  2011.  Curricula for Agricultural Value Chain Development for Universities and Colleges, July 2011. :1-19., Nairobi, Kenya: Gesellschaft Fuer Internationale Zusammenarbeit (GIZ) and Promotion of Private Sector Development in Agriculture (PSDA)
Chemining'wa, GN, Wahome PK, Muthomi JW.  2011.  Soil fertility status and nodulation of selected legumes in farmer’ fields in south-eastern Kenya, 26-28 Sept 2011. aGRO 2011 Inaugural Biennial Conference, Faculty of Agriculture. , Faculty of Agriculture, University of Nairobi
Mureithi, BK, Muthomi JW, Chemining'wa GN, undefined.  2011.  Predisposing factors to aflatoxin contamination of maize in Estern Kenya, 26-28 Sept 2011. aGRO 2011 Inaugural Biennial Conference, Faculty of Agriculture. , Faculty of Agriculture, University of Nairobi, Kenyaidentification_of_predisposing_factors_to_aflatoxin_contamination_of_maize_value_chain_in_eastern_kenya.2.pdf
Muthomi, JW, Muindi EM, Nderitu JH, Olubayo FM, Kabira JN, Chemining'wa GN.  2011.  Integrated management of aphid-transmitted viruses in potato (Solanum tuberosum L.), 26-28 Sept 2011. aGRO 2011 Inaugural Biennial Conference, Faculty of Agriculture. , Faculty of Agriculture, University of Nairobi, Kenya
Kimani, E, Kigamwa J, Chege F, Muthomi J.  2011.  Bridging phytosanitary capacity through the Centre of Phytosanitary Excellence (COPE), 26-28 Sept 2011. aGRO 2011 Inaugural Biennial Conference, Faculty of Agriculture. , Faculty of Agriculture, University of Nairobi, Kenya
Wagacha, JM, Steiner U, Dehne H-W, Muthomi JW, Oerke E-C.  2011.  Variation in susceptibility of wheat parts to major Fusarium head blight pathogens., 26-28 Sept 2011. aGRO 2011 Inaugural Biennial Conference, Faculty of Agriculture. , Faculty of Agriculture, University of Nairobi, Kenyavariation_in_susceptibility_of_wheat_parts_to_major_fusarium_head_blight_pathogens.pdf
Muthomi, JW, Gachu SM, Narla RD, Nderitu JH.  2011.  Management of thrips in bulb onions using vegetable intercrops, 26–28 Sept 2011. aGRO 2011 Inaugural Biennial Conference. , Faculty of Agriculture, University of Nairobi, Nairobi, Kenyamanagement_of_thrips_thrips_tabaci_in_bulb_onion_by_use_of_vegetable_intercrops.pdf
W, DRMUTHOMIJAMES.  2011.  Chemining. African Journal of Horticultural Science 5: 92-97. : Horticultural Association of Kenya
W, DRMUTHOMIJAMES.  2011.  Birithia, R. L., Subramanian, S., Muthomi, J., and Narla, R. D. 2010. Distribution of the tospovirus Iris Yellow Spot Virus infecting onions in Kenya. 10th Horticultural Association of Kenya (HAK) Workshop on Sustainable Horticultural Production in the Tr. 10th Horticultural Association of Kenya (HAK) Workshop on Sustainable Horticultural Production in the Tropics: Analysis of Production Chains of Ornamentals for the Local Market and For Export. 8th - 11th December 2010, Jomo Kenyatta University of Agricult. : Horticultural Association of Kenya (HAK)
W, DRMUTHOMIJAMES.  2011.  Subramanian, S., H.R. Pappu, R. Birithia, O. Shem, J. Muthomi, P. Sseruwagi, R.D. Narla. 2011. Diversity and distribution of Iris yellow spot virus infecting onion in Eastern Africa. 4th Conference of the International Working Group on Legume and Vegetabl. 4th Conference of the International Working Group on Legume and Vegetable Viruses (IWGLVV), May 17-20, 2011 - Antequera, M. : International Working Group on Legume and Vegetable Viruses (IWGLVV)

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