Bio

biography

Prof Kimenju holds a Ph.D Crop Protection (1998), M.Sc. Plant Pathology (1991) and   B.Sc. Agriculture (1987) from the University of Nairobi. Prof. Kimenju is an Associate Professor of Nematology in the Department of Plant Science and Crop Protection having joined risen in the ranks since joining the University as a Graduate Assistant in 1991.

Publications


2016

2015

Luambano, ND, Manzanilla-López RH, Kimenju JW, Powers SJ, Narla RD, Wanjohi WJ, Kerry BR.  2015.  Effect of temperature, pH, carbon and nitrogen ratios on the parasitic activity of Pochonia chlamydosporia on Meloidogyne incognita. Biological Control. 80:23-29.

2014

Kimenju J.W, J.Nzesya M, Maina MW, Peter WM, Elijah GK.  2014.  Reaction of selected coffee germplasm to root-knot nematodes in Kenya. Journal of Natural Sciences Research. 4:68-75.
Kawaka, F, Kimenju J, Okoth SA, Ayodo G, Mwaniki S, Muoma J, Orinda G.  2014.  Effects of soil chemical characteristics on the occurrence of entomopathogenic nematodes. British Journal of Applied Science and Technology. 4:2333-2343.

2013

Kimaru, SL, Kimenju JW, Kilalo DC, Onyango CM.  2013.  Potential of combining host plant resistance and intercropping in the management of root-knot nematodes and insect pests in the indigenous leafy vegetables.. 11th African Crop Science Society Conference 13-17th October 2013. , Entebbe-Uganda
Kimenju, J. W; Karanja, MRNNK; GK;.  2013.  Impact of land use changes on nematode diversity and abundance. Abstract

This study was conducted to determine the effect of land use on nematode community structure. The land use types represented in the study sites were natural forest, plantation forest, tea, coffee, napier grass, agroforestry, fallow and annual crops dominated by maize and beans. Nematode diversity and abundance decreased with intensity of land cultivation or human interference, with the natural forest being regarded as the benchmark. The decrease in nematode diversity was assessed using Shannon, Simpson and species richness indices and was used to reflect the underlying changes in physical, chemical and biological properties of soil environment. The highest maturity indices (MI) for free-living and plant parasitic index (PPI) were recorded in the natural forest and intensively cultivated land under annual crops (maize/beans) respectively. Herbivorous nematodes were predominant in soils that were under agricultural production while saprofagic nematodes dominated the forested land as exemplified by the ratios of freeliving to plant parasitic which were, 5.18 and 0.54 in the natural forest and annual crop ecosystems respectively. Changes in the nematode community structure as exhibited by diversity indices may be a reflection of real differences in soil and ecosystem functions.

Kilalo, DC, Olubayo FM, Ateka EM, Hutchinson JC, Kimenju JW.  2013.  Monitoring of Aphid Fauna in Passionfruit Orchards in Kenya. Abstract

Passionfruit woodiness disease viral pathogens limit passionfruit production and are non-persistently transmitted by aphid vectors. The study was conducted to identify aphid species and assess the population dynamics of potential vectors in the orchards for purposes of developing viral disease management tactics. Field trials laid out in a randomized complete block design with four replicates, were conducted in Kabete and Embu and aphid populations monitored weekly in passionfruit orchards for a year using yellow water pan traps under natural conditions. Aphid transmission tests using commonly found aphids Aphis gosypii, A. fabae, Brevicoryne brassicae, Ropalosiphum maidis, and Sitobion avenae and a CABMV isolate from the field were also carried out in the greenhouse. These tests would establish the ability of the aphid species to transmit CABMV. Twelve species of aphids were captured but the most abundant were Aphis gosypii, Ropalosiphum maidis, Acyrthosiphon pisum and Brevicoryne brassicae accounting for 97% and 95 % of the total aphids collected in Embu and Kabete, respectively. The species diversity was rich and abundant at 0.79 and 0.7 for Kabete and Embu, respectively. The aphid population in Kabete (8000) was significantly (p< 0.05) higher than that collected in Embu (2900) whereas the population collected during the long rains season was significantly (p<0.05) higher than that which was collected in the short rains. Individual species populations were higher in Kabete than in Embu but only A. gosypii, Macrosiphum euphorbiae, Myzus persicaeand R. maidis had significantly (p<0.05) higher populations in Kabete. About 70% of the total aphids were collected during the peak period in both sites indicating greatest aphid dispersal and flight activity. The aphids were present in the orchards throughout the year with one major seasonal peak in June, a time period when food crops and other vegetation such as weeds grow vigorously. The occurrence of aphids in the orchards throughout the year with the peak population density coinciding with the cropping season has serious implications in the management of the pest and spread of viral diseases of passionfruit.

2012

Mutua, G, Devonshire J, Kimenju J.  2012.  The Pochonia chlamydosporia Serine Protease Gene vcp1 Is Subject to Regulation by Carbon, Nitrogen and pH: Implications for Nematode Biocontrol. Abstract

The alkaline serine protease VCP1 of the fungus Pochonia chlamydosporia belongs to a family of subtilisin-like enzymes that are involved in infection of nematode and insect hosts. It is involved early in the infection process, removing the outer proteinaceous vitelline membrane of nematode eggs. Little is known about the regulation of this gene, even though an understanding of how nutrients and other factors affect its expression is critical for ensuring its efficacy as a biocontrol agent. This paper provides new information on the regulation of vcp1 expression. Sequence analysis of the upstream regulatory region of this gene in 30 isolates revealed that it was highly conserved and contained sequence motifs characteristic of genes that are subject to carbon, nitrogen and pH-regulation. Expression studies, monitoring enzyme activity and mRNA, confirmed that these factors affect VCP1 production. As expected, glucose reduced VCP1 expression and for a few hours so did ammonium chloride. Surprisingly, however, by 24 h VCP1 levels were increased in the presence of ammonium chloride for most isolates. Ambient pH also regulated VCP1 expression, with most isolates producing more VCP1 under alkaline conditions. There were some differences in the response of one isolate with a distinctive upstream sequence including a variant regulatory-motif profile. Cryo-scanning electron microscopy studies indicated that the presence of nematode eggs stimulates VCP1 production by P. chlamydosporia, but only where the two are in close contact. Overall, the results indicate that readily-metabolisable carbon sources and unfavourable pH in the rhizosphere/egg-mass environment may compromise nematode parasitism by P. chlamydosporia. However, contrary to previous indications using other nematophagous and entomopathogenic fungi, ammonium nitrate (e.g. from fertilizers) may enhance biocontrol potential in some circumstances.

2011

Luambano, N;, Kimenju JW;, Narla R;, Waceke JW.  2011.  Colonisation of the Rhizosphere of plants which are poor host to root-knot nematodes by the biological agent Pochonia chlamydosporia. Abstract

Management of root-knot nematodes (Meloidogyne spp.,) using fungi that parasitize eggs of root-knot and cyst nematodes has been gaining popularity. Application of this fungus to plants that are poor host to root-knot nematodes has shown good results. This study was conducted to screen plants that support growth of Pochonia chlamydosporia on its rhizosphere. Seedlings of cabbage, sunhemp, maize, velvet bean, African marigold and tomato were planted in pots containing sterilized soil which had Pochonia chlamydosporia. Thirty days after planting, the fungal propagules in the soil and roots increased significantly (P<0.05) in all plants with the exception of velvet beans. Ninety days after planting, the counts of the fungal propagules taken from the soil were significant higher (P<0.05) in the rhizosphere where maize was planted than in other plants. This study concluded that maize is a promising rotational in system where P. chlamydosporia is used as a biocontrol agent.

Wagara, IN, Mwang'ombe AW, Kimenju JW, Buruchara RA, Kimani PM.  2011.  Reaction of selected common bean genotypes to physiological races. Abstract

The wide pathogenic variability occurring in Phaeoisariopsis griseola, the causal agent of angular leaf spot of common bean (Phaseolus vulgaris L.), dictates that new sources of resistance be continuously identified. This study was undertaken to determine the reaction of selected bean genotypes to different races of P. griseola in order to identify potential sources of resistance to angular leaf spot. Selected bean genotypes from Eastern and Central Africa Bean Research Network (ECABREN) and National Dryland Farming Research Centre (NDFRC), Katumani in Kenya were separately inoculated with forty-four races of P. griseola and evaluated for disease development under greenhouse conditions. The genotypes included small- and large-seeded types. None of the genotypes was resistant to all the races, indicating a high complexity of the pathogen population. Thirteen genotypes were resistant (disease score 1 to 3) or moderately resistant (score 4 to 6) to at least 40 of the races. Small-seeded bean genotypes ECAB 0754 and ECAB 0617 were resistant or moderately resistant to all races except Mesoamerican race 33-39 and Afro-Andean race 58-18, respectively. Genotype ECAB 0754 exhibited the highest level of resistance, with an average disease severity of 1.1%. All the resistant or moderately resistant genotypes were of the smallseeded bean types which are commercially less popular. The commonly grown large-seeded genotypes were generally susceptible. Among the bean genotypes evaluated, the small-seeded pintos and browns/yellows possessed high levels of resistance. The results of this study indicate that different bean genotypes have varying levels of resistance to angular leaf spot that can be pyramided into appropriate background to provide durable resistance.

2010

Kimenju, JW, Mweke AN, Mutitu EW, Mutua GK.  2010.  Poor hosts of root knot nematodes and their application as rotation crops in okra production. Abstract

The response of 21 different crop plants to a mixed population of root-knot nematodes, Meloidogyne javanica and M. incognita, and their potential for use as nematode suppressive crops was evaluated in greenhouse and field experiments. Second stage juveniles (J2) were determined under each crop after extracting them from 200 cm3 soil. The reaction of the crops to root knot nematodes was classified as resistant, moderate or susceptible. Crops classified as resistant included maize, sorghum, millet, guwar and pigeonpea, which had galling indices ranging from 1.4-3.6. Cowpea ‘K80’ was rated as moderately resistant with a galling index of 4, while susceptible crops were greegram, cowpea ‘KKI’ and okra (control), with galling indices ranging from 5.6-7.4. Four crops (sweetcorn, babycorn, maize cv. Pioneer (Ph3253) and guwar) were selected from greenhouse tests for the field trials. The selection was based on their poor host status to root knot nematodes as well as relative acceptability to growers. These crops were then incorporated into a rotation programme with okra. Initial and final nematode (J2) numbers in the field was determined before planting and at the end of the season, respectively. Among the crops tested, the highest (44%) decline in nematode populations was recorded in plots under guwar and sweetcorn while the least (21%) was recorded under babycorn. In contrast, 441% increase in nematode numbers was recorded under continuous crop of okra. Okra was then sown in the plots previously grown with the selected nematode suppressive crops and the population of nematodes determined mid-season and at the end of the season. The severity of root knot nematodes on a crop of okra that followed sweetcorn was 3.3 compared to 8.6 in the control which as continuously under okra. This underscores the potential of rotating highly susceptible crops with poor hosts in the management of root knot nematodes

Affokpon, A, Coosemans J, Kimenju JW.  2010.  Suppression of root-knot nematodes in tomato and cucumber using biological control agents. Abstract

Antagonistic fungi are continuously attracting a lot of attention as alternatives to chemical control of root-knot nematodes. The egg-pathogenic fungus Paecilomyces lilacinus, particularly strain 251 has shown promising potential as a biological control agent against various plant-parasitic nematodes. Strain 251 of P. lilacinus (PL251) and Arthrobotrys conoides (Melodogone) were tested for their efficacy against Meloidogyne spp. in tomato and cucumber under greenhouse conditions. The study aimed at determining the application rates and timing of application of the fungi. Both pre-planting and at planting application of PL251 were found to reduce nematode populations and root galling in both tomato and cucumber. Pre-planting soil treatment (0.4g/10 L of soil) reduced final nematode populations by 69% and 73% in the roots and soil, respectively, compared to the non-inoculated control in tomato. However, soil treatment at planting recorded reduction level of 54% and 74% in the roots and soil, respectively. Use of A. conoides showed lower nematode control in cucumber. Only 28% and 21% reduction levels were recorded in the roots and soil when the fungus was applied at planting, respectively. This study has demonstrated that PL251 has a promising potential that could be exploited in the management of Meloidogyne spp. in vegetable production systems.

2009

Odero, GOM, Mutitu EW, Wachira PM, Narla RD, Muiru WM.  2009.  Suitability of Locally Available Substrates for Oyster Mushroom (Pleurotus ostreatus) Cultivation in Kenya. AbstractWebsite

This study aimed at evaluating the suitability of selected substrates for mushroom production. Ten different substrates namely water hyacinth ( Eichhornia crassipes ), maize cobs ( Zea mays ), coconut fibre ( Cocos nucifera ), finger millet straw ( Seteria microcheata ), banana fibre ( Musa sp.), sawdust ( Eucalyptus sp.), rice straw ( Oryza sativa ) bean straw ( Phaseolus vulgaris ) and wheat straw ( Tritichum aestivum ) were tested for their suitability in mushroom production. Plastic bags were filled with 250 g of substrate and arranged in a randomized complete block design. The substrates had a significant (p≤0.05) effect on days to pinning, number of caps and biological efficiency. Compared to the control, which pinned at 28 days, maize cobs, sawdust and coconut fiber had short pinning durations of 19, 22 and 23 days, respectively. With the exception of sawdust, water hyacinth and maize cobs, the rest of the organic substrates significantly increased the marketable caps of the oyster mushroom. The straws, namely, bean, rice, finger millet and wheat had the highest biological efficiency in decreasing order of 106, 92, 85 and 77%, respectively. Stipe length was longest in oyster mushroom grown on bean straw, followed by finger millet straw, maize cobs, banana fiber and shortest in sawdust. Mushroom yield was, 80, 78, 76, 73 and 68%, higher in bean straw, rice straw, millet straw, wheat straw and banana fibre treatment compared to the control. Mushroom yields on sawdust were 60% lower than the control. In descending order of suitability bean, rice, finger millet and wheat straws can be recommended for oyster mushroom production.

Kimenju J.W, Karanja N.K, Mutua G.K, B.M R, Wachira P.M.  2009.  Nematode community structure as influenced by land use and intensity of cultivation. Abstract

This study was conducted to determine the effect of land use and intensity of land cultivation on the nematode community structure. The land use types represented in the study sites were natural forest, plantation forest, tea, coffee, napier grass, agroforestry, fallow and annual crop cultivation dominated by maize intercropped with beans. Nematode diversity and abundance decreased with intensity of land cultivation, with the natural forest being regarded as the benchmark. The decrease in nematode diversity was assessed using Shannon, Simpson and species richness indices and was used to reflect the underlying changes in physical, chemical and biological properties of soil environment. The highest maturity indices for free-living and plant parasitic index were recorded in the natural forest and intensively cultivated land under annual crops (maize/beans), respectively. Plant parasitic nematodes were predominant in soils that were under agricultural production while saprofagic nematodes dominated the forested land as exemplified by the ratios of free-living to plant parasitic which were, 5.18 and 0.54 in the natural forest and annual crop production systems respectively. Changes in the nematode community structure, as exhibited by diversity indices, may be a reflection of real differences in the soil characteristics and changes in ecosystem functions. Key words: Abundance; diversity; richness and maturity index.

Mibey, RK, Okoth SA, Kimenju JW, Wachira PM.  2009.  Stimulation of nematode-destroying fungi by organic amendments applied in management of plant parasitic nematode.. Abstract

A screenhouse experiment was conducted to evaluate the effect of cow manure, chicken manure and their combinations on nematode destroying fungi, nematode community and growth of tomato (Solanum lycopersicum L.). The amendments were applied at the rate of 5% w/w in all the treatments. Isolation of nematode destroying fungi was done using the soil sprinkle technique. Nematodes were extracted from soil using the modified Baermann technique. Tomato growth was estimated through plant height and dry weight. Application of the organic amendments resulted in significant differences (p≤0.05) in occurrence of nematode destroying fungi amongst the treatments. The nematode destroying fungi occurred at frequencies of 50, 29.4, 17.6 and 2.9% in soil amended with chicken manure, cow/chicken combination, cow manures and the control, respectively. Eight species of nematode destroying fungi were identified in this study. The fungus Arthrobotrys oligospora (Fresenius) was most dominant fungus in all the treatments including control pots with an isolation frequency of 38.2%. Addition of organic amendments into the soil also resulted in an increase of bacterial and fungal feeding nematodes and reduction of plant parasitic nematodes. Specifically there was a 225, 96 and 62% increase in bacterial feeding nematodes and 391, 96 and 74% increase in fungal feeding nematodes in soil amended with chicken manure alone, combination of chicken and cow manure alone in that order. Numbers of plant-parasitic nematodes were 92% lower in soil treated with chicken manure compared to the control. Plant height and leaf widths were highest in plants treated with combination of cow and chicken manures. The plants mean dry weight were 6.6, 5.6, 2.0 and 1.5 in combination of chicken and cow manure, chicken manure alone, cow manure alone and control, respectively. This study has therefore, revealed that organic amendments stimulate the occurrence of nematode destroying fungi in the soil and also reduce plant parasitic nematodes. In addition, the combination of cow and chicken manure stimulates plant growth

2008

Mweke, AN, Kimenju JW, Seif AA, Mutitu EW, Mutua GK.  2008.  Potential of sequential cropping in the management of root-knot nematodes in okra. Abstract

The response of different crops to a mixed population of root-knot nematodes, Meloidogyne javanica and M. incognita and their potential as suppressants in sequential cropping systems was evaluated in greenhouse and field experiments. Crops rated as resistant were five maize cultivars, four sorghum cultivars, two millet varieties, guwar and two pigeonpea cultivars which had galling indices ranging between 1.4-3.6. cowpea cv. K80 was rated as moderately resistant with a galling index of 4 while greengram and cowpea cv. KKI were rated as susceptible with galling indices ranging from 5.6 to 7.4. Four crops namely sweetcorn, babycorn, maize cv. Pioneer (Ph3253) and guwar were selected after the greenhouse tests for field trials, based on their poor host status to root-knot nematodes as well as relative acceptability to vegetable growers. These crops were then incorporated into a rotation program with okra. Initial and final J2 numbers in the field were determined before planting and at the end of the season, respectively. Okra was then sown in the plots previously grown with the selected nematode suppressive crops and the nematode numbers determined mid and end of the season. A 44 and 21% decline in nematode numbers was recorded in plots under guwar or sweetcorn and babycorn, respectively. In contrast, a 441% increase in nematode numbers was recorded in plots under continuous crop of okra. The galling index on a crop of okra that followed sweetcorn was 3.3 compared to 8.6 in the control which was continuously under okra, resulting in an increase in yield within a range of 60-92%. This underscores the potential of rotating highly susceptible crops with poor hosts in the management of root-knot nematodes.

Otieno, W, Muiru WM, Mutua GK, Kimenju JW, Langat JK.  2008.  Response of free-living nematodes to treatments targeting plant parasitic nematodes in carnation. Abstract

This study was carried out with the aim of evaluating the effect of ecologically sound approaches for nematode management on non-target organisms, free-living nematodes. The materials tested were sugarcane bagasse, molasses, tea and flower composts, neem (Achook), a biological agent (Paecilomyces lilacinus) and fenamiphos (Nemacur). The treatments were administered before planting carnation var. White Natila in flower beds that were naturally infested with nematodes. Application of bagasse, molasses, tea and flower composts resulted in increased abundance of free-living nematodes compared to the control where nothing was applied. Bacterial feeders, fungal feeders, and predators comprised 73, 14 and 13%, respectively of the free-living nematodes recovered. Members of the genus Rhabditis were the most abundant (10%) among the bacteriovores while Mononchus (10%) and Aphelenchoides (14%) dominated among the predators and fungivorous trophic groups, respectively. The highest numbers of free-living nematodes were recorded at 90 Days after Planting (DAP) in plots treated with bagasse and molasses but the numbers declined at 180 DAP. A steady increase in numbers of free-living nematodes was observed in plots treated with tea and flower composts up to 180 DAP. Significant reductions in abundance of free-living nematodes were recorded in plots treated with fenamiphos and neem. This study has established that application of organic substrates serve as a stimulus to processes leading to build-up of free-living nematodes. The organic substrates can strongly be recommended for use in sustainable carnation production systems.

Muiru, WM, Kimenju JW, Mut EW, Tiedemann AV, Koopmann B.  2008.  A review of the Amplified Fragment Length Polymorphism (AFLP) technique in genotyping and DNA fingerprinting studies. Abstract

Amplified fragment length polymorphism (AFLP) is a marker based on polymerase chain reaction amplification of restricted fragments ligated to synthetic adaptors and amplified using primers which carry selective nucleotides at their 3’ ends. The technique generates highly reproducible markers from DNA of any organism and allows high resolution genotyping. AFLP has broad applications and has been used to investigate genomes of different complexity from microbes to higher organisms for purposes of species, strains and varieties identification, systematics, pathotyping, population genetics, simple and complex trait mapping, population genetics, construction of linkage and physical maps. In addition, it is being used in medical diagnostics, forensic analysis and microbial typing. AFLP is superior compared to other markers in that it has time efficiency, generates more information, is highly reproducible and has a wide range of applications. The marker has a drawback in that it generates dominant rather than co-dominant markers and can also be expensive if automated systems are used.

Chirchir, AK, Olubayo FM, Mutua GK.  2008.  Abundance and Distribution of Plant Parasitic Nematodes Associated With Sugarcane in Western Kenya. AbstractWebsite

A study was conducted to determine the factors influencing plant-parasitic nematode occurrence, abundance and distribution in the sugarcane fields. Four sugarcane growing zones; Nzoia, Mumias, West Kenya and Busia of Kenya were selected from which 81 fields randomly selected and sampled. Soil samples were taken from sugarcane rhizospheres and nematodes extracted from 200 cm3 soil using the modified Baermann funnel technique. Nematodes were then fixed and mounted on slides and identified to genera level using identification keys. Nematodes of the genera Pratylenchus, Scutellonema and Meloidogyne were predominant in the sugarcane belt of western Kenya with mean densities of 61, 54 and 39, respectively. Nzoia, which falls in a marginal sugarcane zone harboured the highest proportion of these plant parasitic nematodes (55%), while West Kenya zone had the least proportion (4%). Soil texture influenced nematodes with more than 50% occurring in sandy soils compared to other soil types. Build-up of plant parasitic nematodes occurred with subsequent ratoon crops up to the second ratoon before declining in the third ratoon. Anthropogenic effects were significant with 70% higher numbers of plant parasitic nematodes in the out-grower farms compared to the factory-managed farms. This study has revealed the influence of soil texture, crop cycle and anthropogenic factors on abundance and distribution of plant parasitic nematodes in western Kenya sugarcane zones. It has also set the justification of further work to determine the economic importance of the nematodes

2007

Kimenju, JW;, Kagundu AM;, Nderitu JH;, Omuolo FM;, Mutua GK.  2007.  Use of green manure plants in cropping systems to suppress root-knot nematodes. Abstract

Green manure plants namely Calliandra calothyrsus, Canavalia ensiformis, Chenopodium quinoa, Crotalaria juncea, Desmodium uncinartum, Gliricidia sepium, Leucaena leucocephala, Mucuna pruriens, Tephrosia purpurea, Tithonia diversifolia and Vicia villosa were evaluated to determine their reaction to Meloidogyne javanica. Sesbania sesban and Tagetes minuta were included as susceptible and resistant checks respectively. In the glasshouse, pots were filled with steam-sterilized soil, sown with the green manure plant, and then infested with 4,000 eggs and juveniles of M. javanica. Field experiments were conducted in plots infested with a mixed population of M. javanica and M. incognita. Crotalaria juncea, D. uncinartum, G. sepium, L. leucocephala, M. pruriens, T. diversifolia and T. minuta had galling and eggmass indices lower than 2 and reduced nematode populations by up to 80%. Calliandra calothyrsus, C. quinoa and C. ensiformis had galling indices lower than 4 and eggmass indices less than 3.2. Vicia villosa and T. purpurea were susceptible with galling indices greater than 7 and nematode population buildup of up to 500%. Chenopodium quinoa, C. juncea, D. uncinartum, G. sepium, L. leucocephala, M. pruriens and T. diversifolia are suppressive to root-knot nematodes and can therefore be recommended as rotation, fallow or cover crops.

Narla, RD;, Muiru WM;, Olubayo FO;, Kimenju JW;, Kagiki MN;.  2007.  Efficacy Of Glyphosate 360sl On Weed Species Common In Vegetable Gardens With Different Types Of Weed Species.

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