Bio

Dr. MUIRU WILLIAM MAINA

I am a Senior lecturer in the Department of Plant Science and Crop Protection, a position I have held since 2014. I obtained my PhD degree in Plant Pathology in 2008 from the University of Nairobi. I have been involved in teaching, research and outreach activities in crop protection. I am currently the head of the Plant Pathology Unit of the Department. I have also held other positions of responsibility in the department including coordination of examinations, coordination of students’ research projects for both Diploma and fourth years.

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Publications


2011

Muiru, WM, Koopmann B, Mutitu EW, Kimenju JW.  2011.  Production, purification and separation of phytotoxins from Exserohilum turcicum isolates of Kenyan, German and Austrian origin. Abstract

The study was carried out to compare production, purification and identity of phytotoxins from Exserohilum turcicum isolates of Kenyan, German and Austrian origin. Phytotoxins were extracted from maize leaves inoculated with the pathogen and liquid media seeded with the pathogen isolates. Detection of the phytotoxins was done by checking on inhibition of chlorophyll synthesis using the detached leaf bioassay technique. Thin layer chromatography, high performance liquid chromatography and sephadex columns were used to separate, purify and identify the phytotoxins. Of the 86 isolates used in the study, 48.3% were found to produce phytotoxins either in the liquid media or from the inoculated leaves. The study showed that, a number of phytotoxins including monocerin are produced as indicated by the several peaks and retention times. Maize plants inoculated with the pathogen produced more phytotoxins than the liquid media seeded with the pathogen and each of them had mean lesion sizes of26 mnr' and 14 mm'', respectively. E. turcicum has a high variability in production of different types and amounts of phytotoxins. Maize leaves inoculated with E. turcicum produce more phytotoxins and detached leaf bioassay is a reliable technique in the preliminary detection ofphytotoxins.

Mganga, KZ, Musimba NKR, Nyangito MM, Nyariki DM, Francis J, W A, Ekaya WN, Muiru WM, Clavel D, Verhagen J.  2011.  Technologie de réensemencement d'herbages graminacées comme moyen de réhabilitation des terres dégradées et d'amélioration des moyens de subsistance des communautés agro-pastorales dans la région semi-aride du Kenya. Abstract

La dégradation du sol constitue un problème majeur dans les zones semi-arides d'Afrique subsaharienne. La lutte contre cette dégradation du sol est capitale pour garantir une productivité durable et à long terme des terres semi-arides habitées. Le Cenchrus ciliaris (vulpin des prés africains), l'Enteropogon macrostachyus (seigle sauvage) et l'Eragrostis superba (Eragrostis Maasai) sont d'importantes graminées vivaces dans les zones semi-arides d'Afrique de l'Est. Une étude a été faite pour évaluer la contribution de ces herbages graminacées indigènes à l'amélioration des propriétés hydrologiques du sol, la réhabilitation, la sécurité alimentaire et les moyens de subsistance des communautés agro-pastorales dans les districts semi-arides du Kenya. Les propriétés hydrologiques du sol ont été testées à l'aide d'un simulateur Kamphorst, à diverses hauteurs de chaume, pour donner une image de trois différentes intensités de pâturage (faible, moyenne, élevée). L'estimation de la couverture végétale s'est faite à l'aide de la méthode d'échantillonnage step-point. Une étude a également été réalisée dans 50 ménages agro-pastoraux pour évaluer les avantages multidimensionnels des herbages graminacées. La production de sédiments (comme fonction d'écoulement et capacité d'infiltration) était considérablement différente (P<0,05) à diverses hauteurs de chaume. Les estimations de la couverture végétale des herbages graminacées étaient également considérablement différentes (P<0,05). Le Cenchrus ciliaris avait le plus grand impact en matière d'amélioration des propriétés hydrologiques. L'Enteropogon macrostachyus et l'E. superba se classaient respectivement en deuxième et troisième positions. L'Enteropogon macrostachyus avait la plus grande couverture. Le Cenchrus ciliaris et l'E. superba se classaient respectivement en deuxième et troisième positions. Ces résultats étaient dus à la croissance et aux caractères morphologiques des herbages graminacées. En général, une augmentation de la hauteur de chaume augmente la capacité d'infiltration et réduit l'écoulement et la formation de sédiments. Les résultats de l'enquête réalisée auprès des ménages révèlent que les herbages graminacées constituent une source de revenus par le biais de la vente de foin, de graines de graminacées et de lait, ce qui participe également d'un régime équilibré. Les herbages graminacées constituent également une source bon marché de matériel pour la confection de toitures de chaume et d'aliments pour le bétail. (Résumé d'auteur)

2010

Muiru, WM, Koopmann B, Tiedemann AV, Mutitu EW, Kimenju JW.  2010.  Race Typing and Evaluation of Aggressiveness of Exserohilum turcicum Isolates of Kenyan, German and Austrian Origin. Abstract

Exserohilum turcicum the causal agent of northern corn leaf blight is a threat to corn production in many areas of the world. The pathogen has a high genetic variability in terms of virulence, genetic structure and several races have been reported. Diseased corn plants from Kenya, Germany and Austria were used to isolate the pathogen following the standard isolation procedures. Detached leaf technique using leaves of maize plants with (Ht0) genes for resistance were used to evaluate aggressiveness and the parameters assessed included incubation period, size of chlorotic and necrotic lesions, lesion density, area under disease progress curve (AUDPC) and rate of lesion expansion. Differential cultivars bearing Ht1, Ht2, Ht3, HtN and Ht0 resistance genes were used to perform race typing on 87 isolates under greenhouse conditions. Isolates from the three countries showed a great variation in aggressiveness with incubation periods ranging from 2 to 6 days, lesion size ranging from 1.81 mm2 to 57.04 mm2, rate of lesion expansion ranging from 0.29 mm2/day to 21.67 mm2/day and AUDPC ranging from 31.3 mm2 to 133.9 mm2. Twelve races namely 0,1,2,3,N,12,13,13N,3N,123,23,23N were identified from the three countries. Race 2 was the most common and had 27% frequency of occurrence followed by race 0 and 1 which had frequency occurrence of 22% and 12% respectively. There was no distinct correlation between the type of the race and its origin and different races scattered within the various countries. The high level of genetic variability may explain the occurrence of the disease in the different geographical localities and the ability of the pathogen to infect most of the germplasm including the resistant varieties

2009

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

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.

MAINA, MRMUIRUWILLIAM.  2009.  Isolation and screening of actinomycete isolates for antagonistic activity against plant pathogens. UoN research meeting. : Botswana Journal of Agriculture and Applied Sciences Abstract
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2008

MAINA, MRMUIRUWILLIAM.  2008.  Infectious structures and response of maize plants to invasion by Exserohilum turcicum in compatible and incompatible host pathogen systems. UoN research meeting. : Journal of Applied Biosciences Abstract
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MAINA, MRMUIRUWILLIAM.  2008.  Distribution of Turcicum leaf blight of maize in Kenya and cultural variability of its causal agent, Exserohilum turcicum. UoN research meeting. : J. Trop. Microbiol. Biotechnol Abstract
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MAINA, MRMUIRUWILLIAM.  2008.  Identification of selected actinomycete isolates and characterization of their antibiotic metabolites.. UoN research meeting. : Journal of Biological Sciences Abstract
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MAINA, MRMUIRUWILLIAM.  2008.  Evaluation of antibiotic metabolites from actinomycete isolates for the control of late blight of tomatoes under greenhouse conditions.. UoN research meeting. : Asian Journal of Plant Sciences Abstract
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MAINA, MRMUIRUWILLIAM.  2008.  Response of free living nematodes to treatments targeting plant parasitic nematodes in carnation. UoN research meeting. : Asian Journal of Plant Sciences Abstract
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MAINA, MRMUIRUWILLIAM.  2008.  A review of the Amplified Fragment Length Polymorphism (AFLP) technique in genotyping and DNA fingerprinting studies.. UoN research meeting. : Journal of Applied Abstract
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2007

MAINA, MRMUIRUWILLIAM.  2007.  Characterization of antibiotic metabolites from actinomycete isolates. UoN research meeting. : Botswana Journal of Agriculture and Applied Sciences Abstract
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MAINA, MRMUIRUWILLIAM.  2007.  Efficacy of Glyphosate 360SL on weed species common in vegetable gardens with different types of weed species. UoN research meeting. : Botswana Journal of Agriculture and Applied Sciences Abstract
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MAINA, MRMUIRUWILLIAM.  2007.  Use of repetitive extragenic palindromic, enterobacterial repetitive intergenic consensus and BOX sequences in fingerprinting Exserohilum turcicum isolates. UoN research meeting. : Botswana Journal of Agriculture and Applied Sciences Abstract
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MAINA, MRMUIRUWILLIAM.  2007.  Reaction of some Kenyan maize genotypes to Turcicum leaf blight under greenhouse and field conditions.. UoN research meeting. : Asian Journal of Plant Sciences Abstract
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2006

MAINA, MRMUIRUWILLIAM.  2006.  Reaction of maize genotypes to northern leaf blight under controlled and field conditions. UoN research meeting. : Botswana Journal of Agriculture and Applied Sciences Abstract
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2005

2003

MAINA, MRMUIRUWILLIAM.  2003.  Field management of late light of tomatoes caused by Phytopthora infestans using antibiotics from Streptomyces spp. UoN research meeting. : Botswana Journal of Agriculture and Applied Sciences Abstract
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