Browsing by Author "Muturi, Jamleck"
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Item Effects of biocontrol bacteria and earthworms on the severity of Alternaria brassicae disease and the growth of oilseed rape plants(Elsevier, 2017-04) Ayukea, F. O.; Lagerlöfa, J.; Jorgea, G.; Söderlunda, S.; Muturi, Jamleck; Saroshe, B. R.; Meijere, J.Biological control of plant diseases through the addition of microbial biocontrol agents and the promotion of earthworms can be an environmentally friendly alternative to the chemical control of plant diseases. However, possible risks with biocontrol agents and their interactions with earthworms and other soil biota have not been well studied. The aim of this study was to assess whether the beneficial bacterium Bacillus amyloliquefaciens and the earthworms Aporrectodea caliginosa or Aporrectodea longa could reduce disease in oilseed rape (Brassica napus) challenged with the pathogen Alternaria brassicae. Plant growth and productivity were measured as plant survival, height, biomass, and flower development as well as disease index. A second objective was to assess whether the presence of the bacterium at high concentrations would influence the survival, growth, and reproduction of the earthworms. One outdoor and one greenhouse experiment were performed with Br. napus plants challenged with Al. brassicae inoculated to the plant leaves in the presence or absence of Bacillus amyloliquefaciens inoculated to the root environment and in the presence or absence of earthworms (Ap. caliginosa or Ap. longa) added to the soil. All treatments were replicated three times. In the outdoor experiment, inoculation with Al. brassicae reduced the growth of plants and the addition of Ap. caliginosa increased plant height. In the greenhouse experiment, pairwise comparisons of plants challenged with Al. brassicae showed that treatment with B. amyloliquefaciens led to significantly lower disease index than the treatment with Ap. caliginosa plus B. amyloliquefaciens, while other treatments had intermediate disease indices. The addition of Al. brassicae or B. amyloliquefaciens increased the survival and mass increment of Ap. caliginosa as a main effect when used separately but not when used in combination. This study did not give any clear indication of the usefulness of B. amyloliquefaciens for biocontrol of plant pathogens such as Al. brassicae when growing plants in natural soil. In addition, no significantly positive effects from the tested earthworm species were seen.Item Performance Evaluation of Proximal Sensors for Soil Assessment in Smallholder Farms in Embu County, Kenya(MDPI, 2016-08) Piikki, Kristin; Söderström, Mats; Eriksson, Jan; Muturi, Jamleck; Muthee, Patrick I.; Wetterlind, Johanna; Lund, EricFour proximal soil sensors were tested at four smallholder farms in Embu County, Kenya: a portable X-ray fluorescence sensor (PXRF), a mobile phone application for soil color determination by photography, a dual-depth electromagnetic induction (EMI) sensor, and a LED-based soil optical reflectance sensor. Measurements were made at 32–43 locations at each site. Topsoil samples were analyzed for plant-available nutrients (N, P, K, Mg, Ca, S, B, Mn, Zn, Cu, and Fe), pH, total nitrogen (TN) and total carbon (TC), soil texture, cation exchange capacity (CEC), and exchangeable aluminum (Al). Multivariate prediction models of each of the lab-analyzed soil properties were parameterized for 576 sensor-variable combinations. Prediction models for K, N, Ca and S, B, Zn, Mn, Fe, TC, Al, and CEC met the setup criteria for functional, robust, and accurate models. The PXRF sensor was the sensor most often included in successful models. We concluded that the combination of a PXRF and a portable soil reflectance sensor is a promising combination of handheld soil sensors for the development of in situ soil assessments as a field-based alternative or complement to laboratory measurements.Item Performance Evaluation of Proximal Sensors for Soil Assessment in Smallholder Farms in Embu County, Kenya(MDPI, 2016) Muturi, Jamleck; Kristin, Piikki; Mats, Söderström; Eriksson, Jan; Muthee, Patrick I.; Wetterlind, Johanna; Lund, EricFour proximal soil sensors were tested at four smallholder farms in Embu County, Kenya: a portable X-ray fluorescence sensor (PXRF), a mobile phone application for soil color determination by photography, a dual-depth electromagnetic induction (EMI) sensor, and a LED-based soil optical reflectance sensor. Measurements were made at 32–43 locations at each site. Topsoil samples were analyzed for plant-available nutrients (N, P, K, Mg, Ca, S, B, Mn, Zn, Cu, and Fe), pH, total nitrogen (TN) and total carbon (TC), soil texture, cation exchange capacity (CEC), and exchangeable aluminum (Al). Multivariate prediction models of each of the lab-analyzed soil properties were parameterized for 576 sensor-variable combinations. Prediction models for K, N, Ca and S, B, Zn, Mn, Fe, TC, Al, and CEC met the setup criteria for functional, robust, and accurate models. The PXRF sensor was the sensor most often included in successful models. We concluded that the combination of a PXRF and a portable soil reflectance sensor is a promising combination of handheld soil sensors for the development of in situ soil assessments as a field-based alternative or complement to laboratory measurements.Item Short communication: Efficacy of two commercial disinfectants on Paenibacillus larvae spores(2021-03) Kiriamburi, Joseph; Muturi, Jamleck; Mugweru, Julius; Forsgren, Eva; Nilsson, AnnaPaenibacillus larvae is a spore-forming bacterium causing American foulbrood (AFB) in honey bee larvae. The remains of a diseased larva contains billions of extremely resilient P. larvae spores viable for decades. Burning clinically symptomatic colonies is widely considered the only workable strategy to prevent further spread of the disease, and the management practices used for decontamination requires high concentrations of chemicals or special equipment. The aim of this study was to test and compare the biocidal effect of two commercially available disinfectants, “Disinfection for beekeeping” and Virkon S on P. larvae. The two products were applied to P. larvae spores in suspension as well as inoculated on two common beehive materials, wood and styrofoam. “Disinfection for beekeeping” had a 100 % biocidal effect on P. larvae spores in suspension compared to 87.0-88.6 % for Virkon S which, however, had a significantly better effect on P. larvae on styrofoam. The two disinfectants had similar effect on infected wood material.Item Short Communication: Efficacy of Two Commercial Disinfectants on Paenibacillus larvae Spores(Frontiers, 2022-05) Kiriamburi, Joseph; Muturi, Jamleck; Mugweru, Julius; Forsgren, Eva; Nilsson, AnnaPaenibacillus larvae is a spore-forming bacterium causing American foulbrood (AFB) in honey bee larvae. The remains of a diseased larva contains billions of extremely resilient P. larvae spores viable for decades. Burning clinically symptomatic colonies is widely considered the only workable strategy to prevent further spread of the disease, and the management practices used for decontamination requires high concentrations of chemicals or special equipment. The aim of this study was to test and compare the biocidal effect of two commercially available disinfectants, “Disinfection for beekeeping” and Virkon S on P. larvae. The two products were applied to P. larvae spores in suspension as well as inoculated on two common beehive materials, wood and Styrofoam. “Disinfection for beekeeping” had a 100 % biocidal effect on P. larvae spores in suspension compared to 87.0–88.6% for Virkon S which, however, had a significantly better effect on P. larvae on Styrofoam. The two disinfectants had similar effect on infected wood material.Item Speech by Dr. Jamleck Muturi Representing Governor of Embu County on Book Donation Day at Embu University College(Embu University College, 2016-05) Muturi, JamleckSpeech made on behalf of His Excellency Hon. Martin Wambora, Governer Embu County during book donation Ceremony at Embu University College on 24th May 2016 at the Dining Hall.Item Tomato Leaf miner (Tuta absoluta) (Meyrick 1917) (Lepidoptera: Gelechiidae) prevalence and farmer management practices in Kirinyanga County, Kenya(Academic Journals, 2018-08) Nderitu, Peris Wangari; Muturi, Jamleck; Otieno, Mark; Arunga, Ester E.; Mattias, JonssonPest invasion is one of the limiting factors affecting food production. Tomato leaf miner (Tuta absoluta) (Meyrick 1917) (Lepidoptera: Gelechiidae), is an invasive insect pest of tomato. However, In Kenya, there is limited information on the level of invasion of the pest in tomato producing areas in the country. We assessed the level of invasion of T. absoluta and farmer management practices in Kirinyaga County. Tomato farmers were interviewed using questionnaires aimed at identifying the management practices used by farmers to control T. absoluta and their awareness on the insect pest. Two hundred and eight tomato farmers were interviewed, 90% of the respondents rated T. absoluta as a major pest of tomato. Results show that 94% of the respondents use synthetic chemicals in the control of T. absoluta with an average frequency of 12 times per growing season of three months with the highest frequency being 16 times. Increased use of synthetic insecticides was associated with a negative impact on the natural enemies. Among the interviewed farmers, 52 and 46% of respondents stated that after chemical spraying natural enemies disappear and are killed respectively, while 2% did not know what happened to them. It is therefore imperative to design an integrated pest management program that integrates biological control and environmentally friendly chemicals for sustainable control of T. absoluta populations.Item Trophic interactions among soil arthropods in contrasting land-use systems in Kenya, studied with stable isotopes(Elsevier, 2017-04) Lagerlöfa, Jan; Maribie, Crispus; Muturi, JamleckUnderstanding how land use intensification changes organism communities and trophic interactions in soil is important for development of sustainable agriculture and forestry. We analysed the food web of soil arthropods with help of natural 13C/12C and 15N/14N ratios (δ13C and δ15N) in two habitats in the Kenyan Highland – a natural forest and an agricultural site on former forest land. Aims of the study: (1) to describe the structure and feeding relationships in the two systems for major soil arthropod groups, (2) to find differences in feeding strategies within major arthropod groups, (3) to determine if soil arthropod groups have the same trophic positions in forest and agricultural soil, (4) to evaluate if δ13C and δ15N can be explained by additional reasons, e.g. the physiology and C:N ratios of organisms. This is one of few studies of the trophic structure of soil arthropod communities in tropical ecosystems. It confirms that the structure is similar to comparable systems in the temperate zones. There was a large variation in δ15N among families of Oribatida, Mesostigmata and Collembola (the most common groups) indicating great variety in feeding ecology. Collembola and Diplopoda had comparatively high δ15N, indicating a contribution of animals to the diet. Although lower abundance and diversity of arthropods in the agricultural soil, the trophic positions of particular taxa, indicated as δ15N level, were similar to the forest. The δ13C values were negatively correlated to the C:N ratio, therefore increasing values of δ13C with trophic level could not be demonstrated.