Crop In Kenya Research Articles

Food Loss-Reducing Intervention Strategies for Potato Smallholders in Kenya—A Positive Business Case with Reduced Greenhouse Gas Emissions

This paper is focused on intervention scenarios for smallholder potato value chains in Kenya that improve yields, reduce losses, minimize greenhouse gas (GHG) emissions and increase economic performance and food security. For that, business models and GHG emission estimates are developed, based on the existing data, combined with relevancy and time-to-impact analysis using practical real-life information from stakeholders in the potato sector, which is the second largest agricultural crop in Kenya after maize. The results show that profitability, environmental improvement and food security can go hand in hand with realistic short-term interventions for potato production at smallholder farms.

Integrated Management of Phthorimaea operculella (Zeller) Infesting Solanum tuberosum L. in Storage in MT Elgon Region, Kenya

The production of potato, a second major staple food crop in Kenya is being constrained by an insect pest potato tuber moth (PTM), Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae). The present study investigated two Integrated Pest Management techniques which would reduce (PTM) population in potato storage, four potato cultivars and two botanical quantities were used in storage in Mt Elgon region of Western Kenya. The insecticidal efficacy of Lantana camara L. and Azandiracta indica A. Jusss (Sapindales: Meliaceae) and in storage at Kapsokwony and Chemoremo villages were investigated in the present study years. In each of the studied site the experiment was laid down in randomized block Design (RBD) in a split plot arrangement at room temperature of 27 ± 2. Four cultivars (Tigoni, Sherekea, Mayan gold and Asante) were the first factor and treatments (L. camara and A. indica leaves powder and control) as the second factor, each of which was repeated three. The room was partitioned at the center into two (3m x3m) using a PVC sheet to separate two portions for the two botanical and to prevented insect migration. We set up 4 caring bags per cultivar per botanical. We placed 2 kg PTM-free tubers per each cultivar in one caring bag hence 4 caring bags/split/ cultivar and 16 caring bags / block, therefore the total number of caring bags was (4 x 4)= 16 bags per cultivar hence (16 x 4) = 64 caring bags/ botanical. The splits had four 2kg caring bags hence (2x4) = 8 kg per split and (8x16) = 32kg/cultivar hence N =128kg. The caring bags were covered with a layer of the botanicals at a rate 100g, 150g, 200g, and untreated control respectively. Twenty (10♀ + 10♂) newly emerged moths were introduced inside the storage. We assessed for week one number of tubers infested and tunnels of PTM larvae, at week two for number of tubers infested and tunneling length. Week three number of tubers infested, tunneling length in tubers and number of second generation larva. Analysis was done by comparison of the means and there mean differences using R software. Results indicated use of 200g/ 2kg of the botanicals significantly reduced number of PTM larvae. Lantana camara was the most effective insecticide followed by Azadrachta indica compared to the controlled tubers. Thus the use of 200g of L. camara and Tigoni cultivar may be promising components of IPM strategies for reducing P. operculella population in potato fields and storage.

English

Although tomato is the leading vegetable crop in Kenya, not much work has been done to develop improved tomato varieties with farmer preferred and market demanded traits. This study aims to characterize ten tomato genotypes for morphological and agronomic traits and to identify potential parental lines for use in the breeding program. The experiments were conducted in Kenya during the 2017 long and short rain seasons. Trials were laid out in a randomized complete block design with three replicates. Study materials were AVTO1429, AVTO1424, AVTO1314 from World Vegetable Center, four commercial varieties namely; Riogrande, Cal J, Roma VF, UC82 and three farmer selections namely; Valoria, Danny and Eden select. Genotype effects, genotype x environment interactions and location effects for days to flowering, plant height, maturity, fruit yield and related traits were highly significant (P<0.01). Duration of flowering varied from 36 to 42 days; plant height from 66.37 to 182.57cm, duration to maturity from 85 to 100 days, and fruit yield from 18.3 to 55.7 t ha-1. All the genotypes showed a determinate growth habit except AVTO1314 which had indeterminate growth habit. Genotype AVTO1429, AVTO1424 and AVTO1314 had green stem while commercial varieties and farmers’ selection had purple stem. The high genetic variation observed among the test genotypes for the traits evaluated can be exploited in developing the tomato breeding program. Key words: Tomato, accessions, characterization, flowering, morphological traits, agronomic traits.

English

Sorghum is an important staple food crop in Kenya, but its yield is low due to many constraints which include diseases, drought, soil fertility, and pests, notably parasitic weed Striga hermonthica. Twenty elite sorghum genotypes and one resistant check were evaluated in three replications in a complete randomized design in Agar Gel (AG) experiment and randomized complete block design on selected Striga hotspot farms at Kadel and Nyahera in western Kenya. Significant differences (p<0.001) were realized both in the fields (plant height, dry shoot biomass yield, grain yield, field Striga count, and Striga damage ratings) and in the AG experiment with respect to maximum germination distance and numbers of induced germinated Striga seeds. Among the sorghum genotypes evaluated under field conditions, T53B, N57, N68, C26, IESV 92036-SH, T30B, and Uyoma 47 White genotypes had stable yields under Striga infestation in the two sites, whereas Nyadundo 1, Nyadundo 2, and Uyoma 8 were susceptible. In the AG experiment, E117B, T30B, Uyoma 8, Uyoma 42 STR, and T53B induced high numbers of germinated Striga seeds with maximum germination distances (MGD). In contrast, Uyoma 47 Brown, IESV 92038/2-SH, and IESV 92036-SH sorghum genotypes secreted low amounts of SLS suggesting resistance. This study has identified and selected four Striga tolerant (T53B, N68, N57, and T 30B) and resistant (C 26, Uyoma 47 Brown, IESV 92038/2-SH, and IESV 92036-SH) sorghum genotypes which can be utilized in further research programs or adopted to improve sorghum productivity in the highly Striga infested regions of western Kenya. Key words: Striga, sorghum genotypes, resistant, susceptible, tolerant, Agar Gel experiment

Diversity of nematodes on banana (Musa spp.) in Kenya linked to altitude and with a focus on the pathogenicity of Pratylenchus goodeyi

Summary Bananas (Musa spp.) are considered the most important fruit crop in Kenya, grown mostly by smallholder farmers. However, in the past two decades production has declined and has largely been attributed to plant pathogens, including plant-parasitic nematodes. To assess the understanding and awareness that banana farmers have of nematodes, a survey was conducted. The incidence, abundance and distribution of nematodes in relation to altitude were determined for different banana types on 180 farms and the pathogenicity of Pratylenchus goodeyi, originating from three different altitudinal locations, was compared on two banana cultivars. Just 2.3% of farmers were aware of nematode damage and symptoms, none of whom applied any management measures. The highest abundance of nematodes was recorded at an altitude range of 1601-2000 m a.s.l., with Pratylenchus, Meloidogyne and Helicotylenchus being the predominant genera. Across all altitudinal locations, cooking banana had higher densities of nematodes than dessert bananas. In pots, P. goodeyi populations from Embu (1300 m a.s.l.) appeared more aggressive and with higher levels of multiplication than the population from Oyugis (1100 m a.s.l.). Cooking banana (‘Ng’ombe’) was more susceptible than dessert banana (‘Sukari Ndizi’). Nematode damage is more prominent in areas at higher altitude and on cooking banana cultivars. The findings provide key information in guiding informed and suitable management decision thresholds in relation to potential climate change.

In Vitro Efficacy of Native Entomopathogenic Fungi Against Western Flower Thrips Frankliniella Occidentalis (Pergande) of Tomato in Kenya

Tomato Solanum lycopersicum L. is an important crop in Kenya. Arthropod pests are major constraints to its production and farmers rely heavily on synthetic chemicals for control, which increases costs and leads to pollution of the environment. The objective of this study was to evaluate the effectiveness of native Kenyan fungi in managing thrips as an alternative to synthetic pesticides. In vitro studies were conducted to evaluate the effectiveness of native fungi against Frankliniella occidentalis collected from the tomato fields and maintained in the laboratory. The fungi were isolated from soil samples from tomato fields and identified based on their vegetative and reproductive structures. Treatments included fungal isolates and a control; replicated four times arranged in a completely randomized design. The effect of the fungal isolates on F. occidentalis was evaluated by treating thrips with concentrations of 1.0 x107conidia ml-1. Data on mortality of F. occidentalis was recorded daily for 10 days after treatment. Data on mortality of thrips was subjected to Analysis of Variance (ANOVA) using SAS software version 9.4 to test the effect of different treatments. Means were separated using Student Newman-Keuls test at P≤0.05. Gliocladium virens, Trichoderma virens, Fusarium solani, Fusarium oxysporum and Trichoderma afroharzianum were more virulent causing mortalities above 50%. Gliocladium virens was the most potent, causing 62.2% mortality in adults and 43.8% in nymphs at 1.0 x107 conidia ml-1. The findings showed that G. virens is a potential candidate for development as a fungal-based bio-pesticide against F. occidentalis on tomato.

Influence of Rhizobium Inoculation and Phosphate Rock Fertilizer Application on Growth and Yield Components of Green gram (Vigna radiata) in Tharaka-Nithi County, Kenya

Green gram is an important drought tolerant grain legume crop in Kenya. In Tharaka Nithi County green gram is as a major source of food security. Hence, there is need for a cheap and sustainable system of agricultural production is needed to increase its production. The legume/Rhizobium symbiosis in combination with phosphate rock offers a natural system for improving green gram nitrogen fixation. Therefore, this study was aimed at determining the effect of Rhizobium and phosphate rock fertilizer application on growth and yield attributes of N26 and KS20 varieties. The study was carried out at Chuka University Horticultural Research Farm for two seasons, November 2019 to January 2020 and February to April 2020. Factorial experiment of 2x2x2 was laid out in a Randomized Complete Block Design (RCBD). There were three factors, variety (N26 and KS20), phosphate rock (0 and 30 kg P ha-1) and Rhizobium MEA 716 (0 and 100 g ha-1). The experiment contained eight treatments which were replicated three times. The data was collected fortnightly on four randomly selected plants on parameters such as plant height, number of leaves, branches, pods, total dry biomass, shoot and root dry weight and grain yield. These data was analysed using Statistical Analysis Software (SAS). Significant means are separated using Least Significant Difference (LSD) at probability level of 5%. Results for both seasons indicated that combined application of Rhizobium MEA 716 Rhizobium 100 g ha-1 and phosphate rock 30 Kg ha-1 phosphate under variety in treatment (R1P1V2) showed significantly (P<0.05) higher plant height (76.07 cm), number of branches (14.08 plant-1), shoot dry biomass (52.01 g plant-1), root dry biomass (7.60 g plant-1), total dry biomass (146.4 g plant-1), number of pods (84 plant-1) and yield (2158 kg ha-1) compared to variety N26 in treatment (R1P1V1). Therefore, combination of Rhizobium MEA 716 100 g ha-1 and phosphate rock 30 Kg ha-1 under variety KS20 led to improved growth attributes equally yield components of KS20 variety over N26. From these findings, application of Rhizobium MEA716 at 100 g ha-1, and 30 Kg ha -1 phosphate rock under variety KS20 was recommended for improved and a sustainable green gram production in the study area.

English

Although tea is the leading cash crop in Kenya, the industry faces significant challenges. Although application of blue ocean strategy (BOS) could redress some of its problems, few studies have explored the question. This study investigated the relationship between BOS and sustainable performance of the Kenyan tea industry. The study applied the Four Action Framework (FAF) together with elements of Six Searching Paths-Frameworks (SSPF). The strategies resulting from SSPF were fashioned into the FAF, and validated by employees of tea estates in Nandi County.  The sample consisted of 240 workers, selected from a target population of 1150, by stratified random sampling. The study found that all predictors in the regression model, eliminate (β=0.291), reduce (β=0.314), raise (β= 0.435), and create factors (β=0.344) had a significant and positive effect on sustainable performance. Thus, implementation of the four factors could lead to sustainable performance of Kenya’s tea industry. The study concluded that branding tea, adding value to it, increasing domestic consumption, productivity and eliminating long and inefficient supply chain would lead to sustainable performance.  The study recommends that the tea industry should add value and brand its tea.   Key words: Tea, blue ocean strategy (BOS), red ocean strategy (ROS), sustainable performance.

Prevalence and Phylogenetic Diversity of Pathogenic Fusarium Species in Genotypes of Wheat Seeds in Three Rift Valley Regions, Kenya

Wheat is a source of nutrients for around 40% world’s population and the second most important cereal crop in Kenya. However, Fusarium head blight (FHB) hinders sustainable sufficient production of the crop, causing both economic and health losses. With the emerging unfavorable climatic changes, effective disease management strategies and adequate seed system are necessary to meet the deficiency. Current information on prevalence of the causative pathogens in varieties of wheat genotypes is a critical prerequisite to such strategies. This study aimed at determining the prevalence of pathogenic Fusarium species in seeds of developed varieties of wheat genotypes in three major wheat-producing regions in Kenya. A total of 260 samples of 18 wheat genotypes from 123 farms were collected. Peptone pentachloronitrobenze agar was used for fungal isolation, while identification of Fusarium spp. was based on the gene encoding translation elongation factor 1-α (tef1-alpha) sequence analysis. Fusarium spp. isolated include Fusarium poae, F. tricinctum, F. heterosporum, F. culmorum, F. equiseti, Fusarium sp., F. verticillioides, and F. oxysporum. There was no significant difference in prevalence of Fusarium spp. pathogens among the three regions studied. Fusarium spp. diversity index for Nakuru was 2.008, Narok was 1.4603, and Uasin Gishu was 1.2337. Wheat produce from farm-saved seeds yielded 66.25% of the isolates, while the produce from certified commercial wheat seeds yielded 33.75% of the isolates. The significant finding of the study is that Fusarium spp. associated with mycotoxins that contaminate the wheat food chain seem to be flourishing in all the sampled wheat seed genotypes from the regions studied. Information on the prevalence and diversity of the pathogens on persistence of the disease in the crop is critical in advancing integrative FHB control measures.

First Report of Peanut Stripe Virus Infecting Groundnut (<i>Arachis hypogaea</i> L.) in Western Kenya

Peanut (<i>Arachis hypogaea</i>) is a leguminous food crop in Kenya, whose yields are probably affected by Peanut stripe virus (PStV) belonging to the genus Potyvirus and family <i>Potyviridae,</i> that causes Peanut stripe disease (PSD), also referred to as groundnut stripe disease (GSD). PSD/GSD is rapidly spread through seed and mechanically transmitted in a non-persistent manner by aphid vectors causing 30-100% decrease in production. Different isolates of PStV induce different symptoms in groundnut ranging from striping, ring spots, vein banding and oakleaf mosaic. PStV occurrence in Kenya has neither been reported nor its resistance identified in commercial cultivars of groundnut in research stations. This informs the need for resistance breeding programmes of wild genotypes to be explored as the only practical solution. This study reports the first occurrence, distribution and molecular detection of PStV infecting groundnut in western Kenya, which is crucial in developing appropriate crop protection and plant health management strategies for this new disease. A survey of PSD was conducted in western Kenya among the four counties of Bungoma, Busia, Kisumu and Kisii during the short rains season of 2019. A total of 14 symptomatic leaf samples were selected from the collected samples and preserved until use. Total RNA was extracted from the symptomatic leaf samples using GeneJET Plant RNA Purification Mini Kit according to the manufacturers’ protocol. Two-step RT-PCR detection of PStV was done using specific primers that yielded the expected 454 bp. DNA libraries were prepared and sequenced using the Sanger sequencing platform, but produced poor quality sequences after performing sequence quality check using BioEdit workbench that based on the low quality peaks of the electropherograms generated, therefore recommend for further research. To our knowledge, this is the first report of the occurrence, distribution and molecular diagnostics of PStV in Kenya. Further studies are needed to assess the molecular and biological diversity of PStV strains, the spatial distribution and the incidence of this emerging groundnut disease in Kenya.

Farmer Knowledge in Potato Virus Epidemiology and Control in Kenya

Potato is an important food security crop in Kenya. High prevalence of potato viruses is one of the major causes of low potato yields. Implementation of effective virus management strategies requires information on farmers’ perceptions and practices on virus epidemiology and control. To better understand farmers’ knowledge and practices in virus control and set possible pathways for intervention, a household survey involving 147 respondents was conducted in two major potato-growing regions in Kenya. Lack of sufficient technical information on potato virus symptoms, vectors and modes of transmission was found to be the major hindrance to farmers’ efforts towards virus control. A spider diagram approach was therefore used to determine the aspect of virus control that required the highest prioritization for immediate intervention by policy makers. Use of virus-resistant cultivars was found to require the most urgent attention compared to other aspects of virus control and was expected to have greater impact in lowering virus prevalence. This study showed that enhancing farmer knowledge needs to be prioritised as this is a key determinant of the success of the virus control strategy to be selected for implementation.

Assessment of National Performance Trials of Potatoes in Mid-Altitude Regions of Kenya

Potato is the second most important food crop in Kenya after maize. It is a valuable cash and food crop mainly grown by small-scale farmers. Potato is cultivated mainly under rainfed production conditions at altitudes between 1500 and 3000 metre above sea level (masl). Consequently, National Performance Trials (NPTs) test sites are located in these highlands. Recently, potato production has spread to the mid-highlands (1200-1500masl) mostly due to high food demand occasioned by population increase, and migration of small scale farmers from the densely populated highlands to the more spacious midlands. Consequently, there is increased need to breed potato varieties that can grow profitably in the warmer mid-altitudes. This development called for identification of new conventional NPT test sites located in the mid-altitudes. Six mid-altitude sites were identified and client-managed conventional NPTs carried out. Twenty six potato genotypes were evaluated for two seasons. First season crop was planted in 2016 while the second season crop was planted in 2017. There was a significant (p≤ 0.001) effect of genotypes, environments and genotype x environment interaction in the first season. Trans-Nzoia was the highest yielding site. All genotypes yielded between 10 and 25 ton/ha. In the second season, only environments showed significant (p≤ 0.001) effects. Again, Trans-Nzoia was the highest yielding site. Across the two seasons, Trans-Nzoia gave an average yield of 26.96 ton/ha followed by Kabete at 18. 21ton/ha. All the other four sites yielded less than 10 ton/ha. The high yields at Trans-Nzoia and Kabete could be due to higher altitudes in these two sites compared to the others. In order to develop potato varieties that can produce profitably in the warm mid-altitudes, breeding and early generation selections activities should be based in these areas.

Is It Formal or Informal? Choice of Market Outlets for Unprocessed Tea in Nandi County, Kenya

The tea industry plays a key role in the agriculture sector and the economy at large with tea output contributing about 11% of the agriculture sector’s contribution to Gross Domestic Product. Like many other crops in Kenya, tea is produced both on small and large-scale basis. Smallholder farmers in Kenya make a significant contribution to the industry producing 61% of the total national production and with 66% of tea acreage. Formal market outlets are more profitable than informal ones. However, small tea agri enterprises in Nandi County prefer selling their unprocessed tea to informal market outlets. Empirical evidence on what motivates these agri-enterprises to sell most of their tea to these outlets is scanty. The main objective of this study was to compare the profitability of formal and informal market outlets for unprocessed tea in Nandi County. Multistage sampling procedure was employed and 384 respondents interviewed using semi-structured questionnaire. Data were analysed using gross margin analysis. Formal market outlets are more beneficial because of higher gross margin rate of 12.71% compared to informal market outlets having the gross margin rate of 1.08%.The findings are helpful in guiding smallholder tea farmers in information on the most profitable and efficient market outlets and informing policy makers on how to improve the efficiency of market outlets. DOI: 10.7176/JESD/11-22-10 Publication date: November 30 th 2020

English

Diversity assessment of vanilla (Vanilla species) in Kenya is a key strategy for germplasm conservation and improvement. Production of vanilla crop in Kenya is limited due to inadequate knowledge on genetic diversity. This study was carried out to characterize 76 vanilla accessions from five counties of Kenya using 14 microsatellite DNA markers. POPGENE version 1.32 was used to compute variety factors. Amplicons ranged between 1 and 4. A total of 27 (96.43%) alleles were observed and their number ranged from 1.00 to 2.00 with a mean of 1.93. Effective allele values ranged from 1.00 to 1.99 with a mean of 1.63. Gene diversity ranged from 0 to 0.50 with a mean of 0.35, mean Shannon information index was 0.50 and Polymorphic information content values ranged from 0 to 0.38 with a mean of 0.35. Jaccard’s similarity coefficient ranged from 0.08 to 1.00 with an average of 0.54. Unrooted phylogenetic tree was constructed in DARwin 6.0.8 using Unweighted Pair Group Method with Arithmetic Mean, clustering the samples into 3 main clusters (A 99.6%, B 98.96% and C 100%) and 6 sub-clusters (A1, A2, B1, B2, B3 and C1). Vanilla accessions grown in Kenya have a broad genetic background but low genetic diversity. Results inform the need to introduce other vanilla species as sources of genetic variation for breeding. Key words: Genetic variation, DNA markers, breeding, Kenya.

English

French bean (Phaseolus vulgaris L.) is a major export crop in Kenya where it serves as a cash crop for smallholder farmers and a source of employment. However, there is limited information on characterization of available germplasm which is essential in genetic improvement of this crop. The present study was therefore aimed to identify the gene pool affiliations of Kenyan French bean germplasm using specific molecular markers in order to understand the available germplasm for future use in breeding programs. The germplasm panel consisted of 46 accessions, comprising 40 French bean and six dry bean genotypes. The accessions were characterized using four gel-based molecular markers: SHP1-A, SHP1-B, SHP1-C and phaseolin protein marker. The most informative marker was the phaseolin protein marker which indicated that 82% of the French bean genotypes are of Andean origin, while 18% are of the Mesoamerican origin. Low polymorphism was observed for the SHP1 markers and the data from the three SHP1 markers did not correspond to the phaseolin protein marker for the French bean germplasm although SHP1-A and SHP1-B were able to differentiate the Andean from the Mesoamerican differential cultivars. The information on the gene pool affiliations of Kenyan French bean accessions is important for breeders to harness the divergence between the two gene pools in order to broaden the genetic base of the crop. &nbsp; Key words: Gene pool, phaseolin protein, shatterproof, molecular markers, French beans.

Seed Borne Fungal and Bacteria Pathogens Associated with Farmer-Stored Sorghum Seeds from Eastern, Coast and Nyanza Regions in Kenya

Sorghum ( Sorghum bicolor (L.) Moench) is an important cereal crop in Kenya. Access to good quality seeds is one of the constraints facing the small scale farmers in key areas growing sorghum. Good quality seed is an important factor for maintaining plant population and increasing crop yield to attain food security. One of the important aspects of good seed, besides high germination and purity is the absence of seed borne pathogens. In the present study, an experiment was carried out to identify fungal and bacterial pathogens associated with farmer-stored seeds of sorghum. The seeds were collected from farmers in Nyanza, Coast and Eastern regions, Kenya. The seeds were washed with sterile distilled water and sterilized in 1% Sodium hypochloride for 5 minutes, rinsed with sterile distilled water and dried using a blotting paper. The dried seeds were placed onto prepared Potato Dextrose Agar (PDA) and macerated seeds streaked on nutrient Agar (NA) on sterile Petri dishes and incubated at 23±2 0 C. The growing pathogens were sub-cultured on new media to make pure cultures. A segment of mycelia from the sporulating colonies in each pure culture was examined under a compound microscope and identified based on their morphology, colour and mycelia growth characteristics for fungi while bacterial identification was done using colony color and morphology on nutrient agar and biochemical tests. Ten fungal pathogens and one bacterium were identified growing on the sorghum seed samples. These were Acremonium spp ., Alternaria spp ., Aspergilus niger, Bipolaris cookie, Collectotrichum graminicola, Fusarium moniliforme, Fusarium solani, Fusarium ventrichosum, Phythium aphanidermatum, Rhizoctonia spp. and a bacterium Xanthomonas spp. It was observed that majority (32%) of the seed samples from Coast region were infected with bacteria Xanthomonas spp. Phythium. aphanidermatum was the most prevalent fungal pathogen detected on seed samples from Nyanza region with about 20% prevalence. Results showed that majority of the seed samples from all the regions were contaminated with various pathogens. This study highlights the need to create awareness to farmers on the use of proper production practices, storage facilities and conditions to improve the quality of stored sorghum seeds. Keywords : farmer-stored seeds, seed-borne pathogens, sorghum DOI: 10.7176/JBAH/10-18-06 Publication date: September 30 th 2020

Evaluation of Irrigation Water Resources Availability and Climate Change Impacts—A Case Study of Mwea Irrigation Scheme, Kenya

Rice is an important cereal crop in Kenya, where it is mainly grown in the Mwea Irrigation Scheme, MIS. The serious challenges of MIS include low water use efficiency and limited available water resources. The objective of this study is to analyze the current and future irrigation water resource availability for the improvement of future water management. A Soil Water Assessment Tool (SWAT), a public domain software supported by the United States Department of Agriculture’s Agricultural Research Service in Bushland, TX, USA, was used to estimate the current and future water resources availability from the MIS’s main irrigation water supply sources (River Thiba and River Nyamindi). CropWat, a computer program developed by the Land and Water Division of the Food and Agriculture Organization (FAO), Rome, Italy, was used to estimate irrigation water requirements from 2013–2016 and into the future (2020–2060 and 2061–2099). Future climatic data for total available flow and irrigation requirement estimations were downloaded from three General Circulation Models (GCMs). The data was bias corrected and down-scaled (with observed data) using a Climate Change Toolkit, a toolkit for climate change analysis developed by the Water Weather and Energy Ecosystem, Zurich, Switzerland. The results indicated that the highest irrigation water deficits were experienced in July and August based on the existing cropping pattern. Under a proposed future pattern, estimates show that MIS will experience water deficits mainly from June to October and from January to February. This study recommends that MIS management should put into strong consideration the simulated future estimates in irrigation water availability for the improvement of water management.

Influence of Spiral Nematodes (Scutellonema spp.) on Maize Performance and Growth under Natural Field Infestation in Mwea, Kenya

Maize (Zea mays L.) is a significant food security crop in Kenya and it serves as the main source of nutrition and calories among the small-holder farmers. The overall maize yields per hectare have been fluctuating in the past few years posing a great risk to food security. Among the stress factors associated with maize yield loss include plant-feeding nematodes. In this regard, this study was conducted to evaluate the impacts of plant-parasitic nematodes specifically Scutellonema spp. under field conditions on maize performance in Mwea, Kenya. The field trials were laid out in a randomized complete block design with each treatment comprising of four replicates. The treatments included maize plots without nematicide (MPWN) and control plots treated with nematicide. The experiments were conducted in two trials. Soil samples were taken at a 0–20 cm depth at monthly intervals during 2018–2019. During the two trials, MPWN recorded significantly lower plant height and number of leaves per plant. Correlation analysis revealed a significant negative relationship between Scutellonema abundance with leaf area index, plant height, and number of functional leaves in MPWN during the 2019 trial. This implies that high population of Scutellonema perhaps has the potential to affect leaf area index, plant height, number of leaves per plant, which are aspects that in turn influence maize productivity. Therefore, holistic sustainable management practices to control Scutellonema spp. in maize fields such as use of organic amendments, resistant maize cultivars, and antagonistic organisms are crucial in order to alleviate negative impacts linked to Scutellonema infestation.

Nematode metabolic footprints, ecological and functional indices in tropical maize-beans agro-ecosystems under different farming practices

Maize and beans contribute significantly to food security in Kenya. Farming practices used in production of these crops may affect nematode community assemblages and influence agricultural productivity. Information on response of nematofauna, particularly free-living nematodes, under various agronomic practices in Kenyan maize-beans intercrop is scarce. This study reports on the effects of farming practices on nematode community dynamics, ecological and functional indices, nematode metabolic footprints, and predator-prey relationship in maize-beans cropping systems in Mwea, Kenya. The field trials were set up in two seasons in a randomized complete block design with each treatment consisting of four replicates. The treatments included cow manure plus chemical fertilizer (CmDCF), cow manure plus wood ash (CmWa), cow manure combined with wood ash plus fertilizers (CmWaF), chemical fertilizers only (DNF) and unamended controls. Soil samples were collected at 0–20 cm depth at bimonthly intervals during 2018–2019. During the two seasons, 54 nematode genera were identified. Cephalobus, and Heterocephalobus (bacterivores), Labronema (omnivore) and Nygolaimus (predator) were abundant in CmDCF, CmWa, CmWaF, and DNF while Aphelenchus and Aphelenchoides (fungivores) were dominant in all treatments. Principal response curve analysis showed that CmWaF significantly reduced the population of Helicotylenchus, Scutellonema and Rotylenchulus during the 2nd and 4th month in the second season. Renyi diversity analysis indicated that CmWaF had higher diversity of omnivores while functional metabolic footprints categorized it as structured in both seasons. Predator-prey analysis suggested that CmWa and CmWaF have the potential to provide suitable conditions for predators, target prey and amplifiable prey biomass. This study provides an insight on the implication of farming practices, on nematode abundance and soil food web in two economically important crops in Kenya. It also provides a basis for exploring the potential role of organic amendments containing cow manure in control of plant parasitic nematodes in maize-beans cropping systems.

False codling moth, Thaumatotibia leucotreta (Meyrick) a new threat to horticulture industry: Stakeholders’ perspectives on the status, impact and management in Kenya

False codling moth (FCM) has emerged as a major constraint to the production of horticultural crops in Kenya and is currently the leading cause of interceptions of Capsicum and cut flowers exported to European Union. Use of pesticides to control this pest is not only unsustainable, uneconomical but also contributes to interceptions of export produce due to higher levels of pesticide residues in the produce. Further, due to cryptic nature of feeding by the pest, pesticides often do not result to efficient control. Growing crops under protected areas though effective is not affordable to smallholder resource poor farmers necessitating search for a holistic integrated approach to manage this pest. In order to gather baseline information about the pest and current practices being used to manage the pest, a national deliberative stakeholders’ workshop was held in August 2018 at Kenya Agricultural and Livestock Research Organization, Katumani, Machakos bringing together farmer organizations, research scientists, agricultural extension service providers, regulators, policy makers and farmers and followup national meetings and trainings to advance the workshop deliberations. The paper presents perspectives of different stakeholders on the status and impact of FCM in horticultural crops in Kenya.