Abstract: Roads constructed on weak sub-grade clay soils with high plasticity may be affected by the behaviour of the clay soils. Weak sub-grade clay soils undergo volume change due to the changes in the moisture content which triggers cracking, settlement, heaving and damage of the road pavement by breaking up the pavement. Stabilizing these types of weak sub-grade clay soil is required to overcome the swelling of the clay soil and increase the soil strength and improve the performance. The...
Abstract: A study to determine the association of fertilizer with soil water deficit in tea [Camellia sinensis (L.) O. Kuntze] was conducted in a rain-out shelter using potted plants, in which five rates of fertilizer (0, 75, 150, 225 and 300 kg Nitrogen ha−1) and six levels of soil water content (38, 34, 30, 26, 22 and 18% v/v) were applied in a complete randomized design and replicated three times.The soil water treatment was maintained for a period of 12 weeks during which shoot growth,...
Abstract: Ocimum grattissimum L. (Labiatae) leaves are widely eaten as a vegetable in Nigeria, and in the eastern parts, are traditionally used in post-harvest protection and relieving stomach aches. The effect of the essential oil of O. grattissimum leaves on Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae) was assessed for repellency, mortality, progeny emergence and maize damage in the laboratory. The oil was found to be moderately repellent to the maize weevil and induced hig...
Abstract: Vegetable export production is a major source of income and contributes to the alleviation of poverty in Kenya. However, emerging....(continue from the attached pdf)
Abstract: Studies were conducted to assess the numerical response of grounddwelling arthropods to a habitat management system (‘push–pull’) developed to control maize stemborers using spiders (Araneae) as an indicator group. In this cropping system, maize is intercropped with a stemborer moth-repellent (push) plant while an attractant trap crop (pull) is planted around this intercrop. Two study sites in western Kenya and one site at the Grain Crops Institute of the Agricultural Researc...
Abstract: Push-pull strategies involve the behavioral manipulation of insect pests and their natural enemies via the integration of stimuli that act to make the protected resource unattractive or unsuitable to the pests (push) while luring them toward an attractive source (pull) from where the pests are subsequently removed. The push and pull components are generally nontoxic. Therefore, the strategies are usually integrated with methods for population reduction, preferably biological contro...
Abstract: Diamondback moth (Plutella xylostella) is a globally significant pest of Brassicaceae crops that has attracted enormous research investment. It is typical of many agricultural pests, with insecticides remaining the most common method of control, despite frequent cases of resistance in pest populations and the potential for other management options such as natural enemies to provide suppression. Here we review scope to make better use of neglected natural enemy taxa and integrate re...
Abstract: The Kenyan horticultural industry faces a new challenge following invasion by the quarantine Liriomyza leafminer species Liriomyza huidobrensis, Liriomyza sativae and Liriomyza trifolii which have recently become pests of economic importance. Controlling Liriomyza leafminers poses serious difficulties due to their biology and quarantine status. This paper examines farmers’ awareness of the pests and difficulties faced in controlling them. (1) A questionnaire survey showed that sn...
Abstract: Background and Objective: Brachiaria, a warm season C4 grass, is rapidly gaining popularity as fodder crop in Africa where it is also used as a component of a habitat management strategy for maize stem borers. However, increasing drought limits productivity of this grass species. The aim of this study was to evaluate and select high yielding brachiaria genotypes under simulated drought conditions. Materials and Methods: The morphological and physiological performance of 18 apomicti...
Abstract: 1 Field experiments were conducted on maize and sorghum at three locations in the Amhara state of Ethiopia to determine the effects of mixed cropping on stemborer infestation, borer natural enemies and grain yields. In the cool-wet ecozone of western Amhara, sole maize was compared with maize intercropped with faba bean, mustard, potatoes and cowpea. In the semi-arid ecozone of eastern Amhara, the trial was conducted on both maize and sorghum with the companion crops haricot bean, ...
Abstract: Thrips-transmitted Iris yellow spot virus (IYSV) (Family Tospoviridae, Genus Orthotospovirus) is a major constraint to onion (Allium cepa L.) production in Kenya. Determining seasonal patterns of the vector and alternate hosts of the virus could help onion farmers plan Integrated Pest Management strategies; while allowing them to move away from calendar-based applications of insecticides. The objective of this study was to determine the distribution, seasonal variations and alterna...
Abstract: Competitive or facilitative interactions characterise phytophagous insect ommunities that utilise the same resources. These interactions are often mediated by the host plant. Plant mediation influences the oviposition choices that a community of insects, sharing the same host plant make. In this context, the oviposition choices of females within a community of lepidopteran cereal stemborers namely Busseola fusca, Sesamia calamistis and Chilo partellus were studied in plant choice-e...
Abstract: Push–pull technology (PPT) simultaneously reduces the impact of three major production constraints, pests, weeds and poor soil, to cereal–livestock farming in Africa. In order to ascertain the social value of the technology and to make decisions about the trade-offs in the allocation of scarce resources in research, gross margin analysis and the Dynamic Research for Evaluation Management economic surplus model were applied to calculate and analyze the benefits of PPT for 568 ho...
Abstract: The witchweed, Striga hermonthica (Del.) Benth., is a major constraint to maize (Zea mays L.) and sorghum [Sorghum bicolor (L.) Moench] production in sub-Saharan Africa. Intercropping maize and sorghum with desmodium (Desmodium spp.) effectively controls Striga and enhances grain yields. Studies were thus conducted to assess the potential role of intercropping maize and sorghum with different food legumes for control of Striga. Seasonal Striga counts in the intercrops, other than g...
Abstract: Plants may defend themselves against herbivores via morphological traits, chemical traits, or a combination of both. Herbivores that overcome the defensive echanisms of a plant tend to specialize on this plant due to enhanced protection from natural enemies. Well-known examples of plants possessing a suite of defensive mechanisms are found in nightshades (Solanaceae), especially in the tomato genus Lycopersicon . The spider mite Tetranychus evansi Baker and Pritchard (Acari: Tetran...