PhD Graduands December 2020

Lepidopteran stemborers are still among the most important pests that are reported to cause maize yield losses in sub-Saharan Africa. In Kenya, they seriously limit potential maize yield.

Lepidopteran stemborers are still among the most important pests that are reported to cause maize yield losses in sub-Saharan Africa. In Kenya, they seriously limit potential maize yield. The recent invasion of the fall armyworm in the maize growing region of the country has further complicated the management of stemborer pests in maize fields. For proper management of maize pests, the knowledge of the behavioural and chemical ecology, eco-environmental factors and interaction among various pests species in the field is essential.

African nightshade (ANS) is known for high micronutrient content, medicinal properties and fast growth with low production costs. The challenges facing its production include low quality seed, low leaf/seed yields per hectare, pests and diseases, poor harvesting and processing methods. The objectives of this study were to evaluate the quality status of African nightshade seed, detect seed borne pathogens, identify the most prevalent viral pathogens and determine a suitable seed processing method for clean ANS seed production.

Banana is one of the major fruits produced in Kenya. However, its full potential is not fully exploited due to several constraints including high postharvest losses. The present study was conducted to assess the effectiveness of hexanal, a naturally occurring compound in prolonging the shelf-life of ‘Grand nain’ and ‘sweet banana’ varieties produced under two agro-ecological zones (AEZ) of Kenya.  Further, the study sought to validate the effect of hexanal treatments on the fruits’ postharvest quality and elucidate the molecular basis of its mode of action.

The Kenya annual coffee production has in recent years declined due to different factors such as change of land use and biotic stresses, despite the country being one of the world’s producers of high-quality coffee. This study analysed the agronomic potential of Arabusta hybrids developed from C. arabica and C. canephora for their bean yield, quality, and disease resistance.

The root rot disease complex has continued to be a major constraint in the production of common beans (Phaseolus vulgaris) resulting in losses of up to 70% in Kenya. The aim of this study was to establish (i) the occurrence and quantification of root rot fungal pathogens of common bean in Western Kenya and (ii) the effect of farming practices on the populations of the pathogens. A survey was conducted in Western Kenya’s LM1 LM2 UN1 and UM3 AEZ’s to obtain data on different farming practices and soil characteristics.