Browsing by Author "Mutisya, D.L."
Now showing 1 - 2 of 2
- Results Per Page
- Sort Options
Item Effect of Agro-Ecological Zones on Predacious Mites (Acari: Phytoseiidae) and Pest Mite Eutetranychus africanus (Acari: Tetranychidae) Populations in Citrus Orchards of Kenya(Persian Journal of Acarology, 2022-07-15) Kiptoo, J.J.; Mutisya, D.L.; Ndegwa, P.N.; Irungu, L.; Godfrey, R.; Oduor, G.R.; Kiptoo, G.J.; University of Nairobi ; Kenya Agricultural and Livestock Research Organization ; Machakos University ; Masinde Muliro University of Science & Technology ; CABI ; Egerton UniversityPhytoseiidae mites' survival and reproduction depend on optimal environmental factors. A total of five different agroecological zones (AEZs) were surveyed twice each year from 2017 to 2019 in Kenya. In Eastern Kenya sample farms were small scale citrus orchards in the counties of Machakos [Low Midlands-Four (LM4)] and Makueni [Upper Midlands-Three (LM3)]. In the Coastal Lowlands-Four (CL4) similar small-scale citrus plots were sampled in Kwale, while in the highland Rift Valley region sample sites were ADC-Suam orchards of Kitale of the Lower Highlands-Two (LH2), where the large-scale farms were under citrus crop culture. The fifth site sampled was Baringo area of the Low Midlands-Five (LM5) where small plot citrus crop dominated the sample sites. Out of 68 fields of repeat surveys, 40% of citrus plots yielded varied diversity of phytoseiid mites. The major pest from the sites was citrus brown mite, Eutetranychus africanus. In this study, population fluctuation of phytoseiid mites was observed under different climatic conditions of temperature, relative humidity, dew-point and citrus plant age (in years). On the major pest E. africanus, three factors were evaluated for correlation and significance to infestation levels on the citrus crop. Of the three evaluated factors of temperature, citrus tree age and phytoseiid density in the orchards, temperature parameter did not significantly influence the pest mite (E. africanus) infestation levels for all combined AEZs factors. In the present case studies of specific AEZs, older trees led to higher pest mite density while low phytoseiid numbers correlated inversely to higher E. africanus infestation levels on the citrus trees. The information here could be used proactively to plan for management of E. africanus as the major pest in citrus orchards in specific agro-ecological zones.Item Enhancing Sorghum Production and Marketing in Semi-Arid Kenya(Kenya Agricultural and Livestock Research Organization, 2014) Karanja, D.R.; Kisilu, R.K.; Kathuli, P.; Mutisya, D.L.; Njaimwe, A.N.; Keya, G.; Ouda, J.; Ayemba, J.; Kenya Agricultural and Livestock Research OrganizationSorghum is an important food security crop especially in semi-arid lands of Kenya. It is adapted in a wide ago-ecological zones. Sorghum requires less water than maize thus offering great potential for supplementing food and feed resources. Although sorghum varieties with a yield potential of 2 to 5t/ha are available, their productivity has remained low, at 0.7t/ ha. The major constraints to sorghum production are: inadequate soil moisture, low soil fertility, bird damage, pests and diseases, high cost of inputs, low adoption of improved varieties, weeds, lack of markets and limited utilization options. Farmers consider lack of markets, low producer prices and bird damage as the main constraints to increased sorghum production. Most sorghum is grown at altitudes of less than 1500 m above sea level. However there are varieties suitable for up to 2400 m a.s.l. It requires a rainfall of 250-400 mm during the growing season. Most dry land sorghum cultivars are those that thrive best in areas with a small range of diurnal temperatures i.e. the day and night temperatures do not differ greatly. Sorghum does best in wide range of soils including sandy, clay and loamy ones. It thrives well on fertile soils but will grow on somewhat exhausted soils.
