Abstract

O. E. V. Magenya*, J. Mueke and C. Omwega

Maize (Zea mays L.) is a staple food for more than 100 million people in Africa. Its production is constraint by maize streak virus (MSV) disease. This study investigated the interrelationships between altitudes and levels of soil macronutrients with MSV disease and its vectors. The influence of nitrogen, phosphorus and potassium levels on MSV and on populations of Cicadulina spp. (Homoptera: Cicadellidae) were investigated at six geographically separated maize producing regions in Kenya. Comparisons of numbers of sampled Cicadulina spp showed that areas at lower than 1550 m above sea level had significantly more leafhoppers than those at higher altitudes (p < 0.05, SNK). Soil analysis showed that nitrogen was low (0.06 - 0.12%), phosphorus (13.5 - 37.3 ppm) and potassium adequate (86 - 707 ppm). The yield loss due to MSV expected by the farmers in Oyani was similar to that in Mwea (>40%) and higher than that in Bahari, Muhoroni, Kimilili and Githunguri (< 30%) and it correlated positively with numbers of Cicadulina mbila. A significant positive correlation was detected between potassium with C. mbila. This study shows that soil nutrient levels influence MSV vector (Cicadulina spp) and that this relationship is critical during the design of crop protection packages.