| Maize streak was observed in 17 of 19 districts of Kenya surveyed in 1994-1995. The highest disease incidence in the farmers' maize (Zea mays L.) fields (53.5%) was recorded in the Kiambu district in the Central province. Maize streak geminivirus (MSV) was identified from maize, wheat (Triticum aestivum), finger millet (Eleusine coracana) and various grass species including Coix lacryma-jobi, Dactyloctenium aegyptium, Digitaria velutina, Eleusine indica, Eragrostis macilenta, E. tenuifolia, Panicum maximum, P. trichocladum, Setaria homonyma, S. verticillata and Urocloa brachyura. Among 11 grass species found naturally infected with MSV, D. velutina was the most abundantly diseased. However, P. maximum with streak symptoms was seen in more locations, but in fewer numbers. All grass and maize isolates tested positive for MSV in F(ab;MSV isolates from 11 grass species and five maize plants collected from different districts were transmitted to Poaceae species including maize, wheat, finger millet and various grasses by Cicadulina mbila. The most efficiently transmitted from the 11 grass species was the was the one from E. tenuifolia. Both severe and mild MSV variants were recovered from S. verticillata, D. velutina and P. maximum. Maize resistance-breaking variants of MSV were identified by C. mbila transmission to maize with high levels of MSV resistance. All but two of the mildest MSV isolates were transmitted to a susceptible maize type, H511, by vascular puncture inoculation of maize kernels.;The highest Cicadulina leafhopper population density (25/m... |
