Evaluation Of Sweetpotato Varieties Response To Sweetpotato Virus Disease
Abstract
Sweet potato is an important food, feed and cash crop in Eastern Africa but its productivity is
greatly reduced by the sweetpotato virus disease (SPVD). Variety based tolerance to SPVD is
a cheap and sustainable way of increasing productivity for smallholder farmers who are the
predominant producers. The objectives of the study were to (i) identify the best technology
for multiplication and maintenance of healthy sweetpotato planting vines, (ii) evaluate and
disseminate farmer-preferred sweetpotato varieties tolerant to SPVD. A study to evaluate the
best technology (spraying, maize barrier, control, net and polyethylene cover) to multiply and
maintain healthy planting vine was conducted at University of Nairobi Kabete Field Station
farm. Sweetpotato varieties were evaluated for tolerance to SPVD in three sites at the coast
between May 2006 and February 2007 at Kenya Agricultural Research Institute (KARI)-
Mtwapa in Kilifi district and two on-farm sites in Lukore and Mwaluvanga locations, Kwale
district. The experimental design in the two experiments was randomised complete block
design. Net and polythene covers effectively excluded insect vectors. Spraying kept the
population low compared to the maize barrier. A preliminary survey revealed that farmers
lacked adequate knowledge on SPVD diagnosis and management. Variety based tolerance
was identified among sweetpotato varieties that had farmer and market desired traits. Disease
incidence was positively correlated to vector population. The yield of the tolerant varieties
was high and stable in seasons and sites. Tolerant varieties had thicker leaf cuticle and longer
internodes while hairy varieties tended to be susceptible. Farmers learnt that roguing is a
cheap effective way of managing the SPVD disease in both nursery and field. Varieties were
disseminated in the region and more than fifty farmers planted them. Dissemination of
disease tolerant sweetpotato varieties with desirable traits coupled with building farmers
capacity to maintain clean vines can sustain sweetpotato productivity
Citation
Master of Science degree in Agronomy, University of Nairobi, 2008.Publisher
University of Nairobi. Department of Plant Science and Crop Protection