Influence of sweetpotato rooting characteristics on infestation and damage by Cylas spp

Abstract

Studies were carried out in the field at Serere Agricultural and Animal Production Research Institute (SAARI), Eastern Uganda, to establish whether the existing sweetpotato germplasm in Uganda has cultivars resistant to the sweetpotato weevils, Cylas spp. The trials were conducted during the two growing seasons of 1997. Root size was the only sweetpotato rooting characteristic that significantly influenced tuber infestation (P=0.009) and damage (P=0.049). Root size was positively correlated to tuber infestation by Cylas spp. (Y=0.0456x + 21.206; R2 = 0.2731) and negatively correlated to damage by Cylas weevils (Y=-0.027x + 29.684, R2=0.1647). A laboratory study demonstrated the effect of temperature on oviposition, survival and developement of Cylas puncticollis (Boheman). The variety 'Tanzania' that was used as the susceptible check registered the highest weevil emergence under both wet and dry weather conditions while varieties 'Kasira' and 'Akere-Ikokolak' registered the least emergence of adult C. puncticollis. These results indicate that the latter two varieties posses considerable levels of resistance to sweetpotato weevils.



Key Words: Germplasm, resistance, sweetpotato weevils, Uganda


(African Crop Science Journal 2001 9(1): 165-174)