Variability in potato late blight severity and its effect on tuber yield in Uganda

Abstract

Variability in severity of potato late blight and yield loss associated with the disease was studied in the major potato growing agro-ecologies of Uganda. Late blight incidence and severity varied significantly (P<0.05) from district to district to season during the four surveys (2 years). Overall, the highest late blight severities were recorded in Kabale district (mean severity of 27.6%), followed by Mbale (21.8%), and Mbarara the least (8.7%). There was more disease during the month of December 1997, with mean severity of 40.2%, while the least severity was in May 1998 (10.8%). The highest severity was recorded on cultivar Victoria (62.1%), followed by Wafrika (61.8%), Sangema (59.5%) and Maboni (48.2%). Rutuku and Musitamya recorded the least severities, less than 20% during 1998/99. Overall, there was no significant correlation between late blight severity and yield of potatoes, likely because the yield loss assessment was done during a season of low late blight occurrence (season was dry).



Key Words: Phytophthora infestans, Solanum tuberosum, varietal resistance, Uganda


(African Crop Science Journal 2001 9(1): 195-202)