A study was conducted to determine the occurrence and severity of sorghum downy mildew on
three major hosts (maize, sorghum, and Johnson-grass) in Uganda. Five surveys were conducted
in four growing seasons, between 1994 and 1995. The disease was encountered in 11 of the 22
districts surveyed. In the majority of the areas, incidence was less than 10%, but it was significantly higher (P < 0.05) in the second season of 1994 than in the first season of 1995. Soil type
significantly (P = 0.001) influenced the incidence of sorghum downy mildew, with high incidence being associated with sandy soils, followed by loamy soils, and lowest incidence in clay
soils. Incidence, shredding, and oospore production were comparatively higher on sorghum and Johnson-grass than on maize.