Sulphur dusts are widely used in Tanzania to control powdery mildew on cashew trees, caused by the fungus Oidium anacardii. Sulphur distribution on mature cashew trees obtained using a motorised backpack duster, a manually powered backpack duster and a locally developed dusting bag were compared. The most efficient application was from the motorised duster, although sulphur distribution throughout the canopy of the tree was uneven with all three methods. The presence of dew when dusting was demonstrated to increase sulphur deposition. Following application, sulphur deposits on the canopy were found to decline by as much as 80% in 3 weeks.
