Effect of Sulphur and Irrigation Regimes on Potato Common Scab Development in Khartoum Area

Potato common scab development was assessed under the traditional farming system (TFS) and modern farming system (MFS) using irrigation interval and side dressing of Sulphur-based fertilizer application along the ridge. The 4-day irrigation interval starting with the tuber formation suppressed the disease development significantly producing 33.6% and 22.2% reductions in scab incidence and severity, respectively. Sulphur applications [Wettable Sulphur and (NH4So4)] resulted in a significant decrease in incidence of 50 and 73% in TFS and MFS respectively; severity was also decreased by 44% and 60% in TFS and MFS respectively. The effect was particularly pronounced when Sulphur was applied at tuber initiation and to a lesser degree when it was applied at planting. The combined effect of short irrigation interval and Sulphur application under TFS had a synergistic significant impact on scab development resulting in ~ 60% and 55.6-58.3% reductions in incidence and severity, respectively. Significant increases in tuber yield of 138% and 91-103% were obtained under TFS and MFS, respectively, when Sulphur was applied at planting. However, the yield was comparatively less when Sulphur was applied at tuber initiation. These results indicate that the common scab of potato in Sudan can practically be managed through short irrigation interval and application of Sulphur-based fertilizers during the early stages of tuber formation at planting or tuber initiation.