POWDERY MILDEW APPEARS EVERY YEAR IN ALL OVER SUGAR BEET FIELDS IN IRAN AND DECREASES THE QUALITY AND QUANTITY OF THIS CROP. IN ORDER TO COMPARISON BETWEEN 2 FURROW AND sprinkle irrigation METHODS ON RESTRICTING POWDERY MILDEW AND EFFECT ON THE CROP YIELD SOME EXPERIMENTS WERE PERFORMED IN AGRICULTURAL RESEARCH STATION OF MAHIDASHT, KERMANSHAH DURING 2011-2012. THE EXPERIMENT INCLUDED 8 CULTIVARS WITH VARIOUS SUSCEPTIBILITY TO POWDERY MILDEW UNDER 2 sprinkle AND FURROW irrigation METHODS IN A COMPLETE RANDOMIZED BLOCK DESIGN WITH 4 REPLICATIONS. 2-YEAR COMBINED ANALYSIS SHOWED THAT irrigation METHOD HAD EFFECT ON ROOT YIELD BUT STATISTICALLY IT WAS NOT SIGNIFICANT. SUGAR CONTENT IN FURROW irrigation WITH 15.04% WAS HIGHER THAN sprinkle irrigation WITH 13.59% WHICH RESULTED IN 1.26 TON/HEC MORE SUGAR UNDER FURROW irrigation SYSTEM. INFECTION TO POWDERY MILDEW DECREASED SEVERELY IN sprinkle irrigation SO THAT IN THIS METHOD INFECTION SUPPRESSED AT 5 TO 6% WHICH WAS EVEN LOWER THAN THE INFECTION AFTER PERFORMING CHEMICAL TREATMENT. FOR ROOT YIELD THE DIFFERENCE AMONG THE CULTIVARS WAS SIGNIFICANT. IN THIS EXPERIMENT TORBAT WHICH IS A NEW IRANIAN CULTIVAR WITH A REMARKABLE ROOT YIELD SHOWED A MODERATE INFECTION TO POWDERY MILDEW SO IT CAN BE GROWN IN THE REGIONS WITH HIGH LEVELS OF POWDERY MILDEW INFECTION.