effects of sprinkler and furrow irrigation systems on powdery mildew disease severity in sugar beet

powdery mildew of sugar beet is a common disease in many sugar beet growing areas causing root yield and sugar content reduction. the aim of this study was to evaluate the effects of different irrigation methods on powdery mildew severity in sugar beet. eight susceptible and resistant commercial cultivars were evaluated under sprinkler and furrow irrigation systems in a randomized complete block design with four replications for two years at mahidasht station, kermanshah, iran. the combined analysis results showed that the infection index in furrow and sprinkler irrigation systems was 49.1 and 5.9%, respectively. sprinkler irrigation had significant effect on the control of powdery mildew. the highest and the lowest rates of infection were observed in sbsi004 (36.6%) and brigita (10.62%) cultivars, respectively. furrow irrigation yielded 0.7 t/ha higher root yield than sprinkle irrigation, although it was not statistically significant. the highest root yield (65.13 t/ha) was noted in cultivar brigita. the effect of irrigation on sugar content was significant with 15.04% in furrow irrigation and 13.59% in sprinkler system, respectively therefore furrow irrigation resulted in 1.45% increase in sugar content and also lower accumulation of sodium and amino nitrogen in roots.