comparison of a new fungicide (opus) with common fungicides in controlling powdery mildew of sugar beet

in this study, recently produced fungicide opus was compared with current fungicides dinocap, sulfur and calyxin for controlling powdery mildew disease of sugar beet in completely randomized block field experiments conducted in kermanshah and west azarbaijan provinces. fungicides were applied according to the recommended field dosages. there were five treatments (four fungicides plus a water-spray control) each with four replicates. disease incidence was evaluated 15 days after the last application based on infection index on sugar beet leaves collected from different treatments. infection index varied from 1 (no infection) to 6 (81-100% infection). analysis of the results indicated that in miandoab experiment for both years there were significant differences among different treatments in disease incidence and the fungicide opus was the most effective in reducing infection. in the first year of mahidasht experiment there were no significant differences among different treatments due to very low occurrence of the disease in the field. in contrast, in the second year significant differences were observed in different treatments.  despite higher root yield and sugar content in fungicide treatments, compared to the control, these differences were not significant.