THE EFFECT OF FUNGICIDES ON SUGAR-BEET INFECTED WITH BEET MILD YELLOWING VIRUS

Studies were made in 1989, 1990 and 1991 to establish whether carbenda zim (MBC) had a direct therapeutic effect on sugar beet plants infecte d with beet mild yellowing virus (BMYV), resulting in detectable yield benefits. In a field trial in 1989 virus-infected plots treated with carbendazim gave a significantly higher yield, of 0.66 t sugar/ha, tha n virus-infected plots sprayed with sulphur to control powdery mildew. This response to carbendazim in virus-inoculated plots was not repeat ed in subsequent trials in 1990 and 1991, and a glasshouse study showe d no apparent effect on virus concentration within inoculated plants. Neither was any effect of carbendazim on symptom development observed in any of the trials or glasshouse experiments.