Effectiveness of bio-medicaments against oat powdery mildew

In order to compare the effectiveness of seven bio-control fungicides against natural oat powdery mildew (Blumeria graminis f. sp. avenae) infections, a field experiment was conducted in Huajialing Township, Tongwei County, Gansu Province, China. At 7 d after the 1st application, the biocontrol agents were generally less effective than either of the chemical fungicides (triazolone and myclobutanil), and only matrine and physcion provided sufficient control (85.01% and 83.93%, respectively). At 7 d after the 2nd application, the effectiveness of each biocontrol agent was better than at 7 d after the 1st application, and physcion and Bacillus subtilis provided the greatest level of control (91.82 and 91.46%, respectively). At 20 d after the 2nd application, physcion provided the greatest level of control (85.12%), which was greater than provided by either of the chemical fungicides, triazolone (80.60%) and myclobutanil (84.12%), and there was no significant difference in the control provided by the chemical fungicides and that provided by osthole, B. subtilis, or matrine. Furthermore, plants treated with the biocontrol agents yielded significantly greater flag leaf chlorophyll content, 1 000-grain weight, and seed yield, with 0.5% physcion treatment yielding the best results, also with 0.5% physcion treatment the seed yield increased by 16.77% compared with the control. These results indicated that biological fungicides were slightly less effective against oat powdery mildew at 7 d after the 1st application but were more persistent. Furthermore, 0.5% physcion was an effective control agent against B. graminis f. sp. avenae with regard to control efficacy, persistence, and seed yield. In the early onset spraying pesticides on plants and spraying the 2nd time interval 7 d, could effectively control occurrence of powdery mildew, achieve to ensure the production and reduce economic losses.