Effect of fungicides for controlling Fusarium head blight of wheat on the yield depending on the phenological stage of treatment

Ivo Yanashkov, Tzenko Vatchev

Abstract: Application of fungicides during the growing season is considered to be the primary means of controlling Fusarium head blight (FHB) of small-grain cereal crops. In this study, two field experiments were carried out to compare the ability of Allegro® (suspension concentrate, 125 g/l epoxiconazole + 125 g/l kresoxim-methyl) and Opera® (suspo-emulsion, 85 g/l pyraclostrobin + 62.5 g/l epoxiconazole), both applied at the recommended doses of 75 ml/da and 150 ml/da, respectively, to reduce winter wheat yield losses caused by Fusarium head blight. As the main yield component one thousand grain weight was recorded. Statistically significant increase in the one thousand grain weight – by 9% to 19%, was achieved in plants artificially inoculated with Fusarium oxysporum after single treatment with each fungicide alone during heading or flowering phenological stage. Single spraying with Opera® during flag leaf stage, heading or flowering resulted in 17.6%-23.3% yield increase in plants inoculated with F. graminearum as compared to untreated control. Under the same conditions, treatment with Allegro® leaded to 3.5%-9.8% increase in the one thousand grain weight. Experimental plants inoculated with F. culmorum and treated with Opera® during heading or flowering showed a significant increase in the one thousand grain weight – by 43% or 62%, respectively, compared to the untreated, inoculated control. An increase in the estimated yield parameter was observed in all fungicide treated plots where plants were inoculated with mixed inoculum of the three pathogenic fungi, with one exception, the plots treated with Allegro® during the heading stage. According to the results in this study, Allegro® and Opera®, applied at the recommended doses of 75 ml/da and 150 ml/da, respectively, would significantly reduce grain yield losses due to FHB of wheat.

Keywords: cereals; fungicides; Fusarium head blight; one thousand grain weight; phenological stages; wheat

Date published: 2020-03-10