Suppression of wheat Fusarium head blight by novel amphiphilic aminoglycoside fungicide K20

Abstract New fungicidal chemicals with unique modes of action are needed to counter widespread fungal resistance to current fungicides. K20 is a novel amphiphilic aminoglycoside capable of inhibiting many fungal species, has low toxicities to animals and plants, and is produced in scalable amounts. Experiments were conducted to examine K20’s capabilities to inhibit Fusarium graminearum , the causal agent of Fusarium head blight (FHB) in wheat and barley, and to suppress this disease in wheat grown in the greenhouse and field. In vitro, K20 inhibited the growth of F. graminearum (minimum inhibitory concentrations, 7.8 to 15.6 mg L -1 ) and exhibited synergistic activity when combined with commercial triazole and strobilurin fungicides (fractional inhibitory concentration indices, -1 onto wheat heads in a greenhouse experiment had no phytotoxic effects. Spraying wheat heads in the greenhouse with K20 alone at 360 mg L -1 lowered FHB severity below controls while combining K20 with half–label rates of Headline (pyrachlostrobin) improved its disease control efficacy. In field trials, spraying K20 at 180 mg L -1 and 360 mg L -1 combined with half-label rates of Headline, Proline 480 SC (prothioconazole), Prosaro 421 SC (prothioconazole + tebuconazole), and Caramba (metconazole) reduced FHB indices synergistically. In addition, the K20 plus Proline 480 SC combination reduced levels of the mycotoxin deoxinivalenol by 75% compared to the control. These data suggest that K20 may be useful as a fungicide against plant diseases such as FHB particularly when combined with commercial fungicides applied at below recommended rates.