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

K20 is a novel amphiphilic aminoglycoside capable of inhibiting many fungal species. K20's capabilities to inhibit Fusarium graminearum the causal agent wheat Fusarium head blight (FHB) and to this disease were examined. K20 inhibited the growth of F. graminearum (minimum inhibitory concentrations, 7.8-15.6 mg L-1) and exhibited synergistic activity when combined with triazole and strobilurin fungicides. Application of K20 up to 720 mg L-1 to wheat heads in the greenhouse showed 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 (pyraclostrobin) 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.