[Effect of the fungicide matador (tebuconazole/triadimenol) on mycotoxin production by Fusarium culmorum].

Applications of the fungicide Matador to winter wheat (Slejpner) inoculated at earing with Fusarium culmorum resulted in a considerable decrease in the incidence of Fusarium headblight. In the study presented here, subsequent mycotoxin analyses by selected ion monitoring gas chromatography-mass spectrometry revealed higher levels of nivalenol (NIV) in samples singly treated with Matador at 1 L/ha. Amounts as high as 2432 micrograms NIV/kg and 860 micrograms NIV/kg, representing a 16- or six-fold increase as compared to controls, were found in wheat treated with the fungicide 3 h before or 24 h after inoculation of the grain with F. culmorum, respectively. In parallel, higher cytotoxic activities of these samples were obtained when testing crude sample extracts in the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT)-cell culture bioassay using swine kidney monolayers as target cells. It is concluded that treatment of grain with the fungicide Matador could result in a marked stimulation of the production of NIV by F. culmorum. As the incidence of Fusarium headblight did not correlate with the amount of mycotoxins found, the need for mycotoxin analyses combined with bioassays such as the MTT-cell culture assay is recommended for a meaningful assessment of the quality of grain treated in such a manner.