Lew


Die Bodenkultur - Journal for Land Management, Food and Environment

H. Lew, A. Adler, W. Edinger, W.Brodacz, E. Kiendler and J. Hinterholzer:

Fusarium species and their toxins in Austrian maize

Summary

Since in the middle term the EU is likely to set maximum admissible values for fumonisins as well as other Fusarium toxins, one urgent task was to obtain a representative picture of Fusarium infestation and the toxin content of domestic maize.

Consequently, the project set out to investigate maize grain samples from the major maize growing areas of Austria.

The project, which spanned three vegetation periods and focussed on Fusarium infection, distribution of species and toxin contamination, involved the toxins deoxynivalenol (DON, vornitoxin), 15-acetyldeoxynivalenol, 3-acetyldeoxynivalenol, zearalenone, nivalenol, T-2 toxin, HT-2 toxin, fumonisin B1, B2 and moniliformin.

The relatively humid vegetation periods of 1998 and particularly 1996 were dominared by E graminearum; so that in both years relatively high concentrations of deoxynivalenol and zearalenone could be detected in the maize grain samples. Thus, 41 out of 46 samples from the 96 harvest showed a DON content of over 0.1 mg/kg, with an average content in the positive samples of O.645 mg/kg. The tests also showed that 15-acetyldeoxynivalenol is far more common in Austrian maize than 3-acetyldeoxynivalenol.

The occurrence of the chief moniliformin producer F. subglutinans remained largely uninfluenced by any climatic variations. In all vegetation periods the proportion of this fungus in the total figure of isolated fusaria was around 30 %.

The percentage of F. auenaceum, also a moniliformin forming species, varied between 14 % in 1996, an extremely wet year, and 23 % in 1997. In all three vegetation periods about 15 % of the maize samples considered showed a moniliformin content of well over 0.05 mg/kg, with an average value of the positive samples of 0.22 mg/kg.

In contrast to F. graminearum, F. poae appeared to find favourable conditions especially in 1997, a fairly dry vegetation period. However, infestation of the ears was much less conspicuous; in fact the nivalenol content in all tested maize samples was below the detection limit of 0.05 mg/kg. Finally, the occurrence of the trichothecenes T-2 toxin and HT-2 toxin in the three years under study was limited to a few isolated cases, with consistently low concentrations.

Compared to a similar investigation in the years 1988/89, a significant increase in the incidence of F. prolifiratum, a fumonisin-producer, could be observed. Especially in the unusually warm vegetation period of 1998 conditions for the development of F. prolifiratum were very good, so that some of the maize samples yielded toxicologically relevant fumonisin contents (up to 2 mg/kg).

Key words: Maize, Fusarium species, trichothecenes, zearalenone, fumonisins, moniliformin.