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Report no. 506Lise Nistrup Jørgensen Ghita Cordsen Nielsen Ulf Thrane Inge Dorthe Hansen 15.02.2001
Mycotoxins in wheat – effect of fungicides
Abstract The study comprised a total of 18 field tests divided into 12 localities. One sample was collected for determination of toxin content and prevalence of Fusarium per treatment in each field study. The study comprised the following treatments:
Of the four studied toxins, vomitoxin (deoxynivalenol) was detected in 71 out of 72 samples, and nivalenol was detected in 54 out of the 72 samples. Fusarenon-X and 3-acetyl-deoxynivalenol were in all the studies below the detection limit. The average content of vomitoxin was 116-195 ppb in the four treatments, and the content of nivalenol was 17-32 ppb. Assessed on the basis of the guiding maximum limit of 1,000 ppb for vomitoxin in feed for weaners, the observed levels were not alarming. However, in some samples the content of vomitoxin was 400-500 ppb. No significant effect was found of the three fungal treatments when measured on the content of vomitoxin. The content of nivalenol was significantly lower when Folicur was used compared to untreated, and there were no significant differences between Amistar and Folicur and Folicur+Amistar compared to the untreated wheat. It should be noted that there was great variation in the data, which means that no great and far-reaching conclusions can be made on the basis of this study alone. Assessed on the individual studies, the distribution of treatments yielding the highest level of vomitoxins was as follows: untreated was highest in four studies, Amistar was highest in 7 studies, and Folicur was highest in 4 studies. For nivalenol, the distribution of treatments with the highest level was as follows: untreated was highest in 8 studies, Amistar in 3, and Folicur in 1. The mix Amistar+Folicur did not result in the highest content of the two toxins in any of the studies. A significantly higher content of toxins was observed with an increasing number of wet days in the flowering season. The data set only comprised one, two and three wet days, respectively, and most localities only experienced one or two wet days, and this gives an unbalanced data set. The amount of rainfall (mm) in the flowering season showed no clear connection to the content of toxins. There was no connection between the content of vomitoxin and the choice of wheat variety. However, a higher content of nivalenol was found in Ritmo compared to the other grains. The content of vomitoxin did not differ depending on the choice of previous crop whereas a significant effect of the previous crop was seen on the content of nivalenol. A lower content was found with winter wheat as a previous crop compared to the other previous crops, which is not in agreement with foreign test results. Fusariumwas found in all samples with an infection percentage from 2% to 68%. The average of all samples was 19%. Besides this, Alternaria was found in all samples. The four most frequent species were F. tricinctum, F. avenaceum, F. poae and F. culmorum that together covered 98% of the cultivated Fusarium cultures. There was no connection between Fusarium percentage, neither totally nor at species level, and the observed mycotoxins. Nor was there any connection between treatment and the observed Fusarium species. As shown by other foreign studies, this study showed that use of Amistar does not cause a higher content of the measured toxins. Furthermore, the study indicated that use of a mix of Amistar and Folicur is the spraying yielding the lowest toxin levels. Other conditions such as climate, choice of variety, previous crop and soil cultivation have far greater influence on the content of toxin than choice of fungicide. In the future, it would be desirable to have information on the susceptibility to Fusarium of the wheat varieties cultivated in Denmark so it becomes possible to choose the least susceptible varieties. To read
report 506 in its entirety as PDF file, please click here. ppb En forkortelse af Parts per billion (fx er 1 ppb er lig med 0,000000001). |
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