Investigations into the occurrence of alkaloids in ergot and single sclerotia from the 2007 and 2008 harvests.

As a contribution to the occurrence of ergot alkaloids in ergot from German rye and triticale, samples from the 2007 and 2008 harvests were analyzed. Twelve alkaloids-six pairs of main alkaloids and their corresponding epimers-were determined in extracts prepared under alkaline conditions by HPLC with fluorescence detection without preceding purification. The total alkaloid content was found to be 0.03-0.18% in ergot from rye (n = 19) and 0.06-0.22% in ergot from triticale (n = 4), respectively. Furthermore, single sclerotia (n = 40) were investigated in terms of alkaloid content and distributional pattern. The main alkaloids in ergot were ergocristine, ergotamine and ergocornine, although the alkaloid composition was highly variable.

Level ofFusarium infection in wheat spikelets related to location and number of inoculated spores.

The flowering time is the most susceptible period for primary infection of wheat heads byFusarium spp. During this period spores can be deposited into the opened wheat florets where they may later cause infections. We quantitatively explored the relationship between variables related to the flowering process and the infection level byFusarium graminearum in single spikelets. We imitated open (chasmogamous) and closed (cleistogamous) flowering by injecting well-defined amounts of spores into and between wheat florets. Applying the spores between the florets resulted in weaker disease symptoms and significantly lower amounts ofFusarium mycotoxins. With larger numbers of spores, the disease symptoms became more pronounced and the mycotoxin amounts per spikelet increased significantly.Our results indicate that the probability of primary infection is approximately proportional to the number of spores reaching the open florets during the flowering process. The breeding of wheat lines which flower partially or completely cleistogamously might reduce theFusarium susceptibility in wheat.

[Not Available]. / Untersuchungen zur pathogenität und mykotoxinbildung vonFusarium sambucinum, dem erreger der trockenfäule an kartoffeln.

Investigation into virulence and mycotoxin formation of the dry rot causing pathogen Fusarium sambucinum on potatos 11 strains ofFusarium sambucinum were isolated from tubers with dry rot symptoms from three different depots in the Land Brandenburg and Saxony-Anhalt. All isolates produced diacetoxyscripenol in artificially infected potato tubers. Additionally, two isolates produced T-2 and HT-2 toxins as well. The virulence and mycotoxin formation of the isolates was dependent on the potato varieties 'Sieglinde' and 'Berber' used in the experiment. The amount of diacetoxyscripenol in diseased tissue was positively correlated with the virulence of theF. sambucinum isolate and the susceptibility of the potato variety as well.

Results of long-term field studies into the effect of strobilurin containing fungicides on the production of mycotoxins in several winter wheat varieties.

In total, 23 field trials have been performed during the past 5 years to assess the effect of strobilurin containing fungicides on mycotoxin production in winter wheat. In 85% of the plots, the treatment with strobilurins at growth stages before blossom increased the content of deoxynivalenol in comparison with untreated controls. This effect was intensified by treatments at BBCH stage 45-49 and could be demonstrated in a great number of various cultivars. Application of strobilurin containing fungicides at early growth stages seems to be a risk factor for mycotoxin formation in wheat, especially under favourable conditions forFusarium infections.

Mycotoxins in potato tubers infected byFusarium sambucinum.

Potato tubers artificially infected withF. sambucinum were contaminated with diacetoxyscirpenol in concentrations up to 200 µ/tuber. The toxin could also be found in tubers without any disease symptoms. The duration of storage and an increased temperature raised toxin production in infected tubers. Susceptibility of potato cultivars towardsF. sambucinum was well correlated with toxin levels. The concentration of diacetoxyscirpenol in the susceptible cultivar was five times higher compared to the more resistant one. The toxin could not only be found in rotten tuber tissue but also in distant healthy looking parts. There is a gradient in toxin concentrations showing a strong decline with an increasing distance from the infection point. Tissue being 10-15 mm far from the diseased area contained up to 110 µg/kg. Consumers should pay attention to the fact that cutting out the diseased tissue may be not sufficient enough to prevent the intake of mycotoxins.

Fusarium toxins in cereals - Results from eight German Federals States in 2000.

A total of 353 cereal samples from 8 German Federal States were analysed for Fusarium toxins in the 2000' survey. The level of mycotoxin contamination of the samples was higher than in the previous year due to higher moisture during flowering in some regions. Concerning deoxynivalenol (DON), the prevailing mycotoxin in all the samples, we have to consider, that 24% of the samples as well as the average concentration exceed the advisory level of 500 µg/kg. The application of Fusarium active fungicides reduced the DON level from 963 µg/kg (samples without treatment) to 630 µg/kg (all samples from treated and untreated fields). It has to be emphasised that the number of nivalenol (NIV) positive samples increased in comparison to the previous year from 9% to 17%. In addition, an increase in the level of NIV was detected, the maximum concentration in winter wheat was 3480 µg/kg. Cereals were rather moderately contaminated with zearalenone (ZEA), more than 80% of the samples contained less than 50 µg/kg.