The prevalence and impact of Fusarium Head Blight pathogens and mycotoxins on malting barley quality in UK

Fusarium head blight (FHB) caused by Fusarium and Microdochium species can significantly affect the yield of barley grain as well as the quality and safety of malt and beer. The present study provides new knowledge on the impacts of the FHB pathogen complex on the malting and brewing quality parameters of naturally infected barley. Quantitative real-time PCR and liquid chromatography double mass spectrometry were used to quantify the predominant FHB pathogens and Fusarium mycotoxins, respectively, in commercially grown UK malting barley samples collected between 2007 and 2011. The predominant Fusarium species identified across the years were F. poae, F. tricinctum and F. avenaceum. Microdochium majus was the predominant Microdochium species in 2007, 2008, 2010 and 2011 whilst Microdochium nivale predominated in 2009. Deoxynivalenol and zearalenone quantified in samples collected between 2007 and 2009 were associated with F. graminearum and F. culmorum, whilst HT-2 and T-2, and nivalenol in samples collected between 2010 and 2011 correlated positively with F. langsethiae and F. poae, respectively. Analysis of the regional distribution and yearly variation in samples from 2010 to 2011 showed significant differences in the composition of the FHB species complex. In most regions (Scotland, the South and North of England) the harvest in 2010 had higher concentrations of Fusarium spp. than in 2011, although no significant difference was observed in the Midlands between the two years. Microdochium DNA was significantly higher in 2011 and in the North of England and Scotland compared to the South or Midlands regions. Pathogens of the FHB complex impacted negatively on grain yield and quality parameters. Thousand grain weight of malting barley was affected significantly by M. nivale and M. majus whilst specific weight correlated negatively with F. avenaceum and F. graminearum. To determine the impact of sub-acute infections of the identified Fusarium and Microdochium species on malting and brewing quality of naturally infected samples, selected malting barley cultivars (Optic, Quench and Tipple) were micromalted and subjected to malt and wort analysis of key quality parameters. F. poae and M. nivale decreased germinative energy and increased water sensitivity of barley. The fungal biomass of F. poae and F. langsethiae correlated with increased wort free amino nitrogen and with decreased extract of malt. DNA of M. nivale correlated with increased malt friability as well as decreased wort filtration volume. The findings of this study indicate that the impact of species such as the newly emerging F. langsethiae, as well as F. poae and the two non-toxigenic Microdochium species should be considered when evaluating the quality of malting barley. © 2014

Susceptibility of UK oat ( Avena sativa ) varieties to infection by Fusarium species and subsequent HT‐2 and T‐2 toxin contamination

The aim of this study was to compare the susceptibility of oats to Fusarium langsethiae infection, as measured by combined HT-2 and T-2 mycotoxin concentration (HT2 + T2) in harvested oat grain samples. Over 10 years (2004–2013), samples from single replicates of each UK Recommended List oat trial were analyzed for HT-2 and T-2. For spring oats, there were small but statistically significant differences between varieties, whereas for winter oats, they had a broader range and higher mean of HT2 + T2 concentration compared with spring oats. For winter oats, the short-strawed varieties had consistently high HT2 + T2 levels compared with other varieties, whereas naked varieties were at the lower end of the range, and short, naked varieties had intermediate levels. A separate set of harvested oat grain samples of eight common varieties from 17 field experiments were analyzed by modified joint regression analysis. Results showed that environment had the strongest impact on HT-2 and T-2 concentrations but that the varietal susceptibility to HT-2 and T-2 contamination was highly stable across environments. This methodology can be used to calculate a Fusarium (HT2 + T2) resistance score for oats to aid grower selection of suitable varieties, as is available for Fusarium (DON) resistance for wheat varieties in many countries

Impact of pre-harvest rainfall on the distribution of fusarium mycotoxins in wheat mill fractions

Legislative limits for Fusarium mycotoxins decrease from unprocessed wheat to processed products. A previous observational study identified a seasonal difference in the distribution of deoxynivalenol (DON) but not zearalenone (ZON) within mill fractions. Rainfall is known to influence the production of these mycotoxins in wheat, but the effects of rainfall on their distribution within mill fractions is not known. Laboratory and field experiments were conducted to determine the impact of different watering regimes on the distribution of DON and ZON in wheat mill fractions. Results indicated that repeated wetting and drying could cause movement of DON towards equilibrium across the mill fractions. Whereas, high levels of rainfall could cause a large reduction of DON in the grain, predominantly from the bran fraction, resulting in a proportional increase within white flour. ZON was detectable in fewer samples but results indicated it is less mobile within the grain. It is important for processors to be aware of the variation of mycotoxin distribution within mill fractions and the drivers of this variation to ensure limits set for grain intake result in mill products within mycotoxin legislative limits

Impact of agronomic factors on fusarium mycotoxins in harvested wheat

The aim of this study was to model fusarium mycotoxins against agronomic factors in order to identify those that have the greatest impact on mycotoxin levels in harvested wheat. To achieve this, fusarium mycotoxins levels were monitored, and associated agronomic data collected, in approximately 150 English wheat fields/year between 2006 and 2013. Results showed large seasonal variation in fusarium mycotoxin levels, with high levels in 2008 (13% and 29% exceeding legal limit for unprocessed soft wheat intended for human consumption for deoxynivalenol (DON) and zearalenone (ZON), respectively) and 2012 (10% and 15% exceeding legal limit for unprocessed soft wheat intended for human consumption for DON and ZON, respectively) and low levels in 2006 and 2011 (no samples exceeding legal limits for unprocessed soft wheat intended for human consumption for DON or ZON). Analysis of agronomic factors identified previous crop, cultivation and variety as the greatest risk factors. The greatest risk of mycotoxin development in grain was following maize as a previous crop and minimum tillage. The combined effect of these factors gave respective average DON and ZON levels 20 and 14 times higher than other previous crop and cultivation combinations. A newly quantified risk factor was harvest date. A 1-month delay in harvest resulted in a 10 and 25 times greater mean DON and ZON concentration, respectively, when compared to crops harvested around the long-term regional average harvest date. These results highlight the highly seasonal variation in fusarium mycotoxins in wheat and the agronomic factors that should be avoided to minimise fusarium mycotoxin levels in harvested wheat

In vitro growth characteristics of Fusarium langsethiae isolates recovered from oats and wheat grain in the UK

Fusarium langsethiae is a fungus that has recently been implicated in the contamination of small-grain cereal crops such as oats, wheat and barley with high levels of HT-2 and T-2 toxins in many European countries. The epidemiology of this fungus is not well known and may therefore be a bigger problem than currently thought to be. A study was carried out investigating the in vitro growth characteristics of F. langsethiae isolates from contaminated oats and wheat at various temperatures; 15, 20, 25 and 30 °C. Results indicated similar growth trends of oats and wheat isolates of F. langsethiae. Wheat isolates grew significantly (p<0.001) faster than oat isolates although this difference may have been confounded by the age of cultures, with oat isolates collected one year earlier. The estimated optimum growth temperature for all isolates was 24 °C. Isolates were macro-morphologically categorized as having lobed or entire colony margins, and either possessing one of the following colony colours: white, orange or purple. Since the estimated optimum growth temperature of F. langsethiae is typical in temperate summers when small-grain cereals are flowering, it is possible that this species can infect, colonise and possibly contaminate the developing grains with HT-2 and T-2 toxins which are of food safety concern

Susceptibility of cereal species to Fusarium langsethiae under identical field conditions

Experiments were conducted to determine the extent of Fusarium langsethiae infection in wheat, barley and oats grown under identical experimental conditions. In total, four experiments were conducted with both winter and spring sown experiments at two locations. The amount of F. langsethiae infection was determined by quantifying F. langsethiae DNA and quantifying the combined concentration of the trichothecene mycotoxins HT-2 and T-2 (HT-2 + T-2) in cereal head fractions (grain and rest of the head) after threshing at harvest. Results of the study showed that under identical experimental conditions, oats had the highest F. langsethiae DNA and HT-2 + T-2 concentrations compared to wheat and barley. This indicates that the high levels detected on UK oats compared to wheat and barley from surveys of commercial crops is a consequence of genetic differences rather than differences in agronomy applied to the cereal species. The concentration of HT-2 and T-2 per unit of F. langsethiae DNA in oats compared to wheat and barley was also significantly higher indicating host differences in either the stimulation of HT-2 and T-2 production or in the metabolism of HT-2 and T-2. The study also showed that the proportion of F. langsethiae DNA in threshed grains was significantly lower than that in the rest of the cereal head

Book review of perspectives on organizational fit by Cheri Ostroff and Timothy A. Judge (Editors)

From the first moment you set your eyes on this book, you are aware that it is a serious endeavor. Edited by two of the most published people in the field and sporting an imposing black and lime green dust cover containing an image of a swarm of black skull-headed moths, it contains chapters written by virtually all of “the good and the great” of the field. A flick through the pages reveals hundreds of pages of narrow margins and dense typescript interspersed with equations and three-dimensional graphs. This is a book that demands attention

Book review of 'the people make the place: dynamic linkages between individuals and organizations edited by D. Brent Smith'

The People Make the Place is a festschrift celebrating the work of industrial/organizational psychologist Benjamin Schneider. It contains 11 specially written chapters each addressing a different element of Schneider’s work. The twelfth chapter, written by the honored scholar, summarizes the contributions and uses the opportunity to clarify many of the ideas surrounding attraction-selection-attrition (ASA) theory

Screening of fungicides and comparison of selective media for isolation of fusarium graminearum from soil and plant material

The culture media recommended for the isolation and enumeration of the Fusarium spp. lack selectivity for Fusarium graminearum. Five fungicides—Amistar® (250 g·L−1 azoxystrobin), Filan® (500 g·kg−1 boscalid), Comet® 200 (200 g·L−1 pyraclostrobin), Imtrex® (62.5 g·L−1 fluxapyroxad), Poraz® (450 g·L−1 prochloraz)—were investigated for their potential as selective inhibitors in culture media for the isolation of F. graminearum from soil and plant material. Based on the screening, fluxapyroxad was further tested for selective inhibition for the isolation of F. graminearum from soil. Additionally, selective media were compared for the isolation of F. graminearum from plant material. The fungicides tested did not prove to be effective inhibitors for the development of selective media. For the detection of F. graminearum in plant material, Czapek Dox propiconazole dichloran agar was found to be a better medium than Komada’s media, as the former resulted in colonies with darker pigmentation over a shorter incubation time and appeared to have a less inhibitory effect on F. graminearum growth