Regional mycotoxin risk highlighted

WHEAT CROPS in some regions may be at higher risk than normal from mycotoxin contamination, despite low levels of fusarium head blight (FHB), the Central Science Laboratory has warned.

In England, 2.5% ears were affected by FHB in 2005, compared to a 10-year average of 3.8%, but incidence of Fusarium graminearum was the highest since monitoring began in 1998, according to CSL’s Crop Monitor.

“We are seeing a steady rise in the amount of F. graminearum coming out of fields infected with FHB,” said CSL’s Steve Parker. “This is significant as F. graminearum is a mycotoxin producer.”

The highest incidence was found in south Lincolnshire, where F. graminearum was isolated from 54% of fields sampled.

Dr Parker said this could be due to more rainfall in this area during anthesis – the main period for fusarium infection. Longer term, changing agronomic practices, such as increasing maize area and minimum tillage could be contributing, he said.

But there is no cause for alarm, as overall fusarium and mycotoxin risk is low this year, he added.

“Longer term, it may be a worry if there is more catchy weather in June – due to climate change for example – increasing F. graminearum incidence.”

Other Crop Monitor results found that overall disease levels in wheat during 2004/05 were low, although there were significant yellow and brown rust epidemics in some untreated plots, he noted.

While fungicide control was largely effective, the untreated epidemics highlight the susceptibility of some varieties to such diseases, as growers look for other traits, like septoria resistance, he said.

Disease levels in winter barley were generally low this season, despite some high levels of net blotch in more susceptible varieties like Pearl, results also found.

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