With wheat ear emergence fast approaching we ask experts about the risk from ear diseases this season.
Dr Philip Jennings, principal plant pathologist at Fera, has studied fusarium and microdochium species for several years and has a wealth of knowledge on the subject which enables him to paint a bigger picture of the issue in the UK.
He says: “1998 was the first big year for fusarium ear blight [FEB] infection, with 60 per cent of samples from the winter wheat survey assessed with FEB symptoms. Most of these symptoms were caused by the non-toxin producing microdochium species.
“But, the UK was not the only European country to see this sharp rise in FEB during 1998. The marked difference being the predominant species responsible for the disease across Europe were toxin-producing fusaria such as Fusarium graminearum.
“Since then, Fera has monitored the progress and prevalence of the main pathogens responsible for FEB symptoms in the UK, and to date we have seen some noticeable trends.”
Following the increased FEB levels in 1998 there has been a general increase in the number of crops recorded with FEB symptoms, with peaks seen in 2007 and 2012 where 86 per cent and 98 per cent of samples, respectively, had FEB symptoms caused by microdochium species.
See also: Reduce mycotoxin risk in winter feed
“The peaks in disease have arisen when we have had a wet flowering period. For example, 2012 was a year many growers would rather forget. The extended flowering period paired with consistent rain during this time meant conditions were ideal for infection by FEB pathogens.”
Dr Jennings also points to the change in the type of fusaria infecting crops which produce deoxynivalenol (DON) since 2003.
“We have seen Fusarium graminearum has taken over from F. culmorum as the dominant species. Generally regarded as being the more aggressive species due to the production of windborne spores which allow it to spread further, we are now seeing a marked increase in UK wheat samples infected by F. graminearum.
“This has a huge bearing on crop potential with the risk of reducing yields in wheat by up to 30 per cent.
“This change can be explained by two driving factors, a move towards minimum tillage and an increase in maize production. As the acreage of maize increases across the country, without the removal of the trash left behind, we could see a huge increase in the level of F. graminearum,” Dr Jennings says.
Fusarium infection has historically been a problem in German crops. Following the 1998 harvest, high DON levels were discovered in baby food and legislation was introduced in 2006 setting threshold levels permitted in food. As a result, T3 protection against the disease has become standard practice among German growers.
Germany’s fusarium problem is relatively regional, mainly affecting the south east of the country where higher rainfall and temperatures are recorded at flowering.
According to Dr Katharina Treyse-Kunne of chemical manufacturer Spiess Urania, in southern Germany growers apply up to three sprays against fusarium, culminating in a final treatment during flowering when the risk of infection is at its highest.
She says: “We know from experience if you want to produce a quality grain then you must control mycotoxin levels with a thiophanate-methyl product at T3. The addition of a broad-spectrum triazole at this timing can also help extend protection from late season septoria and rust.”
Zantra agronomist and technical director Chris Bean says there is a key role for T3 treatments in the UK to prevent yield losses, reductions in specific weights and mycotoxin issues.
See also: Seeking the way of least resistance
“This year has been similar to last, with a dry and cool April which has resulted in low levels of fusarium inoculum at the base of plants,” he says.
“At present the risk of a high fusarium year is low, however, this can all change in the coming weeks if temperatures rise and we have more rain at flowering.
“A number of fungicides are available for use at T3 but are mostly triazole-based. Adding a partner product containing thiophanate-methyl is a strategy which is well worth considering.”