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Managing ear diseases at T3

Within the UK, T3 sprays are often overlooked. But, based on UK research and lessons from Germany, there are clear benefits to yields and quality to be seen.

With ear development fast approaching for growers across the country, we look at monitoring trends to understand the predicted risks from ear diseases, to see where a well-timed T3 spray at flowering will come into its own.

Dr Philip Jennings, Principle Plant Pathologist at Fera, has studied the trends of Fusarium and Microdochium species for several years, and has a wealth of knowledge on the subject that paints a bigger picture of the issue in the UK.

“1998 was the first big year for Fusarium ear blight (FEB) infection, with 60% of samples from the winter wheat survey assessed with FEB symptoms, with the majority of these symptoms 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 however, that across Europe the predominant species responsible for the disease were toxin producing fusaria such as Fusarium graminearum,” says Dr Jennings.

“Since then, Fera has monitored the progress and prevalence of the main pathogens responsible for FEB symptoms in the UK, and to date we’ve seen some noticeable trends,” he explains.

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% and 98% of samples, respectively, had FEB symptoms, caused by Microdochium species. 

“The peaks in disease have arisen when we’ve 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 that conditions were ideal for infection by FEB pathogens.”

Dr Jennings also explains the change in the type of deoxynivalenol (DON) producing fusaria infecting crops since 2003.

“We’ve seen that Fusarium graminearum has taken over from Fusarium culmorum as the more dominant species. Generally regarded as being the more aggressive species due to the production of windborne spores which allows it to spread further, we’re 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%.

“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,” he says.

The situation in Germany

In comparison, Germany has historically suffered at the hands of Fusarium, with toxic species influencing mycotoxin levels seen in crop samples.

Following the 1998 harvest, high DON levels were discovered in baby food. As a result of this, in 2006 EU legislation was introduced that now stipulates the mycotoxin threshold levels allowed in food sources.

Hence, T3 protection against the disease has become standard practice in the country.

Like the UK, Germany’s Fusarium problem is relatively regional, mainly affecting the south east where higher rainfall and temperatures are recorded at the time of flowering.

Dr Katharina Treyse-Künne of Spiess Urania, explains how in the south of the country growers are spraying against Fusarium species, with up to three sprays in some cases, culminating in a final treatment during flowering when the risk of infection is at its highest.

“We know from experience that 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 to extend late season Septoria and rust protection.”

Managing Fusarium

Zantra agronomist and Technical Director Chris Bean, explains that there is a key role for T3 treatments in the UK to prevent yield losses, reductions in specific weights and mycotoxin issues.

“This year has been very similar to last year, with a dry and cool April which has resulted in low levels of Fusarium inoculum at the base of the plants,” explains Mr Bean.

“At present the risk of a high Fusarium year is low, however, this can all change in the coming weeks, if the temperatures rise and we have more rainfall at flowering.

“A number of fungicides are available for use at T3, but are mostly triazole based. Adding a partner product containing the active substance thiophanate-methyl, such as Taurus or Topsin, is a strategy which is well worth considering.

“We have been conducting trials over recent years with thiophanate-methyl products against a range of T3 diseases including the Fusarium species, with some surprising yield responses.

“We’ve found that whereas a standard T3 application usually offers a response of around 0.25t/ha, the addition of thiophanate-methyl has often doubled this response,” says Mr Bean.

T3 is an important timing in terms of Fusarium control. The value of which should not be underestimated in the UK. With the use of a cost effective thiophanate-methyl option growers can protect their crops and deliver the yields and quality required.