Fusarium may blight another cereal season

Fusarium ear blight could be a big disease headache again for cereal growers this summer as further wet weather may spark an epidemic like last year.

With plenty of inoculum carried over from last season on infected seed and crop trash, experts warn that rain at flowering in June could spell trouble for growers.

Of the many species that cause fusarium ear blight in cereals, they say a high level of microdochium is being seen as stem-based browning while Fusarium graminearum is seen on crop trash.

“We will have a problem this year if we get heavy rain. It is so dependent on weather in June,” says Jonathan Blake, senior research scientist with adviser ADAS.

Humid weather with rainfall before, during and after flowering is very conducive to the disease; these conditions produced wide-spread problems last summer, he adds.

The disease causes yield loss when ears become infected during flowering, but it can also produce mycotoxins in the grain, which are harmful to humans and animals.

No treatment gives 100% control, but an ear wash triazole fungicide applied at early- to mid-flowering is the best approach, Mr Blake says.

Phil Jennings, plant pathologist at the Food and Environment Research Agency (FERA) advises growers not to miss out on a fungicide spray, especially if it is wet through June.

“It’s all down to the weather, so growers should keep an eye on forecasts and look to apply a robust rate of an approved product at early flowering,” he says.

Microdochium was the big problem last year and is being seen on 90% of crops this year, but graminearum, seen on 40% of crops, is potentially a bigger headache as it can cut yield more sharply and produce mycotoxins.

Control is key at the T3 stage of early- to mid-flowering (GS61-GS65) and Dr Jennings says the triazole prothioconazole gives the best control of both microdochium and graminearum.

He adds that other triazoles, such as metconazole and tebuconazole, give some control of graminearum, but have little effect on microdochium.

“It is not worth missing a spray especially if it is wet, while graminearum can still spread in heavy dews,” he adds.

Dr Jennings points out the problem last year was that flowering lasted three weeks rather the normal one week, so there was a longer period for potential infection.

Alison Daniels, Bayer CropScience’s campaign manager for cereal and oilseed rape fungicides, says growers should assess the risk, select the right product and dose, and then get the spray timing right.

She points out that prothioconazole, as Bayer’s Proline, will control both microdochium and graminearum, but needs to be applied at a robust rate of 0.55 litres/ha.

“We need the high dose due to the difficulty in covering the whole ear and to allow the spray to last as growers should be aware of extended flowering such as happened last year,” says Dr Daniels.

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