INCREASING LEVELS of brown rust in a range of varieties over recent weeks could pose a serious threat to output this season, experts have warned.

The disease has particularly affected Claire, Consort and Solstice, prompting speculation that a new race of the fungus may be present.

“This season we’ve been seeing it nibbling away for most of the year, even on Claire and Robigus, which is unusual,” said ADAS pathologist Bill Clark.

Normally the disease appears in autumn and fades away in cold weather, only re-emerging in hot weather when crops are close to ripening, he added.

Unusual weather patterns this season could be responsible for increased levels of the disease, said Bill Angus of Nickersons.

“It’s a sporadic disease. It is subject to big temperature changes which we as breeders really haven’t a clue about.”

Neither expert believes that the increase in brown rust this season is due to changes in fungicide products and the disease is relatively easy to control, Mr Clark added.

Problems with the disease this season could mean the resistance rating of new variety, Alchemy, could slip from its current score of 9, Mr Angus believes. But companion variety Hyperion will stay at 9, he predicted.

For more on Brown rust and the first confirmed case of tan spot in the UK, see this week’s FARMERS WEEKLY magazine (July 8).