ALL EYES are on devastating soyabean disease Asian bean rust to see if its arrival in the USA leads to crop losses that could top $2bn, pushing global feed grain prices higher.

But fears that US fungicide demand could raise UK fungicide prices were played down at the annual conference of the US National Alliance of Independent Crop Consultants in Los Angeles last week.

The $2bn loss is the worst-case scenario painted by USDA economists, following the disease’s arrival in the southern USA last September, when hurricane Ivan swept spores up from South America.

Much now hinges around the pathogen’s ability to overwinter on host plants in southern states and how quickly it can move north through the USA’s huge 31m ha (74m acre) soya crop.

“The disease can explode before your eyes,” USDA expert Kent Smith warned. Total defoliation can take just two weeks, leading to 90% yield loss.

Even if fungicides are used, US soya output could drop by as much as 9.5%, the USDA believes. That would represent a $2bn loss to US farmers, pushing feed grain prices higher as markets are left short around the world. But fungicide supply should meet demand, particularly since the entire crop is unlikely to need treating, said Dr Smith.

That was echoed by Bayer’s Jim Bloomberg, who felt it unlikely that European fungicide stocks would be affected. Production of Folicur (tebuconazole), which is particularly effective against the disease, has been stepped up at the firm’s global manufacturing facility in Kansas City.

“We, as Bayer, have drastically changed our production to meet the need.”

Triazoles, strobilurins and chlorothalonil are all effective against the disease, but epoxiconazole (Opus) and flusilazole (in Punch C) have yet to receive emergency EPA approval for use in the crop, he noted.

In the UK, Masstock’s Peter Corbett has forecast an 8% rise in triazole price this season, mainly driven by raw material costs. Andy Selley for DuPont UK believes global triazole demand will rise by a third as a result of bean rust.