The UK's sodden summer cost it three places in Europe's wheat yield league, analysts have revealed, amid growing expectations that the wet conditions since will prompt a mass switch to spring barley for 2013.

Coceral, the Brussels-based industry group, trimmed 123.97m tonnes, from 124.69m tonnes, its forecast for this year's European Union wheat harvest, pegging the decline from the 2011 result at 5.4m tonnes.

The downgrade reflected in part a further cut, of 250,000 tonnes, to the estimate for the UK crop, which has been dubbed the worst in a generation, with yields hitting a 20-year low, and bushel weight, a key quality test, dropping to its weakest since records began in 1977.

The result reflects the wettest UK summer in a century, which has been followed by a rain-plagued autumn and early winter too, hurting production of a range of crops.

Separately, the UK's Potato Council estimated the domestic potato harvest at 4.64m tonnes, down24% year on year, and the weakest result in 36 years.

'Slugs are a problem'

Coceral pegged the average UK wheat yield - typically the best among the major producing countries, in part because of a stress on more productive feed varieties – at 6.7 tonnes per hectare.

That demoted the UK from fourth to seventh in the yield table, falling behind Denmark, France and Germany, if remaining well above results from Eastern Europe, where dry weather in some areas added to penalty from relatively less advanced production techniques.

And the data comes amid concerns for the 2013 harvest too, after data from consultancy Adas showed that only 75% of winter crop was planted as of the end of last month, compared with the 100% typically, and with much of what has been planted in poor condition.

"Crop establishment has been less than ideal and slugs are a problem in many areas," Helen Plant, at the HGCA crop bureau, said.

Seed squeeze?

Indeed, the bureau restated a warning by consultancy Andersons over a shortage of spring barley seed, given the prospect of a huge switch to the grain to fill fields which growers have been prevented from planting with winter crop, or which require reseeding thanks to crop damage.

"Poor weather this autumn has hampered winter crop planting and has created uncertainty around the condition of some crops, largely oilseed rape," the HGCA's Lloyds Dixon said.

"Spring barley offers a relatively competitive gross margin. But seed availability is likely to be a limiting factor. It is logical to assume that a large proportion of the spring cropping could be barley."

Andersons said last month that "seed availability could change" ideas of a jump in spring barley sowings to their highest since at least the 1990s.

"Land destined for spring barley [is] also likely to be cropped with spring wheat or spring oats should there be insufficient seed available."