A tricky oilseed rape harvest, beset by very dry weather, is likely to produce a lower national crop this season as experts downgrade their yield predictions.

Growers have been holding off cutting due to low moisture levels, so this weekend’s rain may actually help combining crops that still have to be cut in northern England and Scotland.

Owen Cligg, trading manager at co-operative United Oilseeds, is looking for an average yield of 3.4t/ha after estimating 3.5t/ha pre-harvest and compared with 3.9t/ha last year. However, he warns this may go lower as harvest progresses north.

“We have seen very variable yields between 2.5t/ha and 4.5t/ha, very dry seed and there are worries about next year’s crop with the lack of moisture,” he told Farmers Weekly.

See also: Harvest 2018: English harvest disappoints but Scots happy

Rapeseed crushers have difficulty in processing seed below 6% moisture, so many growers have cut early in the day with morning dew on the crop, while further rainfall will probably be needed before drilling the new crop can start.

A 3.4t/ha yielding crop across more than 600,000ha is set to give a 2m-tonne harvest, down from 2.2m tonnes at harvest 2017 from a smaller area but boosted by that higher yield of 3.9t/ha.

Philip Kimber, oilseeds trading manager at Frontier, sees rapeseed yields down this year, with about 60% of the national crop cut by the start of this week.

He added that rapeseed prices have responded to the lower-potential crops in the UK and in most of continental Europe, with November prices currently about  £315/t ex-farm before any oil bonuses.

However, any further rises might be capped by a potential big US soya crop, as users could substitute soya for high-priced rapeseed.