Forecasts suggest aphids will appear later than last year and in low numbers.

Experts for the Rothamsted Insect Survey anticipate the first round of aphids to be captured in suction traps by the end of this week.

Dr Richard Harrington said: "Due to the exceptionally cold winter, these first flight predictions are more than two weeks later than last year's and about a month later than average. Potato aphid numbers are also expected to be much lower than average during the critical part of the growing season when potatoes are especially susceptible to viruses."

British crop planting was largely completed by the end of April. Subsequently spuds are likely to gain an extra fortnight before peach-potato aphids can affect them.

But Science & Advice for Scottish Agriculture's (SASA) Dr Jon Pickup added that growers of Potato Virus A(PVA) and Potato Virus Y(PVY) susceptible varieties will need to take account of non-colonising aphids that could transmit these non-persistent viruses before peach-potato aphids arrive.

He said: "In a potentially late aphid year like this, monitoring is more important than ever. Keep a close watch on the Rothamsted/SASA aphid bulletins and the Potato Council/Central Science Laboratory aphid monitoring website to inform decision making. As always, the need for thorough early 'rogueing' of all seed crops cannot be over-stated."

A less rigorous programme of spraying may be suitable for non-susceptible spud varieties.