THE loss of neonicotinoid seed treatments has led to AHDB pushing more resources into improving the understanding of barley yellow dwarf virus (BYDV) and its risk to cereal crops.

It is to invest £60,000 in research into the disease following the decision by the European Commission (EC) to ban outdoor use of neonicotinoid seed treatments, which are used to protect cereal crops from BYDV infection by aphid vectors.

This latest research will deliver results during autumn 2019, just as winter cereals without the option of a neonicotinoid seed treatment are being drilled.

In untreated crops, BYDV can cause average yield losses of 8% in wheat and 2% in barley and in most of the key cereal producing regions in the UK, the grain aphid is the main virus vector.

Charlotte Rowley, who manages pest research at AHDB, said: “Seed treatments affected by the ban will need to be used up by December 19, 2018. That means alternative control measures will be needed next year.

“Although full-rate pyrethroid sprays can provide effective control of aphids, they are becoming increasingly resistant, though at present this is limited to moderate levels of resistance in grain aphids. But knowledge about BYDV risk needs to be improved to make sure sprays are only ever used as a last resort.”

The search for new data is essential, as little research has been conducted in the UK this century. The research will look at the potential to generate field-specific risk forecasts for BYDV in wheat, barley and oats. It will also update guidance to inform BYDV management strategies.

Commercially, some chemical businesses are already gearing up advice on managing the disease. According to Bayer experts, an integrated pest management approach to controlling the aphid vectors that transmit barley yellow dwarf virus (BYDV) will be needed.

That means consideration should be given to drilling later, the use of aphid monitoring systems, regular crop walking and only using pyrethroid insecticide sprays where necessary.

Claire Matthewman, for Bayer, said that if an aphicide spray is necessary (Bayer makes Decis (deltamethrin)), then growers should use a full recommended dose and optimise the timing of the spray, instead of increasing the number of sprays. This will reduce the chance of aphids developing resistance to the insecticides.

She added: “Using the T-sum calculation, based on air temperature and establishment timescales, can help growers work out the optimum time to spray. Aphids only breed at certain temperatures and T-sum calculation is a reliable predictor of when that will be.”

* T-sum is calculated by subtracting 3°C from the average temperature each day and adding the result to the running total. When the T-sum reaches 170, it’s an indicator that the second wingless aphid generation could be starting to emerge. When the T-sum reaches 340, significant aphid activity is likely and BYDV spread will accelerate.