Specialist Norfolk scientists have advised sugar beet growers how to minimise crop virus risks this spring – and revealed the experimental ideas which could help them in the future.
Earlier this month, researchers published a worrying forecast which estimates 62pc of the East’s sugar beet crop could be affected by virus yellows (VY) in 2026, if no control measures are taken.
It also predicts the first aphids – which spread the damaging disease – will begin flying on April 22, guiding farmers on when to check their crops for yield-threatening infestations.
Dr Alistair Wright, head of crop protection for the Norwich-based British Beet Research Organisation (BBRO) said the forecast is “not as bad as it was in 2020 when VY was really rife.”
But, in the absence of banned neonicotinoid pesticide seed treatments, he said rigorous crop monitoring for the first signs of aphids, optimising the timing of the three available foliar sprays, and good agronomy were key tools to protect beet crops.
Dr Alistair Wright, head of crop protection for the Norwich-based British Beet Research Organisation (BBRO) (Image: BBRO)
“We are better prepared now,” he said. “I think people are generally a lot better at finding and counting aphids, and we’ve got a better array of foliar sprays as well that should protect the crops sufficiently to get through the main risk period.
“But it’s not as straightforward as applying a seed dressing and leaving the crop to fend for itself. So regular monitoring is required, because spraying in a timely fashion is crucial.”
He said other considerations include choosing disease-tolerant beet varieties, and using spray options which don’t adversely affect beneficial insects like ladybirds – natural predators which can help control aphids.
Meanwhile, with the forecast model assuming a sowing date of March 30, farmers are advised that “earlier sowing will reduce VY risk, and later sowing dates will increase risk”.
Dr Wright added: “There is no silver bullet. It is a case of stacking all these technologies on top of each other and taking it on a field by field basis. It is labour intensive, but we need to monitor and appreciate the risk.”
For the longer-term, some novel new solutions are being explored to repel or confuse aphids without the need for chemical pesticides.
The BBRO has sprayed trial sugar beet plots with coloured dyes to camouflage the plants and confuse virus-carrying aphids (Image: BBRO)
“For the last three or four years, we have been using red, green and blue dyes on [sugar beet] plots, and got some really promising results where they have reduced the numbers of aphids on the plant,” said Dr Wright.
“The main effect is removing the plant/soil contrast. That is how the aphids find the plant, so anything you can do to remove that contrast helps.
“We’re now looking at scaling that up to find out if it works on a field basis, and then finding the correct products to actually produce that effect on a field-wide scale.
“So it’s not finished, but it’s really promising steps in the right direction.”
Virus-carrying aphids on a sugar beet plant (Image: BBRO)
The BBRO has also been working with French company Agriodor, which markets an aphid repellent scented with cloves and cinnamon.
“It smells like a Christmas candle, quite a pleasant smell,” said Dr Wright.
“We’ve tested that two years now. We haven’t had years that have been particularly favourable for testing, but the French data sets are quite compelling.”
BBRO scientists are also collaborating with the John Innes Centre and British Sugar to develop crops with heightened disease resistance, using new technologies such as gene editing.
North Norfolk beet grower and NFU Sugar chairman Kit Papworth said virus yellows is “hugely problematic for sugar beet growers”.
“The worry here is we are going to have very young plants which are very vulnerable to aphids and VY at just the wrong time, and we’ve got very few chemical options,” he said.
“It reminds us as an industry how reliant we are going to be in the future on genetics and finding tolerant varieties.
“For now, it’s about vigilance. We know that once we get to the middle of April, we’re going to need to be in that crop every day, looking under leaves, finding and identifying aphids, sending them into the BBRO plant clinic, and then working on [spray] thresholds, because there’s no point in spraying too early or running out of chemistry.
“We’ve just got to get the timing exactly right to make sure we make the best use of what little chemical control we’ve got, until we can find genetic solutions for this.”