There are reports of an uncommon moth larvae infecting sugar beet crops across the east of England, raising fears of significant yield penalties as harvest nears.

Experts from the British Beet Research Organisation (BBRO) are advising growers to closely monitor crops for symptoms of the beet moth, which include blackening of the crown and the loss of new leaves.

They are also urging farmers with infected crops to review their planned harvest dates and consider lifting crops early to avoid further reductions in yield and quality. 

What is the pest?

A rare pest in the UK, the beet moth (Scrobipalpa ocellatella) is frequently found in mainland Europe, where it is associated with warmer and drier climates.

This summer’s hot temperatures, coupled with a dry and warm autumn, is thought to have favoured the moth’s spread and development, triggering its first attack on UK beet crops.

The pest has become more widespread since its initial reports in Suffolk and Norfolk.

One grower whose crops is significantly affected is Suffolk farm manager Edward Vipond, who first identified early symptoms of the pest back in July.

“This is the first time we have ever experienced anything like this. Every plant is affected by the larvae to some extent.

“We have almost no new leaf growth as emerging leaves are eaten or badly deformed. The issue is certainly not getting any better,” he says.

The symptoms are easily confused with boron deficiency, with blackening of the crown. It wasn’t until he did a closer inspection that Mr Vipond discovered a number of caterpillars causing significant leaf damage.

With no means of controlling the pest, he suspects 80% of his 130ha beet crop, which is spread over 20 miles, is now infected, causing real concern as harvest looms closer.

It is thought that continued warm, dry autumn conditions will favour the moth’s development into early October, causing further damage to crops and potential secondary pathogen infections.

No solution

Mr Vipond is not only concerned about the yield reduction from the loss of green area, but also potential taproot damage, which may lead to rotting and further yield and quality losses.

“The real issue is that we do not have a solution to the problem. The only way is irrigation to wash the caterpillars off the crop, but we don’t know how effective this would be.”

With the Bury St Edmunds sugar beet factory scheduled to open on 7 October, Mr Vipond plans to start harvest in the middle of the month.

He is aiming to lift a bigger proportion of sugar beet earlier in the season in a bid to overcome the moth infestation and avoid further losses.

But he admits this will mean missing out on the usual extended growing period and additional yield-building phase later-lifted crops get.

Source - https://www.fwi.co.uk