Sugar beet crops could be at greater risk from pests and diseases if recent changes to the industry mean that growers taking on extra quota opt for larger areas and tighter rotations.

That is the warning from several industry experts, following negotiations by British Sugar that will see more contract flexibility and quota trading.

“It is inevitable that beet growing will become more intensive, particularly in the east, which in turn will put more pressure on crops,” says independent consultant Bob Symons.

Alongside diseases such as downy mildew and virus yellows, soil pests, including wireworm, pigmy beetle and millipedes, could become bigger problems.

“We’ve already seen increased wireworm in potatoes and the same might happen to beet,” says Mr Symons.

A trend towards later lifting and milder autumns could also lead to disease symptoms expressing themselves for longer in the season, so that seed treatments and fungicides will need greater persistency of control, he adds.

Broom’s Barn’s Alan Dewar agrees, highlighting beet mild yellowing virus, alongside rhizomania, as one of the key threats to yield.

“Virus yellows is potentially the most yield-robbing disease of beet, although it is not recognised as such because of the seed treatments available to combat it,” he says.

Once infected, plants can lose bulk and sugar throughout the season – possibly up to 35% yield loss from an outbreak starting in May, he says. “You have to stop infection occurring in the first place.”

Dr Dewar also thinks soil pests, such as pigmy beetle in particular, could become bigger problems if beet is grown more intensively. He estimates that 20% of soils have some form of arthropod soil pest that can be controlled by chemical methods, such as seed treatment.