WHEAT GROWERS should identify crops at high risk from Orange Wheat Blossom Midge now, in order to avoid a repeat of last year’s problems, experts have advised.

Last June, an exceptionally large midge hatch coincided with the most vulnerable period of ear emergence in susceptible varieties and cost the UK nearly £60m, the firm estimated.

“There is every chance this could happen again this year,” warned the firm’s technical services leader, David Roberts.

“All we need is warm, moist soils of 13^oC combined with wheat ear emergence in late May to early June.”

But it remains to be seen whether the same conditions arise this season, although growers should prioritise ‘at risk’ crops, with particular focus on premium milling wheats, added CPB Twyford agronomist, Simon Francis.

While it may take quite large infestations to affect yields, only a few larvae per ear can impair grain quality, he warned.

“Low level attacks can significantly reduce specific weights as a result of restricting grain fill. At the same time, any midge that grazes on grains will increase sprouting risks and produce exudates, both of which can wreck Hagbergs.”

Last year earlier flowering varieties, including Malacca, Soissons and Cordiale were worst affected, he said.

Recognised ‘resistant’ varieties include Welford, Brompton, Glasgow and Robigus, and while there is a degree of tolerance in some, all other varieties should be regarded as susceptible, said Mr Roberts.

OWBM control measures should only be applied once threshold levels have been reached, he advised.

Thresholds are one midge per three ears in feed wheat and one midge for every six ears in seed and milling crops when ears are emerging, he said.

Once the crop is flowering, it is no longer at risk, Mr Roberts noted.