WHEAT BULB fly poses the highest risk for many years this season, Dow Agrosciences has warned growers.

Field testing in Cambridgeshire and Lincolnshire by ADAS has recorded exceptionally high egg levels, according to Dow Agrosciences.

Of 20 fields tested, half exceeded the “high risk” of damage threshold of 2.5million eggs/ha, and four recorded over 5 million eggs/ha – “very high risk”.

“Growers who are in high risk areas should know what to expect,” said the firm‘s David Roberts.

He advised growers to carry out a risk assessment based on geography, rotation and state of crop and prepare to spray chlorpyrifos at egg hatch if the risk is sufficiently high.

Cold conditions over Christmas and more recent milder weather means there is a danger egg hatch could have started already, although no evidence had been seen yet, he said.

Growers should keep a close eye on all crops at obvious risk, especially November and later sown wheat drilled in wet conditions, said RAGT cereals technical manager, Cathy Hooper.

She recommended rolling, correcting manganese deficiencies and applying nitrogen early to encourage spring growth to aid recovery from damage.

Growers who believe they are at risk should consider how much chlorpyrifos they require, as stocks are unlikely to be widely available for 2005, after large demand last season, Dow advised.

Stocks were depleted in the summer following the high wheat blossom midge outbreak and North African locust problems, which are still continuing, the company said.