Midge bring other evils

WHEAT GROWERS have been warned to be on the look-out for Wheat Orange Blossom Midge and the diseases they may bring to crops.

There are husbandry factors that make a plant more susceptible to attack, according to senior wheat breeder at Nickersons Bill Angus.

These include growing a midge susceptible variety, mis-timing a growth regulator application, or failing to correct nutrient deficiencies.

This can bring ergot or fusarium into the ear, he warned, as he believes it is no coincidence that a bad year for midge is also a bad year for ergot.

“It is vital the male and female parts mature at the same time – so that pollen is released when the stigma is most receptive,” said Mr Angus.

“Any delay in pollen release will reduce floret fertility and result in gaping florets – an open invitation for ergot infection.

“Insects, midge amongst them, then can act as a vector for ergot spores.”

Blossom midge are a particular threat following rain, which moistens the soil and allows them to hatch from their cocoons.

They like to fly on still evenings when air temperature is 15°C or above.

Their eggs hatch within the florets and develop into larvae that feed on the immature grain, reducing grain yield as well as degrading quality.

Sprouting will also be initiated – which will pull Hagberg falling numbers down.

“The threat of ergot and Fusarium infections from uncontrolled midge is very real in some areas,” said Mr Angus.

“As well as using a tolerant variety, farmers should avoid drilling too early, and make sure the crop does not suffer from any copper aor boron deficiency, as these will also reduce ear fertility.

A DEFRA LINK project has recently established that some varieties, such as the Group 2 breadmaker Einstein, have a high level of genetic tolerance.

An application of chlorpyrifos is advised in high risk situations, where midge numbers exceed threshold levels of one midge per six ears.