Desiccating cereals pre-harvest might help growers improve combine efficiency and guard against mycotoxin contamination of grain, say experts.

Combining speed can be up to 2km/hr faster in glyphosate-treated wheat with fully dry straw, compared with crops with similar grain moisture, but “green” straw, says Claas combine manager, Paul Moss.

Feedback from drivers of the firm’s 580 Lexion showed speeds were typically 4.5km/hr in 10t/ha crops with a 9m cutterbar, against a possible 6.5km/hr in dry, glyphosate-treated crops, he says.

“Green material feeds into the combine far less smoothly than fully dry straw.

Concaves have to be set closer to give the right separation if grain losses are to be minimised and the straw chopper needs half as much horsepower again to tackle it.”

With fuel at 36p/litre and labour at £10/hr, a 2km/hr increase in harvesting speed could save about £2.50/ha on combining costs, he estimates.

Moisture transfer from green straw to the grain during combining can also add to drying costs and increase the risk of storage problems, he says.

“The longer the ripe crop stands around in the field, the greater the opportunity for ear infections to develop,” adds Agrovista’s technical manager, Mark Hemmant.

Prompt harvesting is one way of reducing the risk, but a pre-harvest desiccant can give users a head start in preventing mycotoxins such as ochratoxin A being produced from fungal infections in store, he says.

Desiccating can help control weeds such as couch, thistles and late-germinating bindweed, if they are still green.

It can also help growers with large areas manage their combining schedules more efficiently by evening up ripening and increasing efficiency, he says.

paul.spackman@rbi.co.uk