Getting glyphosate right in harvest management

Timing

Getting the glyphosate timing correct this season will be especially challenging in oilseed rape crops that have compensated for damage from flea beetle larvae with late branching and extended flowering, leading to a wide spread of pod maturity throughout the canopy, he says.

“There is absolutely no advantage in spraying glyphosate before rapeseed moisture levels drop below 30 per cent. Rather than bringing combining forward it just means crops take longer to dry down. It is important to hold off on spraying until two thirds of seeds show that classic change from green to brown.

“The same 30 per cent moisture level applies to pre-harvest spraying in cereals. This is reached when all the grains from the centre of the ear hold an indentation from a firm thumbnail press.”

Coverage

With the biggest challenge with glyphosate getting it into the plant, medium-coarse sprays, together with water volumes, pressures and settings giving thorough canopy coverage and penetration are important, with applications early in the day useful in hot weather, says Mr Scanlon.

He highlights the statutory minimum interval from glyphosate spraying to combining of 14 days for OSR and seven days for cereals but adds that the time taken for crops to dry down depends on the weather.

Crops should only be combined when they are fit – which may be up to three weeks after spraying in some cases for oilseed rape, he adds.

Valuable

“As well as coming to harvest more promptly and evenly, crops managed with Roundup are invariably easier and more efficient to combine, with valuable savings in time and diesel.

“Do remember that seed crops should never be treated; no amount of adjuvant can make up for insufficient glyphosate; and both pre-harvest and subsequent stubble treatments should be carefully integrated with cultivations to guard against resistance development.”