Narrow spray window this spring for weeds in OSR

The race is on to tackle broad-leaved weeds in forward oilseed rape crops before they reach the green bud stage.

Saturated soils have prevented growers from getting out into the field and with oilseed rape and broad-leaved weeds advancing quickly in the mild weather, the window of opportunity for spraying is becoming smaller.

Independent agronomist Luke Cotton says those growers wishing to go on with a Galera or Dow Shield product must prepare now to make the most of the opportunity when it comes along around early March.

“A lot of these August-drilled crops and hybrid varieties such as Excalibur are really forward so I am working out a strategy for them now,” he says

Mr Cotton, who is based in Buckinghamshire, says where charlock has survived the winter then Fox (bifenox) will take care of it and growers can go on as soon as it is dry enough to travel.

“Galera, based on clopyralid and picloram, will be the main spring-applied herbicide which will control a wide weed spectrum including cleavers,” he adds.

“Where cleavers aren’t so much of a problem Dow Shield (clopyralid) will control weeds such as thistles and mayweeds which we’ve seen a lot in headlands,” Mr Cotton says. Dow Shield cannot be used until 1 March.

Getting control of these weeds in the spring will be important in helping reduce the seed return and lower the spend in following crops.

Galera is recommended from the four-leaf stage of the crop up to just before the flower buds are visible.

This cut off is usually at the end of March or beginning of April, but with advanced crops this may be earlier, according to David Roberts of Dow AgroSciences.

He says applied at 0.35 l/ha, Galera will give excellent control of cleavers, mayweeds, creeping thistles and sow-thistle.

“To get the best results on cleavers, conditions will need to be warm before and after application and the weed less than 150mm high. Groundsel is also well controlled up to the six-leaf stage,” he adds.