With the development of both wheat crops and weed growth around three weeks behind this season, don’t be tempted to cut herbicide rates for cleavers control until it warms up.

That’s the advice from David Roberts of Dow AgroSciences, who points out there’s a danger of spraying too soon at rates that won’t be effective.

“The cold, late spring weather will have a bearing on control,” he remarks.

“The weeds have been frost hardened, the nights are still very cold and there’s a risk now it’s April, growers will be thinking about cutting rates.”

Sunny days will be adding to this temptation, he warns.

“Don’t be caught out, there are still frosts at night.

A period of growth is needed before cleavers can be controlled – certainly the hormone herbicides won’t work well in these conditions.”

Where Boxer is to be used, Mr Roberts suggests a full rate of 150ml/ha when temperatures are as low as 2-3C.

And if Atlantis (mesosulfuron-methyl + iodsulfuron-methyl-sodium) is still to be applied, then 100ml/ha of Boxer should be added to the tank-mix rather than 50ml.

Daytime air temperatures of 5C and above, together with soil temperatures of 6C, are suitable for Starane XL, he suggests.

“There will have been sufficient weed growth in these conditions. Go for 1.8 litre/ha, or 1.5 litre/ha if tank-mixing with Atlantis.”

Lower rates of Starane XL are possible later in the season, he admits.

“Then you can use 1.0-1.25 litre/ha. Of course, Starane 2 becomes another good option when air temperatures reach 10C.”

Cambridgeshire agronomist Paul Drinkwater of the Abbots Ripton Farming Company is in no hurry to get the cleavers spray on.

Responsible for 3732ha (9000 acres), of which 1450ha (3500 acres) is in winter wheat, Mr Drinkwater’s previous experience with Starane XL has taught him to be patient.

“We will be waiting until it warms up, so that we get very good control,” he confirms.

“There are plenty of other things to be getting on with in the meantime.”

Another cleavers option, Eagle, can now follow spring applications of Atlantis, notes manufacturer Bayer CropScience.

Previously the cleavers herbicide was only approved in sequence with autumn Atlantis.

fwarable@rbi.co.uk