Buttercups in barley

[5312]

We had 20 acres direct drilled about a month ago with spring barley. It should have been sown last autumn.

Over the winter a lot of buttercups took hold. It was sprayed with Rodeo a week after drilling, it has killed the grass and thistles but not the buttercups.

Is it worth spraying again to kill them or will they be harmless?

 

[neilo]

I don’t know about their effect in cereals, but in grassland they produce a hormone that reduces growth of surrounding plants IIRC.
A (cheap) squirt of 2,4D will see them sorted, for this year anyway.