Effective spring weed control timing critical

With the first signs of spring growth evident, weed control will now be front of mind for grassland farmers.

In many pastures, broad-leaved weeds will be easy to find, and there will be a temptation to control these as soon as possible. However, uptake by many weeds will be relatively poor at present as air and soil temperatures have remained low for such an extended period, says Andrew Speed, Technical Manager for Headland.

Young leaves are needed for best results and more difficult species such as broad-leaved docks need to be topped, and herbicide applied once four plus new leaves are present. Plants then take up larger amounts of herbicide more quickly and efficiently, resulting in improved kill, he says.

It is important that an effective herbicide with a wide weed spectrum is applied at the correct timing: Cimarron, a sulphonyl urea herbicide, is ideal for control of broad-leaved docks, and with additional tank mix partners this activity is extended, and is in a user friendly soluble tablet formulation.

For farmers looking for a wider spectrum for both broad-leaved docks and general weed control, a tank mix of Cimarron with a 60% label dose of a phenoxybased herbicide such as Relay-P or Polo will speed up the initial effects on the target weed, as well as broadening the spectrum to include nettle, thistle, dandelion, buttercup and other troublesome grassland weeds, he adds.

Not only will this tank mix offer powerful weed control in a cost-effective manner for the farmer but also dual modes of action, to promote good resistance management practice, says Mr Speed.

Keith Hallett, Agronomist for Pearce Seeds Ltd, advising in the South-West of England applies the majority of his Cimarron at post-first cut silage in the spring: when the docks have re-grown and are at an ideal stage for treatment.

As a mixing partner Mr Hallett uses Headland Di-Farmon R. I use full rate Cimarron mixed with a reduced rate of dicamba and CMPP, in order to speed up initial effects in the docks and also to broaden the spectrum, to control difficult weeds such as thistles, buttercup and dandelion.

Dont forget that ragwort is also often found in mixture with other species, and being a poisonous weed needs to be dealt with, continues Mr Speed.

In trials last year looking specifically at ragwort, Cimarron in mixture with a 60% dose of Relay-P or Polo will give about 90% control of ragwort, whilst at the same time controlling other species being targeted, he says. Although the optimal timing for ragwort control is the rosette stage, the trials found that these mixtures control plants somewhat larger than this, and better than a phenoxy-based application alone.

Cimarron contains metsulfuron-methyl.

RelayP contains mecoprop-p, MCPA and dicamba. Polo contains 2,4-D and MCPA

Cimarron, Polo and Relay P are registered trademarks of Headland Agrochemicals.

Merfyn Parry, Agronomist for County Crops Ltd., advising in North Wales and the Cheshire borders has had experience with Cimarron, since its inception.

Cimarron may be used in the spring period, but I tend to treat the majority of my fields during the autumn.  This leads to exceptionally clean fields coming into the spring, which will yield the maximum amount of grass says Mr Parry.

As a mixing partner Mr Parry uses Headland Polo; I use 1.5-2.5 l/ha, the lower rate where we are looking to speed up the initial effects on the docks, the higher rate where we are looking to broaden the spectrum of the Cimarron to control difficult species such as dandelion and buttercups.