Weed control essential for sward productivity at this time of year (2025)

Usually as grass growth begins to takes off on farms and soil temperatures rise, weed control can become a difficult and sometimes overlooked task.

The persistence of weeds like chickweed, thistles, or docks can be very damaging to the productivity of any sward, and is economically costly from a control point of view as well as in loss in production terms.

Weeds will be in competition with grass for nutrients, light, and water, and will reduce the area available for grazing. If these swards are getting cut for silage or hay, the palatability will be reduced.

Beef and sheep advisor at the College of Agriculture, Food, and Rural Enterprise (CAFRE), Jack Friar said, in relation to weed control: “A good start is to walk the fields and assess them for signs of weed growth”.

According to CAFRE, weed infestations should be measured. For every 1% infestation of the sward, such as thistles and docks, grassland productivity and forage quality will be reduced by 1%.

Docks

The best way to control weeds on farm is through integrated pest management (IPM), which is not only a more sustainable way of controlling perennial weeds, but is also a more cost-effective method.

IPM is simply a way of controlling weeds throughliming; crop rotation; drainage, and cultivation techniques, rather than using pesticides.

To apply the principles of IPM to a dock infestation, the farmer should walk the fields to evaluate the following information:

• The level of dock infestation and other weeds;
• Stocking rate;
• Fertiliser application and type;
• Soil sample analysis;
• Silage cutting;
• History of dock treatment and products used;
• Poaching and supplementary feeding;
• Slurry application;
• Grazing management;
• Drainage.

This will help the farmer to make the decision on whether they are going to go down the route of an IPM or the chemical route, or a combination of both.

A farmer may take the option of selecting a herbicide and blanket spraying when the docksare green, growing,and are at the rosette stage.

If it is an old pasture that is constantly giving trouble with weed infestation, reseeding is the best option, and preferably in the spring, rather than the autumn, as the grass seed establishment is supported with better weather.

In terms of your chemical control, use herbicides to targets the docks and other weeds before they reach 10cm in height or five to six weeks after reseeding.

Good fertiliser rates to match your stocking rate, rotational grazing, rotating silage fields for cutting, and topping fields when necessary, are good grassland practices that are needed to maintain a clean pasture.

Late April to early May, or again in late August, is the best time to spray docks and products with active ingredients of fluroxypyr and triclopyr will give much better control and products like ProClova will control the dock while protecting the clover.

Weed control

Thistles are common in older swards that are low in nitrogen and phosphorus but high in potash and the best point of control is when the plant is actively growing at the full rosette stage.

Products based on the active ingredients triclopyr and clopyralid will give a high degree of root kill, but it can be hard to kill thistles without impacting on the clover plant.

Chickweed can also be a major burden in grassland swards and can completely smother the grassland if it is not controlled effectively.

Products containing fluroxypyr will control chickweed when temperatures rise and these products will not stunt grass growth according to CAFRE.

Ragwort is a poisonous weed to livestock and should be controlled immediately. If a few are appearing, they should be pulled from the ground, ensuring the full root is removed.

However, if there is a large infestation of ragworth, spraying should be the protocol and should be carried out once there is active growth.

Sprays such asMCPA, 2, 4-D (D50) and Forefrontprovide good control but measures must be taken to avoid stock eating any dying or dead ragwort present. It will usually take four to six weeks for weeds to decay.

Before going out and controlling weeds in your swards, you should consult with your advisor what products will suit your needs.