Best Practices for Managing Newly Reseeded Pastures for Weed Control

The most challenging factors in managing a new grass reseed are based around weed control and pest control. Teagasc trials have shown that killing weeds in the first 2 months after re-seeding will have a long-lasting effect (up to 4 years).

There are some key steps for Weed and Pest Control to Support Your Reseeded Grass:

3. Remove Perennial weeds at seeding stage:

Perennial weeds (Docks, Creeping thistles, Buttercups, Dandelions) are programmed by nature to recover from cutting, grazing, hard winters and dry summers.They all develop a massive root system to store food until it is needed. This is how they can emerge each spring and out-compete grass no matter how well it is managed.Recent Teagasc Dock trials have shown that once the Docks were successfully removed at seedling stage, the grass took over the job and prevented new Dock seedlings from establishing for 4 years!

4. Chemical control against high population & certain weed varieties germination.

Low populations of annual weeds will not affect the establishment of the new sward. Where they survive the first grazing, topping, or cutting can eliminate them, but high populations of annual weeds, especially Charlock & Chickweed, can compete against establishing grass. Chemical control is a good option in this situation as the gaps left after these annual weeds die off in the autumn are ideal places for docks to germinate and grow over the winter months. Chickweed is especially problematic and should be controlled in most situations.

5. Low populations of Perennial Weeds can be tolerated:

Docks, Dandelions, Creeping Buttercup, Creeping Thistle – can be tolerated, especially in an intensive grazing situation. It is rare for any weed to become problematic in a well-managed grazing field.

6. Soil drainage, fertility and grazing management will influence whether a problem occurs in the future.

For example, poaching favours dandelions and buttercups becoming established, while high levels of potassium favour docks becoming established.
In a silage field, under an extensive grazing system, where clover is sown or where these weeds are numerous, my advice is to apply a herbicide to the new ley.

7. Get the basics right for weed control for new pasture from the start and Past the 1st Year

the first point of weed control in new leys is to have an even, vigorously growing sward. Seedbed preparation, soil fertility and seeding rate are key points to get right. In order to help the crop tiller out, keep grazing low and it is preferable to not cut silage from a new sward in the first year. Where this cannot be avoided, cut at a higher length than older swards.

For more information or assistance, contact the RED MILLS agronomy team.