Reseeding your pasture isn’t cheap. So giving your reseed every chance to establish and thrive is a no-brainer. A well-timed grassland herbicide spray six to eight weeks after reseeding (when there are three leaves on the grass and one true leaf on the clover) is the most cost-effective spray a farmer can use on that field.

Killing your key grassland weeds such as docks, thistles and chickweed at the seeding stage will give your new reseed the best chance to successfully establish. Subsequently, as your reseed develops, the grass will naturally out-compete many other grassweeds, helping to maximise the yields and productivity of your sward over its lifetime.

However, reseeding grassland where clover in the mix is set to become increasingly challenging over the next number of seasons.

2,4-DB

2,4-DB is a key chemical active found in herbicides suitable for use on grassland which have been reseeded with a grass and clover mix. The active will be withdrawn from the market in October 2020.

Some of the well-known brand names which contain 2,4-DB are Underclear, Legumex DB, Clovermax, Undersown and Headland Spruce.

The decision to withdraw support for the re-registration of the active on the European market will dramatically reduce clover-safe herbicide options available for weed control on ground reseeded with clover in the sward.

All sprayers which are more than five years old and have a boom width greater than 3m must have passed a Pesticide Application Equipment Test by a DAFM-approved inspector.

Farmers will be able to purchase herbicides containing 2,4-DB until 31 October 2020. Use of these will not be permitted after 31 October 2021.

Reseed weed control

Control of challenging grassland weeds is much more effective when these weeds are seedlings. However, with no suitable alternative clover-safe herbicide for reseeds on the market, farmers will have to rethink their reseed and weed control strategy.

This means farmers will be forced to broadcast or stitch clover into an established grassland after using a non-clover-safe herbicide. There are a number products available for reseeds such as fluroxypyr, florasulam, and clopyralid which are effective for controlling weed seedlings but will also kill clover. However, applying these herbicides and getting good weed kill before sowing clover at a later date still makes economic sense.