Although spring reseeding generally leads to a more successful establishment of the sward, it is important that from the time of establishment, the sward is carefully managed.
Spring reseeding often offers a better opportunity for post-emergence weed control, and so, the opportunity to do so, should not be overlooked.
The optimum time for good control of weeds in a new reseed is 6-8 weeks after reseeding; when there are 3 leaves on the grass
Controlling weeds in a young reseed is the best opportunity for long term clean swards. Once established, the root of a dock plant can be in excess of 1 metre deep, making it a very difficult plant to kill. Furthermore, a single dock plant can produce over 60,000 seeds per year, therefore it pays to eliminate them early.
Seedling docks are much easier to eradicate from your sward in the early days compared to established dock plants, and the same can be said for the most common grassland weeds. These include perennial weeds such as docks and thistles, as well as annual weeds like chickweed.
Which weeds to be concerned about?
Annual weeds such as fumitory, fat hen, and deadnettle only live for one year. These weeds should not affect the establishment of the new sward, unless they are present in high numbers – if so, spray them. They are normally removed by grazing, cutting or leaving them to die naturally over the winter.
Perennial weeds such as docks, dandelions, creeping buttercup, and creeping thistle should be controlled in a new ley to avoid an increase in plant population down the road. Chickweed is also a problem weed in new reseeds, especially with autumn sowings, or when the grass is slow to establish.
Choosing a suitable herbicide
There are a range of products available and approved for new leys. Product choice is decided by the presence or absence of clover. Ensure the product is approved for new leys and seek advice from a qualified advisor. Clover safe sprays suitable for new leys include CloverMax, Legumex DB, Undersown and CloveX; remembering that CloverX cannot be used after 30th June 2020. Non-clover safe sprays approved for use in new leys include Pastor Trio and Envy.
Key points to note when applying herbicides
- Ensure the sward is even and growing vigorously. Avoid spraying in very dry or cold conditions.
- Spray 6-8 weeks after reseeding when there are 3 leaves on the grass and 1 true leaf on the clover. If clover is present, ensure you use a clover safe spray.
- Apply the herbicide onto small, actively growing weeds (e.g. dock leaf = size of €2 coin).
- Adhere to advised application rates on the product label and keep water rates high.
- Always read the label before use.
- Never fill sprayers from watercourses.
- Do not spray in windy conditions or when rain is forecasted.
- Adhere to product label guidelines for timeline between application and grazing.
- Remember to keep the prescribed cross-compliance records and follow the product label.
- Only registered professional users can apply professional use herbicides.
- Discuss with your merchant/advisor if you have any queries
When to get the new reseed back to grazing
Before you consider grazing the new reseed, it is very important to check the label on your post-emergence weed spray, to see when the sward can be grazed. This early grazing is critical to help tillering of the sward, and so, it is encouraged once ground conditions allow. Often cows will do a better job than calves, as although they are heavier, they will graze quicker and can be removed from the new reseed much sooner. This is more of a possibility in spring; as it is dependent on ground conditions being firm enough.