The timing of reseeding is as always a topic of query and discussion at this time of year. Very often the answer is based on recent weather conditions. When it comes to this time of year, if conditions are appropriate, which they currently are, I am encouraging farmers to move on with getting the job done, as I am quick to caution later autumn reseeding due to inclement weather conditions such as frost and wet weather.
Seedlings need to be given the best chance of germination and time to establish growth; this will decline as the year moves on. Reseeding at this time of year, will also open the opportunity to graze young seedlings which will encourage tillering to give strong vibrant swards the following year. I generally advise that silage should not be harvested in the first year of the reseeded pasture as it takes eleven months to establish full cover on reseeded ground. It should be grazed with light livestock to encourage tillering at an approximate height of 6-7 cm.
Current grass growth is ranging from 30-80 kg per DM per hectare which would be below normal for this time of the year but this can change once the hours of sunshine increase. Soil temperatures are currently at 11OC – 13OC (Celsius) of which are normal for this time of the year in my area and this means weeds are also experiencing favourable conditions. I am not so concerned about the sites with low populations of annual weeds as this will not affect the establishment of the new sward. Where they survive the first grazing – topping or cutting can help eliminate them.
In the vast majority of cases where I am witnessing a greater presence of weeds, I advise applying a post emergence weed spray a few weeks after re-seeding as it is the cheapest and most effective spray you can apply to that grass field. This is especially the case where docks, chickweed, charlock, fat hen, redshank, creeping thistles, etc. had been growing in the old grass or have clover in your grass mix. The most suitable herbicides for control whilst protecting white clover in the sward are: Legumex DB, Underclear/Undersown and Alistell. Weeds in newly reseeded ground are best controlled when grass is at 2-3 leaf stage.
Slugs, fritfly and leatherjackets should also be monitored and controlled to get the best opportunity for maximum emergence of the new grass reseeds.
Soil drainage, fertility and grazing management will influence whether a problem occurs in the future.
My overall message to farmers is to get the basics right; this means good seedbed preparation, soil fertility and correct seeding rate followed up with early weed control. A pH of 6.3 is important for soil fertility with soil indexes at 3 or 4 for P and K respectively. Apply 40 units of N per ha when reseeding and no more than 7.5 t of lime per hectare.
When considering what to look for in a grass seed mixture I encourage a high proportion of perennial ryegrass as this can achieve an extra 3tonne of dry matter per hectare. Use highly persistent tetraploid cultivators using a max of 3-4 along with white clover.
- weed control