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Autumn Reseeding – Overcoming the extra challenges

Traditionally many dairy farmers have looked to the autumn to carry out reseeding as their workloads reduce. Reseeding in the autumn presents far more challenges than early summer reseeds. James Moyles, Teagasc Advisor, Tullamore advises on the mistakes he has encountered with autumn reseeds.

In my role as a dairy advisor I often encounter reseeds that have been unsuccessful. The majority of these tend to have been undertaken in the autumn.  This article will try to address some of the main issues with autumn reseeding and the mistakes that are commonly made.

Timing – Leaving it too late

Timing is probably the single most important factor in determining the success or otherwise of reseeds.  Aiming to sow grass/clover seeds after the first week of September is inviting trouble on a number of fronts, namely:

  • Shorter daylight hours & falling soil temperatures hindering germination;
  • Deteriorating soil conditions making it more difficult to establish a firm seed bed;
  • Less opportunity to use a post emergence spray;
  • Less opportunity to graze before the winter;
  • Greater risk of attacks from pests.

If you are currently planning to reseed a field/paddock and haven’t already sprayed off the ground, I would advise you to give serious consideration to postponing the entire operation until next April/May.

No soil sample result for field to be reseeded

Getting soil fertility correct is crucial if perennial ryegrass and clover is to establish well and persist after reseeding.  Working without an up to date soil sample result is akin to working in the dark.  Soil test for P, K and pH (lime requirement) before reseeding.  If ploughing, make sure, you soil sample after ploughing and not before.  With your test result to hand, consult your advisor about a liming/fertiliser programme for the field to be reseeded that will bring the pH up to 6.3 (mineral soils) and the P & K indices up to soil index 3 and keep them there.

Inadequate seed bed preparation

One of the first things that some farmers fail to do is allow enough time for glyphosate spray to work properly.  This is especially true in an autumn reseed as farmers are anxious to get on with the job before weather conditions worsen.  Make sure to leave the recommended time for the spray to fully work.  If ploughing, 10 days is sufficient, however, if disking or power harrowing the period between spraying and tilling increases to two to three weeks.  Remember this is your only opportunity to kill established docks and it takes time for the spray to work its way down into their vast tap root system.  Irrespective of what reseeding method (ploughing, discing & one pass) you use, try to ensure a fine, firm seed bed without any clods.  

Too low a seeding rate

Use a minimum seeding rate of at least 14kgs of grass seed plus 1kg of clover per acre.  A number of ‘off the shelf’ standard acre size bags only contain 11 kgs of grass seed and 0.75kg of clover/acre.  This may be sufficient for perfect conditions in the early summer, but the level of seed inclusion is not something you should ever skimp on for autumn reseeds.  If using the typical 11.75kg acre bags, I would suggest using 4 bags of grass/clover seed for every 3 acres.

Delaying post emergence spray too long

Practically all farmers will agree that a post emergence spray is an essential part of the reseeding process.  Everyone recognises that is your best opportunity to deal with the multitude of weeds that generally emerge along with the grass and clover seedlings.  The timing of when this spray goes on can vary quite a bit between farmers.  The advice is to target the seedling dock when it is the size of a €2 coin.  Depending on growth conditions, this could typically be 5-6 weeks post sowing.  What can happen on farms, is that spraying is delayed due to weather etc. and it is harder to get a “good kill” of some of the stronger weeds.  This is further compounded by the fact that clover safe sprays are not as strong as their non-clover safe counterparts.  Late application of the post emergence spray means later grazing of the reseed.  This presents its own set of problems.  It is not a crime if you have to re-spray a reseed a second time, what is criminal in my view is a field heavily infested with docks a short few years after reseeding it.

Lack of monitoring for pests

Pest damage is not something you usually associate with early summer reseeds, but can often be a problem in the autumn.  Method of reseeding can also impact on the level of pests, with slugs and other pests typically more prevalent in minimum cultivation reseeds. Monitor the new reseed on a least a weekly basis for pest attacks from slugs, frit fly, leatherjackets and rabbits.  If you suspect a problem, don’t delay in seeking advice and dealing with the problem.

Teagasc Advisors are regular contibutors of articles here on Teagasc Daily. Find out lots more on this topic here: Reseeding