Grass growth has been slow so far this spring. A combination of wet soils, low levels of sunshine and heavy grass covers last November and December have all contributed to this. The next six weeks of grass growth is very important to get right, as it is next winter’s fodder. If you have weeds in pastures they need to be managed now to make best use of your fertiliser inputs as well as your time and efforts.

SPRAYER RULES UPDATE

As we are at the beginning of the 2016 grassland spray season, it is important to make sure you are aware of the new spray rules.

If you apply sprays onto grassland or use a knapsack around your yard, you are obliged to be trained and register with the Department of Agriculture, Food and Marine (DAFM) since November 26th, 2015.

Originally there was a derogation for grassland farmers spraying less than 20 litres of sprays per year but that derogation was removed by the Department of Agriculture.

There is still time to register but you must have done a course as part of your agricultural training or a specific sprayer course.

Sprayer courses are being run around the country – details of who is running courses can be found on the Department of Agriculture website.

Once you have the course completed, you register online on the DAFM website – this only takes a couple of minutes and is very easy to follow. If you don’t see the point in getting trained remember that anybody can purchase sprays but you must get a registered person to apply them on your behalf.

If your sprayer has booms wider than 3m, it must be tested by November 2016. Amateur use sprays (e.g. home and garden products) do not come under these rules and can be applied as heretofore by amateurs. Further information is available on the crops section of the teagasc.ie website.

RAGWORT

Ragwort is a danger to all stock and is still listed as a noxious weed. Although largely unpalatable, ragwort may be eaten by horses when green, particularly when other grazing is sparse. It becomes more palatable to animals when cut or sprayed as it releases sugars.

Remember that ragwort is a biennial (a two-year lifecycle) so needs a few years to clean it from pastures.

Small numbers of ragwort can be effectively pulled or dug up and safely removed. For larger numbers, sprays such as MCPA; 2, 4-D; Dicamba and Forefront T provide good control but measures must be taken to avoid stock eating any dying or dead ragwort present.

What I always say to people is that there is no absolute time between spraying and grazing/cutting – it’s when the ragwort is too low for animals to graze it or below the cutting bar of the mower.

CREEPING THISTLE

Creeping thistle spreads by creeping roots which can be metres in length but also spreads by wind-blown seeds (July and August). It can grow new plants from small (1-2 inches length) fragments of its roots thus appearing to explode when reseeding is carried out.

Yield losses of up to 15% have been recorded but they cause most damage by preventing animals grazing around them.

The extensive root system of creeping thistle is its key mechanism of survival in your fields. Frequent topping can reduce the root reserves but will seldom eradicate the problem as root fragments can lay viable and dormant for years.

Thistles emerge in the spring at different times so topping is a useful tactic to even up the growth stages before spraying.

Chemicals such as 2,4-D, MCPA and dicamba reduce top growth but do not translocate down to the roots. For more persistent control use Thistlex, Forefront T etc. but follow-up sprays will be needed.

To get the best transfer of chemical down to the roots apply products to plants in the rosette form before the seed stalk grows up.

DOCKS

Docks are the most common and troublesome weed in grassland. They are perennial (live many years), have a large root system, produce many hardy seeds and are very opportunistic in terms of where they germinate.

For a dock seed to germinate, the amount of light reaching the soil surface is the main limiting factor as moisture and temperature are usually adequate. Also in silage fields, the level of potassium may be in over-supply for the needs of the grass thus favouring the higher needs of the dock.

Research in Johnstown Castle has shown that dock seeds do not survive being ensiled (due to low ph) but can survive passing through the animal’s intestine so the type of fodder and way it is preserved may be important in their spread.

WHAT PRACTICES CAN I APPLY TO REDUCE WEED EFFECTS?

Grassland management practices such as drainage, fertility, grazing, topping and mowing are important when it comes to controlling weeds.

All of these reduce seed return while encouraging the grassland to be competitive and dense which is the key to keeping weed numbers at a level that will not impact on your grassland productivity. What is not absorbed will not activate the weed seed to germinate so that is why new weed seedlings find it so hard to germinate in grassland.

However, creeping thistles, docks, creeping buttercups and nettles have underground root organs that either fragment or clone and spread in this manner. Weeds such as chickweed, dandelion, ragwort only spread by seed so a competitive sward is very important.