THE best results are achieved from spraying when weeds are at the right stage for an effective kill. Weeds should be sprayed when they are green and leafy and are actively growing. Below is a guide of the ‘best times to spray’ for a range of weeds:

  • Docks should be 15cm to 25cm (8ins to 10ins) high or across and before a seed head begins to emerge.
  • Thistles should have four to 10 leaves and be 15-25cm high.
  • Nettles, buttercups and other weeds should be sprayed before flowering.
  • Where weeds are gone beyond these stages, it is best to top them and spray after about three weeks regrowth when they should be at the right stage for an effective kill.
  • If you are using Envy, for example, use plenty of water – a minimum 200l/ha and increase to 300l/ha where weeds are large or where there is shading from dense grass.
  • Keep animals off the pasture for seven days after spraying with Envy.
  • In some situations, a follow up spray may be needed, particularly where there are heavy infestations of weeds such as docks and thistles. Also, bare soil patches following the elimination of weeds can provide an opportunity for new seedlings to germinate.

    • SPOT SPRAYING

    Briars and other invasive weeds at fences, ditches and gateways are best controlled by spot spraying with a product such as GrazonPro. Docks, thistles, nettles, brambles, gorse along with cow parsley and hogweed are among the weeds that GrazonPro is proven to kill.

    Also, where weed infestations across a field or paddock are 5% or less, GrazonPro is a very cost-effective choice.

    It should be applied at a rate of 60ml in 10 litres of water using a conventional knapsack sprayer, a quadbike sprayer or a suitable lance on a tractor mounted sprayer. Best results will be achieved by spraying before weeds reach the flowering stage.

    It is rainfast within two hours and does not affect grass growth.

    Spray to thoroughly wet the foliage of the weeds, but avoid ‘run-off’. Treated weed patches are rapidly re-colonised by grass.

    CHOOSING A WEED KILLER

    For the most effective long term control of weeds in grazing, hay and silage swards, it is vital to use a translocated herbicide. They are formulated to ensure that the chemicals are translocated right down to the root structure of the target weeds. This is critical for an effective kill.

    The next step is to select the product that will kill the target weeds. Here is my advice on product selection:

  • Use DoxstarPro where docks and dandelions are the dominant weeds.
  • Where thistles are the major problem, use Thistlex.
  • The new weed killer Envy should be used where there is a range of weeds such as buttercups, dandelions, plantains, chickweed and docks. It is also ideal in new re-seeds.
  • GrazonPro is the perfect spot spray for dealing with troublesome weeds around ditches, walls and fences and where weed infestations are low across paddocks.
  • Docks should be 15cm to 25cm high or across and before a seed head begins to emerge in order to ensure best control from using a translocated herbicide.

    • Some unsavoury weed facts

    One dock plant can produce 60,000 seeds in a year and these can last for up to 60 years in the soil. Topping docks can spread the seed over a wide area. Similarly, allowing docks into hay runs the risk of the seeds being spread in the dung.

    The seeds of a creeping thistle can survive in soil for 21 years. The roots of one creeping thistle can grow to cover five square metres in one year and up to 80 square metres in two years. In a heavily infested crop of creeping thistles, the root system can weigh up to a tonne/acre. It therefore pays handsomely to tackle weed problems by using an effective weed killer before they reach epidemic proportions.

    The launch this spring of the new weed killer Envy adds greatly to the armoury in controlling weeds in horse paddocks.

    Containing the powerful active ingredient florasulam, Envy is imbued with the most advanced technology in weed control. It also contains the tried and tested ingredient fluroxypyr. The combination of the two ingredients with two different modes of action ensures a very wide spectrum of weed control.

    Envy is effective on docks, chickweed, dandelions, buttercups, plantains and daisies in paddocks and in hay and silage swards. Because there are no issues with residues in manure, it is particularly suited to horse paddocks.

    Its use can be very important where horse manure is used as a nutrient source in gardening.

    Chris Maughan, technical manager with Whelehan Crop Protection, advises that Envy should be applied at a rate of 2l/ha in 200l of water in established pasture. Animals should be kept off the pasture for seven days after application.

    “It is also suitable as a pre-cutting treatment for weeds in hay and silage swards. The key requirement is to apply the weed killer at least three weeks before the crop is cut. This ensures that the chemicals are fully translocated to the root system of the weeds which is vital for effective long-term control,” states Maughan.

    Envy is also suitable for weed control in re-seeded pastures. It can applied up to November 30th, making it an excellent choice for autumn re-seeds.