Introduction to grassland

Choosing the right grassland herbicide for the right situation and applying it at the right time are key to livestock farmers being able to Farm More Forage. Here are some of the main reasons why your livestock farmer should control weeds in their grassland.

Grazed grass remains the lowest cost animal feed (Teagasc 2022) and production should be optimised in order to take full advantage of this.

According to AHDB every 1t DM/ha increase in utilised grass can equate to a potential increase in stocking rate of:
• 1.4 ewes per hectare
• 100kg of beef live weight gain per ha/year.

Another way of putting this is that each tonne of grass DM utilised would require almost a tonne of concentrates to be purchased as an alternative feed source.

Weeds reduce the area of land available to grazing animals e.g. each thistle can affect the grazing of 0.5m 2 of grass.
 

• Some weeds cause stomach irritation e.g. chickweed and buttercup.
• Weeds reduce sward yields, energy content and quality e.g. docks.
• Some weeds are poisonous e.g. ragwort.
• Thistles can facilitate the spread of disease in animals e.g. orf in sheep.
• Buttercup can cause contact dermatitis in horses.

• The presence of even low levels of some weeds in grassland will drastically reduce grass production – a mere 10% dock infestation can reduce yield by 10% (SAC Trials).
• Count the number of docks in a 5m x 7m area.
• The number of docks counted equates to the % weed infestation.

SAC Trials concluded that once the dock population is at 10% or above, there is a direct correlation between the % dock population and the % of grass yield loss, e.g. 10 dock plants in the block (as above) represents a 10% dock population and this means a 10% grass yield loss.

Grassland herbicides choice and best practice

• Our portfolio of solutions meet a wide range of weed problems.
• All kill down to the roots yet offer excellent grass safety.
• All have a short stock exclusion period of just 7 days giving greater flexibility in use.
• They can be applied in a water volume down to 200 litres per hectare
when using low drift nozzles.
• Our PET packaging is lightweight, strong, translucent to help gauge contents and conical to facilitate triple rinsing.

Best practice advice

• Always read the label.
• Know what restrictions are in place - stewardship schemes, codes of practice, IPM needs, cross compliance rules, etc.
• Choose the right (translocated) product for the right situation and weed spectrum.
• Use correct product rate, water volumes and nozzles to optimise coverage with minimal spray drift.
• For optimum results spray weeds whilst actively growing and, if possible, before they flower, or top them first and spray regrowth after.

• Not all weeds will be at the best growth stage for spraying at the time of application, so a follow-up treatment may be necessary.2-3 weeks.
• Consider the proximity of any watercourses.
• We recommend that these products should be applied to grassland using low drift nozzles, if possible:
  - Reduced risk of drift
  - Water volume can be reduced down to 200L water per/ha.
• Observe pre-spraying rolling and cutting intervals.
• Observe post-spraying grazing intervals.
• Consider the presence of clover. If clover is to be maintained switch to a clover friendly herbicide.
• Consider any grass/manure usage restrictions.
• Sprayer cleaning: to avoid subsequent injury to crops other than grassland and cereals, all spraying equipment must be thoroughly cleaned using the recommended method on our product label.
• It may be necessary to ‘stitch’ grass seed into the bare areas left behind after death of treated weeds to avoid new weeds replacing them.
• Corteva Agriscience grassland herbicides are for professional use only, which means that they must be applied by someone with the relevant certificate, or by someone who is being supervised for the whole process by someone who has the relevant certificate.
• It is the responsibility of the purchaser to ensure that this is done.

Weed Spray Timing

Ideal weed sizes to treat in established grass:

Broad-leaved and Curled Dock -  Rosette stage, 150-250mm across or high

Creeping and Spear Thistle - Rosette stage, 150-250mm across or high

Common Nettle - Actively growing, before flowering

Buttercup and Dandelion - Actively growing, before flowering

Ragwort - Rosette stage, up to 200mm across or high

Bramble, Broom and Gorse - Between June and August when actively growing, before onset of senescence. Foliage must be thoroughly wetted

How does a low drift nozzle work?

• It is a flat fan nozzle where an internal
venturi creates negative pressure inside
the nozzle body.
• This creates larger droplets that contain
small bubbles of air.
• The droplet is classified as a Coarse
Spray, as defined by the BCPC system.
• The coarser droplet enables the spray to
travel accurately from nozzle to target.
• On impact the bubble bursts leaving
smaller droplets across the leaf for
absorption.

Corteva Agriscience support the use of
low drift nozzles for the application of our
grassland herbicides and a water volume
down to 200 litres/ha.

We encourage their use for the following
reasons:
• Less drift (up to 75% reduction).
• Reducing spray drift is a requirement of the
Plant Protection Products
(Sustainable Use) Regulations 2012.
• Reduced buffer zone if 3 Star rating
achieved.