Manage weeds in winter to increase pasture life
Pastures are the engine room of the farm. Delaying pasture maintenance can have a knock-on effect on your farm’s productivity and cash flow.
Current conditions are perfect for weeds to germinate and establish in pastures, particularly if the pasture has been stressed by drought, insect damage, overgrazing or pugged during wet conditions.
These cause the pasture to open, letting light through, and giving weeds the opportunity to grow.
Left unattended, seedling weeds like thistles and ragwort can grow to become a significant problem in the following spring and summer, so now is the perfect time to check the condition of pastures and identify those that might need spraying. There can be a temptation to wait until spring, but as the weeds are likely to be larger and harder to kill, methods of control are unlikely to be as effective.
Why spray now?
It is better to control weed seedlings in the late autumn/early winter because they are smaller and easier to control.
As temperatures cool, clover growth slows and the herbicides cause less clover damage, also clovers have more time to recover before spring growth kicks in.
If you leave it until spring, it is vital to spray annual and biennial weeds like thistles and ragwort before they have a chance to bolt. Once bolting has occurred it is often not possible to get effective control without sacrificing the clover in the pasture. This is particularly important with winged and variegated thistles which bolt much earlier in the spring.
The benefits of spraying pastures
Keeping pastures clean results in better pasture production and better quality of feed grown, which will deliver better animal performance. Cleaner pastures will also have a longer productive life.
Where good pasture monitoring is conducted, the poorer-performing pastures can be identified from pasture production data. Otherwise, most decisions are made based on previous experience of whether weeds are bad enough to cause a significant reduction in pasture production and quality.
The real cost sits in the cost of not controlling the weed. There is an old saying in the farming community – “one year’s seeding means seven years of weeding.”, and it’s worth bearing in mind.
What to use
There are several herbicides that can be used for controlling broadleaf weeds in pastures, 2,4-D being one of the more popular options.
It is effective against a wide range of broadleaf weeds, including ragwort and thistles. Note that 2,4-D is very damaging to annual, sub and red clovers so should not be used where these are a key component of the pasture mix.
2,4-D comes in two different forms.
Ester form
Available in brands such as Pasture Guard 2,4-D 680, is a stronger form of 2,4-D. This has a stronger effect on weeds but may cause damage to white clover.
As a more volatile spray with a higher risk of spray drift, the broadcast application is restricted to the cooler months of the year in many regions.
2,4-D Amine
Available in a range of brands including Pasture Guard D-Amine 720. The amine form is softer on white clover and could be a preferred option during more active growth conditions, especially if the weeds are small enough to get good control.
Pasture Guard MCPA 750 is also in the less-volatile amine form and provides an equally good kill on thistles. MCPB-based herbicides like Pasture Guard Nurture provide better safety to all clovers but are not as effective in cooler conditions or when nodding, winged or variegated thistles have grown beyond the seedling stages (2-3 leaf).
Spray now, for better production on your farm
Where there are sufficient weeds present, the late autumn and early winter is an ideal time to spray. The clover growth slows with declining soil temperatures which means stronger herbicides, such as 2,4-D ester, can be used and not cause as much damage to white clover as would occur if this herbicide was applied in spring.
