How To Control Weeds in Paddocks

How To Control Weeds in Paddocks
Smallholder

All Countrywide stores stock a variety of products to control weeds whether for a small lawn or for a 50 acre field. This guide will concentrate on small fields and paddocks and how to effectively control weeds throughout the year. A separate 'How To' Guide is available for weed control on lawns.

Why should we control weeds in paddocks?

Horses in a paddock

In fact there are many reasons: firstly the health of animals including horses and ponies, especially when it comes to poisonous weeds like Ragwort. Weeds also reduce the grazing potential and damage the grass sward. In addition weeds cause cross compliance management issues if single farm payment is claimed against them, and a further potentially serious problem could be insufficient control could result in a breach of the Control of Injurious Weeds Act, sometimes referred to as the Ragwort Act, but which also covers weeds such as docks and thistles.

What are the most likely weeds to be found in a paddock?

The most common weeds found in the UK are:

Ragwort - is poisonous especially to horses. This is a yellow flower and poisoning can occur at ANY time of the year. Ragwort poisoning destroys the liver, leading to a slow, painful death. It is poisonous to most animals but horses and cattle are most susceptible. Once symptoms have appeared in an affected animal little can be done and it will usually die. Animals eating 5 percent or more of their total daily diet of ragwort for periods exceeding 20 consecutive days can be expected to die within a 6 month period. A horse can get ragwort poisoning without actually having
any plants in their paddock! Seeds/spores from plants in neighbouring fields can blow over and contaminate a paddock apparently free from plants. A horse can eat or inhale these - and cumulative poisoning can begin.

Buttercups – are poisonous but less so than ragwort, generally damaging sward density and in time smothering out the grass. Buttercups are easily recognized in early spring by their bright yellow flowers. This attractive 'wildflower' possesses several weedy characteristics that make it difficult to control in pastures. Buttercup populations are greater in low areas of fields that tend to remain wet for a long period and in pastures with poor stands of grass. Overgrazing the forage usually increases the buttercup population. Buttercups have a relatively low potential for poisoning livestock. All above ground plant parts may contain the toxin and the primary signs of toxicity are oral or gastrointestinal irritation. Buttercups pose no threat if harvested in hay since the drying process eliminates the toxic agent.

Typically, buttercups are not palatable and grazing animals rarely consume them if other forage is available.

Docks - are generally found in more fertile swards but again affect its density. They are the most pernicious and damaging of all grassland weeds with more than 15% of productive grassland having a serious dock infestation. Grazing losses amount to more than £30 million/year with docks competing with grass for light, nutrients and moisture thus reducing grass yields. Docks have only 65% of the feed value of grass and are unpalatable. In general, animals will only eat them if there is nothing else available.

Excessive quantities of docks in the diet can cause dietary upsets, especially in young animals. When fields become infested with docks, the available grazing is reduced, which then impacts on the planned grazing cycle.

Thistles - these can gradually invade a sward a may cause irritation to mouths of livestock. Creeping thistle can be a serious perennial weed of land managed for agriculture. High levels of infestation can seriously affect efficient pasture production and
utilisation. Cutting is the most practical and effective means of reducing thistle populations by depleting resources and preventing seed production, whilst not damaging non-target vegetation.

Chickweed - tends to invade grassland when swards are damaged during wet spells and can stifle it as a result. Common chickweed is a matted, herbaceous, winter annual broadleaf plant. Chickweed is a prolific spring weed as it thrives under cool, wet
conditions. It rarely tolerates hot, dry conditions that occur in late spring or early summer. Other common names for chickweed include starweed, winterweed, satin flower and tongue grass. Plants form a thick mat of succulent or tender vegetation in
the early spring that is not eradicated by close mowing.

Nettles – are usually found in clumps but are very damaging to the grass sward. The roots of nettles are not too deep and so are easy to remove. It spreads itself by seeds and stems that creep out from the main plant reproducing new plants.

Brambles - these tend to invade from hedge rows. Young brambles can easily be pulled up with root attached, but older brambles have deep woody roots, which need to be dug out. Prostrate stems can take root. It is best to remove top growth first
before digging the roots out.

Treatment of weeds

When weeds become a problem or there is a specific requirement to control them there are a number of ways of controlling them, from cultural control to chemical control, choice of method tends to rely on time available to do the job and type of weed, the level of weed severity, and the period after treatment that stock must be
kept out of the field, this also varies by chemical, and depending on if there are poisonous weeds present. Many land owners prefer to pull ragwort, and remove it from livestock, rather than treating it, as if left treated in the field it will become palatable to livestock, hence statements on the label for most products that fields should not be grazed if treated for poisonous weeds until they have become unpalatable.

A topper can be a good way of reducing certain weed problems, as will keeping a dense sward, as this prevents weed germination in the first place.

Chemical control: Many products require that they should be applied by a qualified user, possessing PA1 and or PA6 qualifications to use a sprayer, this is relevant for knapsack sprayers too, and is a legal requirement. There are a range of products available for qualified users, but it is more limited for knapsack use.

Organic Control: There are certain non chemical measures that can reduce weed populations.

These include:

  • Hand pulling weeds when necessary
  • Controlling drainage and prevent excess water on the paddock
  • Use proper tools to remove weeds

It should be noted that weeds can provide habitats for other beneficial creatures.

When Will I Need to Treat Weeds?

This is best done when weeds are actively growing usually when at the rosette stage, before stem extension and flowering. For ragwort it may be necessary to treat both late summer/autumn and spring, to ensure a weed free pasture, as this is a biennial weed and seedlings can emerge in both seasons.

Additional applications should then be made if required and a programme followed to ensure effective control. A 'programme' means use of repeat applications at separate timings, either in the same year or in following years because:

  • It is difficult to obtain successful control from one application
  • Fields contain weeds at various growth stages
  • Weeds must be young and actively growing to obtain maximum response from translocated herbicides
  • Docks, nettles and thistles have deep, extensive root systems
  • Perennial weeds have good "defence mechanisms"
  • Dense weed populations lead to shading of smaller plants
  • Large seed reserves in the soil

Therefore in summary follow these four steps for effective weed control:

  • Don't be tempted to treat weeds in grassland too early
  • Target weeds must be at the correct size and growing actively
  • Do not treat weeds under stress from frost, waterlogging, etc.
  • Successful applications normally begin in April, then through May and June
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