Ragwort is a noxious weed that has been let proliferate around Ireland despite its ability to wreck havoc with equestrian stock
You stop eating. You get stomach pains. You're losing weight -- fast. You have no energy. The sun hurts your skin. You lose co-ordination. You're struggling to breathe. Now you're going blind. Worst of all, you can't tell anyone how bad you feel -- and even if you could, it's too late for them to help you.
This is what a horse suffering from liver failure as a result of ragwort poisoning feels, according to international horse welfare charity World Horse Welfare (WHW).
Known in Gaeilge as buachalán buí, this yellow weed has proliferated in the damp summer of 2012. More usually confined to road verges, ditches and waste ground, the past few months have seen the ragwort population explode and there are now huge 'crops' of buachaláns to be seen in every county.
For horse owners, this surge in ragwort is particularly worrying. The weed is poisonous to horses, damaging the liver when eaten. The toxic effect builds up over time, causing irreparable damage. This means that your horse will get just as ill from eating small amounts of ragwort over a long period of time as it would do from eating a large quantity in one go.
There is often no way of knowing if a horse is suffering from ragwort poisoning until it is too late, according to WHW.
An apparently healthy horse could already have serious liver damage from ragwort poisoning and may only need to eat a small amount more to trigger horrific symptoms, according to the charity.
One of the key things to remember is that there is often no sign of any problem until the condition has progressed so far that nothing can be done to treat it. In most cases, once the signs of ragwort poisoning become visible, it is time to humanely put an end to its suffering.
Liver failure is a particularly horrible way for a horse to die.
The first signs of liver failure include lethargy or abnormal behaviour. Next, the horse can become photosensitive, where areas of pink skin become inflamed and painful when exposed to sunlight, like serious sunburn. The horse can also lose significant amounts of weight, even though he or she might continue to eat well or normally.
Eventually the horse will go blind, have to fight for its breath, start to wander or stagger or stand pushing their head against the wall. However, the symptoms and subsequent death often come about so quickly that the owner can simply find the horse dead without any warning.
So how do you deal with the growing problem of ragwort? The first requirement is to know its life cycle.
According to Teagasc, the weed thrives on a wide range of soils, but competes best on lighter, free-draining soils where fertility is reasonably high and grazing not intensive.
Ragwort germinates in the autumn (mainly) and spring. A seed can germinate anywhere the soil surface is exposed and conditions are favourable. In grassland situations this can be due to poor sward establishment, poaching, etc.
Ragwort does not tolerate regular soil cultivation and is rarely a problem in arable fields.
Ragwort is a biennial plant. This mean that it grows from seed and remains in the rosette stage for the first growing season. In the following year, it produces its trademark golden yellow flowers on a stem varying in height from 45-75cm. Flowering normally takes place in late summer after which most plants die off, leaving a gap for new seedlings. It can also become a short-lived perennial (four to five years) if the flower stem is cut, for example, in a lawn situation.
Reproduction and dispersal
Seed is the principle method of spreading this weed, but root fragments are also capable of reproduction. Each plant produces 50,000-200,000 seeds over a four- to six-week period from July to September.
Ragwort produces feathery- type seeds that are dispersed by wind, water, animals, hay and farm machinery. The majority of seeds are dispersed by wind but mainly fall within 5m of the parent. Seeds can remain viable for 5-20 years depending on soil conditions.
The only way to safeguard against loss from ragwort poisoning is to eradicate the weed either by pulling, ploughing, cutting or spraying. Some of the following methods of tackling ragwort can still be implemented in 2012 but others will be part of the 2013 ragwort elimination programme.
Pulling ragwort by hand is recommended where the infestation is not severe and labour is available. The entire plant, including the full root, should be removed from the ground, taken from the field and destroyed. Pulling after heavy rainfall when the ground is soft gives best results, but this should be done before seed has set. As the seedling and rosette stages are not usually removed by hand pulling, the operation should be repeated for two consecutive years to achieve satisfactory eradication.
The 2012 window of opportunity for pulling plants has already closed in many counties as the fine weather of last week pushed plants to maturity and many have already spread their seed for next year.
Ploughing up infested land is the most reliable method of control but, unfortunately, one that is unsuitable for many horse owners who need grazing land. For those who have the option of ploughing, Teagasc advises that the land is put into a three- or four-year rotation of arable cropping before establishing a good ley again.
Ploughing followed by direct seeding will not be a success unless chemical control of newly germinated ragwort is carried out in the new ley. Care should be taken to prevent the development of seeding ragwort in new ley.
Cutting the plant before the flowers are open (usually pre-June) prevents the weed from seeding and spreading, but it is of limited value unless carried out over a number of years and accompanied by good grassland management.
However, in some cases, cutting can induce development of several heads and the affected plants may persist as perennials, Teagasc warns.
Cut plants should be collected and destroyed as an additional precaution against the risk of seed formation and livestock poisoning. There is no point in going to the trouble of cutting or pulling plants if you simply leave them in a corner of the field to potentially spread seeds again.
Herbicides work best on ragwort in the rosette stage of the lifecycle so spraying should be carried out during late autumn (mid September to mid November) or early spring (mid February to mid March). Spraying in spring has the best results.
Either 2.4D or MCPA formulations may be used for spraying during this period however the 2.4D formulation, works best under colder conditions. Forefront is another very effective spray.
The cost of spraying ragwort rangez from €15-30/ac.
Any plants surviving a winter spraying operation are very stunted and weak and can easily be eliminated by a second spraying or by pulling.
Check the label before use to confirm the dose rate, and use the highest dose recommended on the label.
Remember that ragwort plants become more palatable after spraying and consequently livestock must be kept off treated fields and fodder conservation delayed until all plants are dead and sufficiently rotted down (at least three weeks).
Glyphosate products, such as Round-up, can be applied as a spot treatment on dense patches, but grass will also be killed. Selective application of glyphosate by wiper applicators is also possible for plants that have started to extend flowering shoots 10cm above the grass canopy.
However this method requires multiple passes over a number of years to give satisfactory control, as it does not kill ragwort in the seedling or rosette stage.