EVERY summer horse owners across Ireland have to deal with ragwort. I’ve very little, but still spent a good couple of hours clearing the yellow menace from a couple of fields. This deadly poisonous plant can be fatal to horses and is very difficult to ever fully remove from paddocks.

In general, horses will instinctively avoid eating ragwort, however, if grazing is sparse they will eat the weed. It is most dangerous to young and old animals. The poison contained in the weed does not accumulate in the body, over time it destroys liver cells and eventually can result in liver failure.

Owners must be very careful not to leave picked or dried ragwort in paddocks with livestock. The weed is most palatable when it is dried and is just as dangerous. Hay and haylage cut from a field with ragwort may contain the weed, horse owners are advised to always check the bales before feeding.

DAFM’s online information portal for the control of noxious weeds contains a downloadable form for reporting the presence of noxious weeds

Pulling ragwort is a very labour intensive job. The easiest time to pull the weed is before it has flowered, also pulling them after heavy rainfall usually makes them easier to remove. Although ragwort is biennial, if a paddock has a history of infestation then the weed will need to be picked every year to try to control and prevent further growth.

Pulling ragwort

When pulling ragwort it is very important to remove as much of the root as possible because the root can easily regenerate. Special forks are available to help making pulling the weed easier and to try and remove as much of the weed as possible. If you are concerned that you have been unable to remove all of the root when pulling ragwort then it is recommended that you pour rock salt (this is sold in most agricultural merchants) into the hole on top of the remaining root.

Cutting is not recommended as a means of combating ragwort. It can be used as an emergency method when the weed is in the early flowering stage but it encourages vigorous regrowth so it is best avoided. Correct grazing management can also help control the spread of ragwort. Grazing with sheep can help suppress its growth too.

Chemical

As is often the case with using herbicides they can be very effective when they are used correctly and at the right time of year but horse owners should always be careful when using them on land that is grazed.

For most herbicides it is important that the land is not grazed for a period of time afterwards. Always read and follow the instructions carefully. If there is a water drinker in the field when it is sprayed make sure it is thoroughly cleaned out before horses are let back into the paddock.

DAFM recommends that the best time to spray for ragwort is in early spring (February to mid-March) or late autumn (mid-September to mid November). Recommended sprays for ragwort include: MCPA 500, 2, 4-D Amine, Bandock, Forefront and Pastors.

Be vigilant

Natural herbicides are also available to help combat the spread of ragwort. Always wear protective clothing when dealing with ragwort and herbicides and be vigilant for any regrowth of the weed. Ragwort can be a real threat to your stock and your sanity if you’ve broken your back clearing your fields only for the roadside ragwort to seed itself all over your grazing. Did you know a single plant can produce 50,000 to 200,000 seeds over a four- to six-week period and those seeds can remain viable for five to 20 years?

The National Roads Authoruty (NRA) previously listed relevant local authorities as being responsible for controlling non-invasive plants in areas such as road verges, landscaped areas or public amenities.

The NRA merged with the Railway Procurement Agency to establish Transport Infrastructure Ireland with little in the way of direct management for ragwort listed on their website.

Chromosome errors and foal loss

RESEARCHERS from the Royal Veterinary College (RVC), as part of a team from Cornell University, have identified chromosomal errors as a common cause of pregnancy loss in mares. Whilst chromosomal abnormalities are widely acknowledged as a common cause of human miscarriage, responsible for up to 82 per cent of pregnancy loss, there have been limited reports in other species until now. Due to the similarities between human and horse chromosome structures and other pregnancy characteristics, this research supports the use of horses as a novel model organism to study miscarriage in women, particularly due to chromosomal abnormalities.

Veterinary management

The findings of this study mean it is possible to now account for potential causes in 60-70 percent of equine early pregnancy loss – previously this figure was only around 20-30 per cent. This can be used to help inform veterinary management of pregnancies. Also allowing for pregnancy losses to be screened and a diagnosis made retrospectively to provide an explanation for the loss to the owner and inform clinical treatment of a subsequent pregnancy. It also supports researchers to target the mechanisms that lead to these very common chromosomal errors which, in turn, could aid future treatments.

Due to the high level of gynaecological monitoring and care that mares receive, the similarities in gestation length and the pace of early embryonic development, horses present a new viable model to better understand the link between pregnancy loss and chromosomal abnormalities in humans.

This research builds on the RVC’s knowledge and expertise in equine research, where it undertakes and contributes to world leading innovation and projects in various areas of equine science and medicine. More recently, studies have explored pregnancy in thoroughbreds, diet and disease and findings in pre-purchase examinations. Other key areas of the RVC’s ongoing research includes stem cell therapies, laminitis, equine cushing’s disease, elastic band resistance and lameness, and life for racehorses post-retirement.