Ragwort- Tansy

The fields are glowing yellow this week. Not just because the sun is shining, it’s also the time for ragwort to flower.

Tansy ragwort (Senecio jacobaea) is seen as one of the most harmful plants that grow wild and if left to self-seed in its second year can take over a field in next to no time. 

Biennial Ragwort                    

Tansy ragwort is a biennial plant which means that it takes two years for it to complete its lifecycle. It grows as a ground-hugging rosette in its first year. In its second year of growth, it transitions into its mature, tall, flowering form.  Ragwort plants produce a lot of seeds which can remain viable in the soil for a few seasons.  If left to spread, it can form dense patches, either from seed or by vegetative reproduction when its roots or crown are injured and new shoots develop making it extremely hard to control.

Controlling ragwort

Tansy ragwort can be controlled manually by digging or pulling in spring and summer before they flower. Rosettes should be dug up, removing as much as the root as possible. All pulled plants could be bagged and placed in the municipal waste for recycling into compost or burned. Once plants bloom you will have about three weeks until the seeds form to take action.

Mowing is not a good control for ragwort. While it may prevent the plant from immediately producing seeds, it also stimulates additional vegetative growth. This leads to more plants and more stems per plant in the same season. Mowing is especially problematic in pastures, where it can spread the leaves, making it harder for grazing animals to avoid. Chemical control is favoured by some folk.

In the agricultural depression of the 1930s and during the Second World War, there was far more Ragwort around than there is today. There were no selective weedkillers available, so it had to be controlled either by hand-pulling or by allowing sheep to graze off the young plants, which are less poisonous. There were also many more horses in the country, working on farms or pulling delivery vans. Ragwort poisoning was a recognised disease, but not a major problem.

Ragwort types

Ragwort (Senecio Jacobea) is also known as ragweed, buachalán and buachalán buidhe. It is a common weed of Irish pastures and thrives on a wide range of soils, but competes best on lighter free draining soils where fertility is reasonably high and grazing not intensive.

There are four main types of ragwort to be found in Ireland according to An Irish Flora (1996) namely:

Common Ragwort -Senecio jacobaea - found everywhere.

Marsh Ragwort Senecio aquaticus - wet fields, marshes

Ragwort - Senecio squalidius - mainly in larger cities, rare elsewhere.

Ragwort  - Senecio erucifolius – found especially in Dublin and Meath.

All four can interbreed where both parents are found.

Ragwort – Virtues

It’s not all doom and gloom for the plant, it does have its virtues –although it’s a very divisive subject and some will disagree, especially horse owners. 

At least 30 species of insects and other invertebrates are totally dependent on ragwort as their food. Many other species of insects either eat ragwort, or require the nectar and pollen from the flowers. Ragwort is a major nectar source for many insects, including bees, hoverflies, butterflies and moths. 

Make a bit of Money

Entrepreneurial youngsters can make quite a bit of money hiring their weed pulling services out to farms and large private home owners. You could make a few euro clearing areas of the plant before they go to seed. There would be a payoff for the farmer too as they would get a better price for their hay after harvesting.

Whatever the myths and scare stories about this widely disliked plant are, it’s here to stay.  It is very easy to create hysteria about ragwort, those not familiar with scientific methods can often be misled into believing that it poses a much greater threat than it does. Don’t believe everything you read – even in this article, I could be talking a load of nonsense as usual.