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What's the problem with common ragwort?

Ross Hoddinott

While it fills the meadows with beautiful yellow colour, and is a great source of nectar for our wildlife, common ragwort poses a huge problem for cattle and horses. Our Reserve Manager, Lorna Bennett, explains how we go about controlling it at Brockholes.

Common ragwort is a native plant and is very good as a nectar and pollen source for wildlife, so we really value its presence in our nature reserve. However, it is cumulatively poisonous to horses and cattle, with toxic alkaloids causing liver damage if they ingest too much.  

Whilst it is freshly growing in a field our cattle will typically eat around it because the toxins in the leaves make it unpalatable. However, if the plants become particularly abundant then the cows struggle to eat around them and there is a greater risk of them ingesting ragwort leaves and being poisoned. To keep our animals safe we therefore remove ragwort plants if they get too numerous in the cattle fields. 

Cow

Helen Earnshaw

Notably we remove the ragwort plants right at the end of their flowering period (just before they set seed), because very many species of bees, hoverflies and butterflies use ragwort flowers for nectar and pollen sources. 

Additionally, ragwort is the food-plant used by cinnabar moth caterpillars, which eat its leaves and flowers. These caterpillars store the bitter tasting toxins from the plants in their bodies and any birds that ignore their bright warning colours (orange and black stripes) are then repulsed by the taste of the caterpillars.

By removing the ragwort plants late in their growing period (i.e. mid-late August) we allow the majority of the cinnabar moth caterpillars to have taken their fill and dropped to the ground to pupate in the soil, out of harm’s way. 

The few remaining caterpillars that we find are always relocated to ragwort plants that we are retaining, usually outside the field boundaries.

Cinnabar Caterpillars

Trevor Southward

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