It may appear paradoxical that in order to safeguard our most biodiverse habitats, we must eradicate millions of plants utilising herbicides. Nonetheless, a team of proficient experts has been doing exactly this in a section of northern Connemara for several years.
Not long ago, during a drive through Bundorragha, sandwiched between Killary Fjord and the Delphi Valley, I noticed a familiar figure standing in an adjacent field. The individual was Colm Gavin, a sheep farmer of eight generations, felling a cluster of Rhododendron ponticum plants. These shrubs, when not destroyed, have pinkish blossoms that contrast against their shiny green leaves. Yet on that day, the previously decimated rhododendrons, which Colm had demolished roughly a year and a half prior, were withered, devoid of leaves and had a dull, skeletal appearance, resembling immense bony fingers protruding from the earth.
My initial visit to Colm unfolded several years back when I was exploring his approach to farming in a region vital for the freshwater pearl mussel’s survival, an organism residing in the rivers skirting his fields. Bundorragha serves as this scarce, long-living bivalve’s primary European habitat, requiring pure, transparent water to thrive. Both Colm and his father Martin participated in a project that ensured the farmers protected the mussels by constructing mini-dams in the streams to halt silt from trickling into the river.
Colm didn’t hesitate before indicating the invasive rhododendrons that were deeply rooted in this region, covering vast swathes of the blanket bog, agricultural fields uphill, and even the lake’s islands. Since his younger years, Colm has always been aware of the plant owing to its vibrant pink flowers blooming in the mid-May landscape. Yet, only in the past ten years has he truly comprehended the magnitude of the issue. Cutting down the plant in previous attempts had the counterproductive effect of stimulating its growth, much like the many-headed Hydra from mythology.
Exterminating rhododendrons are imperative for habitat restoration despite being an unattractive task. The Dodder has the potential to be one of Europe’s finest urban rivers, demonstrating the possibilities once we better our environmental habits. When EU countries formulate their strategies for restoring nature, they gaze towards the Burren Programme and we should follow suit. Despite the diminishing cries of the curlew, not everyone is ready to surrender.
The plant, recognised as an intrusive species, was initially introduced to Ireland by gardeners in the late 18th century due to its vibrant spring display. By 1843, it found roots in the Derrycunihy Woods in Killarney, soon after self-propagating in the wilderness. Gradually, it proliferated through Mayo and Galway in Western Ireland, overpowering and threatening local habitats and indigenous species.
This plant was first caught off-guard as slow growing for the first several years, delaying any initial detection due to the absence of flowering before the 10-year mark. However, once it blooms, it is capable of dispersing millions of tiny, hair-like seeds that are light enough to spread over a km through wind, water, or through unwitting carriers such as animals or humans. A single blossom can yield an astonishing 5,000 seeds; thus, encouraging the growth of up to 18,000 plants per acre of land within two decades.
The plant thrives best in acidic, damp soils and is capable of enduring harsh wind conditions. It can thrive at high altitudes, in shaded areas, and in direct sunlight. It has the ability to absorb sunrays rapidly using its broad leaves, hence, outgrowing neighbouring plants. Its sprawling branches, upon touching ground, sprout roots and give rise to new plants. It is also a longevity champion, with individual shrubs capable of surviving for up to 120 years.
Without human intervention, rhododendrons create a dense, dark canopy, overpowering native trees like oak and hazel. It has adaptive mechanisms, for instance, absorbing excess overhead water, which can dry out bogland and kill sphagnum mosses. It also produces a chemical that can be toxic to animals and certain indigenous bee species. Besides, it also acts as a host for a fungus, indirectly leading to ‘sudden oak death’.
Despite its invasiveness and adaptability, rhododendrons have one handicap- their intolerance to frost. A sudden frosty spell can eliminate their young saplings. However, recent mild winters have allowed them not merely to survive, but to flower once more. Previous year, in an unprecedented event, rhododendrons in Colm’s valley in Mayo blossomed twice, once in October, leaving Colm, to characterise this as a severely disheartening issue.
In order to successfully manage the rhododendron issue, a hands-on approach is necessary. In 2022, Colm and his father initiated a government-backed project aimed at equipping local people with the skills required to handle this invasive plant. Their method is straightforward: the plant is damaged slightly at its base using a hatchet or chainsaw, then a tiny dosage of herbicide is applied. This effectively penetrates the plant’s cells, causing them to rupture, leading to the plants demise.
Over the last couple of years, Colm has eradicated thousands of these rhododendrons. It is not the most glamorous of tasks, leaving behind standing, deceased shrubs, and even the smallest use of herbicides in such critical ecosystems isn’t perfect. However, it is a vital step in reversing the trend and reestablishing the natural environment.
At present, Colm and a crew of 19 others are committed to the local eradication of these vibrant exotic invaders in their part of Ireland. This mission goes hand in hand with initiatives in other regions like Donegal. For the farmers participating in these campaigns, it expands the scope of their work significantly. Not only do they produce food, but they are also remunerated for their efforts as custodians of the landscape, ridding it of rhododendron, plant by plant.