What’s the problem? Growing up to 8m in height, Pontic rhododendron is thought to be one of the most damaging invasive species in Britain, especially on acid soils in western and southern regions. It was brought to Britain from Spain or Portugal in 1763, and widely planted on Victorian estates for ornamental value and cover for game birds. Established rhododendrons form impenetrable jungles, out-competing other plants for space and light. They suppress surrounding plants by means of phenolic compounds in their leaves, which also make them unpalatable and even poisonous to grazing animals like sheep. Few native species survive, and natural cycles of woodland and moorland regeneration are interrupted. Pontic rhododendron is also a vector for the sudden oak death pathogen. Wetlands and small streams can quickly be overshaded by feral rhododendrons, with serious impacts on algae, insects and fish. Each plant produces many million seeds, which are easily dispersed by wind into new areas, and can remain viable in the soil for several years. As a result, controlling invasive Pontic rhododendron is likely to require partnership on a landscape scale. What you can do Cut each plant manually or mechanically, followed by digging up and burning the roots Spray any regrowth with glyphosate (near water, regulatory approval is likely to be needed).