Rhododendron - Rhododendron ponticum

People are often perplexed when landowners chop down or grub out rhododendron growing wild in woods and other habitats. Are they simply eco-vandals or are they more than justified in their actions? Read on to learn more …

Rhododendron ponticum - origins and uses

A native of SE Europe and Western Asia, this plant was introduced to the UK in the 19th century, and has since escaped and spread from parks, gardens and ornamental plantings to native woodland and other valuable habitats. Despite its attractive show of spring flowers, invasive rhododendron can be a real headache for woodland managers as it produces dense thickets where little else can survive.

Rhododendron was widely planted in woodlands as winter cover for pheasants, but this practice has now stopped. It particularly thrives on peaty or sandy soils although once established it can grow on a wide variety of acid substrates. As well as woodland, rhododendron can also colonise and swamp valuable heath and grassland habitats and even sand dunes.

Rhododendron as invader

Rhododendron's ability to regenerate rapidly from seed, suckers and rootlets means it is invasive, forming tangles of impenetrable evergreen vegetation. This habit has left it few friends amongst conservationists and forest managers. The deep shadow cast by this plant and the leaf litter accumulating under it combine to produce a sterile dank environment supporting little wildlife. Access is tortuous too through both the impenetrable thickets and mature stands. Although rhododendron may be a landscape feature, especially around lakes and ponds and informal or woodland gardens, control may be essentialwhere it becomes rampant.

Controlling Rhododendron

Controlling rhododendron once it is established is an extremely expensive but a necessary task if it is not to shade out other valuable habitats and their associated wildlife. When control is necessary, large excavators may be the only way to root out mature rhododendron. Smaller clumps can be cut manually or with brush cutters and the stumps sprayed to prevent regrowth. Smaller plants from regrowth can be sprayed with approved chemicals.

Further details about eradicating Rhododendron can be found on the Forestry Commission website at www.forestry.gov.uk/fr/INFD-63JJVS.

Rhododendron and Phytophthora ramorum (Sudden Oak Death)

In April 2002, the fungus-like pathogen Phytophthora ramorum was first identified in the UK, on plants in a garden centre. This imported disease is known as Sudden Oak Death (SOD) in California, where it has killed large numbers of American oak trees.

SOD has now spread in the UK, causing a stir among gardeners and foresters, because it affects shrubs and trees. One of the main woody species infected in parks and woodlands is Rhododendron. Efforts to eradicate Rhododendron in woodlands are therefore being doubled, to try to limit and slow the spread of SOD.

For the latest on SOD, go to www.forestry.gov.uk and type Phytophthora in the search box.