Rhododendron ponticum was introduced to Britain in the 18th century as an ornamental, evergreen shrub. It is a woody shrub, can grow to around 4-5m in height and has large, leathery leaves. The plants take between 10-12 years to produce flowers, which bloom in early summer and produce seed pods which turn woody and disperse in Winter. It spreads via these seeds and its shallow rooted rhizomes which can produce suckers of new plants.
Rhododendron ponticum is commonly found growing on acidic, peaty or sandy soils. It has spread from the gardens and parks it was introduced to and is now found in moorlands, woodlands, rocky hillsides and along riverbanks. Its vigorous growth outcompetes native plants, and the dense stands block out light and cause biodiversity issues. It also carries devastating diseases which can spread and destroy native woodland species.
Early intervention is important to limit Rhododendron ponticum's impact on biodiversity and prevent it spreading. It is an offence under the Wildlife and Countryside Act 1981 to cause it to grow in the wild or plant it in the wild.
Features of Rhododendron Ponticum
Elliptical, leathery dull green leaves, between 6-12cm long with a pale underside. Leaves spiral towards the ends of the stems.
Light brown, woody stems, diameter up to 15cm and reaching 5m in height. When a mature plant stem forms into solid trunk, they can reach up to 8m in height.
Pink to purple clumps of individual flowers with 5 petals, 5cm in width. Flowering between May and June.
Seed pods 3cm in length containing between 3,000-7,000 seeds are produced in autumn. They become woody before seeds dispersed in winter. Seeds are spread along watercourses, by wind, birds and mammals. Seeds bank can remain active for up to 1 year.
Types of Rhododendron Ponticum Treatment
In-situ herbicide treatment: This is the application of herbicide to the foliage. Stem injection can be used on larger plants over 1.3m in height. Herbicide treatment is an efficient and effective method for controlling large stands. It is also less labour intensive and intrusive.
In-situ manual treatment: Hand pulling or digging out individual plants. This is effective for controlling small, isolated stands. It is also ideal for sensitive areas not suitable for herbicide treatment.
On-site treatment, ex-situ: Rhododendron ponticum contaminated soil is excavated and moved to a more convenient area of the side for stockpiling and herbicide treatment. Remediated soil can be re-used on site. Woody material can be chipped and used on-site.
Off-site disposal: This option can be used as a last resort when other options are not viable.
ERS has extensive experience in identification, management and remediation of Rhododendron ponticum infested sites. We work with clients to develop a treatment strategy which meets the client's timescales, budget and future development requirements.
When Rhododendron ponticum is identified on a site, ERS can develop and implement a Rhododendron ponticum Management Plan. The plan is essential for both the current owner and any future owners as a record of treatment on the site.
To enquire about a survey or management plan for Rhododendron ponticum on your land, contact us today to speak to one of our Invasive Weeds experts.