Study

Rhododendron – a further method of control

Summary

Originally introduced to Britain from Asia as an ornamental garden shrub, rhododendron Rhododendron ponticum has become naturalised on acidic soils, and is now considered invasive in many areas. Normal methods of rhododendron control during heathland and woodland restoration at Black Down in the Mendip Hills in Somerset (southwest England) had been largely successful, but in some areas of steep terrain or high tree density isolated pockets of rhododendron were difficult to treat. Therefore injection of a herbicide was tested as a possible eradication method.

The trial was initiated in mid-summer when it was thought that there would be a strong flow of sap which would help to transfer the active herbicidal chemicals throughout the treated plants. In dry weather, using a portable electrical drill, a 5 mm diameter hole was drilled 2 cm deep into Rhododendron stems, well below the first branch. Stems with a circumference of over 10 cm had two holes drilled into them. These holes were then filled with glyphosate herbicide.

Five weeks after herbicide injection, the leaves on the treated rhododendrons had browned, tapping of the bushes caused the leaves to fall off and the plants appeared dead. Monitoring of treated bushes for regrowth will continue.
These initial results suggest that this method is an effective way of killing Rhododendron ponticum, and may complement other methods of control typically undertaken in more easily accessible areas.


Note: If using or referring to this published study please read and quote the original paper.

Output references
What Works 2021 cover

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 18

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.


Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape Programme Red List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Bern wood Supporting Conservation Leaders National Biodiversity Network Sustainability Dashboard Frog Life The international journey of Conservation - Oryx British trust for ornithology Cool Farm Alliance UNEP AWFA Butterfly Conservation People trust for endangered species Vincet Wildlife Trust