Do commonly used interventions effectively control Rhododendron ponticum? CEE Review 04-005 (SR06)

  • Published source details Tyler C. & Pullin A.S. (2004) Do commonly used interventions effectively control Rhododendron ponticum? CEE Review 04-005 (SR06). CEE (Collaboration for Environmental Evidence) Systematic Reviews, 6.


In the UK rhododendron Rhododendron ponticum is an invasive plant of acid soils in woodlands, heaths, bogs and sand dunes. Various methods of control and eradication have been attempted, including use of herbicides. The efficacy of herbicide appliaction is however not always clear.


A systematic review (see: for methodology) was undertaken to appraise the evidence for effective control using past and current herbicide management interventions.

Application of the herbicides imazapyr or metsulfuron-methyl to R.ponticum stands, and post-cut application of glyphosate, significantly reduces R.ponticum abundance. No other herbicide control method produced significant reductions.

Potential reasons for heterogeneity were identified as pot-grown versus field trials, length of experiment, herbicide dosage, application method and month of treatment. There was a significant difference between plants treated in the field and those in pots, the effect of treatment in pots being greater. The significantly greater effect of imazapyr on pot-grown plants compared with field plants suggests pot-grown trials do not take into account factors that can reduce effectiveness in the field. Length of experiment was significant for post cut glyphosate application, where longer follow-up monitoring indicated a greater longer-term reduction in R.ponticum.

The weight of evidence suggests metsulfuron-methyl application with post-cut application of glyphosate produces short-term reduction of R.ponticum. Only five studies provided suitable data to analyse the effect of metsulfuron-methyl but these were either performed in an unspecified habitat or in pots in glasshouses. The applicability of these results to field conditions is uncertain.

The use of imazapyr is now illegal in some countries (including UK). Since the majority of experimental work on the R.ponticum control has been on the effect of imazapyr, there is a need for further research into the effect of replacement herbicides and other control techniques.

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