Scientific research

We were asked to find a reliable and effective natural enemy to help control Himalayan balsam by the Environment Agency, Defra and the Scottish Government. Since 2006 the scientific team from CABI have conducted surveys throughout the plant’s native range in order to identify natural enemies that could be considered as biocontrol agents in the introduced range (ie the UK). Many of the natural enemies, both fungal and arthropod species, collected and identified during surveys were rejected as suitable control agents. We undertook safety testing procedures in our UK quarantine facility, and found most were able to attack other plants closely related to Himalayan balsam. However, we found a rust fungus from the Puccinia species which we deem safe for release.

We have tested the safety of this Himalayan balsam rust following strict internationally recognised testing procedures. We compiled a test plant list comprising 84 entries; this consists of 74 species and an additional 10 varieties of three widely grown ornamental species in the UK. There are 26 UK-native plant species, 52 ornamental plants, three economically important crop/ fruit species and three introduced/ invasive species on the list.

Through our research under quarantine conditions we clarified the lifecycle of the rust, thus proving that all spore stages observed on Himalayan balsam in the native range belong to the same species. We have backed up this research with molecular evidence.

Interestingly, through research conducted in the UK, it turns out that the rust species we collected on Himalayan balsam is new to science, and we therefore plan to rename the rust species following the International Code of Nomenclature.

We developed a video diary from one of our research trips and have produced a video about Himalayan balsam and our scientific work.

Research papers

Varia, S., Pollard K. and Ellison, .C (2016) Implementing a novel weed management approach for Himalayan balsam: progress on biological control in the UK. Outlooks on Pest Management 27(5): 198-203.
This article appeared in Volume 5 No 27 of Outlooks on Pest Management, published by Research Information Ltd, and is made available here with the publisher’s permission. Copies of OPM articles are available on the IngentaConnect platform at

Impacts of an Invasive Non-Native Annual Weed, Impatiens glandulifera, on Above- and Below-Ground Invertebrate Communities in the United Kingdom

Puccinia komarovii var. glanduliferae var. nov.: a fungal agent for the biological control of Himalayan balsam (Impatiens glandulifera). 

First release of a fungal classical biocontrol agent against an invasive alien weed in Europe: biology of the rust, Puccinia komarovii var. glanduliferae