Battling the biotypes of balsam: the biological control of Impatiens glandulifera using the rust fungus Puccinia komarovii var. glanduliferae in GB

• Published in: Fungal biology Vol. 125; no. 8; pp. 637 - 645
• Main Authors: Pollard, K.M., Varia, S., Seier, M.K., Ellison, C.A.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.08.2021
• Subjects: Biocontrol; Biotypic variation; Fungal pathogens; Invasive weeds; Rust fungi; Fungal pathogens; Rust fungi; Biotypic variation; CBC; Invasive weeds; Biocontrol
• ISSN: 1878-6146; 1878-6162
• DOI: 10.1016/j.funbio.2021.03.005

Impatiens glandulifera, or Himalayan balsam, is a prolific invader of riverine habitats. Introduced from the Himalayas for ornamental purposes in 1839, this annual species has naturalised across Great Britain (GB) forming dense monocultures with negative affects across whole ecosystems. In 2006 a programme exploring biocontrol as an alternative control method was initiated and to date, two strains of the rust fungus Puccinia komarovii var. glanduliferae have been released. To better understand the observed differences in susceptibility of GB Himalayan balsam stands to the two rust strains, inoculation studies were conducted using urediniospores and basidiospores. Experiments revealed large variation in the susceptibility of stands to urediniospores of the two rust strains, with some resistant to both. Furthermore, the infectivity of basidiospores was found to differ, with some stands fully susceptible to the urediniospore stage, being immune to basidiospore infection. Therefore, before further rust releases at new sites, it is necessary to ensure complete compatibility of the invasive stands with both urediniospores and basidiospores. However, for successful control across GB it is essential that plant biotypes are matched to the most virulent rust strains. This will involve additional strains from the native range to tackle those biotypes resistant to the strains currently released. •Multiple biotypes of Himalayan balsam exist in the UK.•Populations differ in their susceptibility to the rust biocontrol agent.•Susceptibility of a population to the mono- and dikaryotic spore stages can differ.•Susceptibility testing using both spore stages required prior to release at a site.•Additional rust strains required for the control of Himalayan balsam in the UK.