Story: Weeds of agriculture

Biological control of St John’s wort

Biological control of St John’s wort

St John’s wort (Hypericum perforatum) is a toxic weed of hill and high-country pastures, especially in the South Island. The adults and larvae of St John’s wort beetles, introduced in 1943 to control the plant, defoliate plants so severely that flowering and seed production are limited. These plants have been eaten by the beetles, and still have clusters of black, shiny berries but few leaves. St John’s wort is used medicinally and in earlier times was reputed to have magical properties.

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How to cite this page:

Ian Popay, 'Weeds of agriculture - Weed control', Te Ara - the Encyclopedia of New Zealand, http://www.TeAra.govt.nz/en/photograph/16492/biological-control-of-st-johns-wort (accessed 17 September 2021)

Story by Ian Popay, published 24 Nov 2008