Editing Hypericum perforatum (section)

=== Invasiveness ===
[[File:Hypericum perforatum field belair park.jpg|thumb|''Hypericum perforatum'' growing prolifically in [[Belair National Park]], [[South Australia]]]]
Although ''H. perforatum'' is grown commercially in some regions of southeast Europe, it is listed as a [[noxious weed]] in more than 20 countries and has introduced populations in South and North America, India, New Zealand, Australia, and South Africa.<ref name="cabi" /><ref name="feis">{{cite web | url = http://www.invasive.org/weedcd/pdfs/feis/Hypericumperforatum.pdf | work = Fire Effects Information System | title = SPECIES: Hypericum perforatum }}</ref> In pastures, St John's wort acts as both a toxic and invasive weed. It replaces [[native plant|native]] [[plant community|plant communities]] and [[forage]] vegetation to the extent of making productive land nonviable or becoming an invasive species in natural [[habitat]]s and [[ecosystem]]s.<ref name="North West Weeds">{{cite web|title=St John's wort – Hypericum perforatum|url=http://www.northwestweeds.com.au/sample-page/st-johns-wort-hypericum-perforatum/|url-status=dead|archive-url=https://web.archive.org/web/20160331070345/http://www.northwestweeds.com.au/sample-page/st-johns-wort-hypericum-perforatum/|archive-date=31 March 2016|access-date=2015-10-19|website=North West Weeds}}</ref>

Effective herbicides for control of ''Hypericum perforatum'' include [[2,4-Dichlorophenoxyacetic acid|2,4-D]], [[picloram]], [[Metsulfuron-methyl|metsulfuron]], and [[glyphosate]].<ref name="FSControl" /> Insect herbivores have also been introduced as [[biocontrol]] agents in areas outside their native range. Some of the most widely used are ''Chrysolina quadrigemina'', ''Chrysolina hyperici'', ''Agrilus hyperici'', ''[[Aplocera plagiata]]'', and ''Zeuxidiplosis giardi''.<ref name="FSControl" /><ref name="Harper2010">{{cite book |last1=Harper |first1=John L. |title=Population Biology of Plants |date=2010 |publisher=Blackburn Press |isbn=978-1-932846-24-9 }}{{page needed|date=September 2021}}</ref>