State of the Environment Report 2007

Snapshot: St. John’s Wort Control – an uplifting story 

St John’s Wort can help when you’re feeling a bit depressed. Just ask Friends of Aranda Bushland: they grab the plants and pull. Well, not quite! St John’s Wort plant extracts have health benefits in combating depression: but when the plants grow outside their natural habitat, or outside controlled gardens, they can have a depressing effect on other plants.

The Aranda Snow Gums Natural Heritage Site, part of Canberra Nature Park lies on the high southern fringe of Aranda and slopes down towards the Glenloch Interchange. It contains the largest remaining stand of the Snow Gums which once ringed the Canberra area. Friends of Aranda Bushland gained access to the site in 1999 and began a program of feral fauna and flora control. The site is badly infested with St. John’s Wort and this bushland support group ran trials over some 2 years from 2005 to work out the best control method.

Their thoughtful but resource-limited trial tested 5 methods including a couple of herbicides applied in different times and ways, and cutting out the plants by knife in early spring each year: there was a “no treatment” control plot too. Plant numbers were recorded in spring and again in summer.

The results need to be taken cautiously at this stage as there is no replication of plots and the erratic climatic conditions across 2005–07, including severe drought in early 2006, in themselves would have greatly reduced plant numbers. However, the best outcomes seem to have come from dabbing small rosettes with Glyphosate and from cutting out whole plants with a long bladed knife. Both methods have their future place since the bushland group won’t use chemicals within several metres of the dripline of the snow-gums.

The project’s benefits include enhancing the site’s biodiversity values by controlling weed infestations, providing ecological, cultural, recreational and aesthetic benefits.

Now, the pest plants are somewhat depressed, and the Friends of Aranda Bushlands are happier – as should be all Canberrans as a result of the efforts of this environmental group to protect and enhance this rare urban-area remnant of an important regional plant community. Small groups of enthusiastic, passionate people, using commonsense and hard work can make a big difference in their neighbourhood. 

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