Landcare Agony Aunt – Balloon Vine Gone Ballistic

Dear Agony Aunt,

I recently moved to a new property. I am dealing with mountains of this horrible vine smothering the casuarinas along the river bank.  I have tried cutting it but it comes back.  What have I got myself into Agony Aunt?

from Bewildered in Branxton

Dear reader,

You’ve got yourself a mighty case of Balloon Vine (Cardiospermum grandiflorum). It is a real curse along our waterways but you will be rewarded with improved biodiversity if you make a sustained effort to control it, so thanks for writing in.  

Balloon Vine is regarded as a ‘transformer’ species because of its ability to drastically exclude light from understory plants and smother native plants.  It was introduced in the 1920s and 30s from tropical America and its aggressive spread up the east Coast has been mapped in the Figure below. (Plant Protection Quarterly Vol.20(4) 2005). 

The fruits of Balloon Vine are papery, balloon-like capsules with 3 compartments, each containing one seed.  These capsules may drop off the branch and float readily on water down the catchment for several months or be dispersed by wind.  Once mature, mature fruits dehisce and release seeds carried on specialized wings which can remain viable for 2 years if kept moist.  

It sounds like your Balloon Vine has gone ballistic.  For such a large infestation that is growing into the canopy,  cut the vine at head height to skirt the vine and allow the foliage in the tree to naturally die off.

Then you have these options in order of difficulty: 

1. Spot spray:  Lay the stems of the plant on the ground and spray any foliage remaining with herbicide as per these  recommendations: https://weeds.dpi.nsw.gov.au/Weeds/Balloonvine#biosecurity. 
2. Scrape and Paint: Follow the vine back to the root.  Scrape 20cm sections of stem to expose the green layer just beneath the dead tissue and paint with undiluted glyphosate.  Repeat this process up the stem in 20cm sections for about 1m.
3. Hand-pull each vine out from the roots. 

Get your diary out because you need to repeat this process every 3-4 months.  Pay special attention to controls before flowering in mid-summer to prevent autumn seed set. 

Welcome to your new property and this labour of love!  Good luck reader, and remember, the riparian habitat will be so much healthier and love you back if you get on top of your Balloon Vine.