Trial site, accessed from the Gunsynd Way, 100m on the Goondiwindi side of the Boomi Rd turnoff!

Trial site, accessed from Gunsynd Way (100m Goondiwindi side of the Boomi Rd turnoff)

NWW220 LLS_HC_Chem_trials-2-Peg-33HARRISIA TRIALS IN PROGRESS – MAR 2015 to DEC 2017


Local Land Services North West*  is funding a round of herbicide trials on harrisia cactus near Goondiwindi. Conveniently located on the open TSR adjacent to Gunsynd Way, the (drive-through) trial site is just opposite the Boomi Rd turnoff. It’s open to the public for on-going viewing. Twenty one (21) different herbicide mixtures have been applied to a total of 60 plots, all signposted. (*LLS northern office located in Waggamba Square, Goondiwindi Qld)

The first set of ten (10) mixtures was replicated Mar-Jun-Sep-Dec to determine optimum application times. Most of the other mixtures Harrisia-field-day-Jun-2016were also applied at 3-monthly intervals, but with an emphasis on more options for effective winter application (for use in between the main peak farming periods).

Below, with kind permission from the Local Land Services North West, are links to the three documents needed to follow the progress of these trials.

The score sheets allow you to compare (1) the different results for each herbicide between summer, autumn, winter and spring applications and (2) the overall results between the various herbicide mixtures used.

Harrisia cactus is a tough competitor. Easy to kill the top of the plant but it’s what finally happens to the root system that counts. A 2-year timeframe for that has been set, with ongoing results being posted on this site every 3 months. These trials will provide final data on all plots over a minimum 24 month period.

Download site map and herbicide list

Site map and herbicide list


Harrisia plots 1 to 29 Mar 2017Plots 1 to 29 – herbicide results to September 2017- ongoing… Harrisia plots 29a to 60 Mar 2017Plots 29A to 60 – herbicide results to September 2017 – ongoing…


Herbicide trials have been conducted in (NSW) Moree, Gwydir and Inverell Shires since 2008 – thanks to special funding received from the then Border Rivers Gwydir Catchment Management Authority (now Local Land Services) through the Australian Government Caring for Country scheme.

The best results brought forward from these trials were the basis for an extensive trial put down on the Billings family property “Bridgewater” 30 k’s SE of Goondiwindi (our sincere thanks to Mr Ed Billing and Inverell Shire Council for their support with this project). Commenced Dec 2013 and finalised Feb 2015, the results of this trial was summarised in a document provided by North West Weeds – PDF copy attached:  Harrisia trials Bridgewater BW3 Dec 2013 to Feb 2015 Final.

  1. Notes on the BW3 trial summary to Feb 2015:
    20g metsulfuron methyl plus 100mL wetter to 100L water is very effective, especially for large infestations because this basic mixture is so inexpensive – less that 3 cents a litre. But, the downsides:
    (a) not suitable during cooler weather especially if plants approaching fruiting stage (unless adding a  picloram/triclopyr product – see Permit PER80069 for more info on rates)
    metsulfuron can cause collateral damage to trees especially when we are talking high volume applications – for example, wilgas are shallow rooted and very susceptible – box trees are also a problem especially if there is heavy rain soon afterwards to wash the herbicide further into the ground.
  2. Access® and diesel (1 to 60) or Garlon® and diesel (1 to 75) mixtures are both good for treatment of isolated plants because they stay mixed for a longer period. Expensive, but very practical for a spray pack in the back of the quad/ute when you come across a new plant. Also very appropriate to use during winter/cool periods
  3. Grazon-type herbicides (Triclopyr + picloram) at the (standard) rate of 500 mL per 100 litres water appear to be TOO STRONG, taking out the top of the plant before translocation into the root system is complete – thus leaving the way open for excessive regrowth.

Click here to go back to our main Harrisia cactus page.

More information on any of these trials? Please contact the webmaster at    

IMPORTANT: USE OF PESTICIDES – ALWAYS READ THE LABEL Pesticides must only be used for the purpose for which they are registered and must not be used in any other situation or in any manner contrary to the directions on the label. Never use a herbicide in any way contrary to the label recommendations.

DISCLAIMER: The information contained in this web site is based on knowledge and understanding at the time of writing. However, because of advances in knowledge, users are reminded of the need to ensure that information upon which they rely is up to date and to check currency of the information with the appropriate officer of North West Weeds or the user’s independent adviser.