Winning the war on weeds

Guest bloggers
Published 30 Mar 2020 
by Ian Haverly 
about  Goonderoo Reserve  
Aerial view of brigalow scrub showing encroachment of Sword Cactus prior to 2017<br/> Aerial view of brigalow scrub showing encroachment of Sword Cactus prior to 2017
A disintegrating plant following treatment<br/> A disintegrating plant following treatment
A "big baby" needing followup treatment<br/> A "big baby" needing followup treatment

I first visited Goonderoo Reserve back in May 2017 to serve a stint as caretaker for seven weeks. Goonderoo, a Brigalow landscape, had a major infestation of Sword Pear (Acanthocereus tetragonu) across a substantial part of the reserve. In fact, the pastoral paddock next to Goonderoo is classified as the worst site for Sword Pear in the whole of Queensland!

Before my visit Paul Hales, (Northern Savannah Healthy Landscape Manager), had test trialled various herbicides to determine the most effective treatment to tackle the Sword Pear infestation. The magic solution known as ‘Brew F’ was found to be very effective in killing the cactus as can be seen in the before and after photos. During my stay I systematically treated all paddocks on the reserve.

To be effective each finger of the cactus (some of which were as much as 2m high, 20m across and 5m deep) needs to coated until run off with the herbicide. Due to the nature of the terrain most of this has to be carried out on foot with a backpack, crashing through the bush to get to each plant.

I returned to Goonderoo in 2018 to find that although the herbicide is very effective in killing the cactus, due to its size and structure a second and even third follow up treatment is needed. This ‘Stage 2’, as I call it, is where the majority of the plant is dead but may have survived at the core to re-sprout or have produced ‘babies’ prior to dying.

During my stays in May and September that year I surveyed and mapped the entire 593 hectare reserve, mostly on foot, to determine the extent and progress of the treatment regime and to find the yet untreated plants. I then proceeded to treat all the plants found using about 1,500 litres of herbicide, mostly via backpack.

This year in February I arrived back at Goonderoo to check on the cactus and I’m pleased to report that the number of surviving cactus is dramatically down across the paddocks surveyed. In fact, in some of the lessor infested paddocks the number of surviving cactus is minimal and we've reached ‘Stage 3’ – a point of tracking down entirely new plants that have sprouted since the previous year from seed.

The war againt Sword Pear at Goonderoo may not yet be over, but with my help and that of other Bush Heritage volunteers it's certainly being won.
A disintegrating plant following treatment<br/> A disintegrating plant following treatment
A "big baby" needing followup treatment<br/> A "big baby" needing followup treatment