Prickly invaders in the Telegraph Station put up a fight

By ERWIN CHLANDA

 

A new assault on prickly invaders into the Telegraph Station National Park is under way.

 

The coral cactus (Clyindropuntia fulgida), also known as the boxing glove cactus, has infected about 12 hectares of the park, and a treatment trial has brought limited results.

 

Five plants spread over about five hectares have been sprayed with Garlon mixed at 30mL per 1L of water about a year ago.

 

But the kill is taking twice as long as a similar treatment in Queensland, where the method has been pioneered. Big plants are still alive.

 

Sprayers have observed that the fluid runs off easily. Also, the dry conditions may have contributed to the slow absorption of the poison.

 

“The treatment of [three of the plants] would appear to be progressing successfully, with no new segments produced from the remaining green parts of the plant,” says Andy Vinter, of the Batchelor Institute, which is conducting the trial together with the Parks and Wildlife Commission.

 

“They will now work together on a second trial using a different herbicide mix to see if this produces a better result,” says a spokesman for the Parks Minister Matt Conlan.

 

“Cacti are very slow growing and they have a very slow rate of spread, mainly by vegetative reproduction rather than seed.

 

“Most of the cacti come from when the reserve was bordered by a caravan park that had a lot of long term residents who had these plants in gardens.

 

“Cacti have very little impact on native species,” says the spokesman.

 

Says Mr Vinter: “Of this group only [plant 1] may have produced viable segment regrowth (to be determined).

 

“All of these plants were similar in size (medium). The largest plant has not been successfully treated and despite significant die-back is producing new segments from green parts of the stem (and branches).

 

“This patchy die-back may indicate incomplete coverage of the herbicide mixture at the time of application. Presumably being a larger plant its has greater energy reserves for recovery if this is the case,” says Mr Vinter.

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  1. Posted May 25, 2013 at 11:08 am

    Recently I’ve seen a couple of examples of cacti that have clearly germinated from seeds spread by birds.
    One of these was a coral cactus (what I knew as Devil’s Rope many years ago), the other a prickly pear. Both young plants were growing under the branches of trees which indicates the seeds were deposited from bird droppings.
    There was a concerted cactus weed-spraying program in and around Alice Springs in 1989-90, most of it prickly pear cactus that was very slowly spreading along the banks of the Todd River south of town.
    This herbicide spraying program was successful. It came about after Roger Vale, then the Member for Braitling, had observed some of these clumps and he agitated for the Department of Primary Industry and Fisheries (in which the Weeds Section was then located) to do something to control the spread of these plants.
    In light of this development (my office was near the Weeds Officer at AZRI at the time) I wrote to Roger Vale advising of the imminent threat that Mexican Poppy posed to the local river systems – it had just begun to take hold in the Todd River.
    I even sent in a plant specimen to Roger’s electorate office; however, Mexican Poppy had been removed from the official weeds list sometime in the 1980s so there was no response from Roger and, overall, nothing was done about it until too late.
    Several years ago I had trouble with an introduced species of Portulaca that had emerged in my backyard garden in town.
    It was a weed species that appeared to produce a toxin in the soil, preventing other plants from competing with it. Spraying with Roundup was ineffective, and uprooting them also proved to be useless, too, as these plants (being succulents) would simply take root again.
    Even in scorching hot conditions at the height of summer, these plants just wouldn’t die! Eventually I hit upon a very simple solution – I gathered them up into bags and put them in a freezer for a couple of days.
    Once frozen solid I removed the plants and left them out in the sun to thaw, and they just turned to mush – completely killed.
    Perhaps this approach can be scaled up for larger infestations of succulent weeds like cacti, too.

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