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Prickly Pear 3 August 2009

Posted by uggclogs in Life.

If you are at all familiar with Australian flora and the threat it faces by pests, you will be familiar with the Prickly Pear. You may not, however, be familiar with the numerous suggestions that were made on how to combat it.  Here’s the story.


In short (and I paraphrase the information from this site in the interest of keeping it short), the Prickly Pear is a cactus species native to the Americas (and even features in the Mexican Coat of Arms). It became one of the most invasive weeds that was ever imported to Australia.

When the First Fleet came to Australia, (and for you non-Australian history buffs, the First Fleet was the first colonial fleet of European Convicts to arrive in Australia in 1788) it already brought with it the first specimens of Prickly Pear.  The Prickly Pear has little insects on them called cochnieal insects, which, when squashed, produce a red dye which in Europe was considered to die for, even used for the famous red coats of British soldiers. Little is known of the fate of those first plants, but it has been established that that particular variety of prickly pear is still found along coastal areas of New South Wales, and is classified as a noxious weed. 

In the early 1800’s, it is believed that other varieties were introduced as stock fodder, because they could be used during drought years.   Prickly Pear then acclimatised and spread at an alarming rate. By 1925, prickly pear was infesting some twenty-five million hectares in New South Wales and Queensland.

Effective Treatment 

The answer to the main prickly pear problem came in the form of biological control. The first liberations of cactoblastis were made in 1926, after extensive laboratory testing to ensure they would not move into other plant species.

Within six years, most of the original, thick stands of pear were gone. Properties previously abandoned were reclaimed and brought back into production. 

That is not to say that the problem is completely addressed, as Prickly Pear is still extant in Australia, however, it is not such a pervasive pest anymore.

Suggested (and not so effective) Treatments

And now for the fun bit that made me want to blog about the Prickly Pear:

The National Archives of Australia, has some real gems as to the documented background on the Prickly Pear. 

Some of the tamer suggestions anno 1917 included poison (apparently, chloride of arsenic is cheaper and more effective than arsenite of soda), crushing the plants with steamrollers (which, for someoner who knows as little about botany as I do, sounds like a bad idea, wouldn’t that just crush the seeds into the ground for them to resprout?), use the weeds as cattle feed (in 1927 there was a patent application for a more effective machine for mincing pear into fodder) or to turn the weed into commercial products (such as a bio fuel, aka ‘spirits for combustion’, or paper pulp).

There were Legal Acts promulgated which encouraged landowners to shoot and kill animals that ate the pear and thereby spread the seeds (including emus).

More exciting suggestions were:

In 1917, someone suggested that modified tanks would be the best solution to the prickly pear problems when the war was over, because they could “let (our soldiers) attack the prickly vegetable with the same vigor as the spiky helmet.”


And yes, the weed was compared to the enemy in Europe.

In 1919, SGD A. Pentland of the Royal Airforce wrote a letter to the Government suggesting that they should reconsider the use of tanks to clear infested country in Queensland. Because, the argument goes, the war is over, and tanks are being scrapped, and should be freely available to any colony (sic.) asking for them.

See letter here:

Destroy prickly pear with tanks page 1

 Destroy prickly pear with tanks page 2

Another idea that was floated after the war was: Flamethrowers (and why not?)


 Clearly, Prickly Pear was (and remains) a serious issue in Australia. And many people had the issue at the forefront of their minds. Most suggestions were useful and seriously made, even though they sound a little crackpot to someone with the benefit of hindsight.

I wonder if the Governments of the world are still receiving these kinds of letters with solutions to problems they are facing. Probably. More solutions, however, need to incorporate flamethrowers, I say!


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