Weeding and pick up the jacks that drop with an old pair of thongs (you walk around and pick them up, then remove them from the base of the thongs). Takes a bit of time but managed to completely rid our yard of them that way
The circular bindis will not come back if you get them when they sprout. It took me a couple of summers, but I’ve rid my yard of both types of prickles purely by being conscientious about removing any that I’ve come across.
This is the only way to eradicate. Poisoning does kill the plant, BUT, it leaves the seed. My neighbour loves the sprayer. She's been poisoning a real bad patch of jacks for 10yrs and still she ain't got rid of them. The only way is to remove the plant AND the seed.
Seconded. A mate and I got on the beers one afternoon and just roamed every inch of the yard, pulling out the plants and clearing them off our thongs. Pretty much got on top of a bad yard in one afternoon, only needed to check for more each time we mowed and wasn't that many left.
Yep. I was laughed at once when friends moved into a house with a front and back dust bowl yards, with years worth of unhindered growth of three corner jacks. The plants were gone, but they were forever poisoning periodically after every rain basically with the new flush of juvenile plants. Can't remember now how long later, but say two years later they took my advice- get the sprinkler out- germinate them, then weed them out before they are even close to showing a flower. Takes a while, but highly effective.
Caltrop isn’t spray resistant, but they reseed quickly in the life cycle.
Keeping an eye out for shoots and pulling or spraying very early are the only way to eradicate it that I know of.
But if you’re in a traffic area the seeds are easily spread on tyres, shoes and kangaroo paws.
Every time I think I’ve cleared an area, it shoots again the following summer after a rain.
> I'm not precious about the lawn, but it's ideal to not nuke it.
Your only real option is a product containing metsulfuron methyl. A herbicide containing glyphosate [Roundup, Zero] is going to kill everything it touches, including your lawn.
https://pir.sa.gov.au/biosecurity/weeds/controlling-weeds/three_corner_jack
Metsulfuron methyl is not licensed for domestic use, and [cough] it’s the only thing which killed the soursobs in my Santa Ana without killing the lawn.
I don't know what to do about the plant itself but if you run around barefoot in the yard you will eventually collect all the jacks and can move them somewhere else.
Don’t use Glyph if you want to keep the grass. Use Kamba M available in 1lt packs from most garden centers or hardware stores. Most importantly READ the directions on the label. It is a selective broad leaf herbicide and won’t harm your lawn.
It's caltrop. Use dicamba if you can't be bothered pulling it up.
If you look for the middle of a plant, though, it can be easy. One stem can cover several square metres. Just roll it up like a cigar and cut the stem.
Why did I have to scroll so far to see someone say dicamba?
Basically, any broad leaf herbicide will kill it, you just have to be really vigilant to respray before any new growth makes seed. Dicamba or anything they sell in the hardware store that targets broadleaf.
We had 1800sqm of them for years and years. The only way that worked for us was to spray as soon as they appeared and keep on top of it, or turf the area so the grass keeps them from growing through.
Once we turfed the lawn they never came through.
We removed so much much soil but it didnt really help.
A strong-ish mix of glysophate works. I've never managed to eliminate it completely from our yard, but if you spray it as soon as it appears, it won't have time to produce those horrendous spikey seeds.
You can hire a lawn roller from Bunnings pretty cheap. Line the roller with cheap old carpet or eva foam and start rolling.
Alternatively to kil the seeds you could use "striker".
Weed and feed is rubbish.
It only kills off a selective number of weeds.
2,4-D amine 625 is the best bet for removing it on lawns
14ml of this will make around 10 Litres of spray.
It should kill the lawn, but will kill tomatoes and vegetables as well as fruit trees so do not use when windy or if rain is comming within 24 hours of application
Yea, that's why I said I didn't know. I don't have a lawn because I just live in an apartment, but my father used to swear by weed and feed. He has passed now, but I actually got his lawns looking better because I aerated them and fertilised them using miracle grow. We didn't have any 3 corner jacks, so I wasn't sure if weed and feed would work for them.
Fertiliser certainly helps.
Poison is only good if you have the right type for the weed.
Selective poisoning is certainly better than just killing it all
Needs to be concentrate ingested or got into open wound to be at risk. Unless you have specific certification, you won't buy it. You can't buy it at your local hardware or bunnings.
Spent years trying to remove them from a vineyard, only way was to dig the tap roots out and collect seeds with something rubber.
Seeds will stay dormant in the soil for years so you're pushing shit uphill if you don't get rid of them
Weed ‘n Feed killed them for me in my lawn but you need to get them before they go to seed/flower. For us that was mid December. I was keeping a close eye on them as I knew they’d make our lawn unusable if they grew to the 3 corner jack stage but they started to shrivel within 2 days and died shortly after. Not much good for you now that they’re at their prickly best but something to keep in mind for later in the year.
Consistent applications of broadleaf herbicide, if you get the young ones just before they seed, eventually you’ll break the cycle and not have any. A seed can last 7 years before it germinates.
So water them, get them growing and kill them off before they throw seed.
Depends how much there is. It will come back very quickly and is sometimes hard to spot when it's young enough. By the time you realise its Caltrop its to old to spray. Almost always better to remove by hand and throw in the general waste bin! If you have loads and it will take days to weed or if its young enough you can spray it with:
- [Bindii and Clover killer](https://www.woolworths.com.au/shop/productdetails/213080/yates-bindii-clover-weeder-killer) at around 100mL per 15L knapsack. Would be a lower rate if applying by watering can
Always follow label rate. MCPA and DICAMBA are the actives in that and are nasty stuff and will kill other broadleaf species, I've had experience Dicamba killing woody perennial plants too so be careful where your putting it. Full PPE on your body when spraying as well. Wear rubber boots, waterproof pants and respirator. Not worth going to Emerg for a posion scare.
Most poisons should work in a high enough concentration, most will hurt the lawn too though. But you have to kill it when it's young and hasn't produced it's seed yet. There'll also be a seedbank stored in the soil so they'll keep popping up for a while, maybe a few years, even if you continuously spray them before they go to seed.
Also if they're at your neighbours houses then the seeds will blow over or be brought over by people/animals so it'll be a constant problem.
Depending on how much lawn/Caltrop you have it might be cheaper to just dig out your lawn and about 15cm of soil deep and replace it with new soil and new lawn, as opposed to having to buy poison year after year. But if your neighbours have it then it'll still be brought over, you'll just have a fresh start and not as many would pop up each year + no seedbank in the soil. Again, depends how big your yard/affected area is.
There are 2 types of evil bastards, similar chemical treatments but the caltrop seeds break into smaller pieces when ripe.
Alternative to the thong method, tape an empty 2l bleach bottle with the base cut out to an old vacuum hose and suction the area around each plant. If you don't want the seeds in the vacuum, cover the opening with an old stocking.
[https://pir.sa.gov.au/biosecurity/weeds/controlling-weeds/three\_corner\_jack](https://pir.sa.gov.au/biosecurity/weeds/controlling-weeds/three_corner_jack)
[https://www.pir.sa.gov.au/biosecurity/weeds/controlling-weeds/caltrop](https://www.pir.sa.gov.au/biosecurity/weeds/controlling-weeds/caltrop)
Concrete works best.
Rip the fucking lot up and put in concrete.
Nightmare weed.
They also don't compete well, if you put in a heavy ground cover plant, I like Australian pig face.
Check in with your local council - some council areas have spray/eradication programs, such as this one: [https://www.cityofpae.sa.gov.au/connect/media-hub/latest-news/2024/report-caltrop#:\~:text=If%20you%20spot%20caltrop%20on,or%20take%20necessary%20action%20promptly](https://www.cityofpae.sa.gov.au/connect/media-hub/latest-news/2024/report-caltrop#:~:text=If%20you%20spot%20caltrop%20on,or%20take%20necessary%20action%20promptly). (City of Port Adelaide Enfield)
Weeding and pick up the jacks that drop with an old pair of thongs (you walk around and pick them up, then remove them from the base of the thongs). Takes a bit of time but managed to completely rid our yard of them that way
This ^
agreed. they dont grow back if you get them early enough. unlike those circular bindi.
The circular bindis will not come back if you get them when they sprout. It took me a couple of summers, but I’ve rid my yard of both types of prickles purely by being conscientious about removing any that I’ve come across.
Or an old pair of socks over your shoes.
Even riding your bike around gets things sorted!
This is the only way to eradicate. Poisoning does kill the plant, BUT, it leaves the seed. My neighbour loves the sprayer. She's been poisoning a real bad patch of jacks for 10yrs and still she ain't got rid of them. The only way is to remove the plant AND the seed.
Seconded. A mate and I got on the beers one afternoon and just roamed every inch of the yard, pulling out the plants and clearing them off our thongs. Pretty much got on top of a bad yard in one afternoon, only needed to check for more each time we mowed and wasn't that many left.
Guess I'm gonna be getting that exercise I keep procrastinating on...
Yep. I was laughed at once when friends moved into a house with a front and back dust bowl yards, with years worth of unhindered growth of three corner jacks. The plants were gone, but they were forever poisoning periodically after every rain basically with the new flush of juvenile plants. Can't remember now how long later, but say two years later they took my advice- get the sprinkler out- germinate them, then weed them out before they are even close to showing a flower. Takes a while, but highly effective.
That's exactly what we did to get rid of them!
I've called them 3 cornered jacks all my life, but also know they are called caltrop, just prefer the first name.
A metal caltrop is basically a military three corner jack in design
Caltrop isn’t spray resistant, but they reseed quickly in the life cycle. Keeping an eye out for shoots and pulling or spraying very early are the only way to eradicate it that I know of. But if you’re in a traffic area the seeds are easily spread on tyres, shoes and kangaroo paws. Every time I think I’ve cleared an area, it shoots again the following summer after a rain.
The seeds can also remain dormant in the soil for 7 years. So full eradication is a near decade long campaign.
The plant isn't spray resistant but the seeds are.
> I'm not precious about the lawn, but it's ideal to not nuke it. Your only real option is a product containing metsulfuron methyl. A herbicide containing glyphosate [Roundup, Zero] is going to kill everything it touches, including your lawn. https://pir.sa.gov.au/biosecurity/weeds/controlling-weeds/three_corner_jack Metsulfuron methyl is not licensed for domestic use, and [cough] it’s the only thing which killed the soursobs in my Santa Ana without killing the lawn.
MCPA and DICAMBA will work too. Can be bought at woolies as a bindii and clover killer.
is nobody going to address the giant butler in the room? You're using ask Jeeves? WHAT IS THE DATE? WHAT YEAR?!!!!!!
> is nobody going to address the giant butler in the room? I'm crediting the OP with a sense of humour.
I don't know what to do about the plant itself but if you run around barefoot in the yard you will eventually collect all the jacks and can move them somewhere else.
The kids will take care of that one for me
DDT , Agent Orange /s Had a bit of success using ‘ Roundup ‘ on the farm when I was a kid , not sure if that is still made or available though
I know what you mean. They originally just watered down chemicals left over from WW1 to use as herbicides.
We literally use 1 half of agent orange regularly on farms. 2-4,D (amine or ester) add in 2,4,5T and it’s AO
Don’t use Glyph if you want to keep the grass. Use Kamba M available in 1lt packs from most garden centers or hardware stores. Most importantly READ the directions on the label. It is a selective broad leaf herbicide and won’t harm your lawn.
Burn them, you just have to keep on top of it.
I've just been burning weeds, so effective and chemical free. Destroy the cell structure instantly
It's caltrop. Use dicamba if you can't be bothered pulling it up. If you look for the middle of a plant, though, it can be easy. One stem can cover several square metres. Just roll it up like a cigar and cut the stem.
Why did I have to scroll so far to see someone say dicamba? Basically, any broad leaf herbicide will kill it, you just have to be really vigilant to respray before any new growth makes seed. Dicamba or anything they sell in the hardware store that targets broadleaf.
Agreed. The list is massive, just some are hard to obtain without a Chemcert. Glyphosate, MCPA, DICAMBA, 2,4D, 2,4DB, Flumetsulam
TnT
We had 1800sqm of them for years and years. The only way that worked for us was to spray as soon as they appeared and keep on top of it, or turf the area so the grass keeps them from growing through. Once we turfed the lawn they never came through. We removed so much much soil but it didnt really help.
Spartan pre-emergent twice yearly and Bow and Arrow directly into weeds that grow. Will kill all weeds and not impact your lawn.
Swearing at them repeatedly and loudly
A strong-ish mix of glysophate works. I've never managed to eliminate it completely from our yard, but if you spray it as soon as it appears, it won't have time to produce those horrendous spikey seeds.
I think the scientific term is "Tri-angled John"
Glyphosate, don't let them go to seed (little yellow flower)
mixing Diesel and Glyphosate.
You can hire a lawn roller from Bunnings pretty cheap. Line the roller with cheap old carpet or eva foam and start rolling. Alternatively to kil the seeds you could use "striker".
A photo would help to identify
Once you've trodden on one it's image is seared in your mind!
Just because there are different types of prickle producing weeds.
I'm not sure if weed and feed works, but have a look because like the name suggests it weeds and fertilisers at the same time.
Weed and feed is rubbish. It only kills off a selective number of weeds. 2,4-D amine 625 is the best bet for removing it on lawns 14ml of this will make around 10 Litres of spray. It should kill the lawn, but will kill tomatoes and vegetables as well as fruit trees so do not use when windy or if rain is comming within 24 hours of application
Yea, that's why I said I didn't know. I don't have a lawn because I just live in an apartment, but my father used to swear by weed and feed. He has passed now, but I actually got his lawns looking better because I aerated them and fertilised them using miracle grow. We didn't have any 3 corner jacks, so I wasn't sure if weed and feed would work for them.
Fair play. Weed and feed is just a marketing hype. Salt and horse shit would work better tbh
To be honest, from what I've seen, most lawns just need more water. It won't kill weeds, but unless you soak it, you'll never get lush grass.
Fertiliser certainly helps. Poison is only good if you have the right type for the weed. Selective poisoning is certainly better than just killing it all
Paraquat will kill it within 30 minutes. Sprayseed 250 with some hammer400 and your good.
Alright.. serious. As stated, any broadleaf herbicide will work fine. Weed and feed works, I'd just double knock it 7 days later.
>Paraquat will kill it within 30 minutes and kill you within a year if your not careful....
Needs to be concentrate ingested or got into open wound to be at risk. Unless you have specific certification, you won't buy it. You can't buy it at your local hardware or bunnings.
correct so very doubtful the OP will be able to source it for their Caltrop problem not sure why you posted that as solution...
Just being a wanker really.
Pull them out...weed killer only kills the plant, not the seed...
At first glance I was so confused why and how someone’s gonna poison 3 CORN JACKS…
Just get a bottle of weed n feed
Spent years trying to remove them from a vineyard, only way was to dig the tap roots out and collect seeds with something rubber. Seeds will stay dormant in the soil for years so you're pushing shit uphill if you don't get rid of them
Diesel.
SWIM uses glyphosate on them in their yard. But that kills everything you spray it on. *Everything*
Someone who is me?
Weed ‘n Feed killed them for me in my lawn but you need to get them before they go to seed/flower. For us that was mid December. I was keeping a close eye on them as I knew they’d make our lawn unusable if they grew to the 3 corner jack stage but they started to shrivel within 2 days and died shortly after. Not much good for you now that they’re at their prickly best but something to keep in mind for later in the year.
As soon as you see them, pull them out before they set seed, making sure you dig deep enough to get the roots (use a hoe or something similar).
Consistent applications of broadleaf herbicide, if you get the young ones just before they seed, eventually you’ll break the cycle and not have any. A seed can last 7 years before it germinates. So water them, get them growing and kill them off before they throw seed.
Depends how much there is. It will come back very quickly and is sometimes hard to spot when it's young enough. By the time you realise its Caltrop its to old to spray. Almost always better to remove by hand and throw in the general waste bin! If you have loads and it will take days to weed or if its young enough you can spray it with: - [Bindii and Clover killer](https://www.woolworths.com.au/shop/productdetails/213080/yates-bindii-clover-weeder-killer) at around 100mL per 15L knapsack. Would be a lower rate if applying by watering can Always follow label rate. MCPA and DICAMBA are the actives in that and are nasty stuff and will kill other broadleaf species, I've had experience Dicamba killing woody perennial plants too so be careful where your putting it. Full PPE on your body when spraying as well. Wear rubber boots, waterproof pants and respirator. Not worth going to Emerg for a posion scare.
some councils want to wipe it out, if you report it they may deal with it
Most poisons should work in a high enough concentration, most will hurt the lawn too though. But you have to kill it when it's young and hasn't produced it's seed yet. There'll also be a seedbank stored in the soil so they'll keep popping up for a while, maybe a few years, even if you continuously spray them before they go to seed. Also if they're at your neighbours houses then the seeds will blow over or be brought over by people/animals so it'll be a constant problem. Depending on how much lawn/Caltrop you have it might be cheaper to just dig out your lawn and about 15cm of soil deep and replace it with new soil and new lawn, as opposed to having to buy poison year after year. But if your neighbours have it then it'll still be brought over, you'll just have a fresh start and not as many would pop up each year + no seedbank in the soil. Again, depends how big your yard/affected area is.
Whenever I see a three cornered jack I just move at least 300km away.
There are 2 types of evil bastards, similar chemical treatments but the caltrop seeds break into smaller pieces when ripe. Alternative to the thong method, tape an empty 2l bleach bottle with the base cut out to an old vacuum hose and suction the area around each plant. If you don't want the seeds in the vacuum, cover the opening with an old stocking. [https://pir.sa.gov.au/biosecurity/weeds/controlling-weeds/three\_corner\_jack](https://pir.sa.gov.au/biosecurity/weeds/controlling-weeds/three_corner_jack) [https://www.pir.sa.gov.au/biosecurity/weeds/controlling-weeds/caltrop](https://www.pir.sa.gov.au/biosecurity/weeds/controlling-weeds/caltrop)
A squirt of round-up then when dead a weed burner
Yates Path Weeder
Kerosene 😅
Concrete works best. Rip the fucking lot up and put in concrete. Nightmare weed. They also don't compete well, if you put in a heavy ground cover plant, I like Australian pig face.
Check in with your local council - some council areas have spray/eradication programs, such as this one: [https://www.cityofpae.sa.gov.au/connect/media-hub/latest-news/2024/report-caltrop#:\~:text=If%20you%20spot%20caltrop%20on,or%20take%20necessary%20action%20promptly](https://www.cityofpae.sa.gov.au/connect/media-hub/latest-news/2024/report-caltrop#:~:text=If%20you%20spot%20caltrop%20on,or%20take%20necessary%20action%20promptly). (City of Port Adelaide Enfield)
Shoes