What do I need to spray thistles from a quad bike sprayer?

[digger don]

Doesnt bloody well work here, the ones I topped in July are currently seeding...

Really! How odd it definitely worked here!..
Had they been cut earlier in the year too? From what a could see. Its cutting them just before they seed. Hummmmmmm!!

 

[Red Fred]

I've found that creeping thistles really hate getting wet feet. When our meadows flood, it really knocks them and I have it easy for a year or two.

 

[neilo]

They just don't like mowing enough.

Spear/boar thistles will be killed by topping in their second year, as they shoot a flowering stem up. Creeping thistles won't, they will just throw up more shoots to compensate, unfortunately.

 

[Red Fred]

Our agronomist used to say that most creeping thistle seed was sterile, and almost all new growth came from the spreading roots. Don't know if others have heard that.

 

[ollie989898]

You will have to cut them a lot to exhaust the root, I have seen some that died merely from being rolled, they just kind of rotted off, although to be fair the field they were located in was not conductive to anything surviving for very long.

Save the diesel and metal and pulling your hair out and just buy some ThistleX or something.

 

[Pasty]

Spear/boar thistles will be killed by topping in their second year, as they shoot a flowering stem up. Creeping thistles won't, they will just throw up more shoots to compensate, unfortunately.

I'm going to politely disagree there. You absolutely can get rid of creeping thistle by constant mowing. I have done it myself in places where I have kept on it and have also read of others having success with that method. Prevention is obviously easier than curing but the worst bits on my place are definitely retracting this year rather than spreading. Apparently April is a good time to whack them as that's when the reserves are lowest. That's contrary to the 'old' wisdom which maybe applies more to spear, as you say.