Californian thistles

The Californians have many things to answer for, and the worst of their crimes are their thistles.  These have root systems underground, you can mow them but they'll grow back.  And you can grub/dig out the roots, but every fragment you leave down there will turn into a new root system.

Flattened californian thistles

People say grub them out, but have they tried?  And if they have, is their ground as stony as the ground in this field can be?  That white clump in the center back of the photo to the top left of the apricot tree, is a giant pile of large (and varying smaller sizes) of rocks.

I'm hesitant to put roundup on the thistles, grubbing them is impractical, and when mown they often grow back from the stubs, so I take the casual grinding approach.  Whenever I'm walking through the paddock and I pass a thistle, I just stand on it and twist the gumboot.  Bonus points if the weather is wet, as then they're 30% more vulnerable to fungal conditions.

While boot grinding isn't covered in the literature (like Lincoln University's page on non-chemical management of californian thistles) I rate it as more effective (at least in theory) than mowing.  When I cut/mow thistles early in the season, they grow back from the stumps.  When I mow thistles later in the season, then they're large and fill the field full of dried thistle foliage that remains for at least a year (try grabbing a handful of grass containing dried thistle..).

One comforting fact about the linked Lincoln University page, is that it gives good argument that the wind dispersed seeds are nothing to worry about.  Which is a good thing, as my neighbours hill (starting beyond the cattle in the photo) is covered in thistles as is the fields beyond it, and come a windy day late summer/autumn, the skies are filled with thistle seeds.