Bull thistle, aka scotch thistle, is easy to get rid of if you have cattle. On a fine day bruise the leaves(use a harrow, or drag something over the thistles) this causes the leaves to wilt and the catttle will do the rest. The cattle won't eat unbruised thistles. Best results are obtained by bruising at the leafy stage and the cattle will eat the thistle off at ground level.
You can mow, but you must mow BEFORE the seed heads form. Expect to mow at least twice.
Canada thistle, aka californian thistle, requires different tactics (it sprouts from subteranean roots). Wait until the flowers are at the " hardball" stage,(flower head has formed but NOT flowered) then hit with roundup using a weed wiper(zwiper) or roller type wiper (roto wiper) if you want to save the grass, or blanket spray if you are culivating. NOTE the timing is critical to achieve a good kill. Also, take a before and after picture. Timed right, the callies will be exterminated.
You can mow, but you must mow BEFORE the seed heads form. Expect to mow at least twice.
Canada thistle, aka californian thistle, requires different tactics (it sprouts from subteranean roots). Wait until the flowers are at the " hardball" stage,(flower head has formed but NOT flowered) then hit with roundup using a weed wiper(zwiper) or roller type wiper (roto wiper) if you want to save the grass, or blanket spray if you are culivating. NOTE the timing is critical to achieve a good kill. Also, take a before and after picture. Timed right, the callies will be exterminated.