So, how's the battle with blackberry briars going? :-)
they're are big problem here.
Doc

Doc,

Goats! That's the solution. Seriously. I spent 15 years beating back the jungle before I wised up. Now, even as I type, my goats are out there hard at work...

The Canadian thistles will be back,and this time they'll bring along some Canadian wolves to look after the goats .....Monashee

Here is what the propeller heads say: "CONTROL RECOMMENDATIONS

RECOMMENDED PRACTICES IN NATURAL COMMUNITIES OF HIGH QUALITY
Prescribed fire can be effective in controlling this species and is a preferred treatment. Late spring burns, between May and June, are most detrimental to this noxious weed and should be used when possible. Prescribed burns to control this plant should not be conducted early in the spring, as early spring burns can increase sprouting and reproduction of this species. During the first 3 years of control efforts, burns should be conducted annually.
Management practices that maintain and encourage the development of healthy stands of native species will help prevent establishment of Canada thistle or help shade and weaken plants on sites already infested.
Repeated and frequent pulling or hand-cutting of individual plants will eventually starve underground stems. Cutting or pulling should be at least 3 times each season, in June, August, and September. This treatment is feasible for light and moderate infestations, but may be relatively time consuming in heavy infestations. Spot application of the amine formulation of 2,4-D according to label instructions can control this plant. Individual plants of Canada thistle should be treated with a wick applicator or hand sprayer. The herbicide 2,4-D amine is selective for broadleaf plants. To reduce vapor drift, use an amine formulation of 2,4-D rather than an ester formulation. Precautions should be taken to avoid contacting nontarget plants with the solution. Do not spray so heavily that herbicide drips off the target species. The herbicide should be applied while backing away from the areas to avoid walking through the wet herbicide. By law, herbicides may only be applied as per label instructions and by licensed herbicide applicators or operators when working on public properties.

RECOMMENDED PRACTICES ON BUFFER AND SEVERELY DISTURBED SITES
Control procedures recommended above for high quality natural communities are also applicable to buffer and severely disturbed sites. Additional control measures are as follows. On large sites (old fields, ditch banks, roadsides) with heavy infestations, thistles should be mowed when in full bloom, and as close to the ground as possible. Cut flower-heads should be removed to prevent scattering seeds on site. Repeated mowing may be needed for several years to obtain adequate control.
A foliar application of a 1-2% solution of Roundup (a formulation of glyphosate) applied in spring when plants are 6-10 inches (15.2 -25.4 cm) tall is an effective herbicide treatment. Individual plants should be spot-treated with a wick applicator. Roundup normally kills the entire plant, including the roots, when applied in this manner. Roundup is a nonselective herbicide and precautions should be taken to avoid contacting nontarget plants with the solution. Do not spray so heavily that herbicide drips off the target species. As with 2,4-D amine, Roundup should be applied while backing away from the areas to avoid walking through the wet herbicide. Roundup should not be used in high-quality natural areas during the growing season because of the possibility of harming nontarget plants.
On severely disturbed sites with heavy infestations, such as cropland or abandoned cropland, the site could be plowed and sowed to a cover crop (wheat, alfalfa, rye), if practical and desirable. The following May, the cover crop should be plowed under and desired native species should be seeded.

FAILED OR INEFFECTIVE PRACTICES

Fire early in the growing season can increase sprouting and reproduction. Prescribed burns in late spring are effective, as discussed previously.
Tillage disturbance of soil may provide ideal conditions for reinvasion and for introduction of other exotics.
Grazing is not an effective control measure as the prickles prevent livestock from grazing near Canada thistle."

x2 for goats. A neighbour up the road had problems with blackberries and other thistly unpleasantness obscuring his fence line; the guys running the municipal mower couldn't see the fence to trim it back. He's kept pygmy goats for several years now and they've eaten it all back. (And as a bonus, they're cute.) Between them and the mule and a couple of horses, his front yard looks immaculate.

I had a similar problem with blackberries and broom on my property but my next door neighbour started pasturing her llamas and alpacas on it and they pretty well keep it in check. The alders along the fence line are nicely trimmed to about 6'up and the blackberries don't stand a chance. Those critters have leather lips.

Stuart

Just a Hunter: Have any photos or a more definitive id on your problem. Star thistle maybe? 1Minute

Sounds like burdocks.

http://www.haworth-village.org.uk/nature/pictures/large-insects.asp?pic=237

That sounds like Japanese Knotweed:

http://en.wikipedia.org/wiki/Japanese_knotweed

Good luck. Just move and let someone else deal with it.

Well if you go far enough north in Ontario, someone should tell the logging companie's and the M.N.R. about the ban on pesticide's.I can't beleive they get away with it, everything dead for thousand's of acre's, just to protect there all mighty pine sapling's.They eaven post sighn's in english and indian language NOT to eat the berrie's.

just a hunter that lovely weed is called burrdoc it can grow to 8 feet tall in the right conditions ..buy your round up in concentrate and mix it to 1/2 pint to 2 gal or use GRazeon i think its a dow chem prod . y0u need to hit the plants early 4 or 5 leaves and spray heavy grason does not kill grass but will do in alfalfa clover and alot of other vegitation good luck i pulled many a hand full out of manes &tails all the seeds go to garbage can ..