Spot spraying Thistles

I'm slowly getting the thistles under control. Instead of broadcast spraying this year I'm trying to spot spray in the fall. We've had a couple of nights at about 29 degrees, but no other frosts/freezes. Common wisdom is to spray after a light frost, but not a hard frost. I saw a letter from an extension service, but not in SD (PA, I believe) that said if they are green and look healthy spraying will be effective.

What about an area where they are mixed. Some small healthy looking, but half or more curling at the edges and or turning yellow due to the fall? Does it make sense to spray the healthy looking ones or am I wasting my time (since I'll need to come back and get them all next year anyway. I'll never get them all, so should I go ahead and hit the growing ones? I'm not sure if they are Canada Thistle, or "other". Several years ago I was told that I had no Canada Thistle by somebody I believe, but that was then and I can't tell the difference.

Also, what is the plant on right in this photo? The ones on the left are what I'm calling "thistle". The top looks more like an Oak leaf (but it's a thistle-like plant and has a few spikes). I've been just hitting these also. Should I keep doing that or leave them alone?

Current plan (and for the last few years) has been to mow in the spring (June or so) before the thistles get flowers, then spray in the fall.

Thanks

I know this is not practical for most people, but we used to graze the pastures hard and then they really stood out,then we spot sprayed all summer as we grazed the different pastures. I find them in the yard every once in a while, and I just dig them up.

I noticed this when A friend had 30 sheep on my place for a couple of summers (but several years ago). As I was spraying today I was thinking of getting some. They ate everything, including the thistle, and it was real easy to see the thistle when the rosettes popped up over the grass as stuff started growing back. Not a fan of the taste, otherwise that might be a plan.

I hired a helicopter to spray a couple of pastures last fall that had severe thistle problems. that was money well spent. Those pastures did'nt even look like I ever had a thistle problem! I would spray all that you can soon.

I think as long as the plants are"green and growing" the spray should be absorbed by them. I talked with some weed control agents the other day and they indicated fall can be a good time to get control, especially since the plant has by now used up most of it's "stored" neutriants. What spray are you using? I used to use 2-4D or Weedmaster but have changed to Milestone as it seems to be more effective

Using Trimec the past two years and this year. Used 2,4d in/near the "garden" and Trimec elsewhere. I've been told that trees suffer more from Trimec "uptake" through the roots,which is part of the reasons I'm trying to get by with spot spraying this year. If just spot spraying I have enough Trimec for a few years, but will probably try something else when that is gone.

Twenty mph winds today, and I'm limited to spraying on weekends. Not sure what's gonna happen. . .

Like Hayfarmer said, as long as they are green they can still be killed with spray. I have been spot spraying Grazon this fall with good results. I sprayed some thistles after a hard 24 degree frost and the spray curled them up right away. Which reminds me, a half hour ago I saw another healthy thistle, better nail it before I forget again. we have had two nights with temps in the mid-twenties and this thistle I saw is still healthy as a horse.

Bob check with your County Weed Board or county agent he can help. AS a past weed board member in SD i am sure that there is a book that you get that will help with what kinds you have