I seemed to have found the magic potion to kill Canadian Thistles.
Efforts in previous years had poor results. In retrospect, the primary problem is that upper surface of the thistle leaf repels water...and spray. It has a waxy coating and spray seems to bounce off.
This year I bit the bullet and bought a bottle of Dawn dishwashing detergent. The "kids" bought some for dishes and it is clearly far more concentrated than the cheaper Ajax I have been using as a surfacant (wetting agent) in my spray.
I start each load of broadleaf herbicide with a generous squirt of Dawn dishwashing degergent...a good two or three ounces. Then about a teaspoon of swimming pool pH reducer (lower pH changes leaf surface and increases penetration rate of herbicide. It also captures "tramp" ions like Ca++, Mg++, Fe+++ that want to bind with 2,4-D molecules), then a gallon of soft-water (again, to reduce the tramp ions). A couple of ounces of 44% 2,4-D concentrate. Mix. Spray at low pressure to ensure big droplets that do not blow and have enough momentum to "splash" the leaf surface to break-down the resistance to wetting.
This is a very good time to spray Canadian Thistle in my part of the world. The plants are still growing upward and the 2,4-D mimics growth regulators. The faster the plant growth the more it messes them up.
In other news
I drove by Erickson Power Station in Delta Township. Eckert added a gas turbine a few years ago.
I saw that the construction crews were taking down the cooling towers. Good-bye 159 MW of coal generation.
Ecologists are cheering.
I regret that they did not leave the capacity in-place as a back-up.