Triclopyr 3 is really what you want for Ailanthus but this may work as well. There are two methods of treatment, hack and squirt or basal bark treatment. Basal bark treatments are cut with diesel that acts as a surfactant, you spray the bottom 2 feet of the stump making sure you've got good coverage and let it sit. The diesel will hold the triclopyr and glyphosate mixture in place and begin to saturate into the live layer of the tree (the surface right under the bark or the newest ring). Basal bark treatment should only be used with Ailanthus trees under 4-6" in diameter. Hack and squirt method is for any tree larger in diameter than ~6". First you take a hatchet and cut into the base of the tree as low to the ground as possible by using a downward swing (45 degrees or greater is ideal). The downward swing will create a little cup-like wound in the tree. DO NOT GIRDLE THE TREE! Leave even spacings between the hacks, if your hatchet is making 3" wounds then leave 3" of space between each hack. Once you've went around the whole tree you need to immediately apply your triclopyr and glyphosate mixture otherwise the tree gives off a sap that will effectively seal off the wound within 10 to 15 minutes of hacking the tree, so you need to move with intent. For this method I use a handheld 0.5 multi-purpose sprayer with a thumb trigger, not a backpack or wand sprayer as this method requires very little herbicide. Take the multi-purpose sprayer and fill up each cupped wound with your herbicide while trying not to overfill it because you are just wasting it at that point. The best time of year to treat Ailanthus Altissima is from early July through mid-September when the tree is actively sending its energy absorbed from the canopy down into the root system to fortify itself for the next year. This will actively draw the herbicide down into the root ball and give you the best chance of killing this invasive species in one shot thereby minimizing the amount of "suckers" that the root system with try and shoot up because you directly harmed the root system. If the tree you are treating is 50' tall you need to keep an eye out for suckers in a 50' radius of the tree. You can keep cutting them as they come up but I strongly suggest treating with herbicide and even waiting for July to roll around before messing with it because the root system is heavily relying on these suckers to provide the much needed energy to fortify the stunted root system.

What is the mixing ratio of this product per gallon of water or do you have to use it straight?

For foliage application to poison oak and thistle, I use 2 to 2.5 oz per gallon of water, but you must add a surfactant, as the esther form of triclopyr (which this is) is oil soluble, and will not mix without the surfactant. Plus you need to agitate the mixture from time to time, which is not a problem if you are using a hand held tank sprayer. You can also use it for basal bark treatment to kill small trees less than 6-8 inches in diameter, if you dilute it to about 15 % Triclopyr concentration in oil (Pathfinder II is the same Triclopyr 4 specifically premixed for basal bark treatment, with a 13% Triclopyr concentration, but a lot more expensive). You can also use it straight for cut stump treatments or "hack and squirt" treatment to kill large trees, although the water soluble Triclopyr 3 form is sometimes preferred for this application.

I need to control the spread of creeping charlie. Which product, Triclopyr 4 or 4EC would be most effective? When should I apply the product?

Trimec® is a safer alternative for creeping charlie, as it wont harm trees and shrubs as easily. Use 175oz/acre, with a non-ionic surfactant. (the homeowner version is rather dilute because of the Dicamba content). Trimec® will not, however kill wild violets. Triclopyr WILL do that. Use triclopyr 24oz/acre rate, with a non-ionic surfactant, for wild violets. The best time to kill either of these difficult weeds is late September through early November depending upon your climate zone. The weeds will be taking nutrients (and herbicides) into their roots for storage to overwinter. (certified pesticide applicator). Spot spraying is always preferable to broadcast spraying with with either of these herbicides anywhere near trees and shrubs, when possible.

Five acre rural lot with at least a third heavily infested with buckthorn. Hundreds of hours of cutting, spraying with Roundup (in fall). Best?

http://www.dnr.state.mn.us/invasives/terrestrialplants/woody/buckthorn/control.htmlThis site will help.On leaves, a spaced combination of 2-4D and a little glyphosate in water tends to be effective. In fall and winter, 20 t0 30% triclopyr applied to cut stem or basal bark can be effective. Including a die helps keep track of work. A wetting agent like inexpensive liquid soap is desirable. Some people use oils to aid in penetration. I use 4 or 5 oz. of GORDON'S "Amine 400" 46.47% 2,4-D 3.7 lb/gal acid and about 1.5 oz. of glyphosate concentrate in a gallon of water along with an ounce of liquid soap to spray on leaves (foliar) of similar weeds.2-4D is relatively inexpensive compared to triclopyr - try broadcast early in the year including a dose of glyphosate . It might work. However, basel stem application of triclopyr now may deal with the problem - except for seeds!