Toronado3800, really? You have taught yourself to properly treat an Ash tree against the costliest man made arboricultural disaster in human history. So thought by now you would be teaching other tree owners just beginning to deal with EAB themselves lacking real world experience. As a DIY, horse of Zorro. I would purchase a liter of Tree-age G4 and invent a way to refill acer caps with said product. Or if you stop at your local Walgreens pharmacy and ask for few free liquid measurement hypo's, then find an electrical department and purchase a box of No.2 Blue wire Butt crimps. Get nail and pound out metal insert, then saw off one side of fluted ends. Stick hypo in other side of blue tube after 5/8 bit drilling trunk 1 1/2" deep then inserting tube into tree. And before you know it, you will be trunk injecting like expensive professionals! As none leaks out, or you shoot too shallow and lift bark with pressure, otherwise it all goes up tree. Just don't shoot too deep, last three growth rings the goal to inject. Keep tube in tree, and find something to cork it with. And will pop out of tree within 2 years.

Its cool your eyes good enough to detect color change in leaves. Which reveals type of season it had, either perfect moist summer, making lots of colorful sugars and starches. Or color results of lousy droughty season. While I have never heard of or noticed type of product applied influencing fall color, well you may have. Know its really best to fully protect tree real good during several years of peak event, so you have enough tree left when borer population pressure lessens.

It sounds like you do your homework, and no doubt you seen my past posts detailing very successful EAB management here in our city. And hope you checked out my Scottie Ash seed blog, which also details how and why to protect a few ash trees. And I am disappointed for you, owning super long lived White American Ash trees that must have suffered past storms and questionable maintenance before you became their life saving caretaker. Because you had already said several times, your individuals may be past their prime. So either they are 300+ years old, or newer 35-45 old cultivars grafted onto root stock. So you will have to post picture sometime, instead of me guessing.

it would be hard to characterize acephate as the newer, better treatment option to imidacloprid. I'm too lazy to try to look up the development history of the respective chemicals, but my memory tells me the opposite would be considered the general course; ie, that acephate was developed first.

Of course, a periodic change in the means of control is not bad strategy. In fact, this is constantly recommended. both have drawbacks...but then again, so does doing nothing.