That's an interesting one, that Ajuga. I've had it drop dead from 2-4-D, and I've had it stand up to everything short of tactical nukes. I'd try a good 3-way (something like "Weed-B-Gon Max" or one of the Bayer Advanced products. Better luck is obtained by added a couple squirts of dishwashing liquid (avoid the antibacterial ones) to make it stick to the leaves.