I just did that to some grass that was growing in my creeping phlox. It worked pretty good, but had to make sure none of the herbicide dripped as I was brushing. Pulling out the grass would not have gotten the roots, so this was the only way to get to it.

IMHO, this is the best solution. That being said, it is always best to research the product you are using. Some have no soil life, while others can remain active in the soil, therefor damaging roots in the vacinity, while others only work by vascular action. Read the MSDS (material data safety sheet).
History: I spent 18 of my 20 years in freeway landscape going to classes and seminars for my pesticide applicators license. We didn't use Pesticides, but we did use lots of herbicides. What I learned from it mostly was that all the lower forms of life, like viruses, pathogens, and weeds adapt faster than the chemical companies can keep up, and many of the chemicals are at least as harmful to the planet as the current cure. If you use any type of chemicals, rotate them. It is hard to do when you find something that works, but it won't work forever. The same applies to antibiotics.

Good information to know Carol.

Yes, I am with you on that Carol.
I only use on very difficult weeds which can not be just pulled out.
The MSDS are good references on any chemical which might harm living things.
They should probably provide one when we purchase the herbicide.

Caroline, I agree. They should, but they don't. Some of that stuff can render the earth sterile for ever. With a bit of research, the MSDS can be found, and if it can't you don't want to use it!

I like using a sprayer called Blue Viper. Real handy around sensitive plants. (blue-viper.com)