Monsanto - producers of the chemicals we probably use most in controlling invasives. As unlikely as it sounds their Technical advice line is very good, it seems to be manned by one person whose knowledge and helpfulness is very useful. If you have a question about a particular formulation and use near water or standard dilution rates or approvals for stump treatment etc this can be the easiest way to get information quickly - and they do call you back if you leave a message. In conversation earlier I hear there is a new Glyphosate formulation in testing that will be a gel and will not contain any surfactant - the toxic part of Roundup (Glyphosate itself is prectically non toxic) - sounds good for stump treatment, stem treatment and foliar treatment over water. Just a couple of years to wait probably.
I am not a fan of Monsanto particularly but this is a good service.