My business card (and logo) say nothing about my services. If I was going to do what you're describing (and your bus. cards DO list lawn maint.), I'd get another set made that highlighted JUST my chem. apps. IMO, this would take away a lot of the threat.
One thing I've learned pretty quickly........a lot of the guys who are LCO's who say they aren't licensed to spray and apply fert. with herbicides....spray and apply ferts. with herbicides.
This doesn't really bother me, honestly. I'm not exactly seeking LCO or fert/squirt accounts. If it's not a referral or someone I know, I'm not sure I'd take it on. I don't feel like I'm competing with these guys.