On Wednesday, August 22, 2012 10:58:54 AM UTC-4, Jim Hawkins wrote:
Ther seems to be no end of weedkillers for broad-leaved weeds. What is there for narrow-leaved ones ? (of which my lawns has an abundant crop !)

A broader spectrum week killer such as will also do in crab grass may work.
You may need to identify the weed and check with the manufacturer. The big companies will have their labels on line and phone numbers to call for guidance.

I've got a Japanese stilt grass infestation which they will not touch but on discussion with garden shop found that it will respond to pre-emergents. Someone in this group was kind enough to identify my problem by looking at and responding to picture at url I had posted.