Question
How do I get rid of black medoc ein my lawn? Weed-B-Gone works well on most weeds except this one. What product do you recommend.?  Thanks.  

Answer
homer
it is hard to answer garden questions if i don't know your location. much in gardening depends on where you live in the world???

i'm in southern NJ. i'm assuming you are in canada...??
adjust your mowing height to 2-4" depending on the type turf you have(blue grass, tall fescue, etc.). this will eliminate a lot of weed. lime 2x's per year to raise the soil pH. this will help long term.
for now -
in late spring apply scotts +2 post-emergent TB fertilizer as per directions. wet the lawn lightly just prior to the application to aid the weed control in sticking to the weed foliage(dandelions, clover, chickweed, & other broadleaf weeds). no water or irrigation for 24-48 hrs. after that, if it does not rain, irrigate the area for 15 minutes.
you could also use w/roundup herbicide as per the labeled directions(normally 2 oz concentrate/1 gallon water).  appy w/a paint brush carefully. it will only kill the plants whose foliage it comes into contact with.  it won't harm other plants as long as none gets on their foliage.
good luck
rick