generally speaking crabgrass and other prostrate grasses love frequent shallow waterings. if you can change the watering regime you may discourtage the regrowth. Also these grasses need to lay prostrate in lawns, if your lawn is left to grow taller and thicker, you may again discourage these weeds. for spot spraying Roundup can be effective although detrimental to other plants (the lawn) at the same time. re-seeding will be necessary to affected and sprayed areas.
Acclain super is a product registered for use in BC for control of grabgrass on turf lawns. A little expensive, but extremely effective. Can only be purchased by a licenced applicator. Although the Otter Coop in Aldergrove did have some weed n feed with crabgrass killer in it. Good Luck Jim.
One thing that helps to control crabgrass is keeping the vigor and health of your turf grass. That can be accomplished by feeding the soil so the turf grass can grow thick and lush. Core aerating and topdressing with organic material like compost in the fall will help with that. http://www.american-lawns.com/lawns/aeration.html http://www.homeandgardenmakeover.com/lawnaeration.html Sometimes tall fescue is confused with crabgrass. This site will be helpful to id which you have. http://www.agry.purdue.edu/turf/tips/2003/crab318.htm Corn gluten meal can be used as an organic pre-emergent. http://web.extension.uiuc.edu/greenline/i1295_384.html#3 Here's some cultural control ideas. http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7456.html Much of what I've posted has already been mentioned, but maybe the above sites will also be helpful. Newt
