I read an article that says you can use baking soda to kill crabgrass tonight and I'm trying this tomorrow! I try to garden completely organic and if this works I'll be one happy lady! :-)
Simply wet the crabgrass, pour a heavy dusting of baking soda on the weed. The crabgrass should start dying back in 2 or 3 days. CAUTION: When applying baking try NOT to get it on your grass or other plants as too much baking soda can burn and kill them also.