Japenese stilt grass is a summer annual ( like crabgrass it spreads mainly buy seed)that you should be able to control. If you have any existing patches you shoul pull them now. Chemical method of control is to apply pendamethlin ( a preemergent herbicide) in sometime middle to end of April. If the stiltgrass is in a mulched area where you can apply a nonselective herbicide such as round up at high label rate, if the stiltgrass is mixed with some in with some other ornamental plants (pretty much anything except ornamental grasses) you can spray fusillade (fluazifop-p-butyl), if the stiltgrass is in your lawn (and your lawn is ryegrass, fescue, zoysia,Kentucky bluegrass) use acclaim (fenoxaprop-p-butyl), or the home owner versions are Grass-out and Grass-B-Gon. Always spray young actively growing plants ( after a rain with no rain in the forecast for 24 hours) don't let the stiltgrass get to the seedhead stage. Non chemical controls: you pull stiltgrass it comes up pretty easy but make sure you pull it before seedheads form. The only problem with hand weeding is the more stiltgrass you pull up you expose more weed seed. You can also mow the stiltgrass in the late summer just before the seedhead stage and maybe the stiltgrass will not reach seedhead stage by the first frost which will kill the stiltgrass. Remember the most effective weed control is a dense healthy stand of turf grass so if the stiltgrass is in a turf stand reseed thin areas in the fall.

Someone comes to an organic forum and suggests using products that no one that practices organic growing would use. Did that poster even look at what type of forum this is?

Sure I looked at what type of forum this is, and if you will read the original post adiasas said that he or she was not sure where to post. Also I gave them some mechinacal means of control.