Haybay and Kiril need to get their facts accurate. I never said that some post emerges are not dangerous in some way but show me a pre-emerge (like prodiamine) that hurts people,plants or environment. I have natural products that kill broadleaves but no natural or organic product that successfully prevents grassy weeds. Corn glutton is not practical to use when treating residential in a business. This is due to timing,two or three years to have adequate control and cost.
Should be more open to some chemicals used on lawns that pose no threat to health any more (or less) than head & shoulders.