Do triazine herbicides like atrazine or simazine prune roots like DNA herbicides? For the guys spraying bermuda lawns in the South, about when is the best time to apply pre-emerge for winter annuals. The reason that am asking is because I know that Simazine is widely used in my area and it works pre-emerge and post emerge on many broadleafs. So, is timing very critical? Do most of you mix in some 3-way product at the same time? Is spraying for winter annuals about the time the lawns go dormant common practice?