It is still critical to make this application when grassy weeds are in the 2- to 3 leaf grass stage. Prowl provides generally good residual grass weed control. The two possible weaknesses with Prowl are that certain broadleaf weeds can emerge between application and flood up and the other is that under wet conditions or when flushing is required for water stress or when the permanent flood is delayed, Prowl can break and you will need to make additional herbicide applications. Bolero is another commonly-used tank mix partner for Stam or propanil. Bolero's disadvantage would be that it requires wet soil conditions for optimal activity and few Missouri growers are interested in the routine flushing that is required to maintain this activity.
Facet is the newest tank-mix partner and has also gained a lot of popularity.
Facet has fair postemergence activity by itself and is an excellent barnyardgrass herbicide. Stam and Facet together seem to have an almost synergistic effect, providing more weed control than would be expected. Facet also has one of the longest residual activity periods if moisture is good. Growers have used a variety of propanil-Facet mixtures. An expensive, but dependable option is to use a full rate of both.