This question needs a location and intended plant date.

30 days after V1 in 22 inch rows I would not spend any more money on pres use that money to increase your zidua rate.  Do you have any pigweeds coming up before V1 if so than the zidua needs to be chasing the the planter.  

We use 3.2 oz of Zidua at planting and 1.5 to 2 oz of Valor at planting if it is our first pass.  (Only use the 1.5 oz on the above 7 pH soil.) Will reduce valor rate if we put on valor earlier in the season.