We used that in the spring when we put down fertilizer, we used a pull behind and push spreader.  Techny arborvitae's planted in double rows spaced 5 ft apart, we used a Murray lawn mower, it started better than the 4 wheeler and it was more controllable with the throttle and gear selection. 

We haven't used it for the last 2 or 3 years, we suspected some damage from it but that hasn't proved out yet, cost was another one, along with it didn't seem to do much for us, we might try a pre-emerge again, but might do something different. 

There is some different stuff out there if you go with liquid.