Non-selective/Preemergent application on Zoysia

The soil surface of our zoysia fairways was frozen this morning when Assistant Mike started our dormant application of the non-selective herbicide Roundup and premergent herbicide Stonewall combination spray.  Since we are using a non-selective material Roundup, we have to spray it when the turf is dormant and not actively growing.  The preemergent application in thrown in with the Roundup to reduce the number of applications we have to make during a season.  The preemergent will lay on the surface of the turf until rain or snow will release it to the soil.  The non-selective product is targeting poa annua which germinates in the fall and begins to grow rapidly as the days warm in March.  I chose to apply this product at a lower rate but it can be effective on broadleaf weeds such as knotweed as well.

We attempt to make this application anytime in February on a sunny day when the turf is firm enough for the sprayer to drive on without damaging the fairways and when the temperature is near or above freezing. 
Poa annua can become actively growing very quickly with sunny days and temperatures above freezing.  As it becomes active and starts to grow, the Roundup will do its work and kill the plant.  The preemergent will create a barrier for crabgrass and goosegrass.  Most home owners will apply this material toward the end of March through mid-April through a fertilizer spreader or sprayed by a lawn care company.  We will begin applications on our rough in this time frame as well.  We will also spray our zoysia tees and some of our green surrounds that are solid zoysia/bermuda.  Our cool season green surrounds will be sprayed with just the preemergent only because the non-selective will selectively kill our fescue/bluegrass/poa surrounds if we had it mixed in the tank.    

A close up of poa annua that we are trying to control.  There is some additional cool season grass mixed in with this stand.

Assistant Mike on 18 fairway spraying.  You can see the drops of foam that are appliced at the end of each side of the spray boom to help him with his next pass.

A view from the back of the application being made.  This application can only be made on dormant zoysia/bermuda.