Over the past couple of seasons, poa annua, bentgrass, and other cool season grasses have been popping up along perimeter of our bentgrass/poa annua approaches and are attempting to choke out the zoysia. Poa annua has loved the last two seasons of record rainfall and somewhat cooler temperatures. We apply preemergents in the late summer to reduce the level of infestation. Usually, the zoysia will out grow the poa annua and the heat of summer will help to eliminate the rest of the material. We just recently applied a very light application of Roundup on these areas. The picture below shows the backpack sprayer with a flat fan nozzle and a Weed Pro sponge applicator.
Weed Pro sponge applicator on the left and backpack sprayer on the right.
The picture below is on the front of #16 green between the bentgrass/poa annua approach on the right side of the camera case and to the left is the zoysia approach with the cool season grass contamination.
Over the next few weeks, the cool season grass along the collars should begin to turn yellow and will then die. We will probably have to do some additional spot applications where some poa annua might have been missed in the initial spraying. A majority of the zoysia grass should come back but we might have a couple of the more heavily infested spots which might have to be replaced with some new zoysia sod. We will evaluate each approach once they come out of dormancy in April for potential replacement.