Winter grass as most members would call it but known as Poa annua has been a big problem on most golf courses around the world. It is best adapted to shady, moist, or over-watered areas. Poa annua is a winter annual that germinates in the late summer/early fall once soil temperatures fall below 20 C. Seedlings mature in the fall, overwinter in a vegetative state, and produce seed in late spring and early summer. Annual bluegrass is a prolific seed producer. An individual plant is capable of producing more than 360 viable seeds. The seed may lie dormant in the soil for many years before germinating. Poa annua flowers and produces seed over several months and at any mowing height. Poa grows well under short days and cool conditions, and it will outcompete all other turf species during late fall and early spring. Poa often dies in the heat of the summer (but may survive the stress). Today there are some courses that has it as its primary surface.
At Durban Country club we ended summer by spaying a pre-emergence herbicide and did a follow up spray in early spring. This has assisted in stopping the germination process and now we have a substantial amount less poa on the golf course. Previous years with the old paspalum greens going dormant in winter we had problems with poa annua. Because the paspalum goes dormant it cant fight the poa germinating between plants so we had poa annua growing on the some of the shady , more moist greens. With poa on the greens growing and the paspalum not growing,cause the greens to have a bumpy surface.
Currently with our mini verde Bermuda greens still growing through winter we have a surface that can fight poa seed germinating. Our greens are 100% poa free compared to last year where we had between 20-30% poa annua on them. By watering deep every 4-5 days keeping the surface dry, verti draining (aerify greens) as much as we can we are fighting the poa from taking over our course.