Annual bluegrass, also known as poa annua, is a turf type most commonly considered a weed or at least a nuisance. It is a winter annual which means it germinates in the late summer/early fall and matures throughout the winter. During the spring it will set seed and then eventually die off during the summer heat... Theoretically...
|Poa at rough height|
One of the problems with poa is that many types have been able to survive through the summer and act as a perennial. Poa has adapted very well to low mowing heights. It is able to produce seed at this close mowing height, giving it an advantage over more desirable turf that surrounds it. Their seed is easily spread throughout the course often from clinging onto golf shoe spikes and then being transplanted in a different location. This process repeats over and over. It can even be carried from course to course in this same manner. Once a single plant has taken root it can easily form a colony and overtake a putting surface.
|Poa at fairway height|
Poa annua is undesirable because of it tendency to die off in hot weather, its off light green coloring and its seed heads. The main problem lies in the pesky seed heads that grow in early spring. At the close mowing height of a putting green the puffy seed heads are aesthetically unpleasing and affect the smoothness of the ball roll.
At Adams Pointe our plan of action for combating the spread of poa is to use plant growth regulators(pgr). If the application timing is just right you can catch the poa just before it goes to produce its seed heads. The goal of the prg application is to stop the seeds from being produced or render the seeds it produces less viable. Certain plant growth regulators can also hinder the growth of the poa annua and not the bentgrass. This would give the desired bentgrass a chance to infiltrate some of the space occupied by the poa.
|Poa at greens height|
In this picture is a patch of poa in our chipping green after the plant growth regulator application. The seed heads are not obvious in the photo. You can, however, see the off color which is highlighted more so by the pgr doing its job.
All of this is not to be a deterrence. I just played the course the other day(once a week actually) and the greens are currently rolling great!