Many different strategies have been attempted for control of annual bluegrass on golf courses throughout history.

In the 1920’s, annual bluegrass was cut out of putting greens using a knife. This is of course very labor intensive and was not practical for a majority of courses. The arsenate herbicides came along in the late 1920’s; not only were these marginally effective, but also they were taken off the market due to environmental and other concerns.

Since annual bluegrass is, in most cases, an annual, the strategy in the 1960’s was the use of preemergence herbicides. While somewhat effective, the herbicide would usually result in perhaps 80 percent control, but those seeds that did germinate then produced more than enough plants to repopulate the area.

Growth regulators and postemergence herbicides were attempted in the 1970’s, but when a promising new herbicide came along, it was usually very inconsistent, resulting in good control in one location and nearly no control in another.

In the 1980’s there was an attempt to manage the Poa (if you can’t beat, join it). But this eventually gave way to what golf course superintendents do today, which is the use of growth regulators and management of the bentgrass that favors gradual removal of the annual bluegrass.

Check out November’s Turf Health column, which goes into detail about poa control.