6 HOW COMPETITIVE IS POA ANNUA?

Annual bluegrass is one of the five most widely distributed plants in the world (1), and can be found in every zone of adaptation in the United States. It easily invades and persists in irrigated, closely mown, fertilized turfgrass stands. From a competition standpoint against creeping bentgrass, annual bluegrass is more competitive in the spring and fall, while creeping bentgrass is more competitive in the summer (2). Once it invades and becomes established, annual bluegrass quickly becomes the dominant species and cultural management programs are usually adjusted to meet its growth requirements. The success of annual bluegrass is due in large part to the evolution of different survival strategies. Among these is its ability to survive and produce vast numbers of see, even at heights of cut less than 3.2 mm. This allows a viable seedbank to persist on greens, enabling the population to continually regenerate itself (3,4). Annual bluegrass also possesses a broad genetic base, which allows for highly varied populations to occur within relatively small areas such as a single golf green with both annual and perennial genotypes being present. The broad genetic variability is due in part to annual bluegrass ’ origin as a hybrid between Poa infirma H.B.K., an annual species, and Poa supina Schrad., a perennial