Annual Bluegrass

Annual bluegrass (Poa annua), referred to as "annual meadow grass" in Europe, is one of the five most widely distributed plants in the world. There are two main types - the annual form (Poa annua f. annua) and the perennial form (Poa annua f. reptans). The annual form has a bunch-type, upright growth habit. It does not spread laterally and is a prolific seed producer.

The life cycle of annual bluegrass (ABG) begins with quick green-up and prolific seedhead production in the spring, followed by a reduction of growth in the summer months, with some patches dying out if irrigation is not present. In the fall, the soil seed bank germinates, providing a constant state of plant renewal.

This grass offers agronomic advantages in some turf situations, but it is a problem in Ohio because it cannot tolerate extreme temperatures, often producing shallow rooted plants that shear off under intense sports traffic. Infestations of ABG can occur in areas of high soil compaction. This was noticeable at a high school football field I visited last week. The area between the hashes was infested with ABG, while the area outside the hashes was a perennial ryegrass/Kentucky bluegrass blend.

There has been a plethora of research studies into the control of ABG in recent years. Selective herbicides, plant growth regulators, cultural practices, fertility and irrigation programming have all been evaluated, with varying degrees of success. Purdue have produced a factsheet on ABG control, which can be viewed HERE

Ref: Casler, M.D. and Duncan, R.R (Eds.) 2003. Turfgrass Biology, Genetics, and Breeding. John Wiley & Sons, Inc. 111 River Street, NJ. www.wiley.com

Authors: Pam Sherratt