Annual bluegrass (Poa annua) is often considered the most troublesome winter-annual grassy weed on golf courses today. Undesirable due to its yellow-green color and excessive seedhead production during spring months (which disrupt turfgrass appearance, uniformity and playability) Poa annua populations have reached epidemic levels on many golf courses in recent years. Changes in cultural practices and increased input of water and fungicides alongside the evolution of a variety of perennial biotypes have allowed Poa annua populations to maintain growth and vigor in many areas of the country year-round.
The problem with Poa annua on golf courses
Encroachment of Poa annua can be a major problem for golf course superintendents in the transition zone and northern regions of the United States. Poa annua populations can quickly invade highly maintained fairways, greens and tees, causing Poa annua to compete for water, nutrients and sunlight with perennial turfgrass species such as creeping bentgrass. If left unchecked, Poa annua can rapidly become the dominant turfgrass species.
When Poa annua is the predominate turfgrass species on golf courses, it can be troublesome for superintendents to maintain its population year round. Poa annua inherently has less drought and heat tolerance compared to creeping bentgrass, therefore it typically requires more water during the summer and fall months to maintain acceptable growth.
Additionally, Poa annua is susceptible to a large variety of summertime stress diseases that are difficult to control, such as anthracnose, summer patch and bacterial wilt. And, lastly, controlling Poa annua seedheads can be difficult and inconsistent due to differences in biotypes; the resulting variations in seedhead flush make timing chemical applications difficult. Therefore, chemical and cultural practices should be performed to minimize Poa annua populations while promoting perennial turfgrass species such as creeping bentgrass.