THE ENEMY: Annual Bluegrass (Poa Annua)
Strategy: This is probably one of the worst grassy-weeds to invade lawns, including golf courses, in the United States. It grows less than 3 inches in height , is lighter in color, and has narrower leaves than the lawn grasses. This invader grows in round clumps and will not grow taller than the lawn grasses as with Quack grass or Tall fescue. It has an open seed head with hundreds of seeds and is one of the first plants to die and turn brown after the summer heat.
Attack: This winter annual invades turf areas and other disturbed sites by starting as individual patches then spreads into larger patches each year. In fact, if not controlled it becomes one the major plant species on some golf course greens. Like other winter annual plants this plant gets a head start in using the nutrients and sunlight in late fall and early spring. The seeds are spread each time the lawn is mowed and can remain in the soil for years.
Defense: Mechanical control or digging just causes another disturbance for the seeds to germinate. Aggressive watering has been shown to suppress he weed, but not remove it from the sites. Because Annual bluegrass has short roots constant stiff-tined raking with reseeding will be best. Roundup Pro® can be effective if used at the right time, but remember that you are going to kill your lawn grass as well so be prepared to replant soon after the grasses all turn brown. Most herbicides should be put down late in the fall, winter (but not over snow) or very early in the spring. These products include Dimension®, Barricade®, or Prograss®. The previous two can be purchased on fertilizer and used similar to Weed-N-Feed.