Bluegrass (Poa Annua) - Annual

No single control procedure has been successful in controlling annual bluegrass in turf grass. Early removal of solitary infestations has been successful when practiced diligently. Open spots should be over seeded to establish a vigorous turf grass. Removal of grass clippings may help reduce the number of seeds that reach the soil. Check the irrigation output to be sure shady areas are not getting too much water.

The best control for annual bluegrass is to apply a pre-emergent weed chemical in the fall. The best time is usually in mid-September. Any pre-emergent product that controls crabgrass will control annual bluegrass. The pre-emergent will prevent seeds from germinating. Of course, the pre-emergent can not be used on a fescue lawn which you intend to re-seed! If bluegrass is present in winter lawns, imazaquin (Image for Nutgrass) is labeled for use on all grasses except fescue. Since Image must be absorbed by roots, control may not be evident for several weeks. For faster control in bermudagrass only, spray bluegrass patches lightly with glyphosate (Roundup etc.) Make sure bermudagrass is truly dormant before spraying and spray lightly. For fast control in grasses other than bermudagrass, wrap an old towel around the tines of a yard rake and dampen it with the diluted glyphosate. Using the rake like a paintbrush, apply chemical to the "bad" grass blades without harming the "good" grass.

Annual bluegrass is one of the five most widely distributed plants in the world. Annual bluegrass is more prolific and competitive under an ecological regime of close mowing, light frequent irrigation, high fertility, and moist soils. It is a winter annual that germinates in late summer/early fall, once soil temperatures have dropped below 70 degrees F. Seedlings mature in the fall, over winter in the vegetative state, and produce seed in late spring and early summer. Some germination of annual bluegrass seed also occurs in the spring. The seed may lie dormant in the soil for many years before germinating, resulting in a significant build-up of indigenous seed overtime. It tends to be more prolific during wet seasons. Annual bluegrass often dies in the heat of the summer due to heat and drought stress, disease, and/or insect damage. There are currently several products labeled for annual bluegrass control; however, there are limitations on the number of annual applications that can be made. Chemical control of annual bluegrass consists of either a rigorous preemergence program and/or a post emergence herbicide called ethofumesate (Prograss®). Prograss is most efficacious when applied in the fall using multiple applications. See label for specific recommendations. Velocity (bispyribac sodium) is a postemergence herbicide recommended for the selective removal of annual bluegrass in creeping bentgrass. This herbicide has been recently labeled by Valant Chemical Company. Of course, annual bluegrass patches can be spot treated with the non-selective herbicides glyophosate (Roundup) or glufosinate-ammonium (Finale) and then re-seeded.

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