7/2/2013 - By Harrell's

Poa annua, unlike our northern snowbird friends, is an undesirable annual visitor to golf courses in the southern United States.  Its light green color and numerous seedheads make poa annua the most troublesome winter annual weed in southern turf.

Controlling Poa annua effectively begins with a basic understanding of this annual plant’s biology.  Poa germinates when daytime temperatures consistently drop into the mid-70s F and when nighttime temperatures are in the mid-50s F (McCarty, 2001).  This temperature combination usually occurs in late summer to late fall depending on geographic location.  Poa often grows unnoticed in the fall and early winter with seedhead production not occurring until late winter, at which time numerous white seedheads can become highly noticeable and unsightly.  Postponing control until Poa is visible often results in undesirable and unsightly infestations.

Several options exist for post-emergent poa control in non-overseeded bermudagrass.  Poa control can be achieved with both Kerb and Princep.  Kerb and Princep should not, however, be used upslope of desired cool-season turf such as overseeded bermudagrass greens (McCarty, 2001).  Other effective options include Revolver, Monument, Certainty, and Tranxit.  All provide excellent post-emergent Poa control.  Applications of these products should occur in late summer to early fall depending on geographic location.  Forgoing this early post-emergent application and only applying a pre-emergent herbicide during this critical time period often results in a lack of control due to the inability of the pre-emergent herbicide to control the Poa which has already germinated.

Pre-emergent Poa control in non-overseeded bermudagrass can be achieved with a variety of pre-emergent herbicides.    Pre-emergent Poa control is effectively achieved with products such as Ronstar (Restricted Use Pesticide), Barricade, Echelon, Dimension, Pendulum, and Specticle provided they are applied prior to Poa emergence.  The selection of a pre-emergent herbicide for Poa should also consider other problematic weed species at one’s location.  For example, Ronstar (Restricted Use Pesticide) may be the best choice for a location that experiences both high goosegrass and Poa populations.  Echelon may be better if both sedge and Poa control are desired.  Specticle, a newly released pre-emergent herbicide from Bayer, reportedly provides control for both Poa and difficult broadleaf weeds for up to seven months with only a single application.

In summary, effective Poa control can be achieved with an understanding of both Poa biology and the products which effectively control this annual weed species.  With this knowledge in hand, one can expect 90% or greater Poa control throughout the season.  Finally, always follow label recommendations when making herbicide applications.