12 SportsTurf | September 2014 www.sportsturfonline.com
Field Science | By J.T. Brosnan and G.K. Breeden
W
inter annual weeds such
as annual bluegrass (Poa
annua), henbit (Lamium
amplexicaule) and common
chickweed (Stellaria media)
often invade cool and warm-season athletic fields
subjected to traffic from fall sports such as football
and soccer. Traffic can weaken both warm- and cool-
season turfgrass athletic fields leaving voids in the
canopy for winter annual weeds to invade.
Winter annual weeds will often become estab-
lished in the most heavily trafficked portions of an
athletic field during late fall and early spring once
fall sports are complete and turfgrasses are less com-
petitive. In a study conducted during the winter of
2013-2014, plots receiving simulated football traf-
fic in fall contained 35 annual bluegrass plants per
ft2 compared to less than 2 plants per ft2 those not
receiving traffic (Figure 1).
Controlling these weeds is essential to maximiz-
ing both field safety and playability. Researc h at the
University of Tennessee has found that the presence
of weeds on athletic fields can reduce traffic tolerance
potentially leading to greater injuries. Additionally,
failure to remove winter annual weeds will allow
them to persist with desirable turf the following
growing season (Figure 2); which negatively affects
field playability and safety as well. To that end, it is
important to develop a plan for managing winter
annual weeds on athletic field turf.
Cool-season
athletiC fields
On many cool-season athletic fields, annual blue-
grass is a year round problem rather than something
that is seasonally troublesome. Seedhead production
Managing winTer
annual weedS
Figure 1. Top Left: Annual bluegrass invading trafficked hybrid
bermudagrass turf. Few weeds are present in non-trafficked turf.
Figure 2. Non-competitive hybrid bermudagrass growth
following use of POST herbicides for annual bluegrass control
(A). Additionally, clumps of ryegrass competing with bermudagrass
growth on a high school football field (B).
