FIELD SCIENCE
24 SportsTurf | August 2016 www.sportsturfonline.com
Other factors that
affect dislodgeability
include turf type, level
of management, time
between application
and event, time within a
day, mowing practices,
clipping management,
rainfall, sprayer setup
(nozzles, carrier
volume, etc.), among
other factors. It's also
important to note that
pesticides range in their
human-toxicological
concerns and their effect on various human systems and organs.
How much 2,4-D is dislodged from a treated
bermudagrass athletic field immediately after
application? How much is dislodged in subsequent
days? 2,4-D is a selective, postemergent broadleaf herbicide
commonly used on athletic fi elds, golf courses, sod farms,
home lawns, etc., that was originally registered in the US in
1946 and has been scrutinized in recent years for toxicological
concerns. Further, 2,4-D has very high aqueous solubility,
which indicates it may lend itself to readily dislodge from
treated turfgrass foliage.
Recent research has quantifi ed dislodgeable 2,4-D and other
commonly used pesticide residues and investigated factors that
affect pesticide dislodgeability. For example, the amount of 2,4-
D dislodged from hybrid bermudagrass immediately and 1 hour
after application and at 5:00, 7:00, 9:00, 11:00 and 13:00 EST
on subsequent days after treatment was quantifi ed.
Amount of 2,4-D dislodged is affected by time, atmospheric
conditions, application
equipment, and
turfgrass species,
among other parameters.
11.3% of applied
was dislodged
immediately after
application while 0.5%
was dislodged 1 hour
after application
Following
application, 2,4-
D dislodgeability
decreased: (As days
after treatment increased
— 4 times more 2,4-D was dislodged at 5:00, 1 DAT (4.0% of
the applied) than 5:00, 3 DAT (1.0% of the applied); at later
sample times within a day — greater than 15 times more 2,4-D
was dislodged at 9:00 compared to 13:00 within 5 days of
application
As relative humidity decreased
As leaf wetness decreased
As spray droplet size increased
As carrier volume increased
Summary and best management practices to reduce
exposure. When discussing this and related research, the most
common question is, "How long do athletes, pets, etc. need
to stay off the grass after a pesticide is applied?" As alluded
to earlier, this is a very diffi cult question to answer and there
is no simple or "one size fi ts all" answer as it varies widely
with the type of turf, time of year, pesticide applied, etc. 2,4-D
was dislodged through 5-7 days after treatment indicating
athletic fi eld managers and event schedulers should coordinate
Amount of 2,4-D dislodged from a hybrid bermudagrass athletic fi eld.
Days after treatment
Time (EST) 1 2 3 6 12
% dislodged of applied
5:00 4.0 2.1 1.0 0.2 0
7:00 3.8 2.2 1.0 0.2 0
9:00 3.6 1.6 1.0 0.1 0
11:00 0.6 0.1 0.3 0 0
13:00 0.1 0.1 0.1 0 0
11.3 % of applied dislodged immediately after application.
0.5 % of applied dislodged 1 hour after application.
