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1996, No. 2
PREEMERGENCE HERBICIDES USED TO CONTROL ANNUAL GRASSES IN TURF
Each spring, the first pesticide applied to many turf areas is a preemergence herbicide used to control annual grassy weeds such as crabgrass and goosegrass.
There are numerous preemergence herbicides from which turf managers can choose.
Considerations for selecting a preemergence herbicide include the herbicide's effectiveness, potential phytotoxicity, length of weed control, cost, and formulation.
Many preemergence herbicides have been evaluated at the University of Illinois.
The results of six years of U. of I. preemergence herbicide trials are summarized below.
The herbicides were applied to Kentucky bluegrass turf, and crabgrass germination was encouraged by low mowing and heavy irrigation.
The application dates of these preemergence herbicides ranged from April 22 in 1993 and 1994 to April 28 in 1992.
Preemergence herbicide crabgrass control evaluations at the University of Illinois (1990-96).
| |
Crabgrass Control by Year ( weeks after treatment ) |
| |
1990 |
1991 |
1992 |
1993 |
1994 |
1995 |
| Herbicide |
(16) |
(18) |
(11) |
(15) |
(12) |
(19) |
(13) |
(18) |
(13) |
(16) |
(14) |
(16) |
| benefin (Balan) |
S |
S |
A,S |
A,S |
S |
S |
O |
O |
O |
O |
S |
S |
| benesulide+trifluralin (Team) |
A |
A |
A |
A |
A,S |
A,S |
A |
A |
A |
A |
A |
A |
| bensulide (Betasan) |
O |
O |
O |
O |
A |
A |
A |
A |
O |
O |
O |
O |
| dithiopyr (Dimension) |
A |
A |
A |
A |
A |
A |
H |
U |
H,S |
H |
S |
S |
| oxadiazon (Ronstar) |
A |
A |
A |
A |
A |
A |
A |
A |
U |
U |
A |
A |
| pendimethalin (Pre-M) |
A |
A |
S |
S |
H |
A |
A |
A |
A |
U |
A |
A |
| prodiamine (Barricade) |
A |
A |
O |
O |
A |
A |
A |
H |
A |
H |
A |
H |
O - not in trial
A - acceptable control
U - unacceptable control
H - acceptable control at high label rates
S - acceptable control using split applications
As is obvious from the table above, benefin tended to perform best when split applications were employed.
In most years, benefin + trifluralin, bensulide, oxadiazon, pendimethalin, and prodiamine provided acceptable crabgrass control.
Crabgrass control provided by dithiopyr was variable; it appeared to perform best when applied at high label rates or split applications.
The information presented in this Turfgrass Tips is intended to report findings of these trials, not endorse or condemn the use of specific products, whether listed or not.
When using any pesticide, it is important to read, understand, and follow all label instructions to achieve the safest and most effective pest control.
(TOM VOIGT, JEAN HALEY, TOM FERMANIAN, BRUCE BRANHAM)
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