Preemergence Control of Crabgrass in Tall Fescue Using Crew
product that can be applied with a spreader. We tested the preemergence control of crabgrass with Crew versus industry sprayable-formulation standards in a stand of tall fescues. Crabgrass Cover (%) Trt #
By Jeffrey Derr, Ph.D., Adam Nichols, Aman Rana Virginia Tech, Hampton Roads AREC
C
rabgrass is a summer annual grassy weed that detracts from the appearance of lawns. The color difference along with the surface uniformity differences between tall fescue and crabgrass are an issue for homeowners, parks, and commercial grounds. Crabgrass begins to germinate in mid-March on the eastern side of Virginia and continues through most of the summer. In tall fescue, crabgrass tends to invade in areas where tall fescue is thinned out by brown patch during the hot, humid summer. As an annual, crabgrass can be controlled using preemergence herbicides. Crew contains two common preemergence herbicides, isoxaben, and dithiopyr, but is a granular
Treatment
Rate
34 DAT
76 DAT
134 DAT
1
Untreated Check
6 a
38 a
86
a
2
Crew
150 lb/A
0 b
2 b
6
cd
3
Crew
200 lb/A
0 b
0 b
0
d
4
Dimension +
1 qt/A
0 b
1 b
10
bc
1 qt/A
0 b
3 b
16
b
31 fl oz/A
5 a
29 a
84
a
Gallery
31 fl oz/A
5
Dimension
6
Gallery
LSD P=.05
3
10
7
Crew at 200 lb/A provided excellent preemergence control of crabgrass and at 150 lb/A provided comparable control to the industry standards. Crew provides another excellent option for lawn care operators in an easy-to-use product.
Evaluation of Alternatives to Glyphosate in a Field Trial By Jeffrey Derr, Ph.D., Adam Nichols, Aman Rana Virginia Tech, Hampton Roads AREC
Site Description
Conducted at the research station, Virginia Beach RCB 4 reps Plots 3' by 10' native stand of southern crabgrass and yellow nutsedge
Application Information
Treated 8/17/20 76 F Air temperature 82% relative humidity 95% cloud cover wind 2–4 MPH N soil temperature 75 F, herbicides applied on a spray to wet basis Southern crabgrass 6" tall, yellow nutsedge 14" tall
Comments
Roundup Promax, Cheetah Pro, and Weed Slayer + Agro Gold gave complete control of southern crabgrass at 17 and 28 DAT. The other treatments caused significant burning of southern crabgrass foliage at 4 DAT but this weed outgrew that injury by 17 DAT. Roundup Promax and Cheetah Pro gave excellent control of yellow nutsede at 17 and 28 DAT, with good control seen with Diquat and fair control with Weed Slayer + Agro Gold. The other treatments did not provide acceptable control of yellow nutsedge. Cheetah Pro (glufosinate) is an effective conventional alternative to glyphosate while Weed Slayer + Agro Gold appears to be an acceptable organic alternative.
% Control Southern Crabgrass Treatment
Aug1820 1 DAT
Aug2120 4 DAT
Sep0320 17 DAT
Sep1420 28 DAT
3
8
0
0
1
Nontreated
2
Roundup Promax
2 fl oz/gal
0
83
100
100
3
Cheetah Pro
3 fl oz/gal
0
70
100
100
4
Diquat +
0.75 fl oz/gal
100
50
13
5
Capsil
0.25 % v/v
5
Natural Arrmor RTU
25 gal/a
15
23
0
0
6
Weed Zap
6.4 fl oz/gal
3
43
0
0
7
Weed Slayer +
3 % v/v
18
65
100
100
Agro Gold
3 % v/v 12.5 % v/v
0
45
0
0
7 % v/v
13
50
15
15
100 % v/v
35
28
8
8
8
19
11
11
8
Avenger Weed Killer
9
Scythe
10
WeedPharm
LSD P=.05
Journal of the Virginia Turfgrass Council | 29
