Crabgrass: Yes, No, or Maybe??? Chris Teutsch Univerity of Kentucky Grain and Forage Center of Excellence, Princeton, Kentucky Crabgrass is a weed, right? Yes, if it is in your wife’s flowers, maybe if it is in your hayfield, and probably not if it is in your pasture. I spent seventeen years working in the Southern Piedmont region of Virginia and one valuable lesson that I learned was that if it wasn’t for crabgrass and wiregrass (bermudagrass) we would have a lot of hungry cows during the summer months! Crabgrass is a species often shows up in thin stands of cool season grasses or areas where the stand has been damaged by hay feeding or traffic. Crabgrass is a species of opportunity. It is does not show up in a well-managed cool season stand, but rather where there is an opening in a sod. In fact, a crabgrass plant needs a six-inch opening to get started and be productive. The point that I want to make is that crabgrass is NOT
Variety
Proprietor/Distributor
Figure 1. Volunteer crabgrass stand developing in a grazed out annual ryegrass pasture at UK Research and Education Center at Princeton
Seeding Vigor1 JUN 9
Percent Stand
Maturity2
JUN 9
OCT 11
JUL 9
AUG 2
SEP 2
OCT 11
JUL 9
AUG 2
SEP 2
OCT 11
TOTAL
Yield (tons/acre)
Commercial Varieties-Available for Farm Use Impact
Barenburg USA
4.0
99
99
37.0
46.3
58.0
58.0
1.69
1.62
2.11
1.12
6.54*
Mojo w YJ3
Barenburg USA
3.5
98
98
41.0
53.5
58.0
58.0
1.52
1.75
1.93
0.97
6.16*
RedRiver
Noble Foundation
3.5
96
88
45.0
55.5
58.0
58.0
1.65
1.49
1.66
0.68
5.48
QuickNBig
Noble Foundation
5.0
100
23
49.3
55.5
58.0
58.0
1.96
1.13
1.14
0.17
4.39
4.1
97
97
41.0
51.8
58.0
58.0
1.45
1.53
2.00
0.88
5.87*
Mean
4.0
98
81
42.7
52.5
58.0
58.0
1.65
1.50
1.77
0.76
5.69
CV,%
12.3
2
13
7.5
4.5
0.0
0.0
9.98
24.53
10.38
17.01
7.72
LSD,0.05
0.8
3
16
4.9
3.7
0.0
0.0
0.25
0.57
0.28
0.20
0.68
Experimental Varieties BARDSIRR
Barenburg USA
1. Vigor score based on a scale of 1 to 5 with 5 being the most vigorous seedling growth. 2. Maturity rating scale: 37=flag leaf emergence, 45=boot swollen, 50=beginning of inflorescence emergence, 58=complete emergence of inflorescence, 62=beginniing of pollen shed. 3. YJ=yellow jacket coating in the seed. *Not significantly different from the highest numeerical valie in the column, based on the 0.05 LSD. Nitrogen Application: 60 lb/ A of actual nitrogen on May 21 and 40 lb/A on Auguest 3 (Total of 100 lb of N/acre)
going to take the world over anytime soon. When cool season pastures are grazed closely and often during the summer months, the composition of these stands tend to shift toward crabgrass. Unfortunately, these volunteer stands of crabgrass are often not managed to their full potential. The objective of this article is to give you a few pointers that will help you get the most out of crabgrass stands, whether they are volunteer or an improved variety that was intentionally established. Not all crabgrass is created equal. We tend to lump all crabgrass into one category, but there are several species and even improved varieties. Some crabgrass species and even 24 • Cow Country • May
local ecotypes are more productive than others and respond better to improved management. If you want to ensure that you have the most productive crabgrass species, then consider overseeding your volunteer stands with an improved variety of crabgrass (Table 1). More data on crabgrass varieties can be found by clicking on the “Variety Trial” icon found on the UK Forages webpage. Crabgrass seed can be fluffy causing it to bridge in seeders. To help with this problem, it can be mixed a carrier, like pelleted limestone or even some red clover and annual lespedeza seed and broadcast onto closely grazed pastures in late winter or early spring. One variety of crabgrass
comes with a seed coating that makes it flow through seeders better. The downside is that it makes up a substantial portion of the total weight making it necessary to increase the seeding rate, although seed cost per pound tends to be lower. The crabgrass seed will begin to germinate in early to mid-May as soil temperatures start to rise. Although crabgrass seed seems expensive, relatively low seeding rates are used. For overseeding pastures, 3-4 lb/A of uncoated seed or 4-6 lb/A of coated seed should be used. Drag closely grazed pastures to stimulate crabgrass stands. Dragging closely grazed pastures helps to get volunteer seed from the previous season or seed that you have broadcast onto the pasture into contact
