Sandbur Control in Bermuda grass Pastures and Hay Fields

Sandbur Control in Bermuda­
grass Pastures and Hay Fields

by Eddie Funderburg and James Locke NF-SO-11-05

Several species of sandbur infest the
Southern Great Plains of the United
States, including field sandbur (Cen-
chrus spindex Cav.), longspine sandbur
(Cenchrus longispinis Hackel Fern.) and
southern sandbur (Cenchrus echinatus
L.). While they are different species,
they all share the common trait of
being undesirable in pastures and hay
fields, and control measures are the
same for each species. For the remain-
der of this paper, they will be lumped
together and referred to collectively
as sandbur.

Identification and Life Cycle duce sandbur numbers, but is heavily should be thought of only as suppres-
dependent on the timing and intensi- sion methods and not as true control.
Sandbur generally behave as summer ty of the burn. In bermudagrass fields,
annual grasses, although they will it is often difficult to stockpile enough Some sandbur suppression can
sometimes act as weak perennials. fuel for a burn that is intense enough be achieved by not overgrazing and
They can grow as tall as 2 feet. Leaf to kill sandbur seeds. However, the leaving 3 to 6 inches of bermudagrass
blades are smooth, twisted and 2 to burn may stimulate more seed to stubble. Anything that minimizes
5 inches long. Ligules have a fringe of germinate due to reduced crop cover. bare soil and open areas in the grass
hairs. This can allow the producer to kill will help suppress sandbur.
more of the potential sandbur with
Flowers are a raceme of burs, the control measures since more seed will Herbicides Available
spikelets are two-flowered with one to emerge at one time. Dormant season
three spikelets per bur. Plants repro- tillage can sometimes cause the same There are currently four herbicides
duce from seeds, which are contained effect of increasing germination of labeled for sandbur control in
in a bur. The bur is covered with stiff, sandbur, enabling more to be killed at bermuda­grass pastures and/or hay
sharp spines and is painful when one time. fields. One is applied pre-emerge
contacted. Burs generally overwinter and the other three are post-emerge
on or near the soil surface. Seed can Improving the density and height products. Two of these products have
remain dormant in the soil for many of the bermudagrass through aggres- supplemental labels that are subject
years. They can emerge throughout sive fertilization can reduce sandbur to change with little or no notice.
the spring and summer, and a flush numbers by crop competition. How- Always consult the label when using
of sandbur can often occur after a ever, fertilization, disking or burning herbicides to make sure your crop
rain in late summer. This complicates
control techniques since a new crop and intended use are on the label.4
of sandbur can emerge after control
measures have been applied.

Cultural Suppression Methods

Some success in sandbur suppres-
sion can be achieved through cultural
practices. Burning can sometimes re-

The Samuel Roberts Noble Foundation

SOILS

It is illegal to use herbicides in a man- Potential for herbicide injury to bermudagrass was tested on research plots at the
ner inconsistent with the label. Noble Foundation’s Red River Farm near Burneyville, Okla. Plots were evaluated for
visual injury symptoms as well as yield loss associated with application of post-
The pre-emerge product that emergence herbicides.
(is38cu.7r%renptelyndlaimbeeltehdailsinP)r.oTwhilsHp2rOo™duct
is available for established bermuda­ avoid excessive crop injury. Animals grass. It will control some broadleaf
grass hay fields under a supplemental must be removed before application, weeds, but the addition of a general
label. It can only be used on dormant and there is a 28-day haying and graz- broadleaf weed control product such
established bermudagrass pastures ing restriction when using Roundup as 2, 4-D, GrazonNext™, Grazon P+D™
and hay fields, not on any other for- WeatherMax™ immediately after the or Range Star™ will greatly enhance
age species, not on newly planted first hay cutting. the control of broadleaf weeds.
bermudagrass and not after green-
up of established bermudagrass. It Pastora™ (56.2% nicosulfuron plus Panoramic™, Plateau™ or Impose™
is labeled at rates of 1.1 to 4.2 quarts 15.0% metsulfuron methyl) (23.3% imazapic)
per acre. A timely rainfall or sprinkler This product has a full label for ber- This product has a full label for
irrigation within two weeks after ap- mudagrass. No other forage species general pasture and rangeland. It
plication is essential to incorporate is listed on the label. Pastora™ is a can be used on a variety of forage
the herbicide. It will not kill weeds that combination of the active ingredients species. It is applied at a rate of 4 to
germinate before incorporation. Prowl in two products with the trade names 12 ounces per acre. It has both foliar
Hth2eOs™eccaonndbeapspplliitc-aatpiopnlieisdmasadloenbgeafos re Cimarron™ (or Ally™) and Accent™. It and soil activity. It controls sandbur
bermudagrass greens up and the rate is applied to small, actively growing and many other weeds, including
for both applications does not exceed sandbur at a rate of 1.0 to 1.5 ounces johnsongrass and foxtails. The label
4.2 quarts per acre. There is a 45-day per acre. It has little soil activity and states that bermudagrass growth may
grazing restriction and 60-day haying must be applied to sandbur leaves to be suppressed for 30 to 45 days after
restriction after application. The label be effective. A good way to use this application and that some varieties of
states that the treated area must be product is to cut the bermudagrass bermudagrass are injured more than
fenced separately to ensure that live- for hay in mid-May and spray the field others. The label states to not use
stock do not have access to the area about three days after baling. Pas- these herbicides on drought-stressed
for the restricted time. tora™ will also control some grasses bermudagrass, during the transition
such as foxtails and seedling johnson- period from dormancy to green-up,
There are three post-emerge her-
bicides available. Be sure to check to
see if they are still labeled for sandbur
control in bermudagrass pastures
and/or hay fields before using.
Roundup WeatherMax™ (48.8%
glyphosate)
This product is available for estab-
lished bermudagrass hay fields under
a supplemental label. Roundup
WeatherMax™ is labeled for sandbur
control in bermudagrass at a rate of
11 ounces per acre, but only immedi-
ately after the first hay cutting. To clar-
ify, only one application of Roundup
WeatherMax™ per year is allowed, and
for sandbur it must be after the first
hay cutting. It is important to treat as
soon as possible after cutting hay to

2 The Samuel Roberts Noble Foundation

SOILS

within 30 days of aeration, on newly Figure 1. Percent sandbur control Figure 2. Yield loss caused by post-
established bermudagrass or on the with herbicides emergent sandbur herbicides
variety World Feeder bermudagrass.
% Sandbur Control lbs DM/Acre
Research Results – Herbicide Efficacy
0 20 40 60 80 100 0 500 1500 2500
A test was conducted on the Noble
Foundation Red River Demonstration Pastora (1 oz/A) A Check A
and Research Farm near Burneyville,
Okla., in 2010. Nine treatments were Panoramic (6 oz/A) A Roundup (11 oz/A) A
replicated four times. Treatments
were: 1) untreated check; 2) Pastora™ Panoramic (12 oz/A) A
at 1 ounce per acre; 3) Pastora™ at 1.5
ounces per acre; 4) Roundup Weath- Roundup (6.5 oz/A) A Roundup (6.5 oz/A) A
erMax™ at 6.5 ounces per acre; 5)
Roundup WeatherMax™ at 11 ounces Roundup (11oz/A) A Pastora (1 oz/A) A
per acre; 6) Panoramic™ at 6 ounces
per acre; 7) Panoramic™ at 12 ounces Pastora (1.5 oz/A) A Pastora (1.5 oz/A) AB
qpppuleeierradraatccsprreerpe;;e-a8ren)amPdcrer9oer)wg. PPelrrHooow2wnOllA™HHp2a2rOOtil™2™1.,1aw2tqa03us1.2a0ar.ptAs- ll
post-emerge treatments were applied Prowl (3.2 qts/A) AB
on June 14, 2010, three days after the
first hay cutting. Prowl (2.1 qts/A) AB B Panoramic (6.0 oz/A)

All treatments controlled sandbur C Check C Panoramic (12 oz/A)
compared to the untreated check
(Figure 1). All the post-emergence Post-emerge treatments rated 36 days Forage harvested 36 days after treatment
herbicides had control ratings of after treatment. Pre-emerge treatments
>tr9e7a%tm. TehnetsPhraodwcl oHn2Otr™olprareti-negmseorfge rated 119 days after treatment.
62% to 70%. These control ratings are
consistent with those found in other Treatments followed by the same letter are not statistically different at the 0.05 level of probability.
studies. If sandbur are treated ac-
cording to label instructions (correct symptoms were rated at 14 and 36 Pastora™
growth stage of weed, correct rate of days after treatment, and then the Pastora™ was applied at rates of 1.0
herbicide, well calibrated equipment, forage was harvested to determine and 1.5 ounces per acre. Visual injury
etc.), all labeled herbicides should do yield loss resulting from the treat- ratings at both rates were about 35%
a fair to excellent job of controlling ments 36 days after treatment. when rated 14 days after treatment.
sandbur. (Figure 2.) Visual injury symptoms almost disap-
Roundup WeatherMax™ peared at the 36 days after treatment
Bermudagrass Injury Roundup WeatherMax™, at rates of rating and were less than 10% for
6.5 and 11 ounces per acre, caused each rate. When harvested for yield,
A companion study was conducted visual injury symptoms when rated there was no difference between the
on the same farm in a different loca- 14 days after treatment that resulted untreated check and the 1.0 ounce
tion in the summer of 2010 to look in ratings of 19% and 35% injury, per acre Pastora™ treatment. The 1.5
at crop injury resulting from the respectively. The visual injury symp- ounces per acre treatment of Pas-
post-emerge treatments (Roundup toms had almost disappeared when tora™ reduced yields by about 20%
WeatherMax™, Panoramic™ and Pas- rated 36 days after treatment, and compared to the untreated check.
tora™). The applications were made visual injury ratings were <10%. Panoramic™
three days after the first bermuda­ When harvested for yield, there was Panoramic™ was applied at rates of 6
grass hay cutting. Visual crop injury no difference between the untreated and 12 ounces per acre. Visual injury
check and either of the Roundup symptoms were very severe for both
WeatherMax™ treatments.
rates at the 14 days after treatment4

The Samuel Roberts Noble Foundation 3

SOILS

rating with injury levels of 75% and from these products when harvested pauciflorus) control in pastures us-
80%, respectively. At the 36 days after 36 days after treatment. ing Gramoxone, Roundup Ultra, or
treatment rating, injury levels were Touchdown. 2000. Texas Journal of
50% and 75%, respectively, for the 6 Panoramic™ caused severe visual Agriculture and Natural Resources,
ounces and 12 ounces per acre treat- injury symptoms to bermudagrass 2000. Vol 13, pp 1-7.
ments. Yields were correspondingly early, and the injury persisted past the Kohrs, J.A., Medlin, C.R., Gribble,
suppressed. The 6 ounces of Pan- 36 days after treatment time frame. R., Rice, C., and Gregory, M. 2005.
oramic™ per acre treatment reduced Severe yield losses resulted from the Sandbur control in bermudagrass
yields by 40%, and the 12 ounces use of Panoramic™. < pastures and hay meadows.
Panoramic™ per acre treatment ASA-CSSA-SSSA Annual Meeting
reduced yields by 78%, compared to Literature Cited Report 202a.
the untreated check. Matocha, M.A., Grichar, W.J., and
Baumann, P.A. 2009. Grassbur – early Grymes, C. 2010. Field sandbur
Summary recognition is a key for manage- (Cenchrus spinifex) control and
ment. Texas AgriLife Publication bermudagrass response to nicosul-
All labeled products tested controlled SCS-2009-10. furon tank mix combinations. Weed
sandbur. Roundup WeatherMax™ and Technology 24:510-514.
Pastora™ both caused visual injury Grichar, W.J., Baumann, P.A., Baugh- Stritzke, J. Field sandbur. Oklahoma
symptoms to bermudagrass early, but man, T.A., and Nerada, J.D. 2008. Alfalfa. Oklahoma Cooperative Ex-
the symptoms largely disappeared 36 Weed control and bermudagrass tol- tension Service, Oklahoma Agricul-
days after treatment, and there was erance of imazapic plus 2,4-D. Weed tural Experiment Station. Online.
no yield loss due to herbicide injury Technology 22(1):97-100. January.

Gricher, W.J., Jaks, A.J., and Nerada,
J.D. 2000. Field sandbur (Cenchrus

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Ardmore, Oklahoma 73401
Phone: (580) 223-5810
www.noble.org

4 ©2011 by the Samuel Roberts Noble Foundation