weed control in grain sorghum - uaex.edu weed control in grain sorghum often permits escaped weeds...
TRANSCRIPT
1
Chapter 8
DIVISION OF AGRICULTURER E S E A R C H & E X T E N S I O N
University of Arkansas System
Arkansas Grain Sorghum Production Handbook
Weed Control in Grain SorghumTom Barber, Bob Scott and Jason Norsworthy
Weed competition in grain sorghum reducesyields, causes harvesting losses and increasesseed content of the soil seedbank. Even lightweed infestations in the early growing seasonwill reduce yields significantly. Grain sorghumseedlings grow slowly and are weak competitorsto most weeds. Research data have shown
Figure 8-1. Weeds compete for light, moisture andnutrients.
that one pigweed plant per 3 feet of row left uncontrolled until sorghum reaches the 3-leafstage will reduce yields by 10%. Heavy infestationsof grassy weeds may cause up to a 20% yieldreduction in the first 2 weeks after sorghum germination. Late-season weed infestations haveless effect on produced yields but reduce harvest-ing efficiency and may reduce harvested yields.
Most grain sorghum is planted in early tomid-April throughout the state to allow floweringprior to a large buildup of sorghum midge.Although this early planting reduces insect pressure, it contributes additional stress to thegrain sorghum seedling. Grain sorghum was introduced from the warmer climates of Africaand grows best when soil and air temperatures riseabove 70°F. Seedlings stressed from cool and wetsoils are much more sensitive to weed competitionand herbicide injury.
The most troublesome weeds in Arkansasgrain sorghum include johnsongrass, broadleafsignalgrass, barnyardgrass, crabgrass, morning-glory, pigweed, prickly sida and sicklepod. Thereare fewer control options for weed control ingrain sorghum than in corn, cotton and soybeans.Grain sorghum lacks tolerance to many of thecommonly used grass and broadleaf herbicidesand is occasionally injured even by herbicideslabeled for use in sorghum. Unfavorable weatherconditions such as cool, wet soils, delayed cropemergence, deep planting, seedling diseases,poor soil physical conditions and poor qualityseed may contribute to seedling stress andherbicide injury.
Grain sorghum is almost always includedin a crop rotation schedule. Herbicides such as Pursuit, Reflex, Flexstar and other generic
UPDATED 4-2015
UPDATED 4-2015 2
fomesafen applied to soybeans the previous year
can remain in the soil and cause stand reductions
and/or injury to sorghum. ResolveQ, RealmQ
and AccentQ in corn and Staple applied to cotton
the previous year can also injure sorghum. In
addition, Newpath or Clearpath used in rice will
carry over to grain sorghum. Often the carryover
herbicide injury is not visible in very young
sorghum but becomes apparent at the 3- to 6-leaf
stage of growth. For carryover information on
common herbicides, refer to the Extension publi-
cation MP519, Row Crop Plant-Back Intervals for
Common Herbicides (available at www.uaex.edu).
A combination of tillage and chemical weed
control is usually most effective in grain sorghum.
Effective chemical weed control is dependent
upon proper weed identification and matching
herbicide rate and timing to the particular weeds.
Cool-season weeds should be destroyed prior to
planting to ensure that crop seedlings emerge
competition free. Most winter weeds may be
controlled with glyphosate, 2,4-D, dicamba
or paraquat. (For additional information, refer to
Extension publication MP44, Recommended Chemi-
cals for Weed and Brush Control, available from
county Extension offices throughout the state and
at www.uaex.edu.)
Broadleaf weeds may be controlled
postemergence, but there are few options for
postemergence grass control. Grassy weeds are
most effectively controlled with preemergence
herbicide applications. Johnsongrass (Sorghum
halepensea) and grain sorghum (Sorghum vulgare)
are genetically very similar, and there are no
approved herbicides that will selectively remove
johnsongrass from grain sorghum. Even light
infestations of johnsongrass in other crops
planted the previous year often turn into heavy
infestations in grain sorghum due to lack of
selective control. Fields with a history of johnson -
grass or bermudagrass should not be planted to
grain sorghum.
Herbicide programs for effective weed controlmust be developed based on weed spectrum andsoil type. Your county Extension agent receivesextensive training on weed identification andweed control technology and is available to assistin developing economical and effective controlprograms. MP44, Recommended Chemicals for Weedand Brush Control, is updated annually to reflectthe most current information on herbicide labelchanges and revised recommendations based onresearch data.
Herbicides Used forWeed Control
Effective weed control programs start withclean fields at planting. It is critical to removeexisting cool-season weeds with tillage or herbicides prior to planting. Glyphosate andglyphosate in combination with 2,4-D are veryeffective preplant herbicides.
Atrazine is the basis of most chemical weedcontrol programs in Arkansas grain sorghum. Itis estimated that greater than 90% of the acresplanted receive at least one application ofatrazine. In sites where weedy grasses are not aproblem, atrazine may be the only herbicideapplied. Although atrazine has some activity ongrassy weeds, it is considered a broadleaf herbi-cide. It may be combined with the chloroac-etamide herbicides such as Dual II Magnum,Outlook and Lasso to broaden the weed controlspectrum. Concep®-treated seed must be plantedif any of the chloroacetamides are to be used.These active ingredients are also sold in premixeswith atrazine under different names. Bicep IIMagnum and Guardsman Max are examples ofatrazine plus chloroacetamide premixes thatrequire Concep-treated seed.
Preemergence herbicides are applied afterthe sorghum has been planted and prior to emergence. The chloroacetamides such as Dual
UPDATED 4-2015 3
Magnum are taken into the weedy plants throughthe emerging coleoptiles and have little or noactivity on emerged weeds. These herbicides mustbe applied before targeted weeds germinate.Atrazine is effective as a preemergence or earlypostemergence herbicide. Dual Magnum, Lassoand Outlook primarily control grasses such ascrabgrass, barnyardgrass and broadleaf signalgrassbut also suppress yellow nutsedge and offer somecontrol of pigweeds. Combinations of these prod-ucts with atrazine as tank mixes or premixesapplied preemergence will control most seedlinggrasses and broadleaf weeds for 3 weeks.
Rainfall or irrigation is required to incorporatethe herbicides with the soil for activity. This isoften referred to as “activation” of the herbicide.However, large rains immediately after applicationmay move some of the herbicide into contactwith the germinating sorghum seedling and mayactually be taken into the germinating seed as itimbibes water. This usually results in delayedemergence and some crop injury. Under goodgrowing conditions, the symptoms are usuallyonly cosmetic and the sorghum resumes normalgrowth 7 to 10 days after emergence.
Applying high rates (2 pounds active ingredi-ent) of atrazine preemergence to sorghum is considered to be high risk. Significant stand lossesand delayed development of seedlings are com-mon following high rates of atrazine in cool, wetweather. Splitting the atrazine applications andapplying no more than 1 pound active ingredientat planting followed by an additional pound earlypostemergence has proven to be much safer tothe sorghum. Atrazine may also cause more injuryon sandy soils. To reduce injury, wait untilsorghum is up and growing well prior to atrazineapplication. In fields where grassy weeds areexpected to be a problem, a chloroacetamide preemergence alone or in combination with alow rate of atrazine followed by additionalatrazine early postemergence is a safe and veryeffective early-season weed control program.
Figure 8-2. Injury from high rates of Dual and atrazinecan occur under cool/wet conditions.
PostemergenceWeed Control
Control of weeds once they emerge in grain
sorghum can be difficult, especially with grass
species. There is currently no available option
for control of johnsongrass once it emerges in
grain sorghum fields. Other grasses such as
broadleaf signalgrass, crabgrass and barnyardgrass
can be controlled while they are small with
atrazine (AAtrex) and quinclorac (Facet L) applied
postemergence. Atrazine applied at rates higher
than 1 pound active ingredient per acre postemer-
gence may injure and/or kill sorghum in cool
conditions, especially on sandy soils or if it is not
actively growing. Other herbicides such as 2,4-D,
dicamba (Clarity), prosulfuron (Peak), bromoxynil
(Buctril) and Huskie are also effective postemer-
gence broadleaf herbicides for use in sorghum.
Paraquat (Gramoxone Max) is labeled for post-
directed use in larger grain sorghum to control
escaped weeds. Considerable crop leaf burn is
expected, and this option should be used only in
salvage situations where grassy weeds were not
controlled earlier in the season. (See label for
special precautions and injury warnings.)
UPDATED 4-2015 4
Standard Herbicide Program
General weed control strategy for grain
sorghum is as follows:
1. Plant Concep®-treated seed.
2. Dual Magnum 1-1.3 pt/A PRE, or Verdict
10 oz/A PRE, or Dual Magnum 1 pt/A + AAtrex
1.5-2 pt/A PRE.
3. V4 – Atrazine 2 pt/A + 1.3 pt/A Dual Magnum
POST for grass and broadleaf weeds
– Or include Facet L if high grass population.
– Can include Clarity or Huskie if high popu-
lations of pigweeds and morningglories.
4. Huskie can be applied for broadleaf weed
control up to 30-inch grain sorghum.
Figure 8-3. Bicep II Magnum 1.3 qt/A PRE followedby 1 qt/A AAtrex on 3-4 leaf sorghum.
Nutsedge Control in Sorghum
Yellow nutsedge and other annual sedges
are becoming an increasing problem in grain
sorghum. Permit herbicide can be applied for
nutsedge control from 2-leaf grain sorghum
through just prior to grain head emergence.
Application rates should not exceed 1 ounce per
acre when nutsedge is 4 to 12 inches tall. How-
ever, if nutsedge is allowed to reach 4 to 12 inches
tall, severe crop competition has already occurred.
Only one application of Permit can be made in
season to grain sorghum.
Harvest Aids
The absence of approved herbicides for
late-season weed control in grain sorghum often
permits escaped weeds to hinder harvesting opera-
tions. Roundup, Aim and sodium chlorate are
effective harvest aids that will desiccate weeds and
improve harvesting efficiency. Roundup provides
the best harvest aid to increase efficiency; Aim
should be added to desiccate vines. These should
be applied 7 to 10 days prior to harvest.
Watch Out for Drift
Grain sorghum is sensitive to herbicide drift
from other crops. Glyphosate, Clincher, Ricestar,
Select and propanil are especially damaging to
grain sorghum in low rates. Symptoms may range
from stand losses to non-uniform growth and
delayed maturity. Grain sorghum affected by
Figure 8-4. Glyphosate drift on grain sorghum.
UPDATED 4-2015 5
Figure 8-5. Grain sorghum injury from Laudis herbicide POST. Grain sorghum fields next to cornshould be monitored carefully for drift from cornherbicides.
low rates of grass herbicides often suffers much
more damage from sorghum midge due to the
non-uniform growth and flowering throughout
the field.
Herbicide Resistance
Herbicide-resistant weeds are becoming more
of a problem in all crops. Pigweeds (Palmer ama-
ranth) with resistance to atrazine are common in
other states but have not been found in Arkansas
at this time. There are some johnsongrass popula-
tions in Arkansas with resistance to ALS herbicides
and glyphosate. Grain sorghum should not be
planted in fields containing potentially high
populations of johnsongrass if at all possible.
Much of the Palmer amaranth in Arkansas is
resistant to the ALS mode of action herbicides
such as Peak as well as glyphosate. As more corn
and grain sorghum are grown in Arkansas with
more dependence on atrazine, triazine resistance
is more likely. If you suspect resistance after a
herbicide application, treat with an alternate
herbicide and contact your county Extension
agent. The University of Arkansas will collect
samples and test for resistance. Do not let the
weeds go to seed in the field.
UPDATED 4-2015 6
Table 8-1.
Wee
d Respon
se Ratings for Grain Sorghum
Herbicides
SEDG
ES Yellow Nutsedge 0 - 9 7 7 6 7 7 0 9 10 0 0 0 5 5 7 0 0 3*Rating
will be 0 on AL
S inh
ibitor-resistant w
eeds (G
roup 2).
Rating scale
– 0 = No Co
ntrol 1
0 = 10
0% Con
trol.
**Repeat a
pplication
may be needed to
achiev
e these ratings.
BROA
DLEAVE
S
Velvetleaf 8 - 4 7 7 6 6 10 8 6 7 8 8 6 7 7 8 7 7 7
Smartweed 9 - 5 4 4 8 6 9 8 6 7 5 9 0 9 9 9 9 9 5
Sicklepod 8 5 0 8 8 8 8 9 8 4 5 8 8 - 8 8 0 3 6 9
Purslane 9 - 6 9 9 9 9 9 - 7 8 9 - - 9 9 7 - - 8
Prickly Sida 9 7 6 9 9 9 9 9.5 8 7 8 8 - - 8 8 7 - 8 3
Pigweed sp. 9 9 8 9 9 9 9 10 4 0 0 8 9 4 9 9 0 5 8 9
Morningglory 8 8 2 8 8 8 8 9 8 5 6 9 9 8 9 8 4 7 8 4
Lambsquarters 9 7 6 9 9 9 9 9 8 5 6 8 9 6 8 8 5 8 8 9
Horsenettle 5 - 3 3 3 3 3 3 - - - 4 6 - 4 4 0 4 5 7
Honeyvine Milkweed 6 - - 6 6 5 6 7 - - - 9 9 - 6 6 5 7 7 -
Common Ragweed 9 - 7 9 9 9 9 9 8 5 5 9 9 6 8 8 8 7 8 8
Cocklebur 9 - 0 8 8 8 8 9 3 - - 9 8 - 9 9 9 9 9 4
Bigroot Morningglory 4 5 2 4 4 3 4 4 - - - 3 8 4 4 4 3 7 7 -
GRAS
SES
Shattercane 0 - 7 7 7 7 7 5 0 0 0 0 0 0 0 0 0 0 0 0Seedling Johnsongrass 2 - 6 4 6 3 6 3 0 3 3 0 0 0 4 3 0 0 0 8
Ryegrass - - 9 9 8 8 8 9 0 - - 0 0 - 6 5 0 0 0 7
Rhizome Johnsongrass 0 0 0 0 0 0 0 0 0 3 3 0 0 0 0 0 0 0 0 0
Red Rice 8 7 7 9 8 9 8 8 0 0 0 0 0 0 9 9 0 0 0 9
Goosegrass 6 8 9 9 9 9 9 7 0 3 3 0 0 6 7 6 0 0 0 9
Foxtail 6 8 9 9 9 9 9 8 0 0 0 0 0 7 8 7 0 0 0 8
Fall Panicum 3 7 9 9 9 8 9 8 0 3 3 0 0 6 6 5 0 0 0 8
Crabgrass 7 8 9 9 9 9 9 9.5 0 3 3 0 0 7 8 6 0 0 0 9
Broadleaf Signalgrass 4 7 8 8 7 7 8 9.5 0 3 3 0 0 9 9 6 0 0 0 9
Barnyardgrass 6 8 8 8 9 8 9 9.5 0 0 0 0 0 8 8 6 0 0 0 9
MODE OF ACTION 514, 1
515 15, 5
15, 5
15, 5
15, 5
15, 5
, 27
2 2 2 4 4 4 4, 5 5 6 6
6, 27
22
HERB
ICIDESPreemergence
Atrazin
eVe
rdict
Dual Magnum/Outloo
kDu
al II Magnum + Atra
zine
Degree
+ Atra
zine
Micro-Tech + Atra
zine
Outlook + Atra
zine
Lexar
Postem
ergence
Peak
Perm
itPe
rmit Plus
2,4-D
Banvel or Clarity
Facet L
Facet L
+ Atrazin
eAtrazin
e + oil
Basagran
Buctril
Huskie
Paraqu
at directe
d or Hood
7
Table 8-2. R
ecom
men
ded
Herbicides for W
eed Con
trol in
Grain Sorghum
Crop, Situation, and
Active Chem
ical
Formulated Material
Method of Application
Per B
roadcast Acre
Weeds Controlled
Per B
roadcast Acre
Time of Application
and Precautions
GRAIN SO
RGHU
MPreplant
glyphosate @ 1 lb/A
Emerged we
eds.
Glyphosate (4 lb/gal
Prep
lant for veg
etation
Apply
in low volum
e – 5 to 10 gp
a.formulations)
knockdow
n.32
oz/A
.
glyph
osate + 2,4-D @ 1.0
Annual grasses and broa
dleaf
Glyphosate (4 lb/gal
Same as abo
ve.
Improved
con
trol of h
orsewe
ed, curly do
ck+ 0.50 lb/A
weeds.
formulations)+ 2,4-D
and primrose.
32 oz/A
+ 1 pt/A
of 4SL
2,4-
D am
ine.
S-metola
chlor
@ 0.9 to
Red rice, yellow
nutsedg
e,Dual Magnum 7.64 EC
orC
inch
Incorporate thorou
ghly in
Use with Concep-treated sorghum
seed
1.4lb/A
annual grasses and pig
weed
.7.64 EC
top 2 inc
hes within 14
days
only. If broad
leaf w
eeds emerge
, use 2,4-D
1 to 1.6 pt/A
.be
fore plan
ting.
or atra
zine po
stemerge
nce.
dimethe
namid
@ 0.56 to
Red rice, yellow
nutsedg
e,Ou
tlook 6 E
Apply
up to 45 da
ys
Use with Concep-treated seed only.
0.98
lb/A
annual grasses and pig
weed
.12
to 21 oz/A.
prep
lant.
Preemergence
S-metola
chlor
@ 0.95 to
Annual grasses and pig
weed
.Dual Magnum 7.64 EC
orC
inch
At plan
ting.
Use with Concep-treated sorghum
seed
1.9 lb/A
For red rice or y
ellow
nutsedg
e7.64 EC
only.
May be tank m
ixed with atra
zine
use ppi treatment a
bove.
1 to 2 pt/A
.according
to labe
l direction
s or m
ay be fol-
lowed
with atra
zine or 2,4-D fo
r broad
leaf
control as recommen
ded be
low.
S-metola
chlor
+ atra
zine
Annual grasses and broa
dleaf
Bicep II Magnum 5.5 L or
At plan
ting.
Use with Concep-treated seed only. Good
@ 1.25 + 1 lb
/Awe
eds. Fo
r red rice or y
ellow
CinchATZ 5.5 F
treatments for a
verage weed infestations.
nutse
dge, use Dual M
agnu
m1.3 qt/A.
Howe
ver, if r
ed rice is a proble
m, u
se Dual
ppi and atra
zine early post if needed. If
ppi above.
heavy c
ockle
bur a
nd m
ornin
gglory p
ressure
exists, use atrazin
e preemergence at pre-
emergence rates b
elow or use atra
zine early
post as lis
ted below
.
atrazin
e @ 1 lb/A
Germ
inating annual grasses a
ndAtrazin
eAt plan
ting.
Do not pla
nt fall cover crops. Do
not pla
ntmost annual broadlea
f weeds,
1 qt/A 4L or 1.1
lb/A Nine
-0.
crops othe
r than corn in treated
fields
during
includ
ing co
ckleb
ur, annual
the sa
me season. Thoroughly
till soil befo
repla
nting any sp
ring cro
p oth
er than co
rn or
mornin
gglory a
nd sicklep
od.
sorghum. P
lanting deeper than 1 inch will
increase safety m
argin
. Do not use on coarse-
textured so
ils (sand, loa
my s
and, sandy loam)
or on any s
oil with less than 1% o.m. F
orsandy s
oils, see A
Atrex +
oil b
elow. All a
trazin
elab
els have been re
vised because of surfac
eand groundwa
ter co
ncerns. S
pecia
l precau-
tions are re
quired on new
labels.
UPDATED4-2015
Table 8-2. R
ecom
men
ded
Herbicides for W
eed Con
trol in
Grain Sorghum
(con
t.)
Crop, Situation, and
Active Chem
ical
Formulated Material
Method of Application
Per B
roadcast Acre
Weeds Controlled
Per B
roadcast Acre
Time of Application
and Precautions
Preemergence [cont.]
saflufenacil @
0.022
toPigw
eed, velv
etlea
f, mornin
g-Sharpen
Burndo
wn up to preem
er-
For b
est b
urnd
own results, tan
k mix with
0.044 lb/A
glory and horsewe
ed.
1 to 2 oz/A
.ge
nce. Do not a
pply Sh
arp-
glyph
osate or paraq
uat. An
MSO
and
AMS
en over the
top of emerge
dmust b
e used
for b
urnd
own.
sorghu
m.
See lab
el for further re
commen
dations and
restriction
s.
dimethenamid + saflufenacil
Annual grasses, pig
weed
,Verdict
Burndo
wn up to preem
er-
Rainfall or o
verhea
d irriga
tion is requ
ired for
@ 0.31 to 0.62 + 0.04
4 to
velve
tleaf, m
ornin
gglory an
d10
oz/A
.ge
nce. Do nota
pply Ve
rdict
activation
. Verdic
t can
be used
as a bu
rn-
0.088 lb/A
horsew
eed.
over th
e top of emerge
ddo
wn th
at leaves beh
ind re
sidua
l con
trol.
grain
sorgh
um.
For b
est b
urnd
own activity, tan
k mix with
glyph
osate an
d use MSO
1 pt/A
+ AMS. On
med
ium to
fine
soils, the rotation interval to
soybea
ns is 30 da
ys if you
were to lose th
egrain
sorgh
um crop.
Use with Con
cep-tre
ated
see
d.Se
e lab
el for restriction
s.
dimethenamid
For a
nnual grasses and
pig-
Outlook 6E
At plan
ting.
Use with Concep-treated seed only. Rates
0.56 to
0.98 lb/A
weed. F
or re
d rice or yellow
12 to
21 oz/A.
depend on percent organic matter. See
nutse
dge, use ppi tre
atmen
t.label.
dimethenamid + atrazin
eAn
nual grasses and broa
dleaf
Guardsman Max 5L
At plan
ting.
Use with Concep-treated seed only.
package mix
weeds. Fo
r red rice or y
ellow
2.5 pt/A.
nutse
dge, use ppi tre
atmen
t.
Postem
ergence
2,4-D am
ine @
0.5 lb/A
Most b
roadlea
f weeds such as
2,4-D am
ine
Apply
whe
n we
eds are
May be ap
plied
broad
cast overtop to
mornin
gglory, cockleb
ur and
1 pt/A of 4
lb/gal 2,4-D am
ine.
small and
sorgh
um 6 to
12
sorghu
m not over 8
inches. D
irecte
d ap
pli-
sickle
pod.
Do not use a surfacta
nt or o
il.inc
hes.
cations later w
ith drop no
zzles
. Do no
t treat
when
sorgh
um is in bloo
m. A
VOID DRIFT.
Do not app
ly du
ring very active growth, i.e.,
when
com
bination
of g
ood mois
ture, w
arm
tempe
ratures an
d hig
h nitroge
n exist, o
rexcessive
injury may re
sult. Follow all State
Plant B
oard regulations.
dicam
ba @
0.25 lb/A
Most b
roadlea
f weeds such as
Banvel or C
larity 4 SL
From
grain sorghu
m emer-
Ground application
only
. Drift is extrem
elymornin
gglory, cockleb
ur and
0.5 pt/A.
gence up
to 8 inches ta
ll.toxic
to so
ybeans. D
o not apply after soy-
sickle
pod.
Do not use a surfacta
nt or o
il.Be
st results on we
eds
beans b
egin to emerge in general area. Less
3inc
hes or less.
toxic
than 2,4-D to co
tton. Follow all State
Plant Board regulations.
8
UPDATED4-2015
9
Crop, Situation, and
Active Chem
ical
Formulated Material
Method of Application
Per B
roadcast Acre
Weeds Controlled
Per B
roadcast Acre
Time of Application
and Precautions
atrazin
e @ 1 to
2 lb/A
Most small-seeded an
nuals
.AA
trex, Atrazin
eAp
ply from
sorgh
um emer-
Do not
apply
if grain
sorghu
m is taller th
anMore effective on broa
dleaf
1.25
to 2.5 lb/A 80W
or 1
to 2 qt/A
gence up
to “c
lose in.” A
pply
12inc
hes. Do
not
graze tre
ated area
s or fee
dwe
eds. Go
od contro
l of p
igwee
d,4L or 1
.1 to
2.2 lb/A Nine
-0. U
se low
before wee
ds excee
d 1½
forag
e fro
m tre
ated lan
d within 21
days o
f app
li-cockleb
ur, a
nnual m
ornin
gglory,
rate on silt loa
m soil and
high
rate
inche
s in
heigh
t. Best grass
cation. After
June
10,
do not
plant
crops othe
rvelve
tleaf, spurre
d anod
a, prickly
on clay
soil. N
o surfa
ctant is re
com-
control obtained before
than corn or g
rain sorghu
m the
following
year.
sida, smartweed, sick
lepod
and
men
ded on
labe
l.grass we
eds exceed ½
Do not use on sands o
r sandy loam
soils.
red rice.
inch.
For these so
ils, use atrazin
e and crop oil
concentrate belo
w. Do no
t app
ly mo
re th
an2.5
lb/A active atr
azine
per se
ason
.
atrazin
e @ 1.2 lb/A + oil
Same as above.
AAtrex, Atrazin
e +
Same as abo
ve.
Same
as a
bove but
may b
e used
on sand
yconcentra
teCrop Oil Concentrate
loam
soil. Le
ss lik
ely to
cause injury to milo or
1.5 lb/A 80W or 1
.2 qt/A
4L or 1.33
carry
over to
sensitiv
e follow
crop
s.
lb/A Nine-0 + 1 qt/A
oil c
oncentrate.
S-metola
chlor + atra
zine @
Annual grasses, pig
weed, annual
Dual Magnum + AAtrex
Before sorgh
um re
ache
sSo
me injury m
ay occur with high
er ra
tes on
0.75 to
1.3 lb/A + 1 to
1.2
mornin
gglory, velve
tleaf, smart -
0.8 to 1.4 pt/A
+ 1/2 qt/A
.12
inche
s tall. Be
st grass
lighte
r soils.
lb/A
weed and sicklep
od.
control obtain
ed before grass
weed
s exceed ½
inch.
halos
ulfuron @
0.047 lb/A
Yellow nutse
dge, flatsedg
e an
dPermit or Halom
ax 75 WG
Apply
to emerge
d we
eds.
Aerial or g
roun
d ap
plication. Avoid drift to
hemp sesbania.
1 oz/A.
soybea
ns.
Add a no
nionic
surfacta
nt or c
rop oil
concen
trate.
halos
ulfuron + dica
mba @
Ragw
eed, horsewe
ed, n
utsedge
Yukon 67.5 DG
From
sorgh
um emerge
nce
Ground application
only
. Drift is extremely
0.075 + 0.2 lb/A
and broadle
af weeds.
6 oz/A.
up to
8inc
hes tall. Be
sttoxic
to soybeans.Do
not apply after soy-
results on we
eds 3inc
hes
beans b
egin to emerge in general area. Less
or le
ss.
toxic
than 2,4-D to co
tton. Follow all State
Plant Board regulations.
prosulfuron @
0.027 lb/A
Most b
roadlea
f weeds inclu
ding
Peak 57 WDG
Apply
to actively grow
ingWill no
t con
trol A
LS-re
sistan
t wee
ds.
triazine
-resis
tant biotypes.
0.75
oz pe
r acre. Add
0.25%
sorghu
m betwe
en 5 and
20
See cro
p rotat
ion se
ction
for p
recaution
s abo
ut no
nionic
surfacta
nt.
inche
s in he
ight a
nd before
rotat
ional cro
ps.
head
emerge
nce.
Do not
apply
to so
rghu
m un
der s
tress from
moisture or co
ld we
ather.
Do not
apply
to so
rghu
m tha
t has bee
n tre
ated
with
an organ
opho
spha
te ins
ecticide
at p
lanting
or within 15
days o
f a post em
erge
nce orga
no -
phosph
ate insecticid
e ap
plication.
bentazon @
0.75 to 1 lb/A
Cockleb
ur, ragwe
ed, jimsonw
eed,
Basagran 4 S
Poste
mergence. See label fo
rMa
y be tan
k mixe
d with
atrazine
. See
labe
l.sm
artweed, prick
ly sid
a, velve
tleaf
0.75
to 1 qt/A
. specific
timing
for w
eed
Best tre
atmen
t for sm
artwee
d.and yellow nutse
dge.
desired.
UPDATED4-2015
10
Table 8-2. R
ecom
men
ded
Herbicides for W
eed Con
trol in
Grain Sorghum
(con
t.)
Crop, Situation, and
Active Chem
ical
Formulated Material
Method of Application
Per B
roadcast Acre
Weeds Controlled
Per B
roadcast Acre
Time of Application
and Precautions
Postem
ergence [cont.]
bentazon + atra
zine @ 0.5
Most broadlea
f weeds.
Basagran + Atrazin
ePo
stemerge
nce fro
m emer-
Use low
rate
on sm
all wee
ds and
high
er ra
te on
to 0.75 + 0.5 to 0.75 lb/A
1 to 1.5 pt/A
+ 1 to
1.5 pt/A
4L or 0.6
gence to boo
t.large
r wee
ds. A
ll atra
zine lab
els have be
ento 0.9 lb/A 80W
or 0
.55 to 0.8
lb/A
revis
ed becau
se of surfac
e an
d grou
ndwa
ter90
DF. A
dd crop oil con
centrate.
concerns. S
pecia
l precaution
s are re
quired on
Packag
e mix is Laddock. 2½ pt/A
new lab
els.
Ladd
ock = 0.5 to 0.5 lb/A a.i. rate.
brom
oxynil @
0.25 to 0.375
Cockleb
ur, sm
artweed, mornin
g-Buctril 2 E
Poste
merge
nce to wee
ds in
Use hig
h rate on mornin
gglories
and
pig-
lb/A
glories a
nd pigw
eed.
1 to 1½
pt/A. O
n larger w
eeds, tank
seed
ling (2- to 4-lea
f) sta
ge.
weed
. Weeds must be s
mall.E
xpect som
emix with 0.5 lb/A active Atra
zine.
temporary burn.
brom
oxynil +
pyrasulfotole
Annual broadle
aves inclu
ding pig
-Huskie
Apply
on or after 3
-leaf stage
Use hig
h rate on mornin
gglories
and
pig-
@ 0.175 to
0.22 lb/A + 0.03
weed and mornin
gglories
. 12.8 to 16 oz/A. A
dd 0.25%
NIS.
until grain
sorgh
um re
ache
swe
ed. W
eeds must be s
mall. E
xpect som
eto 0.39 lb/A
30 inches ta
ll, or flag
leaf
temporary injury if ta
nk mixe
d with atrazine
.em
erge
s.
paraquat @
0.5 lb/A
Annual grasses a
nd broadlea
fParaquat (2 or 3 lb/gal
After s
orgh
um is 12 inc
hes.
Directed spray with hoods. Spray must
weeds.
formulations)
not touch more than lower 3 inches of
32 or 2
1 oz/A. A
dd 0.25%
nonion
icstalk. Som
e injury will occur.
surfa
ctant.
quinc
lorac @
0.25 to 0.375
Annual grasses a
nd broadlea
fFacet L
Apply
to wee
ds less th
anAp
ply prior to 12
-inch grain sorghu
m.
lb/A
weeds.
22 to 32 oz/A.
2inc
hes tall.
Tank m
ix with 1 lb/A atra
zine for improved
control. Do
not drift o
n cotton or to
matoe
s.
Preharvest
sodiu
m chlo
rate @
4.5 to
6De
siccation of green ve
getation.
Sodium
Chlorate
7 to 10 days prior to harvest.
Use a lab
eled bran
d an
d follow lab
el direc-
lb/A
Several brands a
nd trade names
tions.
available. 2 gal of 3 lb/gal or 1 gal of
6lb/gal.
carfe
ntrazone @
0.016 lb/A
Desic
cation of m
ornin
gglories
.Aim 2 EC
3 days prior to harvest.
Coverage
is im
porta
nt. U
se 10 ga
llons of
1 oz/A.
spray solution
per acre. Can
be tank m
ixed
with sod
ium chlo
rate.
glyphosate @ 1 to 1.3 lb/A
Desic
cation of green ve
getation.
Glyphosate (4 lb/gal formulations)
7 days prior to harvest.
Coverage
is im
porta
nt. U
se 10 ga
llons of
32 to 40 oz/A.
spray solution
per acre. Can
be tank m
ixed
with sod
ium chlo
rate.
glyphosate + carfe
ntrazone
Improved desicc
ation
of vine
s/Glyphosate (4 lb/gal formulations)
7 days prior to harvest.
Coverage
is im
porta
nt. U
se 10 ga
llons of
@ 1 lb/A + 0.016 lb/A
mornin
gglories
.+ Aim 2 EC
spray solution
per acre. Can
be tank m
ixed
32 oz/A
+ 1 oz/A
. with sod
ium chlo
rate.
UPDATED4-2015
UPDATED 4-2015 11
Figure 8-6. Common Weed Seedlings in Grain Sorghum
smooth pigweed, redroot pigweed
Palmer amaranth
tall waterhemp
common lambsquarters
common cocklebur
ivyleaf morningglory
UPDATED 4-2015 12
Figure 8-6. Common Weed Seedlings in Grain Sorghum (cont.)
pitted morningglory
palmleaf morningglory
entireleaf morningglory
purple moonflower
smallflower morningglory
bigroot morningglory
UPDATED 4-2015 13
spotted spurge
prickly sida
Pennsylvania smartweed
nutsedge
large or southern crabgrass
goosegrass