Introduction

44
Making the Spray Decision
Remember that economic thresholds should be used only as guides when making a spray decision. Lost income caused by
dockage or downgrading must also be considered. FIELDS THAT ARE NOT SPRAYED THIS YEAR HAVE A HIGHER POTENTIAL
FOR PROBLEMS THE FOLLOWING YEAR BECAUSE OF WEED SEED RETURN. A farmer’s experience and common sense play
an important role when deciding to spray. Used properly, however, the economic threshold can be an important tool in
making spray decisions.
Weed Resistance to Herbicides
In recent years, the number of herbicide-resistant weeds and the areas they infest have increased.
Most herbicide-resistant weed infestations have developed following repeated use of the same herbicide (or herbicide
group) for a number of years on the same field. Growers who have developed weed resistance on their farms will typically
see a weed, which is normally controlled by a herbicide, escape uncontrolled after a number of years of use of the same
product or product group. Individual plants may be resistant to 1.5 up to 10 or more times the normal field rate.
Herbicide Groups
To help you plan your herbicide program, the following table lists “herbicide groups.” To slow down the process of
developing weed resistance, tank mix products from different groups to control the same key weeds and/or use products
from different groups from year to year on your fields.
Table 8. Herbicide Site of Action and Chemical Family for Resistant Weed Management
Site of Action (Group) Common Name Herbicide Tradename Premix or Co-pack Tradenames*
ACC-ase Inhibitor (1)
Aryloxyphenoxy
propionic acid “Fop”
Cyclohexanedione
“Dim”
clodinafop
fenoxaprop
quizalofop
clethodim
sethoxydim
tralkoxydim
Horizon NG=Foothills NG=Nextstep
NG, Aurora=Bullwhip=Foax=Harmony
Grass=Ladder=Signal=Slam'-R
Puma Advance, Bengal
WB=Cordon=Cougar=MPower
HellCat=Vigil WB=Wildcat
Assure II=Yuma GL
Select=Centurion=Arrow=Shadow
RTM=Patron
Poast Ultra
Achieve=Bison=Marengo=Nufarm
Tralkoxydim
Harmony K*, Harmony SG*, Signal FSU*,
Traxos, Traxos Two*
Tundra*
-
-
Odyssey Ultra*
-
Phenylpyrazolin “Den” pinoxaden Axial Axial iPak*, Axial Xtreme*, BroadBand*,
Traxos, Traxos Two*
ALS Enzyme
Inhibitor (2)
Imidazolinone “Imi”
Sulfonylurea “SU”
imazamethabenz
imazamox
imazapyr
imazethapyr
ethametsulfuron
foramsulfuron
halosulfuron
metsulfuron
nicosulfuron
Assert=Avert
Solo/Solo ADV
-
Pursuit=Gladiator=MPower
Kamikaze=MultiStar=Phantom
Muster
Option (2.25 OD, 35 DF)
Permit
Accurate=Ally=Escort
Accent
-
Altitude FX/FX2*, Ares, Odyssey, Odyssey
Ultra*, Salute*, Tensile*, Viper ADV*
Ares, Salute*
Odyssey, Odyssey Ultra*
-
-
-
Express Pro=Nuance Pro, ReClaim*,
Travallas*
Ultim