W-253, January 2008 R. K. Zollinger, NDSU Extension Weed Specialist
WEED GUIDE INFORMATION
The information in this guide provides a summary of
herbicide uses for many crops grown in North Dakota.
The information is based on federal and state herbicide
labels, research at North Dakota Agriculture Experiment
Stations and other information from the North Dakota
Department of Agriculture. ALWAYS READ AND FOLLOW LABEL DIRECTIONS
Instructions for registered uses of herbicides are given on
container labels. The label is the final guide and should
be followed strictly. The information in this guide only
applies to North Dakota because many herbicide uses
are allowed only by supplemental or specific labeling for
North Dakota. Persons are required to have the
necessary supplemental or specific labeling in their
possession at the time of application.
This bulletin is provided for your information. North
Dakota State University or its officers or employees make
no claims, representations, or guarantees as to product
performance nor accept responsibility for results from
using herbicides. Below is information to aid in using this guide:
Herbicides.
Herbicides in tables are listed by trade name followed by common name in
parenthesis except where several brands are available. Contact chemical
suppliers and the ND Dept of Ag for new information about label changes.
Rates. Rates in tables are based on broadcast application and are
expressed according to formulated product per acre with active ingredient (ai)
or acid equivalent (ae) per acre given in parenthesis. Commercial formulations
of the same herbicide may vary in amount of ai.
For example, a pint of 4 lb ae/gal 2,4-D contains 0.5 lb while a pint of 6 lb ae/gal
2,4-D contains 0.75 lb or
a quart of 3 lb ae/gal glyphosate contains 0.75 lb while a quart of 4.5 lb ae/gal
2,4-D contains 1.125 lbs.
What is the difference between ai and ae? The label of commercial products
list both active ingredient (ai) and inert ingredients. Inert ingredients are
not phytotoxic but are used to create stable formulations, and aid in
application, herbicide retention, deposition, and absorption. The active
ingredient of some herbicides are formulated with salts or esters (See Herbicide
Compendium). Glyphosate is formulated at 3, 4, 4.17, and 5 lb of pure glyphosate
acid per gallon. Glyphosate is also formulated as the pure acid and with three
different salts, isopropyl amine (ipa), diammonium (2(NH3), and
potassium (K). The salts that are formulated with glyphosate molecule do not
contribute to weed control. The ai of glyphosate is the weight of both
glyphosate acid and the weight of the salt formulated with the glyphosate
molecule. The acid equivalent (ae) of glyphosate is just the weight of the
glyphosate without the weight of the salt. Glyphosate formulated at different
concentrations and with different salts require using acid equivalent (ae) when
calculating rates. The following table will help to understand the relationship
between ai and ae.
Weed Control Ratings. Herbicide effectiveness ratings listed in
tables show general comparative ratings based on field observations. Weed
control may be equal or greater than what is indicated in the table under
favorable conditions. However, weed control may be reduced and unsatisfactory
results obtained in unfavorable conditions.
Abbreviations Used
Units of Measurement oz = ounce (16 oz/lb) fl oz = fluid ounce (128 fl oz/gal) pt = pint (8 pt/gal) gal = gallon
ae = acid equivalent ai = active ingredient conc = concentration v/v = volume/volume lb, lb/gal = pound, pounds/gallon gpa = gallons per acre
Crop Designation HRSW = Hard red spring wheat
Type of Application EPP = Early preplant
PPI = Preplant incorporated PoPi = Postplant incorporated PRE = Preemergence EPOST = Early postemergence POST = Postemergence POST Directed = Postemergence directed
= Aerial application prohibited
Type of Formulation
ACS = Aqueous capsule suspension
DF = Dry flowable DS = Dispersible solution EC = Emulsifiable concentrate EDF = Extruded dry flowable F = Flowable G = Granular
HFP = High flash point ME = Micro-encapsulated
MFC = Micro-emulsion forming concentration MTF = Multi-temperature formulation S = Solution
SE = Suspension emulsion SG = Soluble granule SP = Soluble powder WP = Wettable powder WDG = Water dispersible granule
XP = Extruded paste (granules) Miscellaneous AMS = Ammonium sulfate CEC = Cation exchange capacity DAA = Days after application MSO = Methylated seed oil NIS = Nonionic surfactant OM = Organic matter
PHI = Preharvest interval RUP = Restricted Use Pesticide
TPS = Triazolopyrimidine sulfonamide SU = Sulfonylurea herbicides UAN = Urea ammonium nitrate
GENERAL INFORMATION
THE WEED CONTROL SUGGESTIONS presented in
this guide are based on Federal label clearance and on
information obtained from the North Dakota Agricultural
Experiment Station and the Research Reports of the
North Central Weed Science Society and Western
Society of Weed Science.
CAUTION: Instructions for registered uses of herbicides
are given on container labels. Read and follow label
instructions carefully. The weed control suggestions in
this circular are based on the assumption that all
herbicides mentioned in this guide will continue to have a
registered label with the Environmental Protection
Agency. This guide contains recommendations for
herbicides that are labeled ONLY for North Dakota.
The user of any pesticide registered as a state label must
have a copy of the label in their possession at the time of
application. State labels can be obtained from chemical
dealers or distributors.
Use herbicides only on registered crops. Some
formulations of an active ingredient may not be labeled for
certain uses. Federal law makes liable for seizure any raw
agricultural commodity that possesses a pesticide residue
for which no exemption or tolerance has been established
or that exceeds the tolerances established by the Food
and Drug Administration. Persons using herbicides in a
manner contrary to label instructions are subject to
penalty under federal and state laws. North Dakota State
University or its officers or employees makes no claims or
representations that the chemicals discussed will or will
not result in residues on agricultural commodities and
assume no responsibility for results from using herbicides USE PESTICIDES ONLY AS LABELED.
Pesticide Labeling and Registration No pesticide may be sold or used in the United States
until the U.S. Environmental Protection Agency (EPA) has
registered the product and approved of the use and the
labeling. Canadian and other foreign labeled pesticides
may not be used in the United States until registered by
the EPA.
TYPES OF PESTICIDE REGISTRATIONS Federal EPA Registrations, also known as 3e and 2ee
labels, are the most common and widely used type of
pesticide registration. Product labels of
pesticides being applied must be at the application site during the time of
application. Aerial applicators must have the label at the loading site.
Section 24(c) Registrations, also known as
(SLN) State Local Needs registrations:
- are state specific registrations issued by states
- are used to address a specific local need
- must prove there is an existing or imminent pest problem for which a federally
registered pesticide is not available
- can be used to address pesticide resistance management.
SLN registrations can be used to register
additional uses or add limitations for a federally
registered pesticide, like adding
application sites, pests, or alternate control methods to
those listed on federally registered labeling. SLN labels
are initiated by the ND Dept. of Ag (NDDA) and must be
approved by EPA. Supplemental labeling must be
provided for each SLN registration. Applicators must have
the SLN label and federal label in their possession at
application. These registrations are legal only in the state
or local area specified in the labeling.
Section 18 "Emergency" and "Crisis" exemptions from
FIFRA allows the unregistered use of a pesticide to address an emergency pest
situation and are used when an emergency or crisis pest situation:
- is an emergency and non-routine
- has no or ineffective alternative management tools
- is severe and can be documented to cause yield or economic loss (>20%) on the
specified crop.
Both
types of exemptions from registration allows use of a
pesticide for a non-registered purpose for a specified
period of time. ND "Emergency" Section 18 exemptions
are registrations initiated by the NDDA, are approved by
the EPA, and can be declared if both federal and SLN
registrations are not or cannot be enacted in time to
prevent the condition. This process may take several months
to complete. In rare occasions, when time is critical and
the emergency is acute, NDDA has the authority to
declare a "Crisis" exemption without the written approval
of EPA. The NDDA informs EPA of the condition prior to
the action and allows EPA to support the state action.
This process usually takes 10 to 14 days to complete. The
duration of a "Crisis" exemption (14 to 21 days) is shorter
than an "Emergency" exemption. If an "Emergency"
exemption is being reviewed by the EPA at the time the
"Crisis" exemption is declared the EPA may elect to grant
the "Emergency" exemption and increase the period of
duration. An applicator must have the federal label and
the Section 18 exemption labeling in their possession at
application.
CLASSIFICATION OF PESTICIDES
EPA categorizes pesticides as either unclassified (general
use) or restricted. Restricted-Use Pesticides (RUP) are
pesticides that can cause harm to humans or the
environment unless applied safely by certified
applicators. Only certified dealers may sell RUPs and only
certified applicators may purchase, apply or recommend
an RUP. Private and commercial applicators must record
certain information for all pesticide applications.
RESTRICTED USE HERBICIDES: All products and premoxes containing
the active ingredients listed below are restricted use pesticides.
Alachlor (Example Lasso) See Mode of Action #15
at X1 - Herbicide Classification Atrazine (Example Aatrex) See Mode of Action #5 at X1 -
Herbicide Classification Isoxaflutole (Example Balamce/Pro) See Mode of
Action #27 at X1 - Herbicide Classification Paraquat (Example Gramoxone) See Mode of Action
#22 at X1 - Herbicide Classification Picloram (Example Tordon 22K) See Mode of
Action #4 at X1 - Herbicide Classification
Brand names of other RUP: Amitrole-T, Cytrole, Hoelon, Kerb, Sulfuric acid
SAFETY AND EMERGENCY PHONE NUMBERS: ND Poison Control Line: 800
222-1222
ND Emergency Assistance Line: 800 472-2121
Report pesticide incident to NDDA: 701 328-2232
