«Weeds: Mike Moechnig, Darrell L. Deneke, Leon J. Wrage, Jill Alms, Dave Vos, and Mark Rosenberg Insects: Adrianna Szczepaniec and Buyung Hadi ...»
South Dakota Crop Protection Guide
Weed Control (text)
Weeds: Mike Moechnig, Darrell L. Deneke, Leon J. Wrage,
Jill Alms, Dave Vos, and Mark Rosenberg
Insects: Adrianna Szczepaniec and Buyung Hadi
Diseases: Kay Ruden
“This document represents only a portion of the 2013 Corn Crop Protection Guide. The complete
guide is available at iGrow.org. Information in this publicationis based on SDSU and other
research and observations and provides a summary of label recommendations. It is not intended as a label replacement. Always verify information on current product labels prior to use of any pesticide. Users are responsible for following all label directions and precautions.” Published by iGrow, a service of SDSU Extension. For more information in the fields of agriculture, farming and rural living available in print, electronically, or on-line, visit iGrow.org.
© 2013 South Dakota Board of Regents. All rights reserved.
Published as an excerpt from the 2013 Soybeans Crop Protection Guide.
South Dakota State University is an Affirmative Action/Equal Opportunity Employer and offers all benefits, services, education, and employment opportunities without regard for race, color, creed, religion, national origin, ancestry, citizenship, age, gender, sexual orientation, disability, or Vietnam Era Veteran status.
03-3000-2013 1/13 Weed Control in Corn Mike Moechnig, SDSU Extension Weed Specialist Darrell L. Deneke, SDSU Extension IPM Coordinator Leon J. Wrage, SDSU Distinguished Professor – Emeritus Jill Alms, SDSU Research Assistant Dave Vos, SDSU Senior Research Assistant Mark Rosenberg, SDSU Field Specialist
HERBICIDE SUGGESTIONSInformation in this publication is based on South Dakota Agricultural Experiment Station research and other research or observations. An herbicide is included only after it is registered by the Environmental Protection Agency (EPA) as to residue tolerances in crops used for food or feed. Information in this book provides a summary of label information, but is not intended as a lable replacement. Labels change regularly. Always verify information on current product labels prior to application. Users are responsible for following all label directions and precautions.
Rates. Rates for most products are listed as product per acre. Product rates for glyphosate, bromoxynil, 2,4-D, and dicamba are based on acid equivalent (ae). Refer to accompanying tables to determine the amount for the specific product used.
Tank-mixes and Combinations. Selected tank-mixes are listed for several herbicides where specific products and rates are given on the label. Most interpretations allow mixing products unless prohibited; however, the user assumes responsibility if the specific combination is not shown. Tank-mixes having the most promise for local situations are included with at least one of the products.
Check the section for each product alone and each product label for the complete listing of combinations for that specific product.
Herbicide Cost. The cost per acre for low and high rates is listed. Cost of additives is not included. Prices do not reflect special marketing programs. Consult your dealer for actual price.
Resistance Management. Refer to the table on page 41 for a brief description of each herbicide site of action. Repeated use of similar herbicide modes of action over multiple years may result in herbicide-resistant weed populations or shifts in weed populations toward weed species that are difficult or costly to control. Maintaining the efficacy of herbicide chemistries through herbicide rotations may be an effective long-term strategy to reduce weed control costs as herbicide patents expire and weed control technology becomes less expensive. To facilitate proper herbicide rotation, the herbicide site of action number is listed next to the herbicide products in this publication.
Applicator Safety. The most serious risk of exposure is during handling and mixing the concentrated product. Use protective equipment specified on the label. Use chemical resistant gloves, eye shield, long-sleeved clothing, rubber boots, and appropriate respirator as required. In case of emergency,
contact the Poison Control Center via 24 hour phone line:
Poison Control Center – 1-800-222-1222 Water Protection. Water quality is a public concern. Preventing spills and accidents reduces risk of groundwater and surface water contamination. Mix herbicides away from wells and water sources.
Prevent back siphoning. Install anti-backflow devices in irrigation equipment used for pesticides. Triple rinse containers. Store herbicides properly. Identify high-risk areas such as coarse soils or areas where the water table is near the surface. Be aware of herbicide properties that increase the risk of contamination in the critical area. Some treatments have specific restrictions requiring buffer strips and border areas around wells, lakes, and streams.
South Dakota 2013 Crop Protection Guide – Corn 3
GLYPHOSATE-RESISTANT WEEDSGlyphosate-resistant weeds are becoming more common in South Dakota. The following list includes weed species that are known or suspected to be glyphosate resistant. Early detection of resistance will greatly improve your ability to manage the resistant population.
The best solution is to minimize selection for resistant weed species, which may be done by diversifying herbicide programs (using preemergence herbicides and tank-mix partners), rotating different crop species (wheat, sunflowers, alfalfa, etc.), or crop varieties such as Liberty Link or conventional.
Kochia: Several locations in central SD. In no-till, effective burndown applications are critical. 2,4-D may not be effective. Atrazine may have some foliar activity for suppression and residual activity to control later emerging plants. Lumax, which contains atrazine and mesotrione (Callisto), would likely have sufficient foliar and residual activity. To control escapes post-emergence, tank-mix partners with glyphosate may include a bleacher herbicide (Callisto, Laudis, Impact), dicamba (Banvel, Clarity, Status, etc.), or a bromoxynil product. To prevent selection for resistance to additional herbicides, consider rotating modes of action in a growing season by using different herbicides for the burndown and postemergence applications. Ignite will control glyphosate-resistant kochia in Liberty Link corn.
Common ragweed: Some reports and a few confirmed locations in eastern SD. Apply a preemergence herbicide such as atrazine, saflufenacil (Sharpen, Verdict, Integrity), or isoxaflutole (Balance or Corvus). Tank-mix partners with glyphosate may include a bleacher herbicide (Callisto, Laudis, Impact), dicamba (Banvel, Clarity, Status, etc.), or a bromoxynil product. Ignite will control glyphosate-resistant common ragweed in Liberty Link corn.
Horseweed (marestail): Several reports in southeastern and northcentral SD. In the burdown application, tank mix glyphosate with 2,4-D ester or saflufenacil (Sharpen, Verdict, Integrity). Atrazine may provide good residual control, but would likely have less foliar activity than saflufenacil. Atrazine (1 qt) + 2,4-D (1 pt) has worked well for foliar and residual control in some SDSU trials. For postemergence applications, make applications while the horseweed is still small (less than 6 inches) and tank mix glyphosate with a dicamba product (Banvel, Clarity, Status, etc.). Ignite will control glyphosate-resistant horseweed in Liberty Link corn.
Common lambsquarters: May be resistant during adverse conditions, but this has not yet been adequately proven in SDSU trials.
Apply a preemergence herbicide such as atrazine, saflufenacil (Sharpen, Verdict, Integrity), or isoxaflutole (Balance or Corvus). Tankmix partners with glyphosate may include a bleacher herbicide (Callisto, Laudis/Capreno, Impact), dicamba (Banvel, Clarity, Status, etc.), thifensulfuron (Harmony), or a bromoxynil product. Ignite will control glyphosate resistant lambsquarters in Liberty Link corn.
Common waterhemp: Several reports in eastern SD. Apply a preemergence herbicide such as atrazine, saflufenacil (Sharpen, Verdict, Integrity), acetochlor (Harness, Surpass, etc.), or isoxaflutole (Balance or Corvus). Tank-mix partners with glyphosate may include a bleacher herbicide (Callisto, Laudis, Impact) or dicamba (Banvel, Clarity, Status, etc.). Ignite will control glyphosate-resistant waterhemp in Liberty Link corn.
ABBREVIATIONS and DEFINITIONS
EPPS EARLY PREPLANT SURFACE: Usually applied 2 to 6 weeks before planting in no-till.
PPS PREPLANT SURFACE: Prior to planting.
PPI PREPLANT INCORPORATED: Before the crop is planted, incorporate as directed.
SPPI SHALLOW PREPLANT INCORPORATED: Preplant incorporated, but herbicide usually restricted to the top 2 inches of soil with single-pass incorporation.
PRE PREEMERGENCE: After planting, but before crop or weeds emerge.
EPOST EARLY POSTEMERGENCE: After initial emergence or crop and weeds.
POST POSTEMERGENCE: After the crop or weeds have emerged.
CORN HERBICIDESIMPERIUM (EPTC + acetochlor) Site of Action: 8+15 4.5-7 pt per acre. Rates depend on weed species targeted. Controls common grass weed species, such as foxtails, crabgrass, barnyardgrass, wild oats, and partial control of sandbur. Also controls some common broadleaf weed species, such as waterhemp and lambsquarters. May tank mix with atrazine to improve broadleaf weed control.
PPI. Apply as described for Eradicane above.
Eradicane can be tank-mixed with several herbicides to improve broadleaf control and to make grass control more consistent. Refer to label restrictions or the section for each herbicide.
ERADICANE + ATRAZINEPPI. Mix 3.75-7.33 pt Eradicane with 1-1.5 lb ai atrazine per acre. Incorporate as for Eradicane alone. Rates of 4.75 pt Eradicane + atrazine at 1 qt of 4L or 1.1 lb 90DF per acre have been satisfactory in most SDSU tests. Higher atrazine rates improve control of some broadleaves but also increase risk of carryover.
ERADICANE + SURPASS or DUAL or MICRO-TECH or OUTLOOK SPPI. Mix 4-6 pt Eradicane with 1-1.5 pt Surpass or 0.5-0.7 pt Dual II Magnum or 2-3 pt Micro-Tech or 10-21 oz Outlook per acre.
Incorporate uniformly into the top 2-3 inches. Apply within 2 weeks of planting. The low rate is used for most situations. Apply as for tank-mix.
Excellent control of several small-seeded annual broadleaves. High rate provides fair control of several large-seeded broadleaves.
Annual grass control erratic. Good late-season control. Excellent crop tolerance. Atrazine at 2 qt of 4L or 2.2 lb of 90DF per acre has been satisfactory.
The maximum atrazine rate is 2 lb ai per acre for soil applications. The maximum rate is reduced to 1.6 lb ai per acre on fields designated as “highly erodible soil” (HEL) if there is less than 30% residue. A 66-foot buffer setback is required on HEL land.
Atrazine cannot be applied within 66 feet of points where surface water enters streams or rivers or within 200 feet of lakes or reservoirs or loaded or applied within 50 feet of a well or sinkhole.
Carryover may damage soybeans, sunflowers, small grain, and legume/grass seedings the following year. Corn and sorghum are tolerant. Risk of carryover is greatest on high pH, low-organic matter soils or eroded knolls. Soybeans and flax usually tolerate carryover rates up to 1 lb ai per acre. Minimum carrier for ground application is 10 gpa. For aerial preplant or preemergence application, minimum carrier is 1 qt for each quart of 4L or 1 gallon for each pound of dry formulation. Minimum carrier is 2 gpa for postemergence aerial application.
EPPS. Apply two-thirds of the total amount as the first part of a split application if treating 30-45 days before planting and apply the remainder at planting. Do not apply more than 2 weeks before planting on sandy soil.
SPPI. Incorporate into the top 2 inches within 2 weeks of planting. Most consistent application. Provides best large-seeded broadleaf control.
PRE. Requires 0.75-1 inch rain within one week after application. Less consistent.
EPOST. With or without crop oil. Crop oil strongly preferred. Intended for annual broadleaves only. Weeds should be less than 1.5 inches high. Corn should not exceed 12 inches. Rainfall, high humidity, and dew improve results. Grass control is fair to poor. Some crop yellowing or leaf tip burn may occur under extremely cold, wet conditions. Use COC at the rate of 1 qt for ground or 1-2 pt per acre for air. Do not add 2,4-D or dicamba. Do not use liquid fertilizer carrier.
1-2 qt atrazine 4L or 1.1-2.2 lb atrazine 90DF (1-2 lb ai) ($3.70-9.10) FALL. Labeling allows fall application in wheat stubble in a wheat-corn-fallow rotation. Rates of 1 to1.25 lb ai per acre have been used in SDSU tests as late fall application in no-till systems. Do not exceed 1.5 lb ai per acre on soils with a pH over 7.5. Results have been favorable if a follow-up herbicide is used to improve grass control.
Atrazine may be used in several preemergence tank-mixes. Gramoxone and glyphosate may be used for burndown. Atrazine is included in numerous tank-mixes on other herbicide labels.
Apply 2 fl oz/A on coarse soils or up to 3 fl oz/A on fine textured soils. Foliar and residual control of broadleaf weed species such as wild buckwheat, common lambsquarters, waterhemp, pigweed, mustard species, Russian thistle, horseweed (marestail), cocklebur, and several others. After application, at least 0.5 inches of rain is needed to activate the herbicide. May tank mix with glyphosate, atrazine, Outlook, Guardsman, Clarity, Status, Harness, or other herbicides for control of grass and additional broadleaf weed species. Do not apply in fields where organophosphate or carbamate insecticides were applied at planting. Do not apply more than 6 fl oz/A per growing season.