North Dakota State University

CORN

Herbicide	Product/A (ai/A)	Weeds	When to Apply	Remarks and Paragraphs
Glyphosate	0.38 to 1.5 lb ae See Remarks.	Emerged grass and broadleaf weeds.	Preplant or anytime prior to crop emergence.	lb ae/gal lb ai/gal 0.38 ae 0.75 ae 1.125 ae 1.5ae 3 4 = 16 fl oz 32 fl oz 48 fl oz 64 fl oz 4/4.17 5.4 = 12 fl oz 24 fl oz 36 fl oz 48 fl oz 4.5 5.5 = 11 fl oz 22 fl oz 32 fl oz 44 fl oz 5 6.1 = 10 fl oz 20 fl oz 30 fl oz 40 fl oz Non-selective, non-residual, translocated, foliar herbicide. Apply with AMS fertilizer. Refer to label for adjuvant use. A4-6 X1
Paraquat RUP	2 to 4 pt 2SL 1.3 to 2.7 pt 3SL (0.5 to 1 lb)	Emerged grass and broadleaf weeds.		Non-residual, contact, herbicides; thorough coverage is required. Apply with a NIS at 0.25% v/v to small weeds. Refer to pages 108-109 for commercial mixtures. B5 S1 S3-4 Q3 X1
Aim (carfentrazone)	�� to 1 fl oz EW (0.128 to 0.256 oz)	Small broadleaf weeds.
Thifensulfuron	0.3 to 0.6 DF 0.45 to 0.9 oz SG (0.225 to 0.45 oz)	Broadleaf weeds including wild buckwheat and RUR canola.		May be tank-mixed with glyphosate. Improves broadleaf weed control including wild buckwheat. Add NIS at 0.25 to 0.5% v/v. S1 X1
2,4-D	0.5 to 1 pt 4EC/SL (0.25 to 0.5 lb)	Most broadleaf weeds except kochia, wild buckwheat and nightshade.		Excellent wild mustard and winter annual mustard control. May be tank-mixed with glyphosate. Improves broadleaf weed control. Refer to pages 108-109 for commercial mixtures. S1 X1
Select Max (clethodim)	4 to 5 fl oz (0.5 to 0.63 oz)	Annual and perennial grasses.		Controls volunteer corn and other emerged grasses prior to planting.
Soil-Applied Herbicides
Acetochlor & dichlormid safener	1.25 to 2.75 pt 7EC (1.1 to 2.4 lb) 1.5 to 3 pt 6.4EC (1.2 to 2.4 lb)	Grass and some broadleaf weeds.	PPI, PRE, EPOST or Fall.	Weak on wild mustard and wild oat. Greater weed control compared to metolachlor or Outlook. Adjust rate according to soil type. PPI gives more consistent weed control than PRE. Refer to label for tank-mix options. Refer to pages 108-109 for commercial mixtures. A1 A3 C4 S4
Metolachlor & dichlormid safener s-Metolachlor & benoxacor safener	1 to 2 pt (0.95 to 1.9 lb)		PPI or PRE. Fall: After Sept 30 but before ground freezes.	s-Metolachlor may give greater weed control than metolachlor at the same product rates. Poor wild oat and wild mustard control. Adjust rate according to soil type. Less weed control than acetochlor products. PPI gives more consistent weed control than PRE. Refer to label for tank-mix options. Refer to pages 108-109 for commercial mixtures. A1 A3 C11 S4
Outlook Propel (dimethenamid-P)	16 to 21 fl oz (0.75 to 1 lb)		EPP, PPI or PRE.	Refer to pages 108-109 for commercial mixtures. C11 S4
Prowl Prowl H₂O (pendimethalin)	2.4 to 3.6 pt 3.3EC 2.1 to 3 pt 3.8ACS (1 to 1.5 lb)	Annual grass and some broadleaf weeds.	PRE or EPOST. Corn: Before 4-leaf stage. Weeds: Less than 1 inch tall.	DO NOT INCORPORATE. Seed corn at least 1.5 inches deep to ensure adequate separation of seed from herbicide. C14 Y1 Y18 Y24
Atrazine RUP	1.1 to 2.2 lb DF (1 to 2 lb)	Broadleaf weeds.	PPI and PRE. Spring only.	Soil residue will injure most crops planted the following year. Use higher rate on fine-textured soils. Consult label for crop rotation restrictions. Refer to pages 108-109 for commercial mixtures. C6 S4 Y1 Y4 Y8 Y24 X1

CORN

Herbicide	Product/A (ai/A)	Weeds	When to Apply	Remarks and Paragraphs
Python (flumetsulam)	0.8 to 1.33 oz DG (0.64 to 1.06 oz)	Annual broadleaf weeds including nightshade.	EPP, shallow PPI, PRE or POST. Corn: Early spike stage.	Refer to label for tank-mix options and crop rotation restrictions. Python and Hornet have no grass activity and will leave a residue the following year. C15 S4 S7 X1 Y2 Y13 Y24
Balance Pro (isoxaflutole) RUP	1.5 to 3 fl oz (0.75 to 1.5 oz)	Annual grass and broadleaf weeds including foxtails, millet, sandbur, pigweed, kochia, lambsquarters, nightshade, and mustards.	EPP, PPI or PRE. Corn: From 21 days before seeding until prior to corn emergence.	Adjust rate according to soil texture and pH. Shallow PPI and seed corn 1.5 inches deep. Cover seed completely with soil. Refer to label for rates, tank-mix options, and instructions to avoid corn injury. Injury is expressed as yellowing/chlorosis and may occur from misapplication, stress conditions. Refer to pages 108-109 for commercial mixtures. A1 C7 S4 Y8 Y24
POST Herbicides
Atrazine + oil adjuvant RUP	0.42 to 1.1 lb DF + 1 qt (0.38 to 1 lb)	Annual broadleaf weeds.	POST. Corn: Up to 12 inches tall. Weeds: Up to 1.5 inches tall.	Apply with other POST broadleaf and/or grass herbicides. Improves control of many grass and broadleaf weeds. Atrazine soil residue may injure crops planted the following year. Refer to pages 108-109 for commercial mixtures. C6 Y4-7 Y24
Aim (carfentrazone)	1/2 fl oz EW (0.128 oz)	Pigweed spp, lambsquarters, nightshade. Partial kochia control.	EPOST. Corn: Up to 12 inches tall. Weeds: SMALL - Up to 2 inches.	Contact herbicides may cause speckling/spotting on corn leaves that intercept spray. May tank-mix with most registered herbicides except bromoxynil. Refer to pages 108-109 for commercial mixtures. B4 C5 S3 S4-5 X1
Bromoxynil	1 to 1.5 pt EC (0.25 to 0.37 lb)	Small annual broadleaf weeds.	POST. Corn: Prior to tasseling. Weeds: Small	Contact, non-residual herbicide; apply to small weeds. Refer to pages 108-109 for commercial mixtures.
Dicamba	0.5 to 1 pt (0.25 to 0.5 lb)	Broadleaf weeds.	EPOST. Corn: From spike to 8 inches tall.	Apply at 0.5 pt/A with drop nozzles when corn is 8 to 36 inches tall or 15 days prior to tassel. Refer to pages 108-109 for commercial mixtures. C10 X1 Y11 Y24
Permit (halosulfuron)	2/3 to 1.33 oz DF (0.5 to 1 oz)	Most large-seeded broadleaf weeds and nutsedge.	POST. Corn: Up to 36 inches tall.	Add NIS at 0.25 to 0.5% v/v or oil adjuvant with 28% UAN at 2 to 4 qt/A. Refer to label for additional information. C13 C20 Y3 Y24
Callisto (mesotrione)	3 fl oz (1.5 oz)	Most broadleaf weeds.	POST. Corn: Up to 30 inches tall or 8-leaf stage. Weeds: Small.	Apply with petroleum oil adjuvant at 1 qt/A + UAN at 2.5% v/v or AMS at 8.5 lb/100 gallons water. MSO or MSO blend adjuvants are not prohibited. Atrazine at 0.42 lb/A improves broadleaf weed control. Refer to pages 108-109 for commercial mixtures. Refer to label for additional information. C2 C9 X1 Y4 Y9 Y24
Impact (topramezone)	�� to 3/4 fl oz (0.175 to 0.26 oz)	Most broadleaf weeds and foxtail.	POST. Corn: Up to 45 day PHI. Weeds: Small.	Apply with petroleum oil or MSO-type adjuvant at 1 to 1.5% v/v plus 28% UAN at 1.25 to 2.5% v/v or AMS at 8.5 lb/A. Atrazine at 0.42 lb/A improves control of grass and broadleaf weeds. Impact may leave a residue the following year after application. Refer to label or narrative for tank-mix options, crop rotation restrictions, and other restrictions. C9 Y3 Y24
Laudis (tembotrione & isoxadifen safener)	2 to 3 fl oz (0.88 to 1.31 oz)	Most broadleaf weeds and some grasses including barnyardgrass, yellow foxtail, proso millet. Partial green foxtail control.	POST. Corn: Up to V8. Weeds: Less than 3 to 4 inches tall.	Apply with MSO-type adjuvant at 1.25 pt/A or petroleum oil at 1% v/v plus 28% UAN at 1.5 qt or AMS at 1.5 lb/A. Atrazine at 0.42 lb/A improves control of grass and broadleaf weeds. Refer to label or narrative for tank-mix options, crop rotation restrictions, and additional information. C9 Y3 Y24

CORN

Herbicide	Product/A (ai/A)	Weeds	When to Apply	Remarks and Paragraphs
Accent (nicosulfuron)	2/3 oz DF (0.5 oz)	Annual grasses, quackgrass and and some broadleaf weeds.	POST. Corn: Up to 20 inches with 6 or fewer collars. Use drop nozzles on 20 to 36 inch corn.	Use the lower rate when tank-mixed with labeled products. Apply with oil adjuvant at 1 to 2 qt/A + 28% UAN at 2 qt/A or AMS at 2 lb/A or with basic pH blend adjuvant at 1% v/v. Do not apply to corn previously treated with Counter 15G insecticide. Refer to label or narrative for other tank-mix options, crop rotation restrictions, and additional information. A7-8 C2-3 X1 Y3 Y24
Resolve (rimsulfuron)	3/4 to 1 oz DF (0.188 to 0.25 oz)		POST. Corn: Up to 12 inches tall with 5 or fewer collars.	Apply with oil adjuvant at 1 to 2 qt/A + 28% UAN at 2 qt/A or AMS at 2 lb/A or with basic pH blend adjuvant at 1% v/v. For corn hybrids of at least 77 day CRM. Refer to label for tank-mix options and crop rotation restrictions. A7-8 C2-3 X1 Y3 Y24
Steadfast (nicosulfuron & rimsulfuron)	3/4 oz DF (0.375 & 0.188 oz)		POST. Corn: Up to 12 inches tall with 5 or fewer collars.
Stout (nicosulfuron & thifensulfuron)	1/2 to 3/4 oz DF (0.338 to 0.5 & 0.025 to 0.038 oz)		POST. Corn: Up to 16 inches tall with 5 or fewer collars.	Apply with oil adjuvant at 1 to 2 qt/A + 28% UAN at 2 qt/A or AMS at 2 lb/A or with basic pH blend adjuvant at 1% v/v. Use on corn hybrids of at least 88 day CRM. Refer to label for tank-mix options and crop rotation restrictions. A7-8 C2-3 X1 Y3 Y24
Option (foramsulfuron & isoxadifen safener)	1.5 to 1.75 oz WG (0.53 to 0.61 & 0.53 to 0.61 oz)		POST. Corn: 6 or fewer collars. Weeds: 1 to 3 inches tall.	Apply with an approved MSO-type adjuvant at 1.5 pt/A + liquid nitrogen fertilizer at 1.5 to 2 qt/A. All crops can be planted the following year. Apply Option with Define SC at 9 fl oz SC for improved yellow foxtail control. Refer to label for tank-mix options, rotational crop restrictions, and additional information. A8 C12 S2 X1 Y3 Y24
NDSU Micro-rates
Stout + dicamba + atrazine + adjuvant RUP (nicosulfuron + thifensulfuron) or Stout + Lumax + adjuvant RUP (nicosulfuron + thifensulfuron) + (mesotrione & s-metolachlor & atrazine)	1/5 to 3/4 oz DF + 4 fl oz + 0.42 lb DF/3/4 pt L ((0.338 to 0.5 oz & 0.025 to 0.038 oz) + 0.188 oz + 0.375 lb) 1/5 to 3/4 oz DF + 3 pt ((0.338 to 0.5 oz & 0.025 to 0.038 oz) + (0.1 lb + 1 lb + 0.375 lb))	Grass and most broadleaf weeds. Stout rates less than 0.75 oz/A will not control yellow foxtail, wild proso millet, volunteer cereals, and quackgrass Lumax and atrazine improves yellow foxtail control.	POST. Corn: Up to 12 inches tall. Weeds: Small	User assumes all risk of inadequate weed control when herbicides are used at less than labeled rate. Accent at 0.33 to 0.67 oz DF/A or Steadfast at 0.38 to 0.75 oz/A can be substituted for Stout. Apply with basic pH blend or MSO-type oil adjuvant. Steadfast and Stout at 0.38 to 0.75 oz DF/A or Accent at 0.33 to 0.67 oz DF/A will control green foxtail and wild oat. Atrazine at 0.42 lb/A or 3/4 pt/A will allow most crops to be planted the following year, including sugarbeet, sunflower, and canola. Refer to Accent and Steadfast above for other precautions. Refer to label or narrative for tank-mix options, crop rotation restrictions, and additional information. A7 C2-3 C6 C9-10 X1 Y3 Y4 Y7 Y9 Y11 Y24
Preharvest Application
Glyphosate	Up to 3.7 lb ae See Remarks.	Annual and perennial grass and broadleaf weeds.	Preharvest.	lb ae/gal lb ai/gal 0.75 ae 1.5 ae 3 ae 3 4 = 32 fl oz 64 fl oz 128 fl oz 4/4.17 5.4 = 24 fl oz 48 fl oz 96 fl oz 4.5 5.5 = 22 fl oz 44 fl oz 88 fl oz 5 6.1 = 20 fl oz 40 fl oz 80 fl oz Apply when grain moisture is 35% or less and corn seed is physiologically mature (black layer formed). Allow a 7 day PHI. Apply with AMS fertilizer. Refer to label for adjuvant use. Follow label directions. A4-6 X1
Paraquat RUP	1 to 2 pt 2SL 0.8 to 1.3 pt 3SL (0.25 to 0.5 lb)	Annual broadleaf and grass weeds.	Preharvest.	Apply with NIS at 0.25% v/v. Apply when grain moisture is 35% or less and corn seed is physiologically mature (black layer formed). Allow a 7 day PHI. C23

Refer to page 126 for control of volunteer Roundup Ready canola and soybean in Roundup Ready corn.

WEED MANAGEMENT IN ROUNDUP READY CORN
NDSU recommends using herbicides with different modes of action and different weed control management practices in Roundup Ready corn production to delay development of glyphosate resistant weeds. See pages 106-107 for more information on weed resistance.
COMMANDMENT #1 - Control weeds when 2 to 4 inches tall to avoid yield loss.
Remove weeds early especially when grass weed populations are high.
Glyphosate at 1.5 oz ae/A controls foxtail, at 2.25 oz ae/A controls volunteer small grain, and at 3 oz ae/A controls wild oat and downy brome. Use higher rates on broadleaf weeds, larger weeds, tolerant weeds, or if weeds are under environmental stress. See glyphosate section on page 68 for more information about increasing weed control from glyphosate.

Three Systems of Weed Control in RR Corn
1. PRE followed by glyphosate POST: All PRE herbicides require rain for activation.
Pages 16 and 17 list many registered PRE herbicides that can be used in herbicide resistant corn. PRE herbicides (acetochlor) at 2/3 the labeled rate will give 60 to 90% grass and broadleaf weed control, will reduce weed infestations emerging with corn, will allow more flexibility in application of POST herbicides, and will help protect yield from early season weed competition. NDSU studies often show greater grass and broadleaf weed control from acetochlor compared to other similar herbicides. Soil-applied atrazine is less effective than POST-applied due to soil adsorption and tie-up.

2. Glyphosate + POST broadleaf herbicide (different mode of action):
Several herbicides listed in the following table will help improve control of weeds not controlled by glyphosate. Glyphosate has no soil residual and will not control weeds emerging after application. Glyphosate may not control some weed species or biotypes. Many POST herbicides listed will give residual weed control. Most herbicide companies have marketing programs in RR corn. Follow label directions for tank-mix and application information. Corn is most tolerant to dicamba from spike to 4-inch corn stage.

3. Glyphosate (EPOST = 2 to 4 inch tall weeds) followed by glyphosate (POST = less than 24 inch tall corn):
This program will increase the risk of weed resistance unless other strategies are used in rotational crops - see Herbicide Resistant Weed Section, page 106-107.
The following table shows herbicides to apply in tank-mix or sequentially with glyphosate in RR corn for control of weeds not controlled by glyphosate. Weed ratings are control without glyphosate. Refer to label for tank-mix and specific application information. Residual weed control listed in the table refers to control of subsequent flushes of weeds after herbicide application.

Herbicides to apply in tank-mix or sequentially with glyphosate in RR corn for control of weeds not controlled by glyphosate.

2008 North Dakota Weed Control Guide