Vegetable Production Guide

Corn
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Table 1 Corn Weed Control

This section was updated - 06 July 2018

Table 1 Corn Weed Control

 

Pre-plow

(See Preplow Cleanup of Perennial Weeds, Pest Management section of this guide)

Product

Rate

PHI*

Comments

Pre-plant Incorporated (PPI)

After working up the land thoroughly, apply one of the following treatments to the surface of a firm, moist seedbed.
Incorporate immediately by rotovating or double-discing, preferably in two different directions. Rotovators should be set at 6 cm, discs should be set at 10 to 15 cm and driven at least 6 to 10 km/hr. Plant seed at a maximum depth of 5 cm within two weeks after treatment.

Dual II Magnum

(s-metalochlor)

Group 15

 

PLUS:

 

AAtrex Liquid 480

(atrazine)

 

Group 5

1.25 to 1.75 L/ha
(0.5 to 0.7 L/acre)

 

 

 

PLUS:

 

2.1 to 3.1 L/ha
(0.85 to 1.25 L/acre)

45
  • Use as a PPI treatment only in Interior BC.
  • Controls barnyard grass and broadleaf weeds.
  • Use the lower rate on light, sandy soils and the higher rate on medium to heavy soils.
  • Rainfall is required within 10 days or a shallow cultivation will be necessary.
  • Do not incorporate deeper than 5 cm, if tillage is required.
  • Do not apply Dual II Magnum more than once per season.
  • Do not apply more than 3.1 L/ha (1.25 L/acre) of AAtrex Liquid 480 per year.
  • Do not apply to soils with less than 1% or more than 10% organic matter.
  • Most effective on fine textured soils.
  • Heavy rains after application may reduce effectiveness especially on sandy soils.
  • If weeds escape a PPI or pre-emergence application, an additional post-emergence application of Atrazine Liquid 480 may be necessary.  Do not make more than 1 re-application per year.  See Post-emergence section of this table.
  • Do not re-enter treated area for 12 hours.

Dual II Magnum

(s-metalochlor)

Group 15

1.25 to 1.75 L/ha
(0.5 to 0.7 L/acre)

Primextra II Magnum

(s-metolachlor/atrazine)

Group 5 & 15

3.0 to 4.0 L/ha
(1.2 to 1.6 L/acre)

Apply in 150 L/ha (60 L/acre) of water at 200 to 300 kPa
N/A
  • Use as a pre-plant incorporated or a pre-emergent treatment (see pre-emergence section of this table).
  • Do not apply more than 1.5 kg a.i. of atrazine per ha per year.  When applied at 3 L/ha (1.2 L/acre), Primextra II Magnum contributes 1.0 kg a.i./ha of atrazine.
  • Make only one application per season.
  • Provides better grass control than atrazine alone and reduces residue hazards to following crops.

Simazine 480


(simazine)

Group 5

In light sandy soil:
3.4 to 4.7 L/ha
(1.3 to 1.9 L/acre)

OR:

In loamy or clay soil:
4.7 to 8.3 L/ha
(1.9 to 3.3 L/acre)
N/A
  • Controls broadleaf weeds, annual grasses, and perennial species starting freshly from seed.
  • Use 8.3 L/ha (3.3 L/acre) when grass weeds dominate.
  • Apply one week before seeding and incorporate to a depth of 2.5 cm.
  • Rainfall or irrigation is necessary to activate the simazine.
  • Resistant populations of redroot pigweed, lamb’s-quarters, groundsel and other weeds may develop from the continuous use of simazine over several years.
  • Where rates are in excess of 3.65 L/ha (1.4L/acre) do not plant rotational crops the following year.
  • After applying, do not plant any crop in the treated area in the same year except corn.
  • Simazine should not be used for more than 3 consecutive years in the same field.
  • Do not graze or cut for fodder treated immature crop (before ear emergence).

Integrity


(saflufenacil & dimethenamid – P)

Group 14 & 15

0.73 to 1.1 L/ ha
(300 to 450 mL/ac)

Apply in 100 to 200 L/ha (40 to 80 L/acre) of water.
100
  • Use the high rate for season-long control of labeled weeds including BARNYARD GRASS, FOXTAIL, LAMB’S QUARTERS, REDROOT PIGWEED AND WILD MUSTARD. Check label for other labeled weeds.
  • Do not incorporate greater than 3 cm. deep.
  • In mineral soils: observe plant back interval of 100 days for cereal and 11 months for all other crops except corn.
  • Check label for plant back precautions for muck soils.
  • Do not graze or feed treated crop to livestock for 40 days after applying.
  • Do not enter treated area for 12 hours.

Pre-emergence

Apply one of the following treatments to a well-worked, moist, firm and even seedbed after planting, but before crop emergence. Do not disturb the soil after treatment. If conditions are dry, however, a shallow incorporation will provide improved control with Dual II Magnum or Primextra.

AAtrex Liquid 480

 

(atrazine)

Group 5

Light and sandy soils:

2.1 to 3.0 L/ha
(0.85 to 1.20 L/acre)

Loam and clay soils:

3.1 L/ha
(1.25 L/acre)

45
  • Controls broadleaf weeds.
  • Do not apply more than 3.1 L/ha (1.25 L/acre) per year.
  • May be used at the lower rate following preplant Dual II Magnum to give season long control.
  • Atrazine at higher rates may cause injury to susceptible crops the following year.
  • Will not control annual grasses or Canada thistle.
  • Rainfall is required within 10 days or a shallow cultivation will be necessary.
  • If weeds escape a PPI or pre-emergence application, an additional post-emergence application may be necessary.  See Post-emergence section of this table.

Primextra II Magnum

(s-metolachlor/atrazine)

Group 5 & 15

3.0 to 4.0 L/ha
(1.2 to 1.6 L/acre)

Apply in 150 L/ha (60 L/acre) of water at 200 to 300 kPa
N/A
  • Use as a pre-plant incorporated or a pre-emergent treatment (see pre-plant incorporated section of this table).
  • Do not apply more than 1.5 kg a.i. of atrazine per ha per year.  When applied at 3 L/ha (1.2 L/acre), Primextra II Magnum contributes 1.0 kg a.i./ha of atrazine.
  • Rain or irrigation is required within 10 days, or a shallow cultivation or use of a rotary hoe is necessary for pre-emergent treatment.
  • Provides better grass control than atrazine alone and reduces residue hazards to following crops.
  • Make only one application per season.

Dual II Magnum

(s-metalochlor)
 

Group 15

PLUS:
 

AAtrex Liquid 480
 

(atrazine)

Group 5

1.25 to 1.75 L/ha
(0.5 to 0.7 L/acre)

 

 

 

PLUS:
 

 2.1 to 3.1 L/ha
(0.85 to 1.25 L/acre)

45
  • Controls barnyard grass and broadleaf weeds.
  • Rainfall is required within 10 days or a shallow cultivation will be necessary.
  • Use the lower rate on soils with lower organic matter.
  • Do not apply Dual II Magnum more than once per season.
  • Do not apply more than 3.1 L/ha (1.25 L/acre) of AAtrex Liquid 480 per year.
  • If weeds escape a PPI or pre-emergence application, an additional post-emergence application of Atrazine Liquid 480 may be necessary.  See Post-emergence secton of this table.

Dual II Magnum

(s-metalochlor)
 

Group 15

PLUS:
 

Lorox L
 

(linuron)

Group 7

PLUS:

AAtrex Liquid 480

(atrazine)

Group 5

1.25 L/ha
(0.5 L/acre)

 

 

 

PLUS:
 

0.79 to 1.56 L (320 to 630 mL/acre)

 

 

PLUS:

2.1 to 3.1 L/ha
(0.85 to 1.25 L/acre)

50
  • Apply in 150 L/ha (60 L/acre) of water.
  • Controls annual grasses, broadleaf weeds and triazine-resistant weeds.
  • Rainfall is required within 10 days, or a shallow cultivation or use of a rotary hoe is necessary.
  • Do not apply Dual II Magnum more than once per season.
  • Do not apply more than 3.1 L/ha (1.25 L/acre) of AAtrex Liquid 480 per year.
  • Linuron provides best control when 3 to 5 cm of irrigation or rainfall occurs within 7 to 10 days of application.
  • Do not enter treated areas for 12 hours.
  • If weeds escape a PPI or pre-emerence application, an additional post-emergence application of Atrazine Liquid 480 may be necessary.  See Post-emergence secton of this table.

Simazine 480


(simazine)

Group 5

In light sandy soil:
3.4 to 4.7 L/ha
(1.3 to 1.9 L/acre)


OR:

In loamy or clay soil:
4.7 to 8.3 L/ha
(1.9 to 3.3 L/acre)
N/A
  • Controls broadleaf weeds, annual grasses, and perennial species starting freshly from seed.
  • Apply after not later than 3 to 4 days seeding, prior to emergence.
  • Apply at 8.3 L/ha (3.3 L/acre) for control of grass weeds.
  • Rainfall or irrigation is necessary to activate the simazine.
  • Resistant populations of redroot pigweed, lamb’s-quarters, groundsel and other weeds may develop from the continuous use of simazine over several years.
  • Where rates are in excess of 3.65 L/ha (1.4L/acre) do not plant rotational crops the following year.
  • After applying do not plant any crop in the treated area in the same year except corn.
  • Do not graze or cut for fodder treated immature crop (before ear emergence).
  • Simazine should not be used for more than 3 consecutive years in the same field.

Integrity


(saflufenacil & dimethenamid – P)

Group 14 & 15

0.73 to 1.1 L/ ha
(300 to 450 mL/ac)

Apply in 100 to 200 L/ha (40 to 80 L/acre) of water.
100
  • Use the low rate for early season control of labeled weeds including FOXTAIL, LAMB’S QUARTERS, REDROOT PIGWEED AND WILD MUSTARD, when an in-crop application of another registered herbicide is planned.
  • Use the high rate for season long control of labeled weeds including BARNYARD GRASS, FOXTAIL, LAMB’S QUARTERS, REDROOT PIGWEED AND WILD MUSTARD. Check label for other labeled weeds.
  • In mineral soils: observe plant back interval of 100 days for cereal and 11 months for all other crops except corn.
  • Check label for plant back precautions for muck soils.
  • Do not graze or feed treated crop to livestock for 40 days after applying.
  • Do not enter treated area for 12 hours.

Post-emergence

Apply one of the following treatments to the corn crop after it has emerged, but before it is 30 cm high. Weeds should be small, less than 5 cm high.

AAtrex Liquid 480

(atrazine)

Group 5

PLUS:

Kornoil Concentrate

2.1 to 3.1 L/ha
(0.85 to 1.25 L/acre)

 

PLUS:

2.75 to 5.5 L/ha
(1.1 to 2.2 L/acre)

45
  • If weeds escape a PPI or pre-emergence application of AAtrex Liquid 480, this additional post-emergence application may be necessary.
  • Do not make more than one re-application per year.
  • Do not apply more than 3.1 L/ha (1.25 L/acre) of AAtrex Liquid 480 per year.
  • Apply before corn reaches 30 cm in height.
  • Apply in 200 to 300 L/ha (80 to 120 L/acre) water.
  • The risk of atrazine residues are reduced when lower rates are used.
  • The addition of oil may cause corn injury in hot weather or on cold , wet soils.
  • Rate of Kornoil depends on water volume.  Use 300 L/ha (120 L/acre) of water at the higher rate.

Accent 75 DF


(nicosulfuron)

Group 2

33.4 g per ha
(13.5 g/acre)


PLUS:
a recommended adjuvant
40
  • Apply when the corn is at the 1 to 6-leaf stage (4 visible collars).
  • See label for a list of recommended adjuvants.
  • Application should be made when majority of weeds have emerged.
  • For quackgrass control, apply when majority of weed shoots are actively growing and in the 3 to 6-leaf stage.
  • Make only one application per year.
  • Check label precautions when replanting to other crops.
  • Check label for list of tolerant varieties.
  • Do not re-enter treated fields for 12 hours.

Pardner


(bromoxynil)

Group 6

1.0 to 1.2 L/ha
(0.4 to 0.48 L/acre)

Apply in 200 to 300 L/ha (80 to 120 L/acre) of water at 275 kPa
N/A
  • Up to the four leaf stage controls green and pale smartweed, lady’s thumb, wild mustard, kochia, cow cockle, Russian thistle, stinkweed, cocklebur, common ragweed, pigweed, velvet leaf, bluebur and American nightshade.
  • Up to the eight leaf stage controls wild, tartary and common buckwheat, common groundsel and lamb’s quarters.
  • Not effective on grasses.
  • Apply when corn is in the 4 to 6 leaf stage (10 to 12 cm) and weeds are below the 8 leaf stage.
  • Drop pipes should be used when corn is beyond 8 leaf stage.
  • Temporary corn leaf scorching may occur if applied during periods of cool and wet or hot and humid weather. To reduce the chance of scorching, use the lower rate.
  • Do not add oil or surfactant.

Bromotril 240EC


(bromoxynil)

Group 6

1.2 to 1.4 L/ha
(0.48 to 0.56 L/acre)

Apply in 200 to 300 L/ha (80 to 120 L/acre) of water at 275 kPa

Basagran


(bentazon)

Group 6


PLUS:

 

Assist

1.75 to 2.25 L/ha
(0.7 to 0.9 L/acre)


 

 

PLUS:
1.0 to 2.0 L/ha of Assist
(0.4 to 0.8 L/acre)

Apply in 100 to 400 L/ha (40 to 160 L/acre) of water at 275 to 425 kPa

N/A
  • Not effective on grasses.
  • Use the higher rate when lady’s thumb is over 7.5 cm in height or when difficult weeds such as lamb’s-quarters or pigweed are present.
  • The smaller the weeds, the better the control (see label for recommended weed growth stages).
  • Use split applications 7 to 15 days apart at 1.75 L/ha to suppress field bindweed (2.5 to 6.0 cm) or to control Canada thistle (15 to 20 cm)
  • Apply at 1 to 5 leaf stage of the crop.
  • Rainfall within 6 to 8 hours of application may reduce effectiveness.
  • Cool weather conditions or drought will delay herbicide activity and, if prolonged, may result in poor weed control.
  • Use 1.0 L/ha of Assist under hot and humid conditions.
  • Do not use treated crops for grazing.
  • Do not enter treated area for 12 hours.

Basagran Forte


(bentazon)

Group 6

 

1.75 to 2.25 L/ha
(0.7 to 0.9 L/acre)

Apply in 100 to 300 L/ha (40 to 120 L/acre) of water at 275 to 425 kPa
  • Not effective on grasses.
  • Controls broadleaf weeds such as common groundsel, wild mustard, Shepherd's purse.
  • Use the higher rate when lady’s thumb is over the 6-leaf stage or when difficult weeds such as lamb’s-quarters or pigweed are present.
  • The smaller the weeds, the better the control (see label for recommended weed growth stages).
  • Repeat at an interval of 7 to 15 days.
  • Use split applications 7 to 15 days apart at 1.75 L/ha to suppress field bindweed (2.5 to 6.0 cm) or to control Canada thistle (15 to 20 cm).
  • Apply at 1 to 5 leaf stage of the crop.
  • Rainfall within 6 to 8 hours of application may reduce effectiveness.
  • Cool weather conditions or drought will delay herbicide activity and, if prolonged, may result in poor weed control.
  • Can cause injury to cucumbers.
  • Do not use treated crops for grazing.
  • Do not enter treated area for 12 hours.

Compas 480 EC


(bromoxynil)

Group 6

585 to 700 mL/ha
(237 to 283 mL/acre)

Apply in 200 to 300 L/ha (80 to 120 L/acre) of water at 275 kPa
 
  • Apply any time after 4 leaf stage.
  • Use higher rates during higher infestation.
  • Temporary crop injury may occur in the form of leaf scorching (especially if applied during period of cool and wet, or hot and humid weather).
  • Do not add oil or surfactant.
  • Do not use treated crops for grazing or cut for hay until 30 days after application.

Callisto 480 SC


(mesotrione)

Group 27

210 mL/ha
(85 mL/acre)

Apply in 100 to 200 L/ha (40 to 80 L/acre) of water at 205 to 300 kPa


PLUS:

0.2% v/v Agral 90
50
  • Apply at the 3 to 6 leaf stage.
  • Make only one application per year.
  • Controls the following broadleaf weeds: lambsquarters, redroot pigweed, velvetleaf, mustard.
  • Suppresses common ragweed.
  • Do not apply to soils with less than 1% or more than 10% organic matter.
  • Do not make a foliar application of any organo- phosphate or carbamate insecticide 7 days before or 7 days after applying Callisto 480SC or severe crop injury may occur(check label for more details). 
  • Do not re-enter treated area for 12 hours.
  • A recropping interval of two years is recommended following application of Callisto for broccoli, carrot, cucumber and onion. Snap beans, peas and tomatoes may also be injured at low concentrations of Callisto 480 SC in the soil.
  • Check label for recropping precautions.
  • Consult label for crop tolerance information.

Permit

(halosulfuron)

Group 2
47 to 70 g/ha (19.0 to 28.3 g/acre)
 
Apply in 100 L/ha (40 L/acre) of water
30
  • Do not use on Jubilee sweet corn.
  • Apply over-the-top or with drop nozzles from the spike through row closure (10 to 12 leaf stage) of the crop.
  • Use the low rate for broadleaved weeds.
  • Use the high rate when nutsedge is present.
  • When used early post-emergence, a sequential application may be necessary to control later weed flushes.
  • A sequential treatment at the low rate may be applied only with drop nozzles semi-directed or directed to avoid application into the plant whorl.
  • Do not apply with crop oil concentrates or MSO based adjuvants.
  • Do not apply more than two times per season.
  • Repeat using a 21 day interval.
  • Do not apply more than 140 g/ha (56.6 g/acre) per season.
  • Avoid applications when conditions favour rainfall.
  • Wait 2 to 3 days to irrigate after applying.
  • Avoid disturbing treated areas (e.g.  cultivation) for 7 days after application.
  • Controls broadleaf weeds including ladysthumb, wild mustard, yellow nutsedge and redroot pigweed.
  • Suppresses horsetail, shepherd's purse and smartweed.
  • Will not control ALS-inhibitor resistant weeds.
  • Applications should be made to actively growing weeds at the heights defined in the "USE RATE GUIDE" section of the label.
  • Treat actively growing nutsedge plants at the 3 to 5 leaf stage.  Heavy infestations may require sequential applications.
  • Observe plantback interval of 15 months for cabbage and carrots, 18 months for broccoli and cauliflower, 24 months for spinach and 36 months for beets.  See label for other crops listed.
  • Do not enter treated area for 12 hours.

Impact

(topramezone)

Group 27

PLUS:

Aatrex 480

(atrazine)

Group 5

PLUS:

Merge or Assist

37 mL/ha (15 mL/acre)

 

 

PLUS:

1.04 L/ha (0.45 L/acre)

 

Apply in 100 to 200 L/ha (40 to 80 L/acre) of water at 140 to 276 kPa.

45
  • Apply when the corn is at the 1 to 7-leaf stage, broadleaf weeds are at the 1
    to 8-leaf stage and grass weeds are at the 1 to 4-leaf stage.
  • Effective against triazine resistant weeds.
  • Controls common lamb's quarters, lady's thumb, Eastern black nightshade, wild mustard and redroot pigweed.
  • Suppresses velvetleaf, common chickweed, green foxtail and barnyard grass.
  • For Impact tankmix, use Merge (0.5% v/v i.e. 5 L per 1000 L spray solution) or Assist (0.125% v/v, i.e. 12.5 L per 1000 L spray solution).
  • For Impact tankmix, use high water volume rate.
  • For Armezon tankmix, use Assist (0.125% v/v, i.e. 12.5 L per 1000 L spray solution).
  • Plants under stress can show some temporary transient bleaching.
  • Do not graze or feed treated corn for 45 days after applying.
  • Observe a plantback interval of 4 months for winter wheat.

Armezon

(topramezone)

Group 27

PLUS:

Aatrex 480

(atrazine)

Group 5

PLUS:

Assist

Dual II Magnum

(s-metalochlor)
 

Group 15

PLUS:
 

AAtrex Liquid 480
 

 

(atrazine)


Group 5

1.25 to 1.75 L/ha
(0.5 to 0.7 L/acre)

 

 

 

PLUS:
 

 2.1 to 3.1 L/ha
(0.85 to 1.25 L/acre)

45
  • Controls annual grasses and broadleaf weeds.
  • Do not tankmix with fluid fertilizers, oiils, oil concentrates or surfactants when using Dual II Magnum post-emerge.
  • Apply when corn is in the spike to 6-leaf stage and before weeds pass the 2-leaf stage.
  • Use the lower rate on soils with lower organic matter.
  • Do not apply Dual II Magnum more than once per season.
  • Do not apply more than 3.1 L/ha (1.25 L/acre) of AAtrex Liquid 480 per year.

Atrazine Resistant Weeds

Atrazine resistant weeds can be controlled with the following:

Pardner


(bromoxynil)

1.0 to 1.2 L/ha
(400 to 485 mL/acre)
N/A
  • See under Post-emergence treatment above.
  • Controls atrazine resistant groundsel below the 8 leaf stage.
  • To reduce the chance of burning the leaves, use the lower rate.
  • Group 6 herbicides.

Bromotril 240EC
 

(bromoxynil)

1.2 to 1.4 L/ha
(0.48 to 0.56 L/acre)

Basagran


(bentazon)

PLUS:


 

Assist Oil Concentrate

1.75 to 2.25 L/ha
(0.7 to 0.9 L/acre)


PLUS:
1.0 to 2.0 L/ha
(0.4 to 0.8 L/acre)

 

N/A
  • See comments under post-emergence treatment above.
  • Controls groundsel below 10 cm and lamb’s-quarters below 2.5 cm, and suppresses redroot pigweed below 2.5 cm.
  • Apply in 100 to 400 L/ha (40 to 160 L/acre) water at 275 to 425 kPa.
  • Group 6 herbicide.

Basagran Forte


(bentazon)

Group 6

1.75 to 2.25 L/ha
(0.7 to 0.9 L/acre)


 
  • See comments under post-emergence treatment above.
  • Controls groundsel below 10 cm and lamb’s-quarters up to the 8 leaf stage, and suppresses redroot pigweed up to the 4 leaf stage.
  • Apply in 100 to 300 L/ha (40 to 120 L/acre) water at 275 to 425 kPa.
*PHI = Pre-harvest interval
BUFFERS – Refer to product label for buffer requirements. See also Pesticide Regulations and Safety section of this guide.
PESTICIDE GROUP DETAILS – see Pesticide Toxicity Table of this guide.

 

Viewing Section 11 of 12