Parameters for Using Preemergence Herbicides on Emerged Corn

Parameters for Using Preemergence Herbicides on Emerged Corn

May 18, 2007

With wet spring conditions in many parts of Nebraska, producers may be pressed to adjust their intended herbicide program. Each year questions arise on the limits of using preemergence herbicides on emerged corn. In 2006, Alex Martin assembled a table of these products, which we have updated for this year. Table 1 lists a number of commonly used premergence herbicides labeled for broadcast application after corn emergence, along with crop and weed stage or height information. This list is not comprehensive. If your herbicide choice is not listed in Table 1, check the label for use restrictions.

If the product you are using contains atrazine, adding a crop oil concentrate can enhance control. Atrazine is primarily translocated upward in the plant (xylem mobile). When a foliar application is made, atrazine behaves more like a contact herbicide.

If you planted glyphosate-resistant corn, tank mixing glyphosate with one of the preemergence herbicides will improve total weed control, especially if weeds are larger than you had anticipated. If you tank mix glyphosate with a preemergence product in this situation, adding 17 lbs/100 gallons of AMS will improve its performance. The same will apply to tank mixing Liberty on Liberty Link corn varieties, however, you will want to use 3 lb/ac AMS (1.5 lb/ac if tank mixing with Lumax or Lexar).

Remember, applying preemergence herbicides with a liquid nitrogen carrier is not advised. Unacceptable crop injury will occur.

Lowell Sandell
Extension Educator, Weed Science, Lincoln

 
Table 1. Preemergence herbicides that can be applied postemergence in corn.
           
Herbicide Active Ingredient(s)
Crop Stage
  Weed Stage
  Aatrex/atrazine Atrazine
0-12"
  1.5" G
  Bicep II Magnum/Cinch ATZ S-metolachlor, atrazine
0-5"
  2-leaf G&B
  Bicep II Lite Magnum/Cinch ATZ Lite S-metolachlor, atrazine
0-5"
  2-leaf G&B
  Bicep II Magnum FC S-metolachlor, atrazine
0-5"
  2-leaf G&B
  Bullet Alachlor, atrazine
0-5"
  2-leaf G&B
  Callisto1 Mesotrione
0-30"
  0-5" B
  Camix1 S-metolachlor, mesotrione
0-12"
  0-3" B
  Degree Acetochlor
0-11"
  unemerged
  Degree Xtra Acetochlor, atrazine
0-11"
  2-leaf G&B
  Dual Magnum S-metolachlor
0-5"
  unemerged
  Dual II Magnum/Cinch S-metoloachlor
0-5"
  unemerged
  Dual + atrazine S-metolachlor, atrazine
0-5"
  2-leaf G&B
  Expert1,2,3 S-metolachlor, glyphosate
0-12"
  weeds < 6"
  FieldMaster*,2 Acetochlor, atrazine, glyphosate
0-11"
  weeds < 6"
  G-MAX Lite Dimethenamid, atrazine
0-12"
  1.5" G&B
  Guardsman Max Dimethenamid, atrazine
0-12"
  1.5" G&B
  Harness/Confidence Acetochlor
0-11"
  unemerged
  Harness Xtra/Confidence Xtra Acetochlor, atrazine
0-11"
  2-leaf G&B
  Hornet WDG Flumetsulam, Clopyralid
0-20"
  2-6"G&B
  Keystone Acetochlor, atrazine
0-11"
  unemerged
  Keystone LA Acetochlor, Atrazine
0-11"
  unemerged
  Lasso Alachlor
0-5"
  2-lea fB
  Lasso + Atrazine Alachlor, Atrazine
0-5"
  2-leafG&B
  Lasso + Banvel Alachlor, dicamba
0-3"
  2-leaf B
  Lightning (IMI corn) Imazethapyr, Imazapyr
corn < 8 leaf
  weeds < 3"G&B
  Lumax/Lexar1 S-metolachlor, atrazine, mesotrione
0-5"
  0-3" B
  Marksman Atrazine, Dicamba
0-8"
  0-4"B
  Me-Too-Lachlor II Metolachlor
0-40"
  2-leaf B
  Outlook Dimethenamid
0-12"
  unemerged
  Penimax/Prowl Pendimethalin
0-24"
  1" G
  Harness/Confidence Acetochlor
0-11"
  unemerged
  Prowls + atrazine Pendimethalin, atrazine
up to 2-leaf
  up to 2-leaf
  Prowl H2O Pendimethalin
0-30"
  1"G
  Stalwart Xtra Metolachlor, atrazine
0-5"
  2-leaf G&B
  Surpass Acetochlor
0-11"
  unemerged
  Topnotch Acetochlor
0-11"
  unemerged
  Trizmet II Atrazine, Metolachlor
0-5"
  2-leafG&B
 
1Severe injury may occur if Callisto is applied postemergence to corn crops that have been treated with Counter or Lorsban. Do not tank mix with any organophosphate or carbamate insecticide. Do not cultivate within seven days of application.
2 Do not tank mix this product with any other herbicide when applied postemergence.
3 Do not mix this product with complex fertilizer mixtures such as 10-34-0 or flowables. Use only water or liquid nitrogen carrier.
* Apply this product to Roundup Ready corn only.
 
G = Grass B = Broadleaf