Does your weed management system make cents?

Does your weed management system make cents?
For every need and desire around the farm, there is always another product or practice that claims to make all the difference.

The good news is many of these items and recommendations can genuinely make a big impact for your operation but the question remains: Will the benefit exceed the cost?

One area with a clear benefit is taking the management of early season weeds seriously and we’re going to show you why it not only makes a lot of sense, it’ll save you a lot of dollars as well.

One of the best ways to eliminate weeds is to attack early on in the growing season using pre-plant or pre-emergent herbicides. Studies show that if weeds grow to be nine inches tall, soybean yield can be reduced by 6%, 12-inch weeds cost 10% yield loss. In corn, 12-inch weeds can cause up to 22% yield loss.

Typical Issues

Pre-emergent weed management can be difficult due to wet springs. Sometimes it is hard to work a field or spray herbicide due to wet conditions and farmers are forced to use the first nice, dry days to plant instead of tilling or spraying.

Herbicide resistance is becoming more of an issue when it comes to weed control. Even though a farmer sprays the field with the right amount of herbicide, at the right time, some weeds are unaffected and continue to grow. One of the best solutions would be to till the field (as long as there are no weeds that reproduce via rhizomes).

If weeds are already established, a pre-emergent herbicide isn’t going to help much, in fact if could cause the weeds to become tolerant and then resistant to the herbicide.

Ensuring that the entire field is getting the recommended rate is the key to having control of the weeds in your field. Make sure your sprayer is properly calibrated and always use full labeled rates.

Equipment Integration

  • Use a properly calibrated sprayer to provide uniform herbicide coverage.
  • Utilize tillage – chisels, discs, field cultivators and vertical tillage tools to tear up weed roots when they are small.

Best Practices

Decide early on if you are going to utilize pre-plant herbicides, pre-emergence herbicides, post-emergence herbicides or a combination. Generally speaking, it is best to combine a pre with residual properties and a post to clean up weed escapes.

If you decide to pre-plant or burndown:

  • Make sure to check if the herbicide needs to be incorporated into the soil, known as a pre-plant incorporated herbicide (PPI). Usually this type of herbicide is applied anywhere from a few days to a few months before planting.
  • Some recommended herbicides for spring burndown from the University of Nebraska are:
    • Corn: 2,4-D, Aim, atrazine, Balance Flexx, Corvus, dicamba, glyphosate, Landmaster II, Lexar EZ and Sharpen.
    • Soybeans: 2,4-D (use esters only), Authority First, glyphosate, Gramoxone, Pursuit and Sharpen.
    • If 2,4-D is applied at 16 fl oz/acre in a burndown program, the pre-planting interval is seven days for corn and soybeans; if 2,4-D is applied at a rate above 16 fl oz/acre in a burndown program, the planting interval should be 14 days for corn and 30 days for soybeans.

If you decide to spray pre-emergence:

  • Spray after planting to have lasting weed control. Some recommended herbicides are:
    • Corn: Aatrex, Balance Flexx, Corvus, Degree Extra, Fierce, Lumax EZ, Outlook, Surestart, Tripleflex and Zemax.
    • Soybeans: Authority MTZ, Boundry, Command, Dual II Magnum, Envive, Optill, Pursuit, Prowl H2O, Valor XLT and Warrant.
  • Remember that spraying pre-emergence herbicide can reduce the number of post-emergence applications.

If you decide to do both:

  • Remember there might be some residual burndown herbicide on your field. Consider how it will react with a pre-emergence herbicide. Always read and follow herbicide labels.

Economics/ROI Example

A farmer has 400 acres of corn and 300 acres of soybeans. His corn typically produces 170 bushels per acre and his soybeans are 40 bushels per acre. Current prices are $3.60 per unit for corn and $9.40 per unit for beans. He decides that this year he is not going to let his weeds get as out of control and applies herbicide before the weeds in his corn field get 12 inches tall and before his soybean fields have weeds 9 inches tall. If possible he will spray when weeds are two to four inches tall and follow label recommendations to ensure the best possible weed control for his herbicide investment.

Original Herbicide Plan
Normal Corn Yield (170 bu./acre) $244,800.00
Normal Soybean Yield (40 bu./acre) $112,800.00
Herbicide Application
(post-emergence x2)Application Cost
($3.70/ac) $5,180.00

Herbicide (glyphosate @ $21/gal – 0.75 lbs/acre) $7,350.00

Traditional Income* $345,070.00
Combating Yield Loss
New Corn Yield (207.4 bu./acre) $298,656.00
New Bean Yield (42.4 bu./acre) $112,800.00
Pre-plant Herbicide Application

Application Cost $3.70/acre – $2,590.00

Herbicide (2,4-D $19/gal, 1 pint/acre) – $1,662.50

Post-Emergence Herbicide

Application Cost $3.70/acre – $2,590.00

Herbicide (Roundup $21/gal, 0.75 lbs/acre) $3,675.00

New Income* $406,706.50
Difference $61,636.50
Note: Weed scientists agree that weeds should generally be sprayed before they reach two to four inches tall in order to provide better control and help prevent weed resistance.
* Does not include deduction of seed, fertilizer, etc.
Source: Fuel/Labor figures from University of Illinois.

Show Buttons
Hide Buttons