Menu

Pre-emergent Herbicides: Will They Still Work as Normal?

With the nice spring, some farmers worked the ground ahead of time but were waiting to plant corn. Then considerable portions of South Dakota received some much needed moisture this past weekend. In many cases some weeds germinated before the pre-emergent product was applied after planting. Most pre-emergent products need about ½ to ¾ inch of moisture to be activated once they are applied. Once this happens, the product is able to kill the weeds.

Effectiveness on early emerging weeds
If weeds germinated before the pre-emergent was activated there may be some weeds that will continue to grow and will need a post-emergent treatment to control them before they get too large. Some pre-emergent products do have the ability to kill some small emerged weeds (kick back). Atrazine is the active ingredient with the largest window to control emerged weeds.

To see if your product does have kick back control check the product label. If not, consider applying a burndown with the pre-emergent to take out emerged weeds, or consider doing one more tillage pass before planting.

Post-activation considerations
Remember that once the product has been activated it will start to control germinating weeds and should work as normal from this time forward. In most cases no chemical is lost waiting for activation, and even if the field had temporary flooding the product is usually still present. In all cases read the label for more information on how your product works. Do not add more of the same product to the field unless it is recommended as this may cause crop injury.

Pest Management Guides

For more information on herbicides labeled for use in South Dakota, consult the following resources:

Source: Paul O. Johnson, South Dakota State University 

Recent News

Federal Reserve: Observations on the Ag Economy- October 2020
10/22/2020

On Wednesday, the Federal Reserve Board released its October 2020 Beige Book update, a summary of commentary on current economic conditions by Federal Reserve District. The report included several observations pertaining to the U.S. agricultural economy. * Sixth District- Atlanta– “Agricultural conditions remained weak. While drought- free conditions prevailed in most parts of the District, some producers reported crop and […]

FAS Report: Corn Ethanol Production Booms in Brazil
10/20/2020

A report earlier this month from USDA’s Foreign Agricultural Service (FAS), Corn Ethanol Production Booms in Brazil, stated that, “Plentiful, and generally cheap, corn supplies in Brazil’s Center-West region have enticed investment in the corn ethanol sector over the last few years. There are currently 16 corn ethanol plants in the Center- West states of Mato Grosso, Goias, and Mato […]

Extended Drydown in Corn
10/20/2020

As fall is progressing, crop harvest is also occurring throughout the state. However, many producers are seeing slower than usual drydown in their corn fields this October. This may be in part due to how the weather conditions impacted corn growth and development this year. In many parts of Ohio in 2020, temperatures were near […]

Your browser is out-of-date!

Update your browser to view this website correctly. Update my browser now