Early Preplant (EPP) Herbicide Applications...How Early Can They be Sprayed

Historically, we have not recommended early preplant herbicide (EPP) application in our region with a couple of exceptions such as for marestail control.
Early Preplant (EPP) Herbicide Applications...How Early Can They be Sprayed - Articles

Updated: August 8, 2017

Early Preplant (EPP) Herbicide Applications...How Early Can They be Sprayed

Howard F. Schwartz, Colorado State University, Bugwood.org

Historically, we have not recommended early preplant herbicide (EPP) application in our region with a couple of exceptions such as for marestail control. In general, residual herbicides applied more than two weeks ahead of planting almost always require additional weed control often in the form of a post application. With the adoption of Roundup Ready soybean and corn, there may be more opportunity to apply a residual burndown program two or more weeks ahead of planting with the idea of coming back with a well-timed post treatment. A number of herbicide labels specify in days what is allowed EPP. Herbicide rates may increase for EPP, so consult a current herbicide label for specific use directions. The table below provides some spring EPP application intervals for some common corn and soybean products.
EPP Application Intervals For Selected Herbicides
CornSpring preplant application
(maximum days ahead of planting)*
* Maximum interval may specify that a sequential application is necessary.
Atrazine30
Degree, Harness, etc.30
Balance Flexx, Corvus21 - 30
Hornet30
Instigate14
Lumax EZ, Lexar EZ14
Dual30
Princep14
Surestart II30
Verdict, Sharpen30
Valor, Fierce30
Zidua45
EPP Application Intervals For Selected Herbicides
SoybeanSpring preplant application
* Maximum interval may specify that a sequential application is necessary.
Authority products45-60
Canopy45
Envive, Trivenceanytime
FirstRate28
Dual30
Optill, Sharpen (2 oz/A)30
Prowl45
Prefix15
Python30
Sharpen (≤ 1 oz/A)anytime
Sonicanytime
Valor14
Valor XLTanytime

Regarding some of the popular PPO/Group 14 soybean herbicides (e.g., Valor products, Envive, Fierce, Trivence, Authority products, Sonic, Surveil, others), if using these in combination with Sharpen/Verdict/OpTill for control of marestail, there is a 14 day restriction before planting. So, if you tank mix Sharpen-containing products with another PPO/Group 14 residual herbicide you must wait 14 days to plant soybeans. Or if Sharpen is applied EPP in a burndown mix without the PPO residual product, then you must wait 2 weeks before applying the Group 14 residual herbicide at planting.

Authors

Managing weedy plants in agroecosystems Conservation tillage and cover crops Herbicide use Integrated weed management Weed management in organic cropping systems

More by William S. Curran, Ph.D.