Planting Restrictions Following 2,4-D Applications

April 24, 2009

By Bob Hartzler, Department of Agronomy

Weeds present at planting time in no-till fields are commonly controlled by adding 2,4-D to  glyphosate.  Its use broadens the spectrum of weeds controlled, provides more consistent control during cool weather, and reduces selection pressure for glyphosate resistance compared to glyphosate only.  The primary disadvantages of including 2,4-D are the added cost and the potential for crop injury.

Crop injury risk is minimized by following the planting delays stated on product labels.  Ester formulations are recommended over amine formulations for pre-plant applications, due to a slightly shorter half-life and less mobility in the soil profile.  Planting seed at the proper depth and ensuring closure of the seed furrow also is important in managing risks.

The restrictions regarding corn planting are based solely on injury risk and vary among manufacturers.  For soybean, the restriction is based on both injury risk and residue tolerance, therefore they are uniform on all products. 

Planting restrictions following pre-plant applications of 2,4-D.  (Rates are based on products containing 4 lb a.i. per gallon. )

Soybean: 
    2,4-D  ester — 7 days following 1 pt; 30 days following 1-2 pt
    2,4-D amine — 15 days following 1pt; 30 days following 1-2 pt

Corn: 
    2,4-D ester or amine:  7 days following 1 pt 4 lb/gal; 14
    days following 1-2 pts

 

Bob Hartzler is a professor of weed science with extension, teaching and research responsibilities. He can be contacted by email at hartzler@iastate.edu or phone (515) 294-1164.

Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Integrated Crop Management News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on April 24, 2009. The information contained within may not be the most current and accurate depending on when it is accessed.

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Bob Hartzler Professor of Agronomy

Dr. Bob Hartzler is a professor of agronomy and an extension weed specialist. He conducts research on weed biology and how it impacts the efficacy of weed management programs in corn and soybean. Dr. Hartzler also teaches undergraduate classes in weed science and weed identificatio...