Can You Distinguish Different Types of Herbicide Damage in Soybeans?

Typical distortion from HG 15 applications includes heart-shaped leaflets like on this plant. Distortion is commonly asymmetrical. ( Iowa State Extension )

While herbicide damage—really any damage—isn’t something you want to see in your growing crop, the reality is it happens. This year it seems to be popping up more than usual in soybean fields according to Iowa State University Extension experts.

“Crop injury may be caused by herbicides applied directly to the crop, carryover from herbicides applied the previous year, contaminated sprayers, or drift from adjacent fields,” says Iowa State University Extension Weed Scientists Bob Hartzler and Meagan Anderson. “Careful assessment of field history, field topography, and field edges is important to help distinguish between different sources of herbicide injury. Also consider how environmental conditions may influence the crop’s ability to tolerate the herbicide.”

Here are a few tips from these experts about how to identify common soybean herbicide injury:

  • Carryover-associated with soil types or can be found in streaks or odd-shaped damage areas where overlap occurs. Last summer’s delayed applications and dry conditions increased carryover issues.
  • Misapplication-tank contamination usually results in field-wide injury and symptoms are often worse in areas with overlap. If field corners are asymptomatic it could be because they were missed by the sprayer.
  • Improperly cleaned spray booms-begins near field entrance and takes on a W, M or V pattern as it works out of the boom.
  • Drift injury-typically has a pattern of declining injury as it moves from the source of drift. Volatilization injury or inversion injury can produce field-wide symptoms.

Check out the quiz below to determine what herbicide damage each of the pictures shows. The same herbicide injury might appear multiple times, in different ways. Your options include herbicide group 4, including 2,4-d and dicamba, group 5, group 14, group 15 and group 27.



Answers, in order: Damage from spray boom (see V pattern); Group 4 damage; Group 14 damage; Group 5 damage; Group 4 damage (contaminated bales of hay rolled though field); Group 27 damage; Group 15 damage