by Rodrigo Werle (UW-Madison Extension Cropping Systems Weed Scientist) and
Maxwel Oliveira (UW-Madison Weed Science Postdoctoral Research Associate)
With the widespread occurrence of herbicide-resistant weeds, corn and soybean farmers are having to diversify their herbicide programs to obtain adequate levels of weed control. The increased herbicide diversification increases the likelihood of crop injury due to carryover, misapplication, tank contamination, and/or drift.
To help you determine which herbicide(s) may be responsible for suspected injury on crops, this key uses the herbicide’s site of action (SoA) and respective Weed Science Society of America group number; herbicides within the same SoA can cause similar symptoms. After reaching a specific SoA, you can check if any of the herbicides from that group are the source of crop response. Herbicide control (selectivity) is specified for broadleaf and/or grass weed species and remember to also observe weeds for injury symptoms.