A grower I work with is seeing more woodsorrel in corn and soybean fields. I can’t seem to find much information on how to control this weed. Any suggestions?
Common yellow woodsorrel, although very common in lawns, pastures and “waste” areas, is rarely found in field crops since tillage often eliminates it.
Because of this, there is little information on the effectiveness of herbicides for its control. Early in my career with OMAFRA, I was involved in a no-till soybean trial where we found that soil-applied herbicide applications, specifically with FirstRate or Broadstrike RC, were more effective than post-emergence herbicides (see table below).
In field corn, one study conducted in no-till corn found that both Callisto + Aatrex and glyphosate controlled woodsorrel that was smaller than 10 cm tall (Armel et al., 2009).
In no-till cereal crops, since this weed, if present, is often emerged prior to planting, a pre-plant application of glyphosate should be effective.