Don’t Control Waterhemp; Manage it

As planting season is approaching for most of the Midwest, so is the battle against weeds.  A recent article in The Bulletin, an online newsletter published by the University of Illinois extension, discusses ways to manage the waterhemp rather than controlling it with herbicides. Based on over 15 years of research on the waterhemp biology, ecology and control, they formed five recommendations to help manage the glyphosate resistant strands of waterhemp in a soybean crop.

Their recommendations are:

1. Apply a full rate (according to label guides for soil type and organic matter content) of a residual herbicide no sooner than seven days before planning and no later than three days after planting.
2. The initial postemergence application of glyphosate must be made when waterhemp is 3- to 5-inches tall.
3. Fields must be scouted seven days after the initial glyphosate application to determine treatment effectiveness.
4. If waterhemp control is inadequate and retreatment is necessary, consider applying a PPO-inhibiting herbicide (lactofen, fomesafen, or acifluorfen) at a full labeled rate (with recommended additives) as soon as possible.
5. Rescout the treated field within 10 to 14 days to determine effectiveness of the PPO-inhibiting herbicide treatment. If scouting reveals that plants treated with a second herbicide application might survive, implement whatever tactics are available or feasible to rogue these surviving plants from the field before they reach a reproductive growth stage.

For more information on these recommendations and how to manage waterhemp, check out the full article from the University of Illinois., or view this Resistance Fighter Case Study or the profile of Weeds to Watch.