Answers are from the Indiana certified crop adviser panel: Gene Flaningam, Flaningam Ag Consulting, Vincennes; Carl Joern, Pioneer, Lafayette; and Greg Kneubuhler, G&K Concepts, Fort Wayne.

 

I feel like I can never get ahead of waterhemp in my soybeans. What is the best plan for control? What routine should I follow?

 

Flaningam: Waterhemp has been one of the most challenging weeds in current grain production. Resistance management is the key to any weed control program. I would

suggest alternating and mixing multiple modes of action when approaching weed control management. Look at multiple growth regulators, contact herbicides and residuals that have longer soil activity. Split applications of residuals would be a great idea. Look at applying a residual as a preemergence, and then an early post-application with a residual herbicide, too.

 

Joern: Beyond chemical control, cultural practices such as planting in narrower rows and maintaining adequate seeding rates can accelerate canopy closure, giving your soybean field a competitive edge over waterhemp. Start clean and stay clean. Waterhemp now seems to emerge continuously from April through October, making early and consistent management essential. The best strategy is to prevent it from ever seeing the light of day.

 

Begin the season with either tillage or a spring burndown application. Before planting, apply a strong residual herbicide; then plan for a second residual application four weeks later. At that point, scout your fields carefully. If weed emergence is evident, an early postemergence application may be necessary. If no weeds are present, continue scouting until the six-week mark, when an early postemergence application with an overlapping residual should be made to further delay waterhemp emergence until your soybeans reach canopy closure.

 

Follow herbicide labels, adhere to best management practices, and don’t hesitate when it’s time to make a postemergence application. Waiting too long only makes control more difficult. The 2-inch waterhemp plant you pass on spraying today will become a 6-inch monster with twice as many growing points, a waxier cuticle, and the ability to survive and push through the canopy next month.

 

Holding back your best tank-mix for a potential second postemergence pass almost guarantees you’ll need that second pass. Don’t rely on Liberty alone for postemergence control. Every application should aim to knock out waterhemp completely. Letting it recover is asking for trouble.