Quick Tips – Effective Post-Emergent Weed Control in Conventional Soybeans

If you have only grown glyphosate tolerant soybeans in the past, the move to conventional soybeans can offer up new challenges in regards to weed control. Good weed control is critical for maximizing yield.  Here are a few quick tips:

    • Remember!! You can’t apply post-emergent glyphosate – Unlike glyphosate-tolerant soybeans, conventional soybeans are not a clean-up crop for weedy fields. They are a crop that needs to be planted in fields that have already been cleaned up.
    • Get in touch with your weed spectrum – If you have not done so already, determine what weeds are present or likely to be present in your conventional soybean fields. Are the herbicides you intend to use going to control the weed spectrum you have identified? A mismatch between weed spectrum and herbicides used is a frequent cause of weed control problems in conventional soybean fields.
    • Did you take advantage of pre-emergent weed control opportunities? If so, how is that working? – The advent of pre-emergent soil applied residual products has been a benefit to weed control in conventional soybeans. If this is a tool you decide to use, it is important to assess its effectiveness before you do post-emergent applications to ensure that weeds you are assuming have been dealt with have been controlled.
    • Amp up the Aggression!! Early and thorough weed control is key – Important regardless of the type of soybean you are growing. Research has demonstrated the critical weed free period for soybeans is emergence to the third trifoliate, where the removal of weeds provides the greatest protection of yield potential. Be timely with control and selective with products that may provide some residual control for an extended weed free period.
  • Know your crop growth stage, know your weed growth stageKnowing your crop and weed growth stages as you time herbicide applications is very important in conventional soybean production. Most of the herbicides available have tighter application windows than glyphosate

 

  • Overgrown weeds are less susceptible to herbicides – this can lead to growers dishing out more money on higher cost options that might not work due to size of plants. Please take note that some herbicides can cause crop damage if they are used at the wrong growth stage. In this competitive fight for yield, you don’t want to set back your crop.

 

 

  • Assess the effectiveness of herbicide applications and adjust your plan – Fields should be scouted after each herbicide application to assess effectiveness. If weeds have shown up that the previous herbicide would not have controlled, you might have to change products for your next application or add extra herbicide passé. Were the weeds that you expected to be controlled, actually controlled? Don’t assume that you have dealt with target weeds until you see the evidence. These post-spraying inspections are key opportunities to detect the development of herbicide resistant weeds before they get out of hand.
  • Weed control in conventional soybeans is going to cost more – Seed may be cheaper, but the cost of an effective weed control program in conventional soybeans is almost always more expensive than in glyphosate-tolerant production. But remember, poor weed control remains the #1 threat to maximizing yield and profit in conventional soybeans. Weed control is a key point of investment in this crop and there are no shortcuts if the weed control situation demands action.

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