Verify Wheat Growth Stage Before Applying Growth Regulator Herbicides

Unconfirmed reports of wheat that is approaching jointing near the WI/IL border prompted an unexpected field trip to the Arlington Research Station today to confirm crop growth stage. Our inspection of the wheat crop found that the wheat head is right at the soil surface and nearly at the Pseudostem erection crop growth stage (Zadoks 30; Feekes 4-5; Image 1). As a point of reference we normally do not reach this crop growth stage until May 1st. As we move forward over the next few weeks it is imperative that retailers and growers properly identify the wheat crop growth stage before applying dicamba or 2,4-D. When wheat has a visible joint (Feekes 6), wheat can be very sensitive to dicamba and 2,4-D herbicides. If we remember back to 2009 we had several reports of 80 bushel wheat dropping to 20 bushel wheat when dicamba was applied at Feekes 6. After jointing there are several other herbicides that can be safely used. Please refer to Pest Management in WI Field Crops Bulletin A3646 for these options.

Please click to view a YouTube video on Identifying the Hollow Stem and Jointing Growth Stages in Wheat

Image 1. Feekes 4-5 or Zadoks 30 growth stage in wheat