Injury Response of Corn Products to Selected Herbicides Under High PH Soils

​Trial Objective

  • High pH soils, due to excess calcium and/or excess lime, are common in Western Kansas and Eastern Colorado.
  • Corn products have varying levels of tolerance when planted in high pH soils and these products may have differential injury responses to HPPD inhibitor herbicides under high pH soils.
  • This trial was designed to determine visual and yield responses of selected DEKALB ® corn products to selected herbicides applied early postemergence when planted in near-neutral pH soils (pH 7.7) and high pH soils (pH 8.3).

Research Site Details

  • Nine DEKALB ® brand blend corn products were planted in two blocks. One block consisted of high pH soils (pH 8.3) and the other block had more neutral pH soils (pH 7.7).
  • Treatments were sprayed with one of three different herbicide products per label requirements at the V2 (two emerged leaf collars) corn growth stage.
  • Each corn product by herbicide treatment was replicated twice in each soil pH block.
  • Plots were visually evaluated for herbicide injury three and ten days after the herbicide application and rated using the following scale:
    • Recommended = 10% or less injury
    • Caution = between 11 to 20% injury
    • Warning = 21% or greater injury
  • Yield data was collected and no significant yield difference was observed in any of the different herbicide treatments. No herbicide injury response was observed in near neutral pH (7.7 pH) soil conditions (data not shown).
  • The ratings for tolerance to the specified herbicides on high pH soils in Table 1 are based on the results of this study.
  • Laudis ® herbicide exhibited the least amount of plant injury with only slight (caution) visual injury observed in DKC55- 84RIB brand blend. Laudis ® herbicide appeared to be the safest HHPD inhibitor herbicide to use on high pH soils among the three herbicides evaluated in this study.
  • Halex ® GT herbicide caused the most visual crop injury and is not recommend (warning) for use on high pH soils when planting DKC47-54RIB, DKC51-91RIB, DKC55-53RIB, and DKC63-21RIB brand blends based on the results of this study.
  • Harness ® MAX herbicide caused slight (caution) visual injury to DKC51-91RIB and DKC63-21RIB brand blends.

What Does This Mean for Your Farm?

  • Corn products have varying levels of tolerance when planted on high pH soils and may also have differential injury responses to HPPD inhibitor herbicides under high pH soils.
  • If high pH soils are a concern, consult your local seed dealer or seedsman about selecting the appropriate seed products that have a tolerance to high pH soils and meet your agronomic needs.
  • Use care when selecting herbicide programs for fields with high pH soils.
  • Visual plant injury from an herbicide application may or may not affect yield potential. 
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