Soybean Germination Issues

What You See

• Sulfentrazone and flumioxazin herbicides are PPO inhibitors (Group 14).  
  • Necrotic lesions on cotyledons and the hypocotyl, malformed leaves, and occasionally death of the primary stem.
  •   More severe in poorly drained, low spots in fields.
• Acetochlor, metolachlor, dimethenamid, and pyroxasulfone herbicides are long-chain fatty acid inhibitors (Group 15).
  •  Heart-shaped leaflets. 
  • Less likely to cause soybean injury than the Group 14 herbicides.
• Metribuzin herbicide is a photosystem II inhibitor (Group 5). 
  • Interveinal chlorosis and necrosis on emerged leaves . 
  • Symptoms occur on unifoliate and first trifoliate leaves, not later-emerging leaves.  
  • Risk increases in fields with high pH soils due to greater availability of the herbicide. 
• Pendimethalin and trifluralin herbicides are mitotic inhibitors (Group 3).  
  • Swelling of the hypocotyl, reduced root growth, delayed emergence.  
  • More likely in cool, wet soils where emergence is slowed, and more herbicide is absorbed by the emerging seedling. 
• Mesotrione is a bleaching (HPPD inhibitor) (Group 27).
  • New leaves initially turn white, then yellow.
  • More likely in soils with pH below 6.5 and low microbial activity due to dry or cool conditions

What You Do

• Don’t compare to corn fields - soybeans are more sensitive than corn to herbicide carryover. 
• Take stand counts and document recovery over the next few weeks. 
• Examine the apical bud- if severely damaged or the plant is girdled, it may not have full recovery. 
• Avoid field operations that could place additional stress on the crop. 
• Avoid tank mixes with flumioxazin + pyroxasulfone prior to heavy rains.