NC Cooperative Extension Updates

YIELDS FROM LATE PLANTED SOYBEANS

Q: Will these late-planted soybeans that now (September 11) have flowers and small pods amount to anything? 

Answer from J. Dunphy: Probably, but not with as high a yield as earlier-planted soybeans would have.  Since soybeans are sensitive to day-length, they have their own built-in calendar.  They know they are late.  They’ll shorten up the time from planting until harvest. They probably don’t need a late killing frost to make, just avoid an early killing frost.  Remember they don’t have to be out of the field; they just have to be safe from frost (physiologically mature).  And they don’t have to be there by the first frost, but by the first killing frost, which is typically another 10 days or so later.

There have been two confirmed samples in NC this year.  Rust is close enough to much of southern and southwest North Carolina to warrant a fungicide recommendation for soybeans that have started blooming, and do not yet have full sized seeds in the top four nodes of the plant. Rust has progressed at a faster rate this year than in years past.  With a late soybean crop, the odds of needing to apply a fungicide is increased.  Now is the time to spray a fungicide in much of the state, and to check spray equipment and be sure to have the proper nozzles for applying fungicides in the other parts of the state. We do not recommend spraying soybeans that have not started blooming with a fungicide to control Asiatic soybean rust.  Such pre-bloom applications have seldom improved yields.   Once soybeans start blooming, we would recommend spraying if rust has been confirmed within 100 miles of the field.