Yellowing soybeans - what’s happening?

  • Jun 21
    Chuck Belanger
    Yellowing soybeans - what’s happening? By Chuck Belanger on June 21, 2013
    Categories: Crop Physiology, Soybean

    While travelling the area, it became very apparent to me that we are at the stage in soybean development when nodules are starting to form. Every year, I get phone calls or emails stating, “My soybeans are yellowing”. We are now at that point, especially in early planted soybeans that are progressing well. Just yesterday, most fields looked amazing, dark green and growing by leaps and bounds. We received a nice rain in most areas and the heat finally came in. This boosted the plants and growing took off. In just one or two days, things have changed. Plants have basically stopped growing while trying to produce its own nitrogen through its nodules on the roots. In about 7 days, soybean fields will green back up and we will see green, lush plants; within another week we should see the emergence of some flowers.

    Below is a quote from Publication 811 Agronomy Guide:

    “Soybeans often go through a period when leaves are light green or
    even pale yellow. This is the period just before the nodules start to supply 
    adequate nitrogen to the leaves and is an important phase in the development 
    of a healthy crop. Once the nodules have established and start providing 
    nitrogen, the leaves will turn a dark-green color. If there is proper nodulation, 
    sufficient nutrients and moisture are present, soybeans will remain yellow 
    for only 7-10 days.”

    There have also been questions as to why some fields look more yellow than others. This is because there are differences among varieties. Varieties that have rapid emergence scores and very vigourous early growth will show these symptoms before a slower, weaker variety.

    Be patient and let Mother Nature take over. If anyone wants to read more about nodulation, http://en.wikipedia.org/wiki/Root_nodule is a very good read, albeit a little complex. If you have further questions, please call or email any of the Maizex Yield Specialists.

    Chuck Belanger, Maizex Seeds Yield Specialist, North Essex and
    South Chatham-Kent Counties

    Twitter: @sprayman63