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Early Grain Crop Field Scouting

Posted: May 28, 2013

Planting season winding down, but scouting becomes critical

For many the corn and soybean planting season for 2013 is coming to a close. As of last Monday, corn planting was near the 5 year average and soybean planting was ahead of normal. With the favorable weather for fieldwork last week, I suspect we are moving ahead of normal in planting on both crops. In general I feel good about the prospects for both crops in our state at this point. Planting was generally done in a timely manner and some of the early planting issues were avoided for both crops. However, its critical now to visit fields as they emerge to assess stands, herbicide injury, weed control and insect issues that we discuss in the Field Crop News.

One of the biggest issues in corn has been the frost or multiple frost issues as another frost occurred this week in some areas. Some scouts are noting variable frost damage where some plants are injured and others are not in the stand. One concern is whether this will cause variation in development and some loss in yield. My colleague at the University of Wisconsin, Joe Lauer, has actually been studying this impact over a number of years by clipping plants at V2 ( two leaves with a collar) and then clipping them in various patterns. Their work has been showing some subtle yield impacts due to this early defoliation. One summary showed a 17 bu/acre reduction with complete defoliation and 8-9 bu/a reductions with the variable pattern defoliation. So the variable frost damage is probably a good thing. Joe indicates the response to early defoliation is variable, with some years having little impact on yields and others much larger than the mean. This data is interesting to me, since most other defoliation reports have suggested minimal impacts from early season defoliation.

Another aspect of this year’s crop has been chlorotic seedling development. I suspect this is a result of cold nights in the 40s that may not have caused frost injury but could have caused a chilling injury to plants in the V2 to V3 stage that cause them to lose the healthy green color and become chlorotic and sometimes purple. Usually a return to war temperatures (forecast for later in the week) should correct this problem. Impacts on yield should be relatively small.

Contact Information

Gregory W. Roth
  • Professor of Agronomy
Email:
Phone: 814-863-1018