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Evaluating emergence


With most field work halted due to weather, it is an opportune time to visit emerged corn fields (you may need boots). Especially those that were planted in less than ideal conditions.

What can we look for?
  • Check emerged population, measure 1/1000 of an acre (17 feet 5 inches for 30 inch rows) and count corn seedlings. Look for variations in population and evenness of emergence between rows. If issues are present can they be traced back to individual planter unit(s)?
  • Measure planting depth, was seed placement at planting speed at or near expectations?
  • Evaluate seedling root systems for the presence of side wall compaction or smearing.
  • With the recent weeks temperatures I'm expecting the likelihood of yellow or purplish corn, both can be partially or fully caused by a limited root system.
  • Look for early season seedling diseases. Cool wet soils favor seedling blights including Pythium, Gibberella, Diplodia and Penicillium. While most hybrids have impressive seed treatment packages, cold and wet is challenging weather for seed and seedling. Look for weak pale green seedlings that may have water soaked lesions on the roots, mesocotyl or coleoptile. Seeds may also rot in the ground without sprouting.
  • Scout for herbicide carryover or injury symptoms. In the MU Integrated Pest & Crop Management page Dr. Kevin Bradley, University of Missouri, reported numerous calls of herbicide injury from Fomesafen products (Dawn, Flexstar, Flexstar GT, Prefix) Dr. Bradleys article can be accessed at
http://ipm.missouri.edu/ipcm/2014/5/A-Lot-of-Calls-about-Carryover/
  • Evaluate early season weed control if herbicides have already been applied. Measure weed size and growth stage of the corn, information needed for herbicide product and rate selection when conditions allow us to return to the field. We are finding impressive Lambsquarter emergence in several plots that did not receive a pre-emergence herbicide application at the NIARC.
Prioritize management strategies and options for pest or crop growth issues before returning to the fields to finish planting the 2014 crop.

In an article posted on the Illinois Bulletin Dr. Aaron Hager reminded growers that is not too early to scout for Palmer amaranth. A monitored field in Kankakee County had emerged Palmer on May 8th. The article can be accessed in its entirety here

http://bulletin.ipm.illinois.edu/?p=2131



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