Iowa State University Extension and Outreach

East-Central and Southeast Iowa Crop Information


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May 29, 2010




Stand Evaluations and Re-plant Decisions


Corn stands in areas with flooding, ponding, or long-term saturated soils have diminished due seedling rots and/or length of time under water.  Some producers are considering re-planting portions of fields or, in some cases, entire fields.  The cost of re-planting and yield loss from late planting needs to be compared to any yield loss from stand losses to make a good decision.  And remember any re-plant crop insurance benefits to which you may be entitled.


The most recent chart on planting date verses population is in Table 2 at  Note that a perfect stand planted at this time is expected to yield 70% as much as if it had been planted a month ago.  Then, note in the April 20 – May 5 column, a uniform stand of 10,000 plants per acre will give nearly an identical yield.


Numerous gaps of up to 4-6 feet can reduce yields by an additional 5-6%.  For more information on the effect of gaps, see NCR 344 “Uneven Emergence in Corn” at  There is also useful information on non-uniform emergence at


At this time producers may want to consider reducing the maturity of corn to be planted by about 5 days.




Armyworms in an area where a rye cover crop had been used were reported by Tom Hillyer.  Armyworm moths are attracted to fields with grass such as winter rye or fields with grassy weeds. Large populations of armyworms can quickly defoliate fields, so fields that may have attracted the moths should be scouted.  Many insecticides are labeled for armyworms. More information can be found at

Black cutworms at low levels continue to be found, but I have heard of only one infestation that warranted treatment.  However, remain vigilant until corn reaches growth stage V5.  Again, scouting and management information can be found at,, and


Common stalkborers are moving from grasses to adjacent corn fields along Highway 34 (Burlington – Mount Pleasant area) and will be moving into adjacent corn in the area along I-80 within a day or two.  For scouting and management options, see






Potato Leafhoppers


Potato leafhoppers (PLH) are now being found in some alfalfa fields.  They should not be an issue for hay that has not yet been cut, but may be an issue as alfalfa begins to re-grow for the second cutting.   PLH scouting and threshold information is found at:   Don’t forget to check for PLH in new alfalfa seedings under oat canopies.





Farm Progress Hay Expo, Strawberry Point

June 16-17


For details about the program, exhibitors, etc. go to:


Spring Field Day & Special Session For CCAs

SE IA Research Farm – Crawfordsville

June 24


The Spring Field Day of the Southeast Research and Demonstration Farm (Crawfordsville) will be on the afternoon of Thursday, June 24, 2010 at the farm.  Certified Crop Advisor (CCA) credits will be available.  The field day will feature Erin Hodgson on new advances in soybean aphid management, Matt Helmers on Tile Drainage Research results, Emily Heaton, on Miscanthus and other Cellulosic Ethanol Crops, and Johns Sawyer on Nitrogen Management and Cover Crops. In addition, Certified Crop Advisors can obtain additional hours of credit (including soil and water) by attending a special session in the morning (9:00 a.m.) followed by the afternoon tour (1:00 p.m.).  Soil drainage will be featured in this special session. More details are at



Muscatine Island Research Farm Field Day and 75th Anniversary, Fruitland

June 29


The Muscatine Island Research and Demonstration Farm was founded 75 years ago.  A special field day will include many special events in addition to the traditional field day.  If you have an interest in horticulture, be sure to attend.  Information will appear soon at



Northeast ISU Research Farm Field Day, Nashua

June 30, 1:00-4:00


Field day speakers include:   Ken Pecinovsky, Farm Superintendent, Robert Hartzler, ISU Extension Weed Scientist, Alison Robertson, ISU Extension Plant Pathologist, John Sawyer, ISU Extension Soil Fertility Specialist, Chad Ingels, ISU Extension Program Specialist, and Brian Lang, ISU Extension Agronomist. CCA Credits available for a fee.  More details are at





If you have any questions, please feel free to contact the Iowa State University Extension Office.
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Last Update: May 29, 2010
Contact: Virgil Schmitt

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