Iowa State University Extension and Outreach

East-Central and Southeast Iowa Crop Information


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April 29, 2011


               We are now midway through the ideal planting window for both corn and soybeans, with very little crop in the ground. Although timely planting by the first part of May is important for obtaining optimum yields for both crops, any potential yield gained can be more than lost if the crop is mudded in to try to beat the clock. Small mistakes made at planting time can haunt you the rest of the season. There is little change in yield potential until planting is delayed after about May 10, and even with late May plantings, yields usually do not drop by more than about 10%. Many producers can get most of their corn planted in about 3-4 days, so starting a day too soon and planting half the corn under marginal conditions usually doesn't make sense. Some points to consider with corn planting this spring:
1.           Don't plant into wet soils. This can lead to sidewall compaction which can lead to season-long problems. The roots will have difficulty growing through the compacted zone made by the planter and will be pancaked into a flat plane in the direction of the planter. This can lead to uneven corn growth, rootless corn, and K deficiency symptoms due to poor root growth. Poor root growth will be an even greater problem later if the summer turns dry, as Elwynn Taylor has been predicting. 
2.           Don't plant too shallow. When soil moisture is plentiful producers are tempted to plant corn more shallow. For every corn field I see with problems caused by planting too deep, I see a hundred fields with problems caused by planting too shallow. If the seed ends up being less than 1.5 inches deep, problems such as rootless corn and K deficiency symptoms are much more likely to occur. Even if the seed is placed 1.5 inches deep, sometimes the soil can settle after planting or there can be soil erosion so that the plant actually “sees” a more shallow depth. Corn should be planted 1.5-2” deep and error on the deep side. 
3.           Even with today's high seed costs, it still pays to shoot for corn stands of 30,000-35,000 plants per acre. Ideal corn seeding rates have been increasing at the rate of about 400 seeds/A/year. Average corn yields per plant haven't changed much in the past 50 years. Most of the yield gain has been from breeding corn that can tolerate an increased population. If you are still planting the same population you did 10 years ago, you're paying 2011 seed prices and only getting 2001 yields. 
4.           Pay attention to details at planting. A little extra time making sure planter settings, seed spacing, depth, and population, and soil conditions are correct can pay big dividends, especially with today's prices.




Burndown Herbicides


Many fields are starting to look like a jungle with the rainy weather delaying the planned herbicide applications. It is not a good idea to plant into standing weeds, with the plan of coming back later to take care of the problem. Some problems weren't taken care of until the corn was 6 feet tall last year. If a burndown herbicide has not yet been applied, you may want to leave 2,4-D out of the mix, so planting can be done soon without the risk of injury.  According to the label, planting of soybeans needs to be delayed 7 days after spraying 1 pt/A of 2,4-D (4 lb gal) ester, and most labels suggest not spraying 2,4-D from 7 days before to 3 days after planting corn. Most of the problems I have seen with corn is when the 2,4-D is included with an amide like Dual or Harness and the spraying is done within that 10 day window. It is also more common when planting is done in less than ideal conditions and the seed furrow remains open, so we could be seeing more problems this year. See Bob Hartzler's article for more details at


Time for Pre-emergence Crabgrass Control in Lawns


Crabgrass seed doesn't germinate until the soil temperatures reach 60+ degrees F, which is also towards the end of the forsythia bloom season or when redbud trees reach full bloom.  Organic control with corn gluten meal should be applied 4 to 6 weeks ahead of this germination window… consider using it now!  Using this product in the first year generally results in a reduction of 50 to 60 percent of the crabgrass.  Two to 3 years of this product is necessary to match the results of synthetic pre-emergence herbicides.  Synthetic control with pre-emergence herbicides can be applied closer to beginning of the germination window.  The Home and Horticulture Newsletter included an article on crabgrass control in their April 7, 2007 issue found at:











Details will be posted soon at




Doug Nolte and the Iowa Learning Farm (Iowa State University), hosts

1021 Highway 6, West Liberty, IA

JUNE 22, 2011, 10:30 a.m. – Noon, followed by lunch

The farm is just in Muscatine County near the Johnson County line. Program details will be forthcoming.




JUNE 29 (tentative), 2011

Details will be posted soon at



If you have any questions, please feel free to contact the Iowa State University Extension Office.

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Last Update: April 29, 2011
Contact: Jim Fawcett

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