Integrated Crop Management News

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Replant Options in Corn Fields

June 1, 2008
Table of herbicides that can control existing corn stands

By Mike Owen, Department of Agronomy

Given the recent bad weather, it is likely that a number of corn fields will be considered for replanting to soybean. However, before this is considered, two things must be resolved; first, how will you remove the existing corn stand and second, was there a residual herbicide treatment applied to the corn?

Replanting Corn – How Do You Get Rid of the Existing Stand?

June 1, 2008

By Mike Owen, Department of Agronomy

The recent deluge of water has destroyed many corn fields and if the previously applied herbicide requires that corn be replanted, how do you kill the existing poor stand?

If the corn hybrid was a known herbicide resistant cultivar, your options are somewhat limited. If the hybrid was Roundup Ready®, the use of Liberty® or paraquat are not likely to consistently control the emerged corn.

Soybean Replant Decisions from Hail Damage and Flooded Fields

June 1, 2008
Image of hail damaged soybean plants

By Palle Pedersen, Department of Agronomy


After talking to many agronomists and farmers around the state today (May 30) it seems that many will have to replant a few fields because of the extensive rainfall that we have received over the last week. Looking at the weather forecast for Iowa today, it just does not seem to give us any relief with chances of rain pretty much every day during the next week.  


Effect of Flooding on Emerged Soybeans

June 1, 2008
Image of a flooded Iowa soybean field

By Palle Pedersen, Department of Agronomy

The excessive amount of rainfall that we have received in Iowa over the last 2 months, and particularly the last week, has caused excessive flooding in many areas. River bottoms are completely flooded and will probably not be able to be planted now for the next 2 to 3 weeks or at all this year. For the majority of the fields the water should drain and dry quickly, barring no more excessive rainfall.

Flooded Corn and Saturated Soils

May 30, 2008
Image of ponding in a field with two-leaf corn seedlings

By Roger Elmore and Lori Abendroth, Department of Agronomy

The storms last Sunday, May 25, and again on the May 29 and 30 have unloaded extraordinary amounts of rain in many parts of Iowa. Soils in the majority of the state are likely saturated. Low lying areas of fields whether they are tiled or not, are covered with ponds and areas along streams and rivers are flooded. It is not an attractive sight for producers!

Now Grow! (No, Not You, Weeds)

May 27, 2008
Image of base 50 degree F degree days in regions of Iowa from May 1 to May 26, 2008

The week of May 19 through May 26 was slightly cooler than average.  Favorable field conditions allowed corn and soybean planting to catch up.  About 60 to 70 percent of soybeans are planted statewide. 

Where Do I Get Weather Information?

May 23, 2008
Screenshot of the weather.gov page

By Elwynn Taylor, Department of Agronomy

There are several sources of weather information available to help farmers make informed crop production decisions.

To see the forecast for your ZIP code go to www.weather.gov. Click the general location of interest within the U.S. map. Now click your “exact” location (if you miss it a bit you get a chance to put in your ZIP code.)

La Nina Diminishes

May 23, 2008

By Elwynn Taylor, Department of Agronomy

The La Nina of the past several months as determined by the 90-day average Southern Oscillation Index (SOI) has ended. The SOI is a measure of the atmospheric pressure deviation from normal and directly influences meteorological conditions in numerous distant locations. The SOI diminished to 0.8 standard deviations on May 19, 2008. 

Timeliness Critical to Protect Corn Yields

May 23, 2008
Image of a weedy cornfield

By Bob Hartzler, Department of Agronomy

Weeds likely are emerging with corn in many fields due to the lack of a preemergence herbicide. Whether this was planned or due to weather constraints, it is critical to control weeds early in order to protect yields.

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