Iowa State University Extension and Outreach

East-Central and Southeast Iowa Crop Information


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July 24, 2012






ISU Extension is compiling resources on a web site to help you deal with the drought.  Resources on the web site are provided under various categories:  “Crops”, “Livestock”, “Dealing with Stress”, “Home and Yard”, “Financial Concerns”, and “Tips for Businesses”.  More information is being added daily.  Local educational events dealing with the drought can also be found on the page which is at


Along with the drought web page, stay tuned to articles posted on the ICM News:


And the ISU Extension Home Page also is focusing on drought issues


ISU Extension will also be conducting a drought webinar; see the “For Your Calendar” section.  The webinar will be recorded and the recording will be posted on the drought web site sometime Thursday, July 26, 2012.




If Chopping Drought Stressed Corn:


1.    Test for nitrates.  Corn that is stunted and has no ears from drought is the most likely to have high nitrates, assuming normal nitrogen fertilization. The greatest risk is when the corn is green chopped and fed directly out of the field. Ensiling will take care of much of the nitrate problem. Leaving the lower 12-18” of the stalk in the field will reduce the problem since nitrates tend to concentrate in the lower stalk. A rain a few days before chopping tends to increase the problem. Before feeding send a sample to the lab to have it tested. A list of some forage testing labs can be found at If you go through your local vet, samples can be sent to the ISU Diagnostic Vet Lab (515-294-1950). Here’s a fact sheet on nitrate toxicity and testing:


2.    Test crop moisture for proper ensiling to insure good fermentation.  Good fermentation is important to reduce nitrate levels in the feed.  Don’t be fooled by how dry the drought damaged corn looks.  Most of the corn is still probably over 75% moisture, which is too wet to just ensile.


a.    To determine actual whole plant moisture:

1.            Sample some representative plants from the field.

2.            Chop the plants, maybe run them through a chipper-shredder or other devise.

3.            Test for moisture using the Koster moisture tester, or other method such as a microwave oven or heat lamp.  The microwave oven or heat lamp method is describe in:

4.            If the moisture is over 70%, the problem then becomes how to harvest and properly ensile this forage.  The answer is easy, but to accomplish this is difficult.  The answer is to add dry matter to reduce moisture content.  Air dry alfalfa or grass forage will decrease the moisture content of wet forage approximately 5 percentage units for each 150 to 200 pounds of material added per ton of wet forage weight.





Foliar Diseases


In general there has been less foliar disease this year, reducing the likelihood of a fungicide paying off.


Some have been reporting Goss’s Wilt showing up in some corn fields in the area again this year. Fungicides have no affect on bacterial diseases like Goss’s Wilt.


It was recently reported that southern rust was found in corn fields in Butler and Grundy counties. Southern rust spreads much faster than common rust and thus is potentially much more damaging. Hot, humid conditions do favor southern rust development, and it is especially concerning that it has been found this early in the season. If you find corn rust in your field, it is much more likely that it is common rust, and thus not as much of a concern. Fungicides are effective on both species. For information on how to distinguish between the 2 diseases, see Allison Robertson’s article at




Drought Webinar

July 25, 2012, 1-3 p.m.

Locally, ISU Extension offices in Delaware, Dubuque, Henry, Jefferson, Johnson, Linn, and Washington Counties will be hosting sites.  See for more details.



Local Drought Meetings Will be Occurring over next 2-3 Weeks

See the ISU Drought Page for Details


One that is not on the list at this writing will be conducted at Buzzy’s in Welton (not Wilton) at 1:00 p.m., Monday, July 30, 2012.  Crop and livestock management issues and options will be discussed.



If you have any questions, please feel free to contact the Iowa State University Extension Office.
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Last Update: July 24, 2012
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