Introduction
Continued much above normal temperatures are quickly advancing area crops towards maturity.  Soybean harvest has begun (early reports indicate favorable yields) and corn is at or nearing physiological maturity.  Heavy rains inundated areas of far N.W. Iowa (see the Intellicast radar estimate), but fortunately west-central IA caught only scattered to moderate rain showers.  Recent warm, dry and windy conditions have rapidly dried soybeans down, use the following information to determine field maturity/schedule field harvest, avoid unseen harvest losses and optimize harvest machinery.  Adjust drying temperatures and storage facilities for on-farm soybean storage.   If soybean aphids were a problem in your fields this year, any reports of treated vs. non-treated areas would be helpful to add to last year’s data set.  A possible stumble of the new corn rootworm B.t. technology occurred this year in Illinois?  Follow the provided web link to read more about it.  Be sure to allow time on January 12, 2005 to attend the 4^th annual Carroll Crop Advantage Conference.

Row-Crop and Forage Information
Growing Degree-day The month of September is quickly making up lost ground in degree-day accumulation.  Last week the area accumulated 30% more degree-days than normal, and the area is forecasted to collect 96% (Table 1) more degree-days than normal this week.  Seasonal total degree day accumulations for April and early May planting dates continue to improve when compared to the 13-year average (92 to 95% of normal).  This equals about 160 degree-days below normal.  Degree-days (average for NW Iowa) can be accessed at this web site:  http://www.extension.iastate.edu/carroll/crops/degree-days-2004.htm

Corn development  Early planted and early maturing corn hybrids should reach physiological maturity (PM) this week.  Physiological maturity is classified when maximum dry weight has been accumulated in the kernel and can be identified by the formation of a black layer at the base of the kernel.

Soybean Development is at or near physiological maturity in many to most fields across the region.  Unlike corn, soybean pods reach physiological maturity over a range of time on each plant depending on its location on the plant and when the pod was formed.  Determining when soybeans are mature (both physiological and harvest maturity) helps to schedule harvest operations and reduces in-field harvest losses.  Physiological maturity is when the soybean (pod) has accumulated its maximum dry weight.  The growth stage classification is R7 - R8.  With an indeterminate soybean, all pods will not reach physiological maturity at the same time.  There is a period of about two to three weeks from the time the 1st pod reaches physiological maturity to the last pod reaching physiological maturity.  The average seed moisture at the time the pod is physiologically mature is 55%.  When all pods on the soybean plant have reached physiological maturity, the average seed moisture for the plant is usually around 44%.

Two main indicators can be used to determine when individual pods reach physiological maturity:

• Seed Shrinkage: Once the seed has attained its maximum dry weight and size, it will begin to shrink. 

• Pod Color: A short time prior to seed shrinkage, the pods will begin to lose their green color and will take on a yellowish cast.

Harvest maturity indicates when all beans on the soybean plant are ready to be harvested.  This is usually when the average seed moisture is 13%.  Harvest maturity is usually reached about one to two weeks after the entire plant has reached physiological maturity, depending on temperature and humidity. 

Grain Harvest Tips
Grain Moisture Content for Safe Storage (by Paul Kassel, ISUE Crops Field Specialist)

• Soybeans – sold by spring                   14.0 %

• Soybeans – stored up to one year        12.0 %

Soybean Harvest losses – rules of thumb.

• 4 soybeans per square foot equal one bu/a loss.

• Be sure to include soybeans in uncut stubble.

Hidden Soybean Yield Loss:  When soybeans are harvested below 13% moisture, yield is lost.  For example: 50 bushel per acre soybean yield at 9 % moisture equals 2.4 bushel per acre hidden soybean yield loss (13% moisture minus 9% moisture equals 4 points of moisture times 0.6 bu/point/acre hidden yield loss, or 2.4 bushel per acre).  

(Excerpted from September 17^th edition of the Nebraska CropWatch newsletter) Always try to run the combine at full capacity to increase harvest efficiency and reduce grain damage. With too little crop going through, the action can become too aggressive and the grain will be damaged. Maintaining grain quality pays through better prices at the elevator or grain that stores better with fewer complications.  Combines are designed to work best when there’s a consistent flow of grain. When the amount of grain going into the combine drops by half, each kernel or bean suffers two to three times the number of blows from the cylinder and concave. With high yield areas it may be necessary to slow down so as not to overload the system and in lower yielding areas, it may be necessary to speed up some. Remember that while increasing combine speed may increase the flow and the quality, it also can introduce more plant material and increase separation losses. At the onset of harvest in the field, check to see if there are any losses and if so, the source of those losses, such as from the header, thresher, or separator.
Comments from William Campbell, Extension Agricultural Engineer and Lisa Jasa, CropWatch Editor; University of Nebraska:  http://cropwatch.unl.edu/

On-farm storage of soybeans  Storage of soybeans on-farm requires some special considerations when compared to corn.  As with most grains, when moisture is too high, spoilage and reduced germination will result.  High oil content of the soybean makes them more susceptible to spoilage than corn; therefore soybeans need to be about two points dryer than corn for proper storage.  For winter storage, store commercial soybeans at 13 percent moisture or less.  Soybeans with less than 15 percent moisture can be dried with bin fans. 

Aerate the stored soybeans to maintain grain temperature at 35 to 40 degrees F in winter and 40 to 60 degrees F in summer.  Check the bins regularly for heating or spoilage.  When drying soybeans in high or low temperature dryers, be careful.  Soybeans are fragile and can be damaged by air that is too hot or too dry, as well as by rough handling.  Soybeans have about 25 percent less airflow resistance than shelled corn; fans sized for corn drying will produce greater airflow through soybeans.  Greater airflow means faster drying.

Pest Management
Although soybean aphids were not near the problem in 2004 as they were in 2003, many fields were treated in some areas of west-central and N.W. Iowa.  And just like last year, in order to determine if insecticide treatments paid for themselves, collection of yield information on treated vs. non treated areas is essential.  Therefore, if you have the data, and the time, please take a moment to take the Soybean Aphid “Treated vs. Non-Treated” soybean yield survey.  This information will be very valuable in future seasons when the aphid problem presents itself again.

Please find the “Treated vs. Non-Treated” on-line and printable form at these URL’s:

• On-line form:  http://www.extension.iastate.edu/carroll/crops/aphid_treatment_form.htm 

• Printable Form: http://www.extension.iastate.edu/carroll/crops/Soybean%20Aphid%20Insecticide%20Treatment%20Survey.pdf

Refer back to the “Aphid Page” for survey results (http://www.extension.iastate.edu/carroll/crops/soybean-aphid.htm).

B.t. Corn rootworm problems?  There have been scattered reports in Illinois of possible problems with the new corn rootworm B.t. hybrids.  Read more here:  http://www.ipm.uiuc.edu/bulletin/article.php?issueNumber=22&issueYear=2004&articleNumber=1

Learning Opportunities
Ag Chemical Dealer Updates. The Ag Chemical Dealer Update meeting in Denison will be November 29 at the Denison Country Club. Watch for the brochures from ISU.

Crop Advantage Conference:  The 4th annual Carroll Crop Advantage Conference is set for January 12, 2004.  Be sure to put this date on your calendar as it looks to be a very informative day.

For questions or comments please respond to vagts@iastate.edu

The information given in this publication is for educational purposes only.
Reference to commercial products is made with the understanding that no
discrimination is intended and no endorsement by Iowa State University with
any specific product(s) used in this is implied

This page last updated on 09/20/04