Crops Bulletin
May 29, 2014 
Issue 3   

Prepared by

Paul Kassel

Extension Field Agronomist



(712) 262-2264




Serving Clay, Buena Vista, Dickinson, Emmet, Hancock, Kossuth, Palo Alto, Pocahontas, Sac and Winnebago Counties



The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, and marital or family status. (Not all prohibited bases apply to all programs.) Many materials can be made available in alternative formats for ADA clients. To file a complaint of discrimination, write USDA, Office of Civil Rights, Room 326-W, Whitten Building, 14th and Independence Avenue, SW, Washington, DC 20250-9410 or call 202-720-5964.

Growing Degree Days (GDD): The accumulation of GDDs lagged behind normal for much of the spring - with many locations showing a negative 30 GDDS by mid-May. However, GDD accumulation has increased since May 21 and now many locations are near normal for GDDs.


The GDD accumulation can be tracked for many Iowa location by using the Mesonet. Select 'Map of Totals', then select the desired dates and then select 'make plot'.


Soybean Stand Evaluation: Check fields for plant population. Replanting may be necessary if plant populations are less than 75,000 plants per acre. Numerous gaps or open areas will often add 3-5% more yield loss. The following are some guidelines on assessing plant population.


Row spacing, inches      Plants/foot of row to equal 75,000

38                                               5.0 - 5.5

30                                               4.0 - 4.5

20                                               3.0

15                                               2.0

10                                               1.5 - 2.0

Broadcast                                    1.5 to 2.0/square foot


The yield potential of a soybean crop replanted in late May would be 95% to 100% of normal. Adapted varieties can be used until mid-June. Mark Licht has an article and some useful tables for soybean replant situations.


Volunteer Soybean Control in Corn: Soybeans were used as a cover crop on some 2013 Prevented Plant acres. There may be enough volunteer soybeans from these acres that could compete with the current year corn crop.


Recent research at NDSU showed the best results with atrazine, Laudis, Status, Hornet, and dicamba. They also found best results when volunteer soybeans were controlled at V2 - V3 stage as compared to V4 - V6 stage.

Prepared by Paul Kassel, Extension Field Agronomist

Phone: (712) 262-2264, Email: