Integrated Crop Management News

Links to these articles are strongly encouraged. Articles may be republished without further permission if published as written and if credit is given to the author, Integrated Crop Management News, and Iowa State University Extension and Outreach. If articles are used in any other manner, permission from the author is required.

Starting Clean in No-till

March 26, 2008

Bob Hartzler, Department of Agronomy

As more Iowa fields develop a history of no-till production, infestations of winter annual weeds are on the increase. The first step in managing winter annuals is proper identification of the species infesting the field. Many agronomists are relatively weak at identifying these weeds. A regional extension publication - Early spring weeds on no-till crop production  (NCR 614) - can assist in this process.

Winter Annual Weeds and SCN – Is There Cause for Concern?

March 25, 2008
Timeline of winter annual weed and soybean growth and SCN activity

By Greg Tylka, Department of Plant Pathology

The frequency of occurrence of winter annual weeds in Iowa fields has increased as more fields are managed with no-till production practices. And in recent years, scientists have discovered that the winter annual weeds purple deadnettle, henbit and field pennycress are moderate to good hosts for the soybean cyst nematode (SCN).

Foliar Fungicides Publication Available

March 18, 2008

Daren Mueller, Extension Plant Pathologist

If the risk of soybean rust development is high and the crop is before growth stage R6, fungicides may be needed. For fungicides to be most effective, they need to be applied as close to the time soybean rust initially infects plants in a field.

Be Careful with Susceptible Soybean Variety in Rotation to Manage SCN

March 17, 2008
Graph of the number of maturity group SCN-resistant soybean varieties available to Iowa soybean growers, 1991-2007

By Greg Tylka, Department of Plant Pathology


The soybean cyst nematode (SCN) can be managed effectively by growing SCN-resistant soybean varieties. There currently are more that 700 SCN-resistant soybean varieties available in maturity groups 1, 2 and 3 for Iowa growers. Information on the varieties is available in ISU Extension publication Soybean Cyst Nematode-Resistant Soybean Varieties for Iowa (PM 1649, pdf).


Check Fields for Soybean Cyst Nematode

March 12, 2008

By Greg Tylka, Department of Plant Pathology

Damage due to the soybean cyst nematode (SCN) can reduce soybean yields in Iowa by 50 percent or more, particularly under very dry conditions. And some believe the chances of severe drought conditions occurring in Iowa are greater for 2008 than for any year since 1990.

Soybean Rust Overwintering in the South

March 12, 2008
March 5, 2008 Rust Observation Map

By Daren Mueller, Department of Plant Pathology

Despite soybean rust infecting fields in Iowa last fall, the pathogen needs to retrace its steps to get back to Iowa in 2008. The first critical step is for the pathogen to survive somewhere over the winter in places like Florida, Texas or Mexico.

An extensive study on the survival of soybean rust was completed in Florida by  W. Jurick, J. Marios, D. Wright and P. Harmon. Their data was presented at the National Soybean Rust Symposium. Some of the main conclusions were:

Should I Be Concerned About Corn Rootworms Now?

March 12, 2008

By Jon Tollefson, Department of Entomology

It is March already, the tillage equipment is being readied, and we are thinking eagerly about planting the 2008 crop of corn. Yet it seems a long time until we have to worry about corn rootworm larval feeding on the corn roots. However, there is something that you should be thinking about now, before you plant the corn.

Pesticide Drift Reduction Starts Now

March 12, 2008

Bob Hartzler, Department of Agronomy

The number of drift complaints in 2007 regarding ground applications of agricultural pesticides received by the Iowa Department of Agriculture and Land Stewardship increased by 36 percent compared to 2006, and was nearly double that of 2004. 

The first step in preventing problems with drift is to develop an effective drift management strategy prior to the spray season.  Important considerations include:

March 2008 La Nina Update

March 11, 2008

By Elwynn Taylor, Department of Agronomy

An area of warm sea surface temperature has formed off the Peru coast. Watch this to possibly “kill” La Nina.  By March 3 the water north of Australia was cooling and west of Peru was warming.Two signs of a La Nina about to fade (and with it the risk of serious Midwest drought diminishes somewhat). 

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