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.

Minimize Soybean Yield Loss from Late Planting

May 13, 2008
Model of soybean planting date response in Iowa based on soybean yield potential

By Palle Pedersen, Department of Agronomy


Soybean responds significantly to early planting. Despite cold soil temperatures and slow plant growth during the seedling phase, there is a yield benefit from early planting, which seems to be influenced by field yield potential.


A Bit Cool, a Bit Wet, but Planting Progresses

May 13, 2008
Image of base 50 degree F degree days in regions of Iowa from May 1 to May 11, 2008

By Rich Pope, Department of Entomology


 


The second week of May continued the 2008 pattern of cool and wet spring weather across Iowa. in spite of a band of locally heavy rain the evening of May 7 that brought over 6 inches of rain to Alden and neighboring areas, corn planting progressed slowly but steadily.


 


Consider Effects on Seedbed Before Tilling Wet Soil

May 13, 2008

By Mark Hanna, Department of Agricultural and BioSystems Engineering, and Mahdi Al-Kaisi, Department of Agronomy

The current weather conditions of frequent rain caused saturated conditions in most Iowa soils. Tilling soil for drying the soil surface or weed control at this time may have significant negative impacts on creating proper seedbed conditions and increase soil compaction.

Beware of a Dangerous Invasive Weed -- Updated

May 12, 2008
Image of cow parsnip

By Mike Owen, Department of Agronomy


Upon further investigation about the location of “local” infestations of the highly invasive giant hogweed, it was determined that the Wisconsin location is in Iron County which is located at the northern boundary between Wisconsin and the Upper Peninsula of Michigan (see colored area on the map). Gogebic County, Michigan also has or had infestations of giant hogweed. The U.S. Forest Service is working diligently to eradicate these populations.


Delayed PRE Herbicide Applications in Corn

May 12, 2008
Table of herbicide options available for corn

By Mike Owen, Department of Agronomy


Given the way the season has developed, the best intentions to apply an Early Preplant (EPP) herbicide application prior to corn planting has gone out the window and it appears that applying a preemergence (PRE) application immediately after planting is also becoming a slim chance. Thus, many who intend to use a soil-applied residual herbicide treatment in corn may be forced to make the application of an early postemergence (EPOST) to the weeds and possibly the corn.


Planters are Rolling and Corn is Growing

May 5, 2008
Image of base 50 degree F degree days in regions of Iowa from May 1 to May 4, 2008

By Rich Pope, Department of Entomology


Today the first weekly report of base 50°F degree-day accumulations is posted for the 2008 Iowa crop season. Statewide, the first four days of May have accumulated degree days at the long-term average, but that follows a cooler-than-normal April.



Seeding Rates in Relation to Maximum Yield and Seed Costs

May 5, 2008
Graph of corn grain yield at varying seeding rates

By Roger Elmore and Lori Abendroth, Department of Agronomy


Increased seeding rates have ignited corn yield increases over the years. If seeding rates are the spark, hybrid genetics fuel the increase. It takes both high seeding rates and high-yielding hybrids that can tolerate increased plant-to-plant competition to maximize yields. If hybrids were not bred to tolerate increased seeding rates, we would have fields of flat corn at harvest. Older hybrids simply cannot tolerate today’s seeding rates without severe lodging and/or barrenness.

It’s a Late Spring: Should You Apply Nitrogen or Plant Corn?

May 4, 2008

By John Sawyer and Roger Elmore, Department of Agronomy

Our best information from planting date experiments show that corn yields are reduced as we plant into the second half of May.  However, looking at planting progress and corn yields over the years, we see that although yields are increasing and in general we are planting earlier every year, above average yields can occur with delayed planting and below average yields can occur with early planting (see Sidebar article ‘Corn Planting Progress‘ from Wisconsin).

Surface Waters: Ammonium is Not Ammonia – Part 2

May 2, 2008

By John Sawyer, Department of Agronomy

A previous article explained the difference between ammonium and ammonia, the relationship between the two nitrogen forms and the implication of a combined (ammonium-N plus ammonia-N) analysis related to water quality criteria for aquatic life. This article focuses on the implication of ammonia and ammonium for chlorination of drinking water.

Field Testing of N-Hibit™ Seed Treatment in Iowa*

May 2, 2008
Map of the locations of experiments in 2007 where n-Hibit seed treatment was evaluated

By Greg Tylka and Chris Marett, Department of Plant Pathology


N-Hibit™ is a seed-treatment that contains harpin protein, a compound that can stimulate plant defense responses. N-Hibit™ is now being sold in the United States for management of the soybean cyst nematode (SCN).  Iowa State University evaluated the effects of N-Hibit™ seed treatment on soybean yield and SCN population densities in experiments at nine locations throughout Iowa in 2007.


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