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11/17/2008 - 11/23/2008

Aerate Grain NOW

By Charles Hurburgh, Department Agricultural and Biosystems Engineering

The current cold weather provides some relief from the wet grain issues that have plagued farmers in 2008.  There is considerable corn in storage over 18 percent moisture, with some over 20 percent. And there is still wet corn in the field that likely will not dry any more.

Temperature control is the most important element of grain storage. Every fan in Iowa probably should be running right now, to get grain temperatures down.  Even 20 percent plus moisture corn will keep for a while if the temperature is cold enough.  See the table below.  If you can keep temperatures below 40F, you can hold 24 percent corn a month or so. This will buy time for dryers to catch up, or to do a second drying pass on corn that was very wet coming out of the field.  The wetter the corn, the more tendency there will be for internal heating - so the internal temperature today may not be the temperature next week. 

Constant monitoring is needed
If your corn is below 54 pounds per bushel test weight after drying (as some 2008 corn is), then shorten the times in the table by at least 30 percent.  Have a method in place to monitor temperature, either manually or with temperature cables. And act on the readings.  A layer of hot corn can form very quickly, and then propagate upward.

Freezing corn works, as long as the grain is clean. Trash and broken corn tend to make clumps that divert the air. Remove about 5 percent in the center core after filling a bin; this will take out a lot of the problem material. Replace with other corn or level the surface after coring.  Wet corn will have more tendency to clump, but the risk may be worth it to get grain out of the field.

corn maximum storage chart


Charles Hurburgh is a professor of Agricultural and Biosystems .

Use of Fungicides to Control Soybean Foliar Diseases: a 6-year Summary

XB Yang, S.S. Navi, and John Shriver, Department of Plant Pathology and Ken Pecinovsky,  Northeast Iowa Research and Demonstration Farm

Prior to 2005, foliar diseases were not of major concern to soybean production in Iowa and much of the north central region, except for soybean seed production.  However, since the report of Asian soybean rust in South America in 2001 and then in the United States in 2004, interest in fungicide applications in soybean production has increased consistently, making use of fungicides on soybeans a hot topic. 

Survey of the literature related to fungicide use on soybeans shows a disagreement among researchers, university extension recommendations, and industry applications.  We have been puzzled by the discrepancy and recognize that the soybean price doubling was a driving force to fungicide sprays. But we are not sure if it is the only force.

Last week, a seminar on climate change presented by Dr. Elwynn Talyor sheds light on the increased use of fungicides in Iowa.  Data from Dr. Taylor showed that Iowa annual precipitation days are increasing, especially in the last five years. One hundred years ago, the annual precipitation was 75 days per year.  In the year 2000, the number was about 100 days per year.  Since 2004, the number has been over 120 days per year.  It seems to us that increased disease risk from higher precipitations leads to increased use of fungicides (foliar sprays and seed treatment).  Dr. Taylor is going to present his findings at the Iowa State University Integrated Crop Management Conference Dec. 10-11,2008. We will also present our findings at the conference.

Field tests of fungicide applications
Since 1993, we have tested various fungicides at the request of chemical companies to determine optimal dose and application times.  The treatments varied by chemical compounds, chemical dose, and timing of application.  In some seasons, over 50 treatments were tested in multiple locations with four replications for each treatment.  In each year, the fungicide trials were comprised of several fungicides from Arysta LifeSciences, BASF Corporation, Bayer CropScience, Cheminova Inc., Dow AgroSciences, DuPont, HeadsUp, Shaeffer, Syngenta Crop Protection, United Phosphorus Inc. and Valent USA.

Entries from chemical companies vary from year to year and the soybean varieties planted were also varied from year to year. The experiments were established at various ISU research farms, such as Northeast Research Station, in Nashua.  On farm testing was also conducted in some years. In each experiment, a typical plot consisted of eight rows, with four rows unsprayed border.  Rows in plots were 30 inches apart.  A randomized complete block design with four replications was used.  Plot yields (bu/ac), the incidence (%) and severity (%) of foliar diseases and white mold were recorded. We summarized the fungicide efficacy of our data collected over the previous 6 years.  We also have reference data published by our colleagues in other laboratories at Iowa State University.

Table 1 summarizes the six-year results by ranking non-spray control treatment tested along with all-sprayed treatments.  Our results clearly showed that use of fungicide as a preventative measure can increase yields in a season when disease pressure is moderate or high.  In such a season, many fungicide treatments yielded better and a few treatments increased yield over 10 bushels.  Keep in mind that treatments in our experiments were to find effective compounds and their optimum spray time in comparison to standard treatments.  Therefore, many fungicide treatments did not increase yields.  In seasons with a low disease pressure, only a few treatments with better efficacy, made with fungicide spray applications and at the optimum stage of growth, consistently produced higher yields.
Below are major findings:

1) There are treatments consistently ranked top in terms of increase in yields in our multiple year tests (except for one season) even when disease pressure was low to moderate. 
2) Application at R1 or earlier did not pay off, except for the Cobra which is to control white mold.
3) Application at R3 consistently produced highest yields.
4) Application twice in a season was no better than a single application at R3 in Iowa.

soybean fungicide research

Fungicide application is best reserved for seasons when foliar diseases are severe.  Correct assessment of potential disease pressure is a key for a good decision.  When disease is prevalent and severe in a season, application of fungicide is likely to increase yields.  Research indicates, the higher the foliar disease severity, the greater the return from the use of fungicides. 

At the December 2008 ICM conference at Ames, will present our data in detail and discuss when and how to make spray decision.



XB Yang is a professor Plant Pathology with research and extension responsibilities on soybean diseases. S.S. Navi is an assistant scientist and John Shriver is a research associate in Plant Pathology Department with research and extension responsibilities in crop production.  Ken Pecinovsky is farm supervisor at Nashua Research Farm assisting with research and extension responsibilities related to crop production.

This article was published originally on 11/24/2008 The information contained within the article may or may not be up to date depending on when you are accessing the information.

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