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Agronomic Crops Network

Ohio State University Extension


C.O.R.N. Newsletter 2013-36

Dates Covered: 
October 22, 2013 - October 29, 2013
Curtis Young

Slug Website

Recently a new web site has been developed by John Tooker and his group at Penn State that they are calling a “Slug Portal”, which provides information on slugs in no-till field crops and management options.  Of importance to growers in our state, this site has been populated with information from many eastern states, including Ohio.  The address for this site is:  We urge anyone interested in slug problems and possible management options to look into this site.  It has their own information, as well as links to other states involved in slug research and management.

Bt Soybeans

Last week Dow announced the development of soybeans containing two different Bt genes for control of lepidopteran pests, basically caterpillars of various moth species.  Because this information will be discussed in various magazines, we thought it important to bring up a few noteworthy points about these new varieties to better inform Ohio growers.  First, these new varieties are intended for South America, mainly Argentina and Brazil, where they have significant problems with various caterpillars.  The likelihood of making them available anytime soon to growers in the U.S. is very low for various reasons, mainly revolving around resistance concerns to the Bt gene from caterpillars that also feed on cotton and the need to maintain natural refuges (which non-Bt soybeans provide).  Second, we do not have any significant caterpillar pests in Ohio, with the only one of concern being green cloverworms.  Although they can sometimes add to defoliation along with other non-caterpillar pests such as Japanese beetle and bean leaf beetle, green cloverworm is a very infrequent pest.  Third, as we know from planting transgenic corn, Bt products are unique in what they control, and these new Bt soybeans would offer no control of our beetle or stink bug pests, nor the soybean aphid.  What will happen with Bt soybeans in the future is anybody’s guess, but we do know that companies are working on varieties that will off control of the other insect pests that do occur in Ohio.  Keep watch in the future!

Prussic Acid Testing in Forages

Some forage species can develop prussic acid poisoning potential when harmed by frost and management practices should be followed to prevent poisoning of livestock (see Forage Toxicity Issues with Frosts article in CORN 2013-35). If doubt remains regarding the safety of the forage, it can be tested for prussic acid (cyanide) content. But keep in mind that prussic acid is a gas, so it is difficult to detect in samples sent to labs. Sample handling is extremely critical to ensure that the lab test will be representative of what is being fed to livestock and that the prussic acid did not volatilize during shipment.

Obtain a representative FRESH sample of the forage to be fed. Collect 1 to 2 lbs of fresh forage from across the field to be grazed. For silage, follow proper sampling protocol to obtain a representative sample.

Do not allow the sample to dry. Place in an air-tight plastic bag, freeze the sample quickly, and ship to the lab the fastest way (overnight express) in a cooler with an ice pack.

Remember, cyanide content dissipates with drying of the sample. So if the sample arrives at the lab drier than the fresh forage that is fed, a false negative result will likely occur.

The following are two labs that will analyze samples for prussic acid (cyanide). Other labs may provide testing for prussic acid, always call ahead to confirm whether the prussic acid test is provided and to ask about sample handling protocols.


The Michigan State University Animal Health laboratory

Diagnostic Center for Population and Animal Health

Michigan State University

4125 Beaumont Road

Lansing, MI48910-8104

TEL (517) 353-1683, FAX (517) 353-5096

Request Procedure 70022

Cumberland Valley Analytical Services, Inc.

14515 Industry Drive

Hagerstown, MD21742

TEL: 1-800-282-7522, FAX (301) 790-1981

Harvest Delays Impact Corn Performance

Leaving corn to dry in the field exposes a crop to unfavorable weather conditions, as well as wildlife damage. A crop with weak plant integrity is more vulnerable to yield losses from stalk lodging and ear drop when weathering conditions occur. The widespread root lodging that occurred as a result of wind storms in July is contributing to this problem. Additional losses may occur when ear rots reduce grain quality and can lead to significant dockage when the grain is marketed. Some ear rots produce mycotoxins, which may cause major health problems if fed to livestock.

Several years ago we conducted a study that evaluated effects of four plant populations (24,000, 30,000, 36,000, and 42,000 plants/A) and three harvest dates (early-mid Oct., Nov. and Dec.) on the agronomic performance of four hybrids differing in maturity and stalk quality. The study was conducted at three locations in NW, NE, and SW Ohio over a three year period for a total of eight experiments. Results of this study provide some insight on yield losses and changes in grain moisture and stalk quality associated with delaying harvest. The following lists some of the major findings from this research.


  • Results showed that nearly 90% of the yield loss associated with delayed corn harvest occurred when delays extended beyond mid-November.
  • Grain moisture decreased nearly 6% between harvest dates in Oct. and Nov. Delaying harvest after early to mid Nov. achieved almost no additional grain drying.
  • Higher plant populations resulted in increased grain yields when harvest occurred in early to mid-October. Only when harvest was delayed until mid-November or later did yields decline at plant populations above 30,000/acre.
  • Hybrids with lower stalk strength ratings exhibited greater stalk rot, lodging and yield loss when harvest was delayed. Early harvest of these hybrids eliminated this effect.
  • The greatest increase in stalk rot incidence came between harvest dates in October and November. In contrast, stalk lodging increased most after early-mid November.
  • Harvest delays had little or no effect on grain quality characteristics such as oil, protein, starch, and kernel breakage.

In this study, yields averaged across experiments, populations and hybrids, decreased about 13% between the Oct. and Dec. harvest dates. Most of the yield loss, about 11%, occurred after the early-mid Nov. harvest date.  In three of the eight experiments, yield losses between Oct. and Dec. harvest dates ranged from 21 to 24%. In the other five experiments, yield losses ranged from 5 to 12%.

Grain moisture content showed a decrease from the Oct. to Nov. harvest dates but little or no change beyond the Nov. harvest dates. Grain moisture, averaged across experiments, hybrid, and plant population, decreased 6.3% points between the Oct. and Dec. harvest dates, with most of the decrease occurring between the Oct. and Nov. harvest dates (5.8 % points); only a 0.5 % point decrease occurred after early-mid Nov. Population effects on grain moisture content were not consistent. Differences in grain moisture were evident among hybrids on the first harvest date in early-mid Oct. but were generally negligible on the later dates.

A Field Loss Calculator for Field Drying Corn

Agronomists at the University of Wisconsin have developed a “Field Loss Calculator” Excel spreadsheet available at:  that allows producers to calculate the costs of harvesting today versus allowing the crop to stand in the field and harvesting later. The spreadsheet accounts for higher drying costs versus grain losses during field drying. It allows the user to account for elevator discounts and grain shrink.


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Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.