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Agronomic Crops Network

Ohio State University Extension


C.O.R.N. Newsletter 2012-22

Dates Covered: 
July 16, 2012 - July 22, 2012
Amanda Douridas

Mid-July Weather Outlook

The outlook remains unchanged, above normal temperatures and below normal rainfall for the rest of July. However, there will at least be some rain chances going forward.

Expect 90s this week to relax into the 80s second half.  Rainfall chances will be focused on Wednesday and Thursday. Most places will see 0.25 to 0.50 inches but as low as 0.10 to as high as 1.25 inches for the week.

Next week will experience highs in the 85-95 degree range with a few rain chances again. Most places will get similar totals to this week.

Rain totals for the second half of July will range from 0.50 to 1.50 inches on average. Normal is about 2 inches.

The National Weather Service took a composite average of the 1895, 1934, 1936, 1954 and 1988 droughts. The result for mid July is something similar to now. If you project historic droughts forward, you see little improvement through August then some improvement into September and October with the center of the drought focused on Indiana with lesser drought outwards from there by October. Therefore, expect some improvement but not much before September.

Looking at Stress Degree Days (SDDs) for corn, which is calculated by the maximum temperature near where you live minus 86 added up for the growing season, Ohio was at 203 on July 15. Usually above 140 for an entire season means below trend line yields. This is above 2002, approaching 1988 and below 1934 or 1936 at this point based on preliminary data. Bottom line, expect below trend line yields which most know by this point.

However, in Indiana which northwest Ohio may be following closer to, the Stress Degree Days was much higher at 284. This is as bad as 1988 heading for worse than 1988. It is not quite as bad as 1934 or 1936.

For Ohio, SDDs are 26 in May, 71 in June and 106 so far in July.

For August, expect above normal temperatures and 50-100 percent of normal rainfall, but the deficits will not be as great on rainfall as we get some return flow around the Bermuda high pressure.

Western Bean Cutworm Counts Still on the Rise

Western Bean Cutworm Counts Still on the Rise

Our trap counts for western bean cutworm (WBC) are still on the rise, see our updated map at  We are probably in peak flight right now, but will not know for sure until our numbers start to decrease.  Nonetheless, moths are still active and the possibility remains that we can still see WBC damage this year.  Scouting corn for eggs is the best method to determine if your corn is at risk. Choose 20 plants in 5 locations in a field, and inspect the upper surface of the 1-2 top most leaves. Female WBC prefer to lay eggs in pretassel corn, so make sure you check areas of late planted, re-planted, or other corn that has not tasseled.  Also keep in mind that not all transgenic corn controls WBC—only those containing Cry1F or Vip3A will offer control (the refuge will still need to be inspected).  Eggs are laid in clumps of 20-100, and start white in color, then tan, and then dark purple.  If 5% of more of the plant have egg masses, then treatment is suggested.  See our 545 bulletin ( for control options.  If you suspect you have an economic situation, please contact insect state specialists ( or your OSU Extension educator.           

Corn and Soybean Crop Water Deficits

With Ohio experiencing abnormally dry to severe drought conditions, corn and soybean crop water deficits are expected.  The average water use of a corn crop during pollination and early grain fill is about 1/3 inch per day.  It is estimated every inch of water produces 8 bushels/acre corn grain.  Average soybean water use is about 1/4 inch per day at flowering, full bloom, and pod filling.  For soybeans, it is estimated every inch of water produces 2.5 bushels/acre.

In areas that have received negligible rainfall during the past 4-5 weeks, what is the water deficit for the corn and soybean crop?

The available water capacity of a soil is dependent on several factors including soil texture, soil structure, and organic matter content.  Available water tends to be greatest for loam soils and least for soils with a high percentage of sand or clay.  To calculate the corn and soybean water deficit based on soil series, see this spreadsheet.  In this spreadsheet, select soil series from the drop-down list.  Then, in the corresponding boxes, type the yield potential (bushels/acre) and rainfall since planting (inches).  Soil series for a particular area can be found using the USDA, Natural Resource Conservation Service web-based soil survey at:  If on-farm rainfall data is not available, rainfall information can be found using the OARDC Weather System at: or using the National Weather Service Forecast Office at:

When the soil series, yield potential, and rainfall since planting are put into the spreadsheet, the water needed to reach the yield potential, available water at planting, total water available since planting, and water deficit is estimated.  The available water at planting is soil series-specific and assumes the soil was at capacity during planting.  (This is a fairly reasonable assumption considering abnormally dry conditions did not begin to appear until the end of May.)  Total water available since planting is the sum of available water at planting and rainfall since planting.  The water deficit is the water needed to reach the yield potential minus the total available water since planting.

As an example, soybeans were planted at the Western Agricultural Research Station in South Charleston (near Springfield, Ohio) on May 21.  The soil series is Celina silt loam, and we estimate a yield potential of 60 bushels/acre.  According to OARDC weather data, this location received 6.5 inches of water since May 21.  In the spreadsheet, we select Celina silt loam as the soil series.  In the corresponding boxes, we type 60 for the yield potential and 6.5 for the rainfall since planting.  When we put these values in the spreadsheet, we see that the estimated water needed to reach the yield potential is 24 inches.  At capacity, this soil will hold approximately 4 inches of water in the top three feet which is assumed to be available at planting.  Available water at planting (4 inches) plus rainfall since planting (6.5 inches) gives 10.5 total inches of water available since planting.  Water needed (24 inches) minus the total rainfall since planting (10.5 inches) gives a water deficit of 13.5 inches. 

This spreadsheet gives a “ballpark” estimate of the water deficit.  Crop rooting depth influences water uptake which can vary based on compaction, crop genetics, nutrient status, and early season water levels.

Potential for Nitrate Problems in Stressed Corn

Very dry to extremely dry soil conditions across Ohio have raised questions concerning the potential for toxic levels of nitrates in corn harvested for silage. Nitrates absorbed from the soil by plant roots are normally incorporated into plant tissue as amino acids, proteins and other nitrogenous compounds. Thus, the concentration of nitrate in the plant is usually low. The primary site for converting nitrates to these products is in growing green leaves. Under unfavorable growing conditions, especially drought, this conversion process is retarded, causing nitrate to accumulate in the stalks, stems and other conductive tissue. The highest concentration of nitrates is in the lower part of the stalk or stem. For example, the bulk of the nitrate in a drought-stricken corn plant can be found in the bottom third of the stalk. If moisture conditions improve, the conversion process accelerates and within a few days nitrate levels in the plant returns to normal.
The highest levels of nitrate accumulate when drought occurs after a period of heavy nitrate uptake by the corn plant. Heavy nitrate uptake begins at the V6 growth stage and continues through the silking stage.  Therefore, a drought during or immediately after pollination is often associated with the highest accumulation of nitrates. Extended drought prior to pollination is not necessarily a prelude to high accumulations of nitrate. The resumption of normal plant growth from a heavy rainfall will reduce nitrate accumulation in corn plants, and harvest should be delayed for at least 1 to 2 weeks after the rainfall. Not all drought conditions cause high nitrate levels in plants. If the soil nitrate supply is low in the dry soil surface, plant roots will not absorb nitrates. Some soil moisture is necessary for absorption and accumulation of the nitrates.

If growers want to salvage part of their drought damaged corn crop as silage, it's best to delay harvesting to maximize grain filling, if ears have formed. Even though leaves may be dying, the stalk and ear often have enough extra water for good keep. Kernels will continue to fill and the increases in dry matter will more than compensate for leaf loss unless plants are actually dying or dead. Moreover if nitrate levels are high or questionable, they will decrease as plant gets older and nitrates are converted to proteins in the ear.    

Where to test forages for nitrates

With many farms now considering early harvest of drought-stricken corn for silage to salvage some value from the crop, attention must be paid to the potential for high nitrate levels in the plants.  If nitrate levels are high enough, they can cause serious health problems for the animals consuming them including death.   Good information on this topic is available in the fact sheet “Nitrates in Dairy Rations” which can be found at

Before beginning harvest, and especially if considering grazing or green-chopping and feeding corn fodder or other forages immediately, drought-stressed plants should be tested for the presence of, and if present, level of nitrates present.  The ensiling process can reduce nitrate levels present in the unensiled crop.

Most labs now offer nitrate tests, so if you currently use a particular lab for forage testing, it is likely that you can get forage plants tested for nitrates by the same lab.  A number of labs are listed below that have nitrate testing available.  This list is for your convenience and no labs are intentionally omitted.   Check your chosen lab’s web site as many are already posting information about nitrate testing and many have specific instructions about how to take and handle the sample.

Samples should be representative of the crop being harvested, and include the parts of the plant that will actually be harvested and fed to the animals.  For corn silage specifically, the sample should include the whole plant cut at the height you will actually be chopping – nitrate concentrations are usually highest in the lower part of the plant. 

Some labs that test for nitrates (in alphabetical order):

Cumberland Valley Analytical Services                          

800 282 7522

Dairyland Labs


Dairy One         


Holmes Lab         


Rock River Lab                                       



Spectrum Analytic


While the “Nitrates in Dairy Rations” fact sheet mentions a quick test that can be done in the field, the chemical ingredients, which include concentrated sulfuric acid and diphenylamine, are dangerous and no longer readily available.  Alternatively, some field test kits are available commercially.  It is important to note that these kits have limitations.  One kit indicates that its testing range is from 0 to 1000 ppm nitrate nitrogen in a fresh plant.  This is the maximum safe level in a feed.  

A lab test would be needed to determine actual levels present in the plants if they are above the kit’s range.

Corn silage and preharvest restrictions for herbicides

Herbicide labels specify the amount of time that must elapse between herbicide application and the harvesting of corn for silage or grain.  This information can also be found in Table 5 of the current “Weed Control Guide for Ohio and Indiana”.  A pdf of this publication can be found at  The time interval is generally short enough for most herbicides that harvesting of corn for silage is not a problem, but several herbicide labels specify an interval of 60 to 85 days, so consulting labels and the Weed Control Guide is not a bad idea.  Use of soybeans as a forage is more of an issue, since labels for many soybean herbicides prohibit use of treated soybeans for any use other than grain harvest.

Growers Can Learn the Latest Plant Products Application Equipment and Techniques during Sprayer Workshop

MARION, Ohio – Growers and other applicators can get an updated look at the most efficient and effective application equipment and techniques offered in agriculture during an upcoming workshop offered by members of the Ohio State University Extension’s Agronomic Crops Team.

The workshop will be held Aug. 8 from 9 a.m. to 3 p.m. at the Fulton County Fairgrounds on State Route 108, in Wauseon. The program, which is free and open to the public, will offer participants the opportunity to learn how to save money, time and effort when spraying their fields, said Greg LaBarge, Field Specialist, Agronomic Systems and one of the leaders of the OSU Agronomic Crops Team.

“Whether a new sprayer is in your farm’s future or you are looking to get a few more years out of your current sprayer, you will find some hints and tips to get the most benefit from your spray applications,” he said. “The goal of the workshop is to demonstrate technologies for the efficient and effective application of plant production products such as herbicides, insecticides, fungicides and foliar fertilizers.”

Some of the information participants will learn include:

·         How to save money with an efficiently operating sprayer.

·         How to assure that your sprayer is delivering the correct amount of herbicide, insecticide and fungicide product in each spray pass to best control the pest and prevent resistance.

·         A demonstration of all technologies needed to address spray drift, which is still an ongoing problem.

·         A demonstrations of the new innovations in sprayer design and new sprayer components that are available for improved applications.

·         An opportunity for growers to see a collection of new spray equipment and accessories and talk with the equipment representatives.

Pre-registration for the course is requested and can be made by visiting or calling the Marion County OSU Extension office at 740-223-4043 by Aug. 6 to guarantee lunch, he said. Pesticide recertification credits for commercial and private applicators in the states of Ohio, Michigan and Indiana have been applied for, LaBarge said.

More information on the workshop can be found at

Ohio State’s Annual Manure Science Review Is Aug. 9 in Northwest Ohio: Learn How to Reduce Phosphorus Runoff, More

GROVER HILL, Ohio -- Reducing phosphorus runoff, a concern related to protecting water quality and preventing harmful algae blooms, will be just one of the topics when Ohio State University presents Manure Science Review 2012 on Aug. 9 in northwest Ohio.

The event is an educational program for anyone involved in the handling, management or utilization of livestock waste, including farmers, Extension educators, government personnel, certified crop advisers and professional nutrient applicators. Featured will be expert speakers from Ohio State and from state and federal agencies.

Among the topics discussed will be: using liquid manure in ways that increase the application window, using swine or dairy manure to side dress corn, best practices and systems for composting livestock mortality, using settling tanks to separate swine manure, using tile drainage to limit nutrient runoff, using draglines to inject manure nutrients, and using cover crops to reduce erosion and increase nutrient retention.

Speaking on phosphorus will be Ohio State University Extension’s Greg LaBarge, who will discuss on-farm practices that can reduce runoff of the nutrient from liquid manure and poultry litter, including timing and mass balance considerations.

Hours are 9 a.m. to 3 p.m. at McClure Farms, 21460 Road 48, in Grover Hill in Paulding County.

Registration is $30 by Aug. 1, $35 after that date and at the door, and includes a continental breakfast, lunch and all materials. Members of the Midwest Professional Nutrient Applicators Association receive a $5 discount. Participants should send their name, affiliation, address, and telephone number or email address to Mary Wicks, OARDC/OSU, Administration Building, 1680 Madison Ave., Wooster, OH 44691. Checks should be made payable to OARDC/OSU.

Participants will be eligible for the following credits: 4.5 Ohio Department of Agriculture Certified Livestock Manager continuing education hours, 2.0 Certified Crop Adviser Nutrient Management continuing education hours, 2.5 CCA Soil and Water Management continuing education hours, and 4.5 Professional Engineer continuing professional development hours.

Sponsoring the program are the Ohio Agricultural Research and Development Center, OSU Extension, the Ohio Livestock Coalition, Ag Credit, Farm Credit Mid-America, the Ohio Department of Agriculture, the Ohio Division of Soil and Water Resources, and the Natural Resources Conservation Service.

OARDC and OSU Extension are the research and outreach arms, respectively, of Ohio State’s College of Food, Agricultural, and Environmental Sciences.

For more information, contact Mary Wicks at 330-202-3533 or, or download the program brochure at

Agronomic Crops Team Drought Resources

As the drought of 2012 continues across much of Ohio and the Cornbelt, we wanted to gather potential resources for the use of crop producers. The Agronomic Crops Team Drought Resources page has been added to the website. Many of these resources are recent articles from the C.O.R.N. newsletter, gathered into one place.

Currently there are half a dozen news articles and links to drought management websites both here in Ohio and from nearby sources. We will add to these Drought Resources as the crop season continues to progress until harvest. Check the link on the left side of our team website or here:

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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.