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Agronomic Crops Network

Ohio State University Extension


C.O.R.N. Newsletter 2012-06

Dates Covered: 
March 20, 2012 - April 2, 2012
Steve Prochaska

Nitrogen Considerations for 2012 Wheat


Wheat fields have reached greenup across the state. Spring nitrogen should be applied between greenup (now) and beginning stem elongation (Feekes 6). Ohio State University research has shown that yields are not affected by delayed nitrogen until after early stem elongation (generally the end of April). Studies over the last five years have shown that yields were the same or slightly better when a single application occurred at Feekes 6 (first node visible of early stem elongation) compared to initial greenup. Yields dropped 10 – 15% when a single application was delayed to early boot stage. At this time, we would recommend producers to apply N as soon as field conditions allow application equipment

Stands need to be evaluated for estimated yields compared to other years. Many fields in Northwest Ohio were planted late and will most likely result in a yield reduction. Also, many fields have drowned out areas. Increased N rates will not correct these problems.

A realistic yield potential is needed to determine the optimum nitrogen rate. As a producer, you can greatly increase or reduce your N rate by changing the value for yield potential. Once you have selected a value for yield potential, the Tri-State recommendation uses the following equation for mineral soils, which have both 1 to 5% organic matter and adequate drainage:


N rate = 40 + [1.75 x (yield potential – 50)]


We do not give any credit for the previous soybean crop, since we do not know if that organic N source will be released soon enough for the wheat crop. Generally, we would recommend that you subtract from the total (spring N) any Fall applied N up to 20 lb/A. Based on the equation above and deducting 20 lb from a fall application, we would recommend a spring application of 110 lb N per acre for a yield potential of 100 bu, 90 for 90 bu potential; 70 for a 80 bu potential and 40 lb N per acre for a 60 bu potential. 


For those who may want to tweak the system consider the following:


·          Because of the mild winter, more N may be available for the crop from the soil organic matter

·          Wheat needs very little N until after jointing begins

·          At the Northwest Research Station near Hoytville, larger yields have never been achieved at Spring N rates above 120 lb per acre

·          Susceptible varieties may lodge at high N rates

·          For split applications, first application should be the smaller amount since it is the most susceptible to N loss


Selection of N source generally depends upon availability and cost, but one may want to consider potential for N loss. Of the common N sources available, ammonium sulfate would have the least potential for loss, followed by urea, and 28% solution the most potential for loss.


The past week we have had conditions for volatilization losses for urea and 28%, i.e., moist soil rapidly drying from warm winds with temperatures higher than 70. Nitrogen losses may be severe under these conditions if rain does not occur between 48 and 72 hours after application. If these conditions occur when applying urea, a urease inhibitor may be used, which should protect urea from volatilization losses for at least a week. Or, delay urea application until rain is expected (rainfall needs to be at least a ¼ inch preferably ½ to insure urea is moved into the soil). Agrotain is the only urease inhibitor we would recommend at this time. Other products claiming to be urease inhibors do not work or lack sufficient research data for a recommendation. I would be glad to review any data.

Nitrogen losses from 28% solution may be reduced by applying in bands. However, the nitrate N portion is vulnerable to loss with heavy rains. Urease inhibitors would only protect the urea component.

ESN products should be applied early to allow time for N release. They should not be applied as the sole N source. ESN is an effective N source as long as other N sources are used for more than 50% of the total N rate.




Alfalfa Weevil and Need to Scout Earlier

Normally we do not reach the time to scout for alfalfa weevil until the first part of April, however, heat unit accumulations already suggest that weevil scouting should begin in southern Ohio.   Heat unit accumulations for the weevil are already above 250 in those areas, and are over 200 in the central part of the state, which suggests that scouting should begin now!  This level is anywhere from one and a half to three weeks earlier than normal, and is a result of the warm winter already discussed in the CORN newsletter.  Weevil scouting is accomplished by collecting a series of three 10-stem samples randomly selected from various locations in a field. Place the stem tip down in a bucket. After 10 stems have been collected, the stems should be vigorously shaken in the bucket and the number of larvae in the bucket counted. The shaking will dislodge the late 3rd and 4th instar larvae which cause most of the foliar injury. Close inspection of the stem tips may be needed to detect the early 1st and 2nd instar larvae. The height of the alfalfa should also be recorded at this time. Economic threshold is based on the number of larvae per stem, the size of the larvae and the height of the alfalfa. The detection of one or more large larvae per stem on alfalfa that is 12 inches or less in height indicates a need for rescue treatment. Where alfalfa is between 12 and 16 inches in height, the action threshold should be increased to 2 to 4 larvae per stem depending on the vigor of alfalfa growth. When alfalfa is 16 inches in height and there are more than 4 larvae per stem, early harvest is recommended. See the OSU alfalfa weevil Fact Sheet at for more information on the insect.  For insecticides that are labeled for alfalfa weevil, see



Black Cutworm and Weed Control

In addition to benefits from early season weed control on crop growth and yield, growers should remember that black cutworm management will be enhanced by removing the oviposition sites that winter annuals provides, especially chickweed.  Although adult cutworms have yet to migrate, removing weeds will help your insect pest situation by removing plants that attract the adults to your field.  With warm temperatures already getting the weeds off to a good start, the additional benefits to black cutworm management should be considered.

Soil Insecticides and Transgenic Crops, NOT

After the recent announcement of resistance occurring with the western corn rootworm to Cry3Bb1, there have been questions about applying soil insecticides to transgenic corn hybrids  to assist in larval control.  Our general attitude on this is that we  do not feel like it is worthwhile, necessary, or cost effective.   Unless you are under extremely severe pressure, transgenic corn with rootworm (RW) proteins should do a good job.   You would be spending money on two things when both, or should I say either of them, should work fine.  If the transgenics really needed the soil insecticide, I would question why I was paying money for it in the first place.  I know there are suggestions by some to use soil insecticides on corn containing the Cry3Bb1 gene, which is the gene that has had rootworm develop resistance to, but that might be true only in the central Midwest (IA, IL, NE, and MN) in the few areas experiencing the resistance problem.   A pyramided hybrid like SmartStax will still work fine, as will hybrids with other proteins.  And Cry3Bb1 will still work well in Ohio as we have yet experienced the resistance issue.  If the transgenics have worked for you in the past, there is really no reason not to expect the same. 

Is It a Dream? Soybeans in Ohio – 5 Million Acres All Yielding More Than 50 bu/A in 2012

This question was asked at a meeting a few weeks ago, through the discussion, we think it is possible providing Mother Nature provides regular timely rains through the season and we minimize losses.  Last summer’s challenges was a testament to what the soybean breeders have been able to do with this great plant.  The genetics are there, so the next question becomes are we doing all we can do to help the soybean achieve its potential and minimize yield losses.  Here are some questions to help pinpoint some easy fixes and to maximize yield.

1.       Seed was purchased for the highest yielding varieties from yield tests – but do they have the right genetics for your farm?

2.       Seed treatment package – what is best for your fields?

3.       Will there be early season insect feeding?

4.       Which fields have the highest populations of SCN? 

5.       When to start planting?

6.       Did you fix the ruts from last fall? 


1.       Those yield trials:  many yield trials are planted on the very best production fields with few issues.  ie: no Soybean cyst nematode or poorly drained spots that favor Phytophthora or other seedling pathogens.  Now that the planter is ready to go and we are waiting for the calendar to catch up with the weather, double check those variety listings to be sure the variety has all it needs for your farm:  SCN resistance for fields with SCN, an Rps gene PLUS high levels of partial resistance for fields with a history of Phytophthora.

2.       In Ohio, poorly drained fields, those with a history of replanting need a seed treatment.  These fields also require a high rate of Allegiance (1.5 fl oz/cwt) and Apron XL (0.64 fl oz/cwt) for the maximum control.  Remember, this does not equal the old Ridomil-in-furrow treatments, but it is as close as we can get with today’s agriculture systems.

3.       When planting does start, monitor the first planted soybean fields for bean leaf beetle and slug feeding.  Both beetles and slugs are expected active early.  Early season bean leaf beetle feeding can set the plants back but more importantly will spread a very common virus, bean pod mottle virus which reduces yield and seed quality.  With the mild winter, this insect could be an issue in the spring, so even more important – for grain where seed quality is an issue, you might want to hold planting food grade soybeans back to limit the seed coat mottling that can occur due to this virus.

4.       When was the last time you checked the SCN populations?  Can’t remember?  Have your yields been stuck in 40’s or less.  It’s time to look, especially if the fields are in continuous soybean or a long term corn-soybean rotation.  If SCN populations are greater than 2,000 eggs per cup of soil, significant yield loss will occur when susceptible varieties are planted.  So to manage SCN – know your numbers.

5.       We thought last year was strange – and this year is already breaking records and it is going to be another one of risks.  Based on experience, it is never good to plant before a field is fit nor before a big storm front. Those conditions favor the seed and seedling pathogens that inhabit our high clay soils.

6.       Ruts mean compaction which mean stand issues when planting does occur.  Hopefully these can be corrected before planting starts –soybeans will produce and fill more pods if their roots can grow.


Wheat Vernalization and Crop Update

This winter has been unseasonably warm and the projections are for the warm weather to continue through early-spring, as the wheat crop begins to green up. Because of the warm winter, some producers are concerned that their wheat may not have vernalized. This is understandable, since here in Ohio we grow winter wheat, and for this class of wheat to produce heads and grains, exposure to a period of cold temperatures is necessary. These temperatures provoke hormonal and chemical changes in the plant that are required for it to convert from vegetative to reproductive growth, in other words, cold temperatures are required for the plant to make the switch from producing leaves and stems to producing heads with grain. This process is called vernalizaton. Timing of exposure to cold temperatures relative to the growth stage of the plant is critical for vernalization. So, after planting in the fall, warm temperatures are required for rapid germination, growth, and tiller development, followed by cold temperatures in late-fall to winter for vernalization to occur.

Even though the winter has been mild, there were several days with temperatures in the mid-to-lower 40s, which is good enough for vernalization. The specific temperature/time requirement varies with variety, but for most of the materials grown here in Ohio, a few days or sets of days in the lower 40s is all we need. Here at the OARDC, in our greenhouse trials we usually expose germinated wheat to 35-40F for about 6 weeks and that is usually more than sufficient for vernalization. According to the weather data from the OARDC Weather System, average temperatures during the months of December, January, and February were below 40F on several days. For instance, data from the Northwest weather station shows that average daily temperatures were below 40F on 20 out of 31 days in December, 27 out of 31 days in January and 25 out of 29 days in February (Figure 1). Data from other weather stations across the state show very similar patterns. Average daily temperatures below 40F means that nighttime temperatures were fairly low, even though we had several warm days this winter. THE WHEAT HAS VERNALIZED!     

Producers are also concerned about the state of this year’s crop. While there are some very good looking fields out there, there are also some very poor-looking fields. Coming out of the winter, it is not uncommon for the wheat to look bad, especially those fields that were planted

Unless fields are in extremely bad shape, with poor stands and huge bare patches, it is still a bit too early to say which fields will do well this year. The next few weeks will be critical. As the wheat continues to green-up and grow, some tillering will still occur (especially in field which did not have a chance to tiller due to late planting). Before making a decision to destroy wheat fields to plant corn or soybean, walk field and count the number plants or tillers per foot of row to get an estimate of the stand count. Yield potential is reduced if tiller numbers fall below 25 per square foot after green up. Pick about 10 to 15 spots in the field and count the number of plants per foot of row. A stand with an average of about 12 plants per foot of row may still result in a good population of head-bearing tillers per acre. For those fields with tillers, 15 tillers per square foot is considered minimum for an economic crop. The number of tillers per square foot is equal to the number of tillers in 19.2 inches of 7 inch wide rows or 14.5 inches of 10 inch wide rows. Our studies have shown that under adequate weather conditions, tillering may compensate for relatively poor initial stand establishment.     


Temperature Data

Ag Nutrient and Water Quality Report Released


Concerns about nutrient enrichment of Ohio's has been a focus of attention over the past two year. In the fall of 2011, ODA, ODNR and OEPA brought together agriculture and environmental organization to discuss how agriculture could have a positive role in improving water quality across the state. The report from the 5 months worth of work this group discussed was released last Thursday and is linked below. The 4 R's of Nutrient Management are encourage. Three resources on the Agronomic Crops Team website are available to help producers with decisions moving forward. The Tri-State Fertilizer Recommendations for Corn, Soybeans, Wheat and Alfalfa E-2567  provides the basic philosophy of nutrient management, Updated Tables for the Tri-State Fertilizer Recommendation Table 13 to 22 (2012) provide recommendations on yields for today's crop potentials for P and K plus Best Management Practices for Mitigating Phosphorous Loss from Agricultural Soils AGF-509-09

discuss ways to keep phosphorous in place to meet crop needs while protecting water resources.


Below is a newsrelease on the report from the Ag Nutrients Working Group.


Awareness and Additional Research Needed, 4R Nutrient Management Encouraged

COLUMBUS – The Ohio Department of Natural Resources, the Ohio Department of Agriculture and the Ohio Environmental Protection Agency today announced their recommendations for reducing excess agricultural nutrients from affecting or entering the western basin of Lake Erie. 


The recommendations come after meetings with a diverse working group of Lake Erie stakeholders and agriculture professionals over a six month period.


“There is no question that there are a variety of factors that are contributing to the increased frequency of harmful algal blooms in Lake Erie, and many of Ohio’s other streams and water resources,” said Scott Nally, director of the Ohio EPA. “Ohio’s agricultural community is not being singled out. With that being said, fertilizer is a contributing source to the problem and that’s why we felt the need to direct the ag communities’ attention to this problem and then take action.”


“Our agencies worked with Ohio’s agricultural community to identify the best ways to decrease this nutrient loading into Ohio’s water bodies,” said David Daniels, director of the ODA. “The farmers, private companies, agricultural organizations, agri-businesses, environmental organizations and academic institutions were all asked to provide their best input, ideas, advice and guidance. That was the foundation for developing these initial recommendations.”


The report establishes the following key recommendations for action by ODNR, ODA and OEPA:

  • Promote the voluntary “4R Nutrient Stewardship,” which encourages farmers to use the right fertilizer source, at the right rate, at the right time and with the right placement;
  • Utilize a three-tiered, statewide structure for prioritizing the implementation of any recommendations, based upon the condition of any given watershed in Ohio;
  • Coordinate research and align funding streams;
  • Coordinate programmatic funding within OEPA and ODNR;
  • Coordinate communication and outreach effort to farmers;
  • Develop a voluntary, statewide “Certified Nutrient Stewardship Program” for farmers (ODNR);
  • Provide ODA authority to better train Ohio farmers about applying commercial fertilizer;
  • Expand the regulatory authority of ODA to collect more specific geographical data on where fertilizer sales are currently made;               
  • Clarify the authority of ODNR to aggressively pursue habitual bad actors; and  
  • Expand ODNR’s authority to development Nutrient Management Plans.


In addition to continuing to stress the use of the 4R nutrient management methodology, the Ohio Department of Natural Resources’ Division of Soil and Water Resources will be tasked with coordinating an extensive education and outreach effort, as well as developing a roadmap for implementing the other policy recommendations going forward.


“We have two goals: reduce the occurrence of harmful algal blooms in Lake Erie and make sure we protect the region’s productive agricultural base," said James Zehringer, director of ODNR. "It’s a complex and challenging problem, and a lot more research needs to be done to fully understand the issue; but these are strong, first steps to move us closer to a healthy Lake Erie.”


The final report also includes a list of participants, summaries of the discussion points and letters submitted by organizations and individuals who participated in the working group. The complete report is available at

The Warm Spring Will Continue.

Temperatures will be 20-30 degrees above normal again this week before some cooling occurs this weekend and early next week. Temperatures will relax to 5-12 degrees above normal at that time. By the middle of next week temperatures will once again push 20-25 degrees above normal. Temperatures will relax to about 5-10 degrees above as we start April. The theme is likely we will set the warmest March on record. The warmer than average weather will continue into April and May, but the deviations from normal should not be as extreme. Normal highs are in the 50s and normal lows are in the 30s.

Soil temperatures at the 4 inch level will likely be near record warm extremes too for this time of the year.  A hard freeze is not visible at least into early April.

Rainfall will average near normal from now through April. But with thunderstorms, expect a wide range in rainfall patterns. Normal is about 0.75 inches per week. However, some places will see less than 0.50 inches in a week while others may see 2-3 inches due to thunderstorms. At some point in May to June, it is likely to turn drier than normal.

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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.