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Ohio State University Extension


C.O.R.N. Newsletter 2007-40

Dates Covered: 
December 5, 2007 - December 19, 2007
Greg LaBarge

Higher Fertilizer Prices, Again

Authors: Edwin Lentz, Robert Mullen

It seems like we have written this article every fall the last few years in response to an increase in fertilizer prices, and again we see this occurring. The question often asked is which nutrient can I cut from my nutrient management program without hurting crop productivity and the bottom line? Unfortunately this is a loaded question that will be specific to every field, so we will provide some tips to help you make a decision on how best to make your nutrient decisions this fall and next spring.

We suspect you have heard this before, but the first place to start is with a soil test. Quantification of the nutrient content of the upper 8 inches of soil will go a long way in determining your nutrient needs. So if you have not traditionally utilized soil testing, now is the time to jump on the bandwagon. Soil analysis determines the need for phosphorus (P) and potassium (K) supplementation quite reliably. Phosphorus and potassium concentrations exceeding established critical levels are unlikely to respond to additional inputs, so this is one potential way of saving some money (at least in the short-term). Established critical levels can be found on the following webpage - Soil testing is the best place to start in a nutrient management program.

When it comes to nitrogen (N) management, we can not rely on preplant soil analysis to provide any insight into nitrogen availability, so we are either stuck with in-season soil estimates or a probability based on average crop response and assigning some economic realities to the decision. The in-season soil analysis we are referring to is presidedress soil nitrate testing (PSNT), but we only recommend PSNT for producers that utilize organic materials as fertilizer sources or producers that grow corn in rotation with alfalfa or some other multi-year legume crop. The reason we do not recommend PSNT in a traditional, conventional crop production systems is because the analysis usually reveals N is needed, so why pay for the analysis. As it relates to using average crop response and economic realities, this is reflected in our new economic nitrogen rate calculator ( In a high cost nitrogen environment, it does not make economical sense to over-apply nitrogen hoping for a greater yield return, particularly when field research reveals only a small chance for a response to high nitrogen rates.

When economics get tight in any production system, the more information used and critically evaluated should result in a better decision. Utilizing soil testing and re-evaluating your nitrogen management will go a long way in making a better decision. Apply the decision and decision tools to each and every field under your supervision.

“Abnormal Corn Ears” Poster Available

Authors: Allen Geyer, Peter Thomison

When we started getting reports of various ear abnormalities in corn this past summer, we prepared a poster for display at the Farm Science Review to help growers sort out various ear disorders and their possible causes. Since then we’ve had many requests for copies of this poster and we can now finally take orders for copies.

A reduced 11 x 14 inch version of the poster is available for online at:

Our Communications & Technology section (contact information below) has
26 x 33 inch copies of the poster available for distribution. Ask for “Abnormal Corn Ears” poster” ACE-1. Poster cost is $10 plus shipping.

The Ohio State University
Communications and Technology
Media Distribution
216 Kottman Hall, 2021 Coffey Road
Columbus, OH 43210-1044
Phone 614-292-1607
Fax 614-292-1248

Ohio residents can contact their local county Extension office to place orders for the poster.

Disease Rating Information From 2007 Soybean Performance Trial

Authors: Anne Dorrance, Dennis Mills

Ohio’s performance trial results are now posted at and there is some good news this year. Almost 30% of the entries have the perfect resistance package for Ohio, a single Rps gene (1c or 1k) combined with high or moderate levels of partial resistance (scores from 3.0 to 5.0). In addition, the best news of all is that less than 15% have very low levels of partial resistance.

Partial resistance levels were higher in the mid-90’s prior to the introduction of the “Round-up Ready” trait into soybean varieties. This is the highest proportion of entries in Ohio’s Performance trial with effective levels of partial resistance since 1997. Ohio’s P. sojae population is quite diverse. Rps1a is no longer effective in 99% of the fields, while Rps1c and Rps1k are still effective in approximately 50% of the fields. Partial resistance will provide protection in all fields, in that it is effective against all races. It works by reducing the amount of root tissue that P. sojae can infect and never causes the stem rot phase. This resistance is an active response, and seeds and seedlings are still vulnerable so it is important to use a seed treatment.

Ohio specializes in testing for Phytophthora sojae, for independent information on BSR, SDS, SCN—look at University of Illinois performance ratings

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SDS and SCN – They are Linked

Authors: Anne Dorrance

This past year, more fields in Ohio had soybeans that developed symptoms of sudden death syndrome (SDS) than in any year previously. In addition, these symptoms were widespread across the state. At this time probably close to a 1 million acres maybe affected. In addition, soybean cyst nematode (SCN) is also prevalent in many areas of the state – almost all of Ohio’s soybean fields have some level of infestation and it continues to increase in numbers as rotations with other crops are reduced.

There are no clear-cut symptoms of SCN. In only a rare case will plants be stunted and yellow – but in these cases the populations are off the charts and the field maybe lost for some time for profitable soybean production. It is kind of like having a teenager in the house. You know you just got cash from the ATM, but it just doesn’t stay in your wallet and you don’t have any idea where it went –except for fast food most likely – maybe a movie for your teenager. I don’t know what movies soybean cyst nematode would watch – but they do eat – and soybean could be considered the “fast food”! Previous studies in Ohio compared yield losses from a highly resistant line to a susceptible line and showed that yield losses to the tune of 10 to 15 bushels with populations ranging from 8,000 to 10,000 cysts/cup of soil.

SDS has beautiful symptoms – there is no denying it. Just about the time producers and consultants are taking those last yield assessments, the foliar symptoms begin. Bright, bright yellow spots which turn brown (necrotic) – and the necrotic areas are surrounded by the bright yellow. The leaves will fall off the plants – leaving the petioles behind. The roots are rotted and the tap root is a gray color and the pith is white. In contrast, brown stem rot has a wimpy yellow color and the pith is chocolate brown. There are numerous cases where both diseases can be found on the same plant.

Several studies from Missouri and Purdue have nicely demonstrated that when plants are inoculated with SDS alone symptom development is much, much lower as is yield loss. With SCN and SDS inoculated together, the beginning of symptom development is much earlier and yield losses are more dramatic. Note that the fields where they screen for SDS resistance in Southern Illinois have SCN. Where we inoculate in Ohio (Wooster) – we rarely get good symptom expression, no SCN and we water an inch per week. I am usually pretty good with making susceptible plants sick!

For the fields that had SDS symptoms develop on the soybeans – these fields need to be checked for SCN. SDS is a great indicator that there is a problem. Once the field has been checked for the levels of SCN – then management plans can be put in place for both of these soybean pathogens. First, for next year (2008) plant something different. If you’ve got a problem in a field the best way to stop it from becoming worse is to plant something else. Then begin the 2009 season with the following plan.

1. If SCN Levels are between 200 and 2,000 – a SCN resistant variety may be the best way to go. If SDS was also present, find a variety that is resistant to both, University of Illinois does test for SDS – and follow this to the Variety Information for Soybeans Page. This is a sortable link to their database.

2. If SCN levels are between 2,000 and 5,000 – plant corn, wheat or alfalfa – all are quite profitable right now and these would be the fields to select.

3.If SCN levels are over 5,000 – again you are looking at least 2 years out of soybeans for that field.

During 2007, one field with extensive development of SDS in the soybeans – when checked the SCN populations had hit 10,000 – no stunting or any other apparent symptoms for SCN were present.

Why is SDS more widespread appearance in Ohio? There may be several reasons for this. One is the switch in the base germplasm over the past 10 years. Williams82 was a predominant variety or crosses with this line were planted widely in Ohio, Williams 82 is resistant to SDS but highly susceptible to white mold. Another feature is early planting. To get the best symptoms in field evaluations, they plant 2 weeks before the normal planting season. The theory is that the cold soils may promote infection, this needs some more study, but Ohio has moved the planting window for soybeans much earlier and this may have contributed to the increase in infections during 2007. Our rotations have gotten much worse. With the exception of 2007 where corn made it onto 4 million acres, there are numerous fields in Ohio that are continuous soybeans. This lack of rotation is also helping build population levels and facilitate the spread of SCN as well.

The management strategies are very similar for both of these soybean pathogens. The key is going to be to monitor SCN population levels and look at the resistance package in the soybean varieties that do get planted in these problem fields. With funding from Ohio Soybean Council, we will be evaluating a greenhouse assay this winter which was developed through check-off dollars to the North Central Research Program. If we can get this to work in our greenhouses, then this could be another addition to Ohio’s Performance trials in the future.

Upcoming Agronomic Meeting and Seminars

A number of programs, meetings and seminars are scheduled with other meetings coming up soon. Full details on location, credits and agendas can be found at Meetings in the next month include:

December 12
Ohio Corn/Soy Annual Meeting

Start Time: 8:00AM Registration
County of Meeting Location: Marion

Name of Meeting Place: All-Occassions Catering
Meeting Place Town: Waldo
Cost: $25 Deadline 12/7
Meeting Coordinator Name: Ohio Soybean Association (888)769-6446 or Ohio Corn Growers Association (740) 383-CORN

December 12
Field Crop Commercial Pesticide Recertification Conference

Start Time: 8:45 AM Registration 7:45 AM
County of Meeting Location: Allen

Name of Meeting Place: Ohio State University, Lima Campus
Meeting Place Address:
Meeting Place Town: Lima, OH
Cost: $75

Meeting Coordinator Name: Joanne Kick-Raack
Phone Number: 614-247-7489
Agenda Web Link:

December 18
Central Ohio Winter Agronomy Day

Start Time: 8:30 am
County of Meeting Location: Licking

Name of Meeting Place: Ohio State University, Newark Campus
Meeting Place Address:
Meeting Place Town: Newark , OH
Cost: $25-$30

Meeting Coordinator Name: Howard Siegrist
Phone Number: 740-670-5315
Agenda Web Link:

January 3
Ohio Crop Production Conference

Start Time: TBA
County of Meeting Location: Franklin

Name of Meeting Place: Fawcett Center for Tomorrow
Meeting Place Address:
Meeting Place Town: Columbus
Cost: $75

Meeting Coordinator Name: Ohio Agribusiness Association
Phone Number: (614) 326-7520
Agenda Web Link:

January 4
Advanced Agronomy Workshop

Start Time: TBA
County of Meeting Location: Franklin

Name of Meeting Place: Fawcett Center for Tomorrow
Meeting Place Address:
Meeting Place Town: Columbus
Cost: $100

Meeting Coordinator Name: Ohio Agribusiness Association
Phone Number: (614) 326-7520
Agenda Web Link:

January 10
Paulding County Agronomy Day

Start Time: 8:30am
County of Meeting Location: Paulding

Name of Meeting Place: Paulding County Extension Building
Meeting Place Address: 503 Fairground Dr
Meeting Place Town: Paulding
Cost: TBA
CCA Credits Offered: YES
PAT Credits Offered: Private: YES Commercial: YES

Meeting Coordinator Name: Jim Lopshire
Phone Number: 419.399.8225
Agenda Web Link:

January 11
Corn/Soybean Day

Start Time: 8:30
County of Meeting Location: Fulton

Name of Meeting Place: Founder’s Hall at Sauder Farm and Craft Village
Meeting Place Address: 22611 St Rt 2
Meeting Place Town: Archbold
Cost: $15 prior to 1/7 & $30 at the door

Meeting Coordinator Name: Greg LaBarge
Phone Number: 419-337-9210
Agenda Web Link:

January 14
Agronomy Day 2008

Start Time: 8:30 AM & 5:30 PM
County of Meeting Location: Shelby

Name of Meeting Place: American Legion Hall
Meeting Place Address: 1265 Fourth Avenue
Meeting Place Town: Sidney, OH 45365
Cost: $10 or more depending on certification needs

Meeting Coordinator Name: Roger Bender/Woody Joslin
Phone Number: 937-498-7239
e-Mail: or
Agenda Web Link:

January 16 & 17
Certified Crop Advisor Pre-Exam Training

Start Time: 9:00 am
County of Meeting Location: Shelby

Name of Meeting Place: Shelby County Extension Office
Meeting Place Address: 810 Fair Road
Meeting Place Town: Sidney, OH 45365
Cost: $175

Meeting Coordinator Name: Wes Haun/Harold Watters
Phone Number: 937-599-4227
e-Mail: or

Archive Issue Contributors: 

State Specialists: Ann Dorrance, Pierce Paul and Dennis Mills (Plant Pathology), Ron Hammond, Bruce Eisley and Andy Michel (Entomology), Jim Beuerlein (Soybean & Small Grain Production)and Peter Thomison (Corn Production). Extension Educators: Harold Watters (Champaign), Howard Siegrist (Licking), Roger Bender (Shelby), Glen Arnold (Putnam), Todd Mangen (Mercer), Steve Foster (Darke), Jonah Johnson (Clark), Greg LaBarge (Fulton), Mike Gastier (Huron) and Gary Wilson (Hancock).

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.