CFAES Give Today
Agronomic Crops Network

Ohio State University Extension


C.O.R.N. Newsletter 2008-04

Dates Covered: 
February 20, 2008 - March 5, 2008
Harold Watters

First Detector Training February 21st

Authors: Nancy Taylor

A plant pathology and entomology training program is giving farmers, crop consultants and others in the agriculture industry a more refined eye in recognizing diseases and pests. First Detector Training generally consists of core learning modules, such as National Plant Diagnostic Network mission and agricultural biosecurity, monitoring for exotic pests and quality and secure sample submission. Additional training modules include the art and science of diagnosis, digitally assisted diagnosis photography tips and programs on specific pests and diseases.

The training is open to anyone interested in the program, but mainly targets any individuals who may notice new or unusual plant disease and insect problems in the course of their daily work or activities. Crop advisors, farmers, master gardeners, master naturalists, extension educators and others involved in pest management can be trained. Those who complete the training become Certified First Detectors, and have the opportunity to receive the national NPDN First Detector newsletter, as well as pest alerts via e-mail through the National First Detector registry.

On February 21, 2008 First Detector training will be offered for the first time at 1PM to Ohio’s Certified Crop Advisors and others attending the Conservation Tillage and Technology Conference in Ada, Ohio. CCA’s will receive 3 Pest Management credits. See the web site:

Agronomic Crops Disease Bulletins Available

Authors: Dennis Mills

Several Plant Pathology disease management bulletins are available from OSU Extension at or from your local county extension office. Effective disease management requires knowledge of the important yield-limiting diseases most likely to occur in the area. Producers facing specific disease problems can fine-tune their disease management strategies to those few diseases encountered each year. When designing a disease management system it is important to consider all of the different strategies to reduce the level of the disease. Integrated disease management systems incorporate as many disease control strategies as possible. Disease resistant varieties, crop rotation, and tillage are especially important. Factors such as balanced fertility and soil pH, planting date and rate, and seed treatments are also important and in some cases foliar fungicides may be used to stop serious disease development.

Wheat Disease Management in Ohio, Bulletin 785
Disease is one of the major factors limiting yields of wheat in Ohio where losses as high as 30 to 50 percent can occur if disease control has not been practiced. Effective disease management requires knowledge of the important yield-limiting diseases most likely to occur in Ohio. This bulletin addresses the essential components of the disease symptoms with color images, the environmental factors favoring the disease, the method of transmission and infection, and management options for the major diseases affecting wheat in Ohio.

Corn Disease Management in Ohio, Bulletin 802
Five to 15 percent of Ohio's corn crop is lost to disease each year, amounting to nearly $100 million in lost farm income. Corn diseases include seedling diseases, leaf blights, stalk rots, ear and kernel rots, and viruses. This bulletin describes the disease symptoms, provides color images, and gives the environmental factors favoring the disease, the method of transmission and infection, and management options for the major diseases affecting corn in Ohio.

Corn, Soybean, Wheat, and Alfalfa Field Guide, Bulletin 827
The Corn, Soybean, Wheat, and Alfalfa Field Guide was designed as a pocket guide to be used by scouts, educators, consultants, and growers when scouting fields. This bulletin contains valuable management information, photos, and diagrams on insect, disease, and weed identification for the listed crops, along with agronomic and no-till information.

Profitable Soybean Disease Management in Ohio, Bulletin 895
Ohio soybean growers are intensifying soybean production, and it is imperative that good disease management programs are in place to limit losses. This bulletin addresses the essential components of the disease symptoms with color images, the environmental factors favoring the disease, the method of transmission and infection, and management options for the major diseases affecting soybeans in Ohio.

The Ohio Field Crop Disease web site: is strongly recommended for additional up-to-date information on disease diagnosis and management options. This site is updated regularly to include new research and pesticide information.

Organic Corn Management Practices Vary

Authors: Peter Thomison

Organic farming is one of the fastest growing segments of U.S. agriculture. Following establishment of national organic standards in 2002, certified organic acreage doubled in 2005. However, adoption of organic farming differs considerably among crops. Organic fruit and vegetables comprise a much greater percentage of total U.S. crop acreage than field crops, e.g., in 2005, organic carrot production comprised 6 percent of total U.S. carrot acreage, whereas organic corn production comprised only 0.2 percent. One obstacle contributing to the low acreage of organic corn is a lack of information on the agronomic performance and grain quality of corn hybrids and varieties in organic cropping systems. Many organic grain farmers are seeking information and knowledge to help them identify organic hybrids and varieties that perform best under varying environmental conditions. This is becoming increasingly important as demand for organic corn increases locally, nationally and internationally, and as the number of organic farmers increase.

In 2006, the Organic Crop Improvement Association, Research and Education (OCIA-R&E), distributed a survey to OCIA – R&E farmer members in Ohio, Iowa, and Wisconsin to determine current organic management practices, especially those relating to corn hybrid and variety selection and management. Results of the survey served as the basis of a 2007 multi-state organic corn variety testing project initiated by corn and organic crop production extension specialists at The Ohio State University, Iowa State University, and the University of Wisconsin. This study was supported by a 2006 USDA North Central Region Sustainable Agriculture Research and Education grant.

Of the 260 questionnaires mailed to OCIA-R&E farmer members, 67 completed questionnaires were returned. The following are some of what the questionnaire revealed about current organic corn management practices in Ohio, Iowa, and Wisconsin.
- Eighty five hybrids were planted by respondents. Of these, 56 were organically produced, 29 were untreated conventionally produced hybrids. The average hybrid maturity was 102 days, with a range of 75-114 days. 91% of the hybrids planted were used for animal feed (grain and silage); 9% were for food grade uses. The average planting date was 5/9/06 with a planting date range of 4/24/06-6/31/06.
- The surveys represented 4,198 acres of organic corn in the three states. Total certified organic acreage in Iowa, Ohio, and Wisconsin was about 44,200 A in 2005 (US total certified acreage was about 130,700 A in 2005). The average farm size was 65 acres, with a range of 3 to 392 acres. The average seeding rate was 28,218 with a range of 18,000-36,000 seeds per acre. Sixty-eight percent of the respondents indicated that corn was planted following a red clover, alfalfa, hay/pasture or some other unspecified cover crop. 72% of the respondents used some form of manure to maintain soil fertility.
- With regard to harvest dates, 45% typically harvest during October, 30% harvest during November, and 3% harvest during December. Drying methods varied with 16% of the questionnaire respondents relying on artificial grain drying, 6% air only, 1% harvesting hi-moisture corn, 45% relying on field drying, and 31% using a combination of field and artificial drying. With regard to storage, 90% of respondents had on-farm storage for the crop (with 1 response having storage for ear corn only).
- Organic farmer respondents indicated that effective weed control was their major concern in organic corn production (cited by 54% of the respondents). Weed control was accomplished with the use of tillage and multiple cultivations, with 4 respondents using flame weeding as part of their weed control strategy and 10 respondents utilizing some form of hand weeding.

Weed Control for Liberty Link vs glyphosate-resistant corn

Authors: Mark Loux

The dominance of glyphosate-resistant varieties and hybrids make it easy to fall into a pattern of continuous glyphosate use. Glyphosate is still a very effective herbicide for many growers, usually because they have integrated glyphosate with other herbicides and continue to recognize the value of 2,4-D ester and residual herbicides. However, continued reliance on postemergence glyphosate treatments in glyphosate-resistant crops will most likely lead to diminished utility of glyphosate, something that we are all trying to avoid.

In a corn-soybean rotation, rotating Roundup Ready soybeans with Liberty Link corn is one way to avoid continuous postemergence use of glyphosate. Corn hybrids that contain the Herculex BT trait are also usually Liberty Link, since the gene that confers glufosinate (Liberty) resistance is a marker for the Herculex BT trait. Some of these hybrids are also glyphosate-resistant, so growers have the choice of Liberty or glyphosate in postemergence applications. One factor that can limit the use of Liberty is the relative scarcity of hybrids that have the Liberty Link but not the BT trait, which makes it difficult to satisfy BT refuge requirements. We have heard about this issue from a number of growers and consultants, but there does not appear to be any move by seed companies to resolve it.

Hybrid seed availability issues aside, our research shows Liberty and glyphosate to be equally effective for control of annual weeds when used in an appropriate herbicide program. Liberty can have an especially good fit in fields where there has been a noticeable decrease in the activity of glyphosate on common or giant ragweed (both herbicides can be weak on lambsquarters, which is best controlled with preemergence herbicides). We consider one of the following to be an appropriate herbicide program for Liberty Link or glyphosate-resistant corn (Roundup Ready, Agrisure GT, etc):

1) application of residual (PRE) herbicides prior to crop emergence followed by POST application of glyphosate or Liberty. Examples of PRE herbicides in this approach include - atrazine premix product (Harness Xtra, Bicep, Guardsman Max, etc), Radius + atrazine, SureStart, Lexar, etc. These can be applied at rates corresponding to 67 to 100 percent of the recommended rate.

2) early POST application (weeds no more than 2 to 3 inches tall) of a mixture of glyphosate or Liberty plus residual herbicides. Residual herbicides should be similar to those used in approach #1, with the exception of Balance and Radius since they cannot be applied to emerged corn.

When used in one of these programs, glyphosate or Liberty will typically be applied to small weeds, which will maximize herbicide activity and minimize differences between them. It is more difficult for us to assess the difference in cost between a glyphosate- and Liberty-based program, due to the variable nature of herbicide and corn hybrid prices. Liberty has historically been considerably more expensive than glyphosate, but prices of the two herbicides appear to be converging. Recent increases in the price of glyphosate products have pushed the cost of a standard glyphosate rate (0.75 lbs ae/A) upwards toward $10/A or higher. There is currently some type of rebate program associated with Liberty that reduces the price to about $9/A, but we don’t know what qualifies one for the rebate. Bayer will be introducing a new higher load formulation of Liberty that will apparently sell for a lower cost than the current Liberty product. So, glyphosate would be the cheaper option if you bought it at the low price or you don’t qualify for the rebate on Liberty. But, the price may be comparable if you are stuck paying the higher prices for glyphosate and qualify for the rebate on Liberty. Then again, if you purchased BT/Liberty hybrids at a lower price than glyphosate-resistant hybrids, the price of a glyphosate vs Liberty program may be comparable even if you bought glyphosate when the price was low. I will leave this to readers to sort out further, because my head’s starting to hurt.

A few other considerations for glyphosate and Liberty:

- Liberty is most consistently effective when mixed with atrazine, and this should be the standard approach where corn height allows.
- Glyphosate will be more effective than Liberty for control of perennial weeds, although Liberty plus atrazine can control the topgrowth of some perennials. The PRE followed by POST approach is generally more effective for management of perennials, compared with the early POST plus residual approach. Most perennials are not large enough to be controlled at the time of an early POST application.
- Both herbicides should be applied with ammonium sulfate.
- Glyphosate is a systemic herbicide, which can allow for considerable flexibility in application volume, nozzles, etc. Liberty acts primarily as a contact herbicide, although limited redistribution of herbicide within the plant can occur. Spray coverage and application parameters are therefore more important considerations for Liberty when compared with glyphosate. The Liberty label specifies application with flat fan nozzles in a volume of at least 15 gpa and a pressure of 30 to 40 psi.
- The activity of both herbicides is influenced by time of day. Control can be reduced when applied in the early morning or evening, and of course during the nighttime hours.
- The Liberty label specifies a 4-hour rainfree period. Glyphosate labels vary on this, but many specify a rainfree period of 30 minutes to one hour (although research indicates that one hour may not be enough time for control of some weed species or biotypes).
- The activity of Liberty can be affected to a greater extent by unfavorable environmental conditions (cool, cloudy, dry), compared with glyphosate. However, use of Liberty in one of the approaches outlined above will usually result in application to small weeds, which helps mitigate the effect of environment on control. Use of the PRE followed by POST approach will result in the most flexibility in the POST application window, making it possible to avoid application during periods of unfavorable weather.

Late Feb & March Agronomic Offerings from the AgCrops Calendar

Authors: Harold Watters

The entire calendar is available on the Agronomic Crops Team website:

Feb 26
Agronomy School – Coshocton & Muskingum Counties
Start Time: 10:00 a.m.
County of Meeting Location: Coshocton
Name of Meeting Place: Conesville United Methodist Church
Meeting Place Address: 195 State St.
Meeting Place Town: Conesville
Cost: $15
CCA Credits Offered: NO PAT Credits Offered: Private:NO Commercial: NO
Meeting Coordinator Name: Mark Mechling and Marissa Mullett
Phone Number: 740-454-0144 or 740-622-2265
e-Mail: or
Agenda Web Link: Will be posted on and

Feb 27
Tri County Agronomy Day
Start Time: 10:00 a.m.
County of Meeting Location: Carroll
Name of Meeting Place: Our Lady of Mercy Catholic Church Hall
Meeting Place Address: 616 Roswell Rd
Meeting Place Town: Carrollton, OH 44615
Cost: $9.00
CCA Credits Offered: NO PAT Credits Offered: Private: YES Commercial: NO
Meeting Coordinator Name: Mike Hogan
Phone Number: 330-627-4310
Agenda Web Link:

Feb 27
Top Soybean Farmer Workshop
Start Time: 9:00 A.M.
County of Meeting Location: Ross County
Name of Meeting Place: Ross County Service Center
Meeting Place Address: Route 50, Western Avenue
Meeting Place Town: Chillicothe, Ohio
Cost: $10
CCA Credits Offered: NO PAT Credits Offered: Private: NO Commercial: NO
Meeting Coordinator Name: David A. Mangione
Phone Number: 740-702-3200
Agenda Web Link:

March 5
Field Crop Commercial Pesticide Recertification Conference
Start Time: 8:45 AM Registration 7:45 AM

County of Meeting Location: Franklin

Name of Meeting Place: Ohio State University, Fawcett Center

Meeting Place Address:
Meeting Place Town: Columbus, OH

Cost: $75

CCA Credits Offered:Yes 5 hrs Pest mgt.
PAT Credits Offered: 5hrs Private:Yes Commercial: Yes
Meeting Coordinator Name: Joanne Kick-Raack

Phone Number: 614-247-7489
Agenda Web Link:

March 4 & 11
Precision Agriculture Data Management, Analysis and Decision Making Workshop
Start Time: 9:00 AM to 3:00 PM 

County of Meeting Location: Fayette 

Name of Meeting Place: Fayette County Extension Office 

Meeting Place Town: Washington Courthouse, OH 


CCA Credits Offered:Yes 
PAT Credits Offered: Private:No Commercial: No
Meeting Coordinator Name: John Yost 

Phone Number: 740-653-5419 
Agenda Web Link:

March 12
Seneca County OSU Extension and SWCD Agronomy Night
Start Time: 5:00 p.m.

County of Meeting Location: Seneca

Name of Meeting Place: Safety Building, Seneca County Fairgrounds
Meeting Place Address: 126 Hopewell Avenue 

Meeting Place Town: Tiffin, Ohio

CCA Credits Offered: YES
PAT Credits Offered: Private: NO Commercial: NO
Meeting Coordinator Name: Ed Lentz and Mark Fritz

Phone Number: 419/447-7073, 419/447-9722

March 17-21
Overholt Drainage School
Session 1- (17-18)
Topics: Laser surveying, Topo Mapping, GPS Mapping
Session 2- (18-20)
Topics: Subsurface drainage design, drainage installation
Session 3- (20-21)
Topics: Water management, Controlled drainage, Subirrigation
Start Time: see schedule for individual sessions 

County of Meeting Location: Hancock 

Name of Meeting Place: Hancock Agricultural Service Center 

Meeting Place Address: 7868 CR 140

Meeting Place Town: Findlay, OH 

Cost: Varies by Session 
CCA Credits Offered:No

PAT Credits Offered: Private:No Commercial: No
Meeting Coordinator Name: Larry Brown 

Phone Number: 614-292-3826 
Agenda Web Link:

Archive Issue Contributors: 

Dennis Mills (Plant Pathology), Peter Thomison (Corn Production), Mark Loux (Weed Science), and Nancy Taylor (Plant Pest Clinic). Extension Agents: Roger Bender (Shelby), Howard Siecrist (Licking), Glen Arnold (Putnam), Greg LaBarge (Fulton), Gary Wilson (Hancock) and Harold Watters (Champaign).

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.