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Agronomic Crops Network

Ohio State University Extension


C.O.R.N. Newsletter 2008-03

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

Don’t Rush Nitrogen Applications on Wheat

Authors: Edwin Lentz, Robert Mullen

Many of us would like to apply N to wheat now while the ground is still frozen (at least the surface) rather than waiting for proper soil conditions in March. Though we may save time and labor with a February application, we run the risk of losing most of the N (a costly error with existing high N prices).

Ohio State University research completed in 2003 revealed that loss of N from a single N application prior to spring green-up may have yield reductions of 19% compared to applications between initial greenup and early stem elongation. This loss occurred for all N sources used in the study (ammonium sulfate, urea and 28%). In this same study, yields did not decrease as long as spring application was made between greenup and early stem elongation.

Producers who choose to take the risk of applying prior to greenup may reduce (not eliminate) yield loss by selecting the proper N source and adjusting management practices (all may be more costly options than waiting till greenup). First select the N source with the least potential for N loss. Of common N sources available, ammonium sulfate would have the least potential for loss, followed by urea, and 28% solution the most potential for loss. Split spring applications may also be appropriate for February applications (small amount applied early, with the larger amount applied closer to early stem elongation). Another management adjustment to consider, apply a normal N application as a strip at greenup and compare to the rest of the field as the crop approaches early stem elongation. A chlorophyll meter may assist in determining differences or a best guess look. A producer will not be able to determine the exact amount of additional N if a significant green color difference is apparent, but additional N may be beneficial. However, waiting to apply spring N between greenup and early stem elongation would still be the recommended practice.

Barley Yellow Dwarf Virus and Aphids on Wheat

Authors: Ron Hammond, Pierce Paul, Andy Michel, Bruce Eisley

We are beginning to receive questions on spraying aphids on wheat this coming spring for the prevention of barley yellow dwarf virus (BYDV). Although we discussed this last fall, it is appropriate to again bring this up. There are several species of aphids that may be found in wheat capable of causing problems, most notably by the movement of a plant virus, barley yellow dwarf virus. The virus for barley yellow dwarf is generally transmitted to the wheat in the fall or early spring before growth stage 4. For aphids to successfully transmit the virus, they normally need between 12 and 30 hours feeding to acquire the virus, and then 4 or more hours of feeding to transmit it. However, aphids are capable of acquiring the virus after feeding on infected plants for only 30 minutes and once they acquire the virus, they can transmit it to healthy plants for the rest of their life. High incidences of BYDV had been reported last spring in some parts of Ohio. Some of those fields reportedly had as much as 20% of the plants showing symptoms typical of this disease: erect leaves with yellowish to reddish-purple tips. Differences in BYDV incidence from one field to another may be due to differences in efficiency of aphid transmission of the virus among fields, the source and strain of the virus being transmitted, difference in aphid mobility and feeding habits, the age and susceptibility of plants when infected, and differences in weather conditions from one field to the next.

Yield reduction due to BYDV is generally greater when infections occur in the fall than in the spring; thus, the greatest concern is past. BYDV tends to be most severe in fields planted before the fly-free date at a time when aphid populations are high and aphids are still actively feeding. However, some fields planted after the fly-free date last year had higher levels of BYDV and aphid densities, most likely because of warm temperatures that kept aphids active for a longer time period. Because the fall was warmer than normal, growers are concerned with the potential for problems.

The recommended management tactics for BYDV are:
1) plant varieties less susceptible to BYDV;
2) delay planting until after the Hessian fly safe date to avoid early fall infections;
3) balanced fertility; and
4) controlling volunteer wheat, barley, and oats (for more on BYDV, visit the field crops disease website at
Spraying insecticide to control aphids in an attempt to manage BYDV is open to discussion, and usually not a recommend tactic. During active feeding, a few aphids will be enough to transmit the virus from one plant to another. Any aphids present prior to spraying may have already transmitted BYDV, while other aphids may continue to arrive in the field after the spraying. When spraying insecticides to control aphids early, growers should know that the residual effect of the insecticide may not last long enough to protect against later aphid population buildup nor virus transmission. Though insecticides applied after infection will reduce the aphid population, it will not prevent the disease from developing once the plants have been infected. Once infections occur, there is very little that can be done.

There are a few situations where it might be acceptable to spray for aphids. These include:
1) wheat under drought stress with aphids present;
2) growing a variety known to be susceptible to BYDV with aphids present;
3) wheat being grown for seed;
4) wheat that is highly intensively managed with a 100+ bu/A potential yield; and 5) wheat planted before the fly-free date.
If a decision is made to spray an insecticide, see the following web site ( for a list of labeled materials. However, for most growers, cost-effective control of BYDV may not be possible by aphid spraying.

February Agronomic Offerings from the AgCrops Calendar

Authors: Harold Watters

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

Feb 7
Soybean Production Workshop
Start Time: 9:00 am

County of Meeting Location: Wyandot County

Name of Meeting Place: Walton Agri-Service

Meeting Place Address: North Fertilizer Plant, 9960 County Rd 49

Meeting Place Town: Upper Sandusky

Cost: free (sponsors to cover direct costs)

CCA Credits Offered: NO

PAT Credits Offered: Private: YES Commercial: NO
Meeting Coordinator Name: Chris Bruynis

Phone Number: 419-294-4931

Feb 12
Winter Wheat Meeting
Start Time: 9:30 am

County of Meeting Location: Monroe County, Michigan

Name of Meeting Place: Cabela's 

Meeting Place Address: 110 Cabela Blvd. East, Dundee, MI 48131 

Meeting Place Town: Dundee, MI

Cost: $20 prior to 2/8 & $30 at the door 

CCA Credits Offered: NO
PAT Credits Offered: Private: NO Commercial: NO
Meeting Coordinator Name: Greg LaBarge, OSU & Ned Birkey, MSU 

Phone Number: 419-337-9210 (OH) 734-240-3170 (MI) 
e-Mail: or

Feb 14
Northern Ohio Crops Day
Start Time: 9:00 am

County of Meeting Location: Sandusky County

Name of Meeting Place: Old Zim's Wagon Shed 

Meeting Place Address: 1375 N State Route 590

Meeting Place Town: Gibsonburg, OH 
Cost: $15 plus adition for PAT credits 

CCA Credits Offered: YES 
PAT Credits Offered: Private: YES Commercial: YES
Meeting Coordinator Name: Mark Koening 
Phone Number: 419-334-6340 

Feb 19 & 26
Precision Agriculture Data Management, Analysis and Decision Making Workshop
Start Time: 9:00 AM to 3:00 PM 

County of Meeting Location: Shelby

Name of Meeting Place: TBA 
Meeting Place Address: TBA 
Meeting Place
Town: Sidney, OH 45365


CCA Credits Offered:Yes 
PAT Credits Offered: Private:No Commercial: No
Meeting Coordinator Name: Roger Bender

Phone Number: 937-498-7239 

Feb 21 & 22
Conservation Tillage & Technology Conference

Start Time: 
County of Meeting Location: Allen 

Name of Meeting Place: Ohio Northern University

Meeting Place Address:
Meeting Place Town: Ada, OH 

Cost: $30 (1 day) $50 (both days) by Feb 15 early registration, 

CCA Credits Offered:Yes
 PAT Credits Offered: Private:No Commercial: No
Meeting Coordinator Name:Gary Wilson

Phone Number:419-422-3851

Agenda Web Link:

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 (agriculture page) when finalized

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:

Archive Issue Contributors: 

Anne Dorrance, Pierce Paul and Dennis Mills (Plant Pathology), Ron Hammond, Andy Michel and Bruce Eisley (Entomology), Ed Lentz (Agronomy) and Robert Mullen (Soil Fertility). Extension Agents: Todd Mangen (Mercer), Roger Bender (Shelby), Howard Siecrist (Licking), Glen Arnold (Putnam), Greg LaBarge (Fulton), Ed Lentz (Seneca), Mike Gastier (Huron), Mark Koenig (Sandusky), 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.