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Agronomic Crops Network

Ohio State University Extension


C.O.R.N. Newsletter 2013-17

Dates Covered: 
June 11, 2013 - June 18, 2013
Amanda Douridas
Spring Insect Concerns

Spring Insect Concerns

Soybeans – A few reports of bean leaf beetle defoliation have come in.  Remember that it takes considerable defoliation, probably over 40-50% before it really is a concern at this time of year unless you are growing seed beans or food grade beans where bean pod mottle virus might be a concern because of quality issues.  See the fact sheet at for more information.

Corn – Numerous reports were still coming in from northern Ohio on the Asiatic garden beetle grubs being found, almost all in first year corn following soybeans planted into sandy soils.  As there are no rescue treatments available, the only decision is whether to replant if stand loss is significant.  More importantly, this pest should be kept in mind next year, and hopefully we will gain some information on how best to handle it.  Obviously, seed treatments do not appear to offer any control.  However, growers in these areas who might have used a granule or liquid soil insecticide on their first year corn should contact us as to whether they felt they got control of this grub or still saw significant stand loss (send an email to  These observations will go far in helping us determine how to best manage it.

Reports have come in of armyworm on corn in rye cover crops and black cutworm feeding on small corn.  This is the time that corn should be scouted for both these early season pests.  With cutworms, remember to scout even though seed treatments were probably used.  Experience has indicated that the seed treatments do not adequately, manage cutworms (see the following fact sheet for more information on black cutworms). 

Alfalfa – As reported last week, this the time when potato leafhopper begins their build up, so alfalfa should be scouted for their presence.  The potato leafhopper fact sheet is at .  

My Corn Plants are Purple? What is Going On?

There have been reports in northwestern Ohio of fields with reddish-purple corn seedlings. The first thing that may come to mind is a phosphorus deficient soil.  This is unlikely the case, especially this early in the year.  In most cases the purple tint is a result of excessive photosynthetic energy accumulating during bright sunny days in slow growing corn seedlings. In many cases growth has been limited by cool nights, limited/excessive soil moisture and other environmental stresses. Soil compaction, herbicide or fertilizer injury, etc will aggravate the stress.  In most hybrids this excessive accumulation of photosynthetic compounds is not visible; however, some hybrids contain a larger percentage of genes that may produce the pigment anthocyanin, which will be present in the photosynthate. This pigment causes the reddish-purple color. As the young seedlings respond to better growing conditions, the concentration of the pigment will diminish and no longer be visible. The reddish-purple color seldom persists past the V6 growth stage and should not affect yields.

Seedlings may be collected for plant analysis but results would most likely not be useful, particularly if growing conditions are not optimal for growth. Also tissue analysis should not be used for fertilizer recommendations. Research has not established a fertilizer rate with a tissue value. Tissue analysis is a diagnostic tool but not reliable or accurate enough for a valid fertilizer recommendation when used alone.

Western bean cutworm monitoring to begin

Western bean cutworm monitoring to begin

For the 7th straight year, OSU-Extension and OARDC personnel will be trapping for western bean cutworm (WBC).  This is a pest of only corn and dry beans (note: NOT a pest of soybean), and has rapidly expanded from its native range in Colorado and western Nebraska.  With the more recent cool weather, we expect adult flights to begin sometime in mid-June. Monitoring WBC adult emergence is critical in knowing when and where to scout for corn.

Our trap counts will be updated weekly on our Agronomic Crops Insects website:  Traps can be easily constructed from milk jugs, or using commercial “bucket-traps.”  These traps use pheromone lures, which are relatively inexpensive (lures cost about $2, and are good for about 4 weeks, so over the course of 3 months, the total for lures is $6).  Both traps and lures can be purchased from Great Lakes IPM (, and for more information see our WBC fact sheet (

What do we expect to see this year? While Ohio has not yet seen economic damage in corn from WBC, we have been able to find eggs and larvae the past 2 years.  Furthermore, our adult trap catches have been relatively steady; suggesting that we still have the risk of infestation.  WBC prefer to lay eggs in corn that has not reached tassel—any corn that hasn’t tasseled by peak flight (likely 2nd or 3rd week of July, depending on temperatures) is at risk.  At this point, however, trapping and scouting remains our best option to determine the impact of WBC.


Sampling for Nematodes on Corn

Nematodes are simple roundworms that exist in the soil. Some species can be parasitic in crop production and their feeding on plant root systems can cause yield losses. We are familiar with soybean cyst nematode, which is specific to soybeans and is a single species of nematode that can be seen with the naked eye as a pinhead sized lemon shape on the root system. When we discuss nematodes on corn, we are in fact talking about a variety of species that feed externally or internally on the root system and they cannot be seen without a microscope after specialized processing. To confirm potentially damaging nematodes in corn, samples that contain both soil and root systems need to be submitted. To get a good sample for analysis, proper sample timing and handling during sampling and transport are critical.

Common Nematodes found affecting Corn

 Species name

Common Name























Losses from nematodes are common but very difficult to detect. Above ground symptoms are usually noted as uneven growth in circular areas. Since uneven growth can be attributed to a variety of factors such as soil type, soil compaction, soil-borne pathogens, poor drainage, poor fertility and herbicide carryover, nematode problems may go undiagnosed. Root symptoms may include stunting, clubbing and other abnormal root growth. Since nematodes feed on the root systems, their injury can lead to infections by other soil-borne pathogens. In cases where corrective management, such as adjustment of fertility, removing soil compaction etc., have been used and yields have not responded as expected, it may be  worthwhile to submit a sample for nematode testing. Nematodes are most likely to cause problems in no-till or corn-on-corn fields and all soil types can be affected.

Nematode sampling in corn is best done at growth stage V3 to V6 (or approximately 20-30 days after planting). This stage gives the best overall counts of all species of nematodes. Samples should be taken with a 1 inch probe, 12-20 inches deep under the row of corn and do not break up the soil cores. The soil and root system parts are needed for a good sample. Sample the edges of hot spots or use a zig-zag pattern for random field sampling.  Take 20 cores, treat cores gently, do not break cores up, do not dry the sample and place a subsample in a quart sized plastic bag. Keep the sample moist so the soil does not dry out. Label each bag in large letters with a permanent marker. Keep the samples cool.  These sampling guidelines are based on research and agreed upon by a consortium of nematologists from the North Central states including Ohio, and the “garbage in – garbage out” rule applies. 

Pack the samples in a cooler or insulated box for shipping. Put a sheet with name, address, phone number and e-mail of the farmer. Record the sample code with previous crop. If the sample is from multi-year continuous corn, note the number of years. Enclose a check for the cost for each sample at $40 payable to the C. Wayne Ellett Plant and Pest Diagnostic Clinic, The Ohio State University,
8995 E. Main Street, Bldg. 23, Reynoldsburg, OH 43068-3399.  

Agronomy Calendar for Summer 2013

June 20

Wheat Field Day-Northwestern Agricultural Research Branch

NW Ag Research Station, 4240 Range Line Road Custar, OH 43511

Fungicide, variety development, insect control and wide row wheat are featured topics for the 2013 Wheat Field Day, from 9 to 11:30AM.

July 2

Cover Crop Field Day

OARDC NW Ag Research Station 4240 Range Line Road Custar, OH 43511

View demo cover crop plantings, cereal rye notill soybean, crimper/roller demo, cover crop supplies discussion

July 10

OSU Weed Science Field Tour

OARDC – Western Agricultural Research Station, 7721 South Charleston Pike, South Charleston, Ohio 45368

Review of weed control plots and issues with Dr Mark Loux at Western Agricultural Research Station. Pre-registration required.

July 17

Agronomy Field Day-Western Agricultural Research Station

OARDC – Western Agricultural Research Station, 7721 South Charleston Pike, South Charleston, Ohio 45368

2013 Western ARS Agronomy Field Day will be held on Wednesday, July 17, 2013 – 9AM to 3:15PM at OARDC – Western Agricultural Research Station. Pre-registration required, payable at the door $20. Register by email or phone to: Harold Watters (, 937 599-4227 or Joe Davlin (, 937 462-8016.

July 25

Field Crops Day-Northwestern Agricultural Research Branch

NW Ag Research Station, 4240 Range Line Road Custar, OH 43511

Rows of corn, soybeans and wheat are easily distinguishable in the fields of OARDC's Northwest Station in Wood County. This area is known as the 'Great Black Swamp' region ­ once an ancient lake bed. OARDC purchased 247 acres of this land in 1951, and since then scientists have focused on the area's unique soils. The soil here is a challenge to area crop producers. Visit with select Extension Specialist and view research activities at the research station.

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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.