C.O.R.N. Newsletter: 11-2021

  1. Cold Weather Impact on Corn and Soybean

    Imbibitional chilling may occur in corn and soybean seeds if the soil temperature is below 50°F when the seed imbibes (when seed rapidly takes up water from the soil, usually within 24 hours after planting). Imbibitional chilling can cause reductions in stand and seedling vigor. If seeds were planted into soil at least 50°F (and have already imbibed), the drop in temperature is not likely a problem if the plants have not yet emerged from the soil. This year, the concern is for seed planted into dry soil that imbibed due to the recent snow melt.

    If your corn and soybean plants were emerged at the time of the cold temperatures last week, fields should be assessed this week as the temperature warms up. The growing point of corn is below the soil surface until the V6 growth stage, and therefore is protected from low temperatures to some extent. For soybean, the growing point is above the ground when the cotyledons are above the soil surface. If damage occurs below the cotyledons, the plant will die.

    Figure 1. Soybean plants seeded at 100,000, 140,000, and 180,000 plants per acre. Photo credit: Will HammanIf your corn and soybean plants were not yet emerged at the time of the cold temperatures last week, you may need to wait longer to assess potential damage. Checking the seeds now may be hard to tell if imbibitional chilling occurred because affected seeds that won’t complete the germination process will still absorb water. As the temperatures warm up, corn and soybean seeds should begin to germinate and emerge from the soil. We suggest assessing corn and soybean stand as plants emerge.

    For soybeans planted in April or May, a stand as low as 100,000 plants per acre can still produce maximum yield. However, we do not recommend replanting until the soybean stand is less than 50,000 plants per acre. At low plant populations, soybean plants can compensate through increased branching (Figure 1). In our research, going from 100,000 plants per acre to 50,000 plants per acre resulted in a 9 to 14% reduction in yield.

    Final stands for corn should be between 24,000 and 26,000 plants per acre in lower yielding environments to optimize yield, though some higher yielding environments maximize yield at stands that exceed 34,000 plants per acre. Early planting dates with lower stands can still produce exceptional yield. For example, in past research, a stand of 20,000 plants per acre planted on April 20 yielded 90% of the optimum. If stands are 15,000 plants per acre or fewer, a replant may be warranted as the yield gained from a higher seeding rate planted in early to mid-May can exceed the yield from corn with a low stand planted in mid-April.

  2. Challenges Ahead

    NAEFS 16-day Ensemble Mean Total QPF from 4/26/2021
    Author(s): Jim Noel

    There are challenges ahead so we will break them into short-term and long-term.


    The recent snow was a rare event for the amount that fell across Ohio. However, the minimum temperatures in the 20s and 30s was not that far off of normal for last freeze conditions for Ohio.

    The strongest typhoon ever in the northern hemisphere occurred east of the Philippines last week and this energy will come across parts of North America over the next week. When that happens weather model performance often drops. Hence, if you see more bouncing around of forecasts the next 10-15 days that may be one reason why.

    We have a big warm-up the first half of this week ahead of a strong storm that will move through Ohio the second half of the week with wind and rain. We could see anywhere from 0.50 inches to over 2 inches across Ohio later this week but placement is not certain and seems to favor central and southern Ohio with the highest amounts. Expect most places to see an inch or less given recent track record of events coming in lighter.  Once the storm passes colder air will push in and some frost will be possible this weekend with lows in the 30s.

    The rainfall the next 30-days is critical for the growing season as moderate drought over northern Ohio already has soil conditions in a shortage.

    The latest drought monitor can be found here:


    Also, some of the greatest evaporative demand in the country has been in parts of northern Ohio the last 30+ days and can be monitored as a leading indicator for drought development at this webpage via NOAA:


    You can keep up on the Ohio River Forecast Center's Water Resources Outlooks at:



    May appears will see periods of well above and below normal temperatures but will average out close to normal or just slightly above normal. Precipitation continues to trend at or below normal but models suggest a normal May for precipitation. If we get timely rains that will help soil conditions for summer. If we miss critical rains in May, this could lead to summer issues.

    The latest rainfall outlook for the next 16-days is viewable in the attached image. Normal rainfall is nearing 2 inches for the next 16-days. We expect 1-3 inches for most areas.

    For summer, most climate models indicate above normal temperatures and medium to high confidence of above normal temperatures during typical peak temperatures from mid-June to mid-August. We will need to monitor this. Confidence in summer rainfall is low. Most outlooks and models suggest not too far from normal rainfall but the reality is since 30-50% of summer rainfall comes from local soils, the next 30-days will be a big player in our summer rainfall outcome.



  3. CFAES Ag Weather System 2021 Near-Surface Air and Soil Temperatures/Moisture

    Figure 1: Daily average air temperature (dashed red), two-inch (green) and four-inch (blue) soil temperatures for spring 2021. Current daily average soil temperatures are noted for each location. Soil type and location of measurements (under sod or bare soil) are provided in the lower right corner of each panel. A map of all locations is in the bottom right.  Data provided by The College of Food, Agricultural, and Environmental Sciences (CFAES) Agricultural Research Stations located throughout the state. All sites are reported on Figure 1 as a daily average.

    A very unusual late season snowfall and three nights near or below freezing led to a significant drop in daily average soil temperatures by mid-week last week (Fig. 1). Most locations fell below 50°F with our northeast site in Ashtabula County dropping below 40°F. Temperatures recovered some throughout the weekend, as two- and four-inch soil temperatures are now at or slightly cooler than this time last week, running in the upper 40s to low 50s. This week will feature a significant warm up for the first half of the week, with maximum air temperatures reaching the upper 70s to low 80s for much of Ohio on Tuesday. Slightly cooler temperatures will occur for Wednesday and Thursday with rain expected, then chillier air temperatures, in the 50s and 60s, along with some morning patchy frost are possible for the weekend

    A solid swath of 3-6” of snow fell with last week’s storm along with some light to moderate rain on Saturday. Still, much of the state fell short of typical weekly averages for this time of year. Figure 2 (left) shows that precipitation was generally 0.50” or less across most of the state. Overall, Ohio remains dry, especially across our northern counties, even to depths of 40 cm (Fig. 2-right). The U.S. Drought Monitor currently shows approximately 46% of the state is at least abnormally dry, with 22% in Moderate Drought conditions.   

    Figure 2: (Left) Precipitation estimates for the last 7 days ending on 4/25/2021. Figure provided by the Midwestern Regional Climate Center (https://www.mrcc.illinois.edu). (Right) 0-40 cm Soil Moisture Percentile as of 4/26/2021 according to NASA’s SPORT-LIS (https://weather.msfc.nasa.gov/sport/modeling/lis.html).

    For more complete weather records for CFAES research stations, including temperature, precipitation, growing degree days, and other useful weather observations, please visit https://www.oardc.ohio-state.edu/weather1/.

  4. Overholt Drainage Workshop

    Author(s): Vinayak Shedekar

    Join OSU Extension for a webinar focused on drainage design, installation, and management including updates on on recently passed H.B. 340 – Ohio’s “petition ditch laws” that address the installation and maintenance of drainage works of improvement in Ohio. A panel of professional engineers representing state and federal agencies, drainage contractors, and tile manufacturers will discuss some standard practices, common issues, and troubleshooting associated with drainage design, installation, and repairs.

    2021 Overholt Drainage Workshop

    Drainage planning, design, installation, and management

    Wednesday, June 9, 2021 9AM to 12 Noon

    Registration: No cost to attend. Registration required. (Register Here)

    Or visit: https://go.osu.edu/drainageschool

    CEU credits available for CCAs and Professional Engineers



    How drainage design affects crop yield and economics?

    Larry Brown, Professor and Extension Agricultural Engineer, The Ohio State University

    Drainage law – recent updates to Ohio Drainage Law

    Peggy Kirk Hall, Field Specialist, Agriculture and Resource Law, The Ohio State University

    Designing drainage & associated practices - standards and good practices for design

    Justin McBride, Ohio Dept. of Ag. 

    Installing drainage & associated practices (safety, standards, and good practices for installation)

    Bob Clark II, Clark Farm Drainage, inc., New Castle, IN

    When drainage goes wrong: Drainage design & installation Panel 

    Moderator: Paul Chester, Retired NRCS Engineer

    Panelists: Justin McBride and Mark Seger, Ohio Dept. of Ag. 

    Greg Wells, Ohio NRCS; Bob Clark II, NLICA 

    Steve Gerten, Rick Galehouse, and Dave Schweiterman, OLICA 

  5. Yes, Another Article About Freeze Symptoms in Winter Wheat

    Author(s): Laura Lindsey

    After a (short) second round of winter last week, there has been some concern regarding winter wheat. As a reminder, the magnitude of freeze damage depends on: 1) temperature, 2) duration ofFigure 1. Photo credit: JD Bethel temperature, and 3) wheat growth stage. During the cold snap last week, the majority of winter wheat in Ohio was at the Feekes 6 to 8 growth stage. In northern Ohio, temperatures were in the low 30s to upper 20s. In Southern Ohio, temperatures were mostly above 30°F with a dip to 26°F on April 23, recorded by the CFAES weather system in Pike County. Underneath the snow, temperatures were warmer (Figure 1 records the temperature under the snow on April 21). 

    A few years ago, we conducted a freeze chamber experiment to examine the effect of low temperature on winter wheat at several growth stages (Table 1). Keep in mind, actual yield reductions in the field can be quite variable depending on the weather for the remainder of the growing season. At Feekes 6 growth stage, temperatures >20°F caused no damage. However, by Feekes 8 growth stage, temperatures of 25°F to 28°F caused a 10 to 25% reduction in wheat yield. These temperatures were from the crown of the wheat plant, not air temperature.

    Table 1. Temperature (15-minute duration) at which wheat yield was reduced by 5%, 10%, 25%, and 50% at Feekes 6, 8, and 10.5.1 growth stages. (Data from Alt, Lindsey, Sulc, & Lindsey, 2020).

    What to look for: After a freeze event, wait one to two weeks after active growing conditions resume to check for visual signs of freeze injury. Make sure to examine several areas of the field as landscape features influence the micro-climates within fields. Small differences in temperatures can cause large differences in damage and grain yield.

    At Feekes 6 growth stage, damage from freezing will cause discoloration of the leaf tissue, with leaf tips or edges exhibiting symptoms first (Figure 2). However, discoloration does not necessarily indicate a reduction in grain yield. At Feekes 6 growth stage, damage can also be assessed by carefully cutting the wheat stem lengthwise to expose the developing spike at the first node. Damaged spikes will appear discolored and shriveled. A healthy, developing spike should be rigid and whitish-green (Figure 3).

    Figure 2. At Feekes 6 growth stage, freeze damage causes yellowing of browning (necrosis) of the leaf and stem tissue. Wheat plants pictured (left to right) were exposed to temperatures of 3, 14, 21, 28, and 39°F corresponding to death of 100%, 80%, 50%, 25%, and 0% death of the plant tissue.

    Figure 3. At Feekes 6 growth stage, freeze injury causes damage to forming wheat spike within the stem. Wheat spikes pictured (left to right) were exposed to 39, 28, 21, 14, and 3°F temperature treatments. At 3°F, the wheat spike appears discolored and deformed.

    At Feekes 8 growth stage, damage from freeze may include yellowing or browning of the flag leaf. The flag leaf may appear twisted or in a spiral (Figure 4). As the plant continues to grow, the wheat spike may get stuck in the leaf sheath, causing a crooked appearance at heading (Figure 5). (Although, this phenology can also be associated with spikes that emerge quickly due to warm temperatures.)

    Overall, I think freeze damage should be minimal from this most recent cold snap. At Feekes 6 growth stage, wheat is still fairly tolerant of cold temperatures. In the southern portion of the state, where wheat stage was more advanced, temperatures tended to be warmer. However, the best way to assess for potential damage is to scout your field after active growing conditions resume this week. For more information, see our new ‘Freeze Symptoms and Associated Yield Loss in Soft Red Winter Wheat’ FactSheet: https://ohioline.osu.edu/factsheet/anr-93

    Figure 4. Twisting or spiral appearance of the flag leaf can be caused by low temperatures. Photo credit: Greg LaBarge.

    Figure 5. At Feekes 8 growth stage, damage may include yellowing or browning of the flag leaf. The wheat head may get stuck in the leaf sheath causing a crooked appearance at heading.




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.


Aaron Wilson (Byrd Polar & Climate Research Center)
Amanda Douridas (Educator, Agriculture and Natural Resources)
Andrew Holden (Educator, Agriculture and Natural Resources)
Andy Michel (State Specialist, Entomology)
Barry Ward (Program Leader)
Beth Scheckelhoff (Educator, Agriculture and Natural Resources)
Bruce Ackley (Extension Program Specialist in Weed Science)
Bruce Clevenger, CCA (Educator, Agriculture and Natural Resources)
Chris Zoller (Educator, Agriculture and Natural Resources)
Clifton Martin, CCA (Educator, Agriculture and Natural Resources)
Clint Schroeder (Educator, Agriculture and Natural Resources)
Curtis Young, CCA (Educator, Agriculture and Natural Resources)
Dean Kreager (Educator, Agriculture and Natural Resources)
Ed Lentz, CCA (Educator, Agriculture and Natural Resources)
Elizabeth Hawkins (Field Specialist, Agronomic Systems)
Eric Richer, CCA (Educator, Agriculture and Natural Resources)
Glen Arnold, CCA (Field Specialist, Manure Nutrient Management )
Greg LaBarge, CPAg/CCA (Field Specialist, Agronomic Systems)
Hallie Williams (Educator, Agriculture and Natural Resources)
Harold Watters, CPAg/CCA (Field Specialist, Agronomic Systems)
Jamie Hampton (Extension Educator, ANR)
Jason Hartschuh, CCA (Educator, Agriculture and Natural Resources)
Jim Noel (National Weather Service)
John Barker (Educator, Agriculture and Natural Resources)
Ken Ford (Educator, Agriculture and Natural Resources)
Laura Lindsey (State Specialist, Soybean and Small Grains)
Lee Beers, CCA (Educator, Agriculture and Natural Resources)
Les Ober, CCA (Educator, Agriculture and Natural Resources)
Mark Loux (State Specialist, Weed Science)
Mark Sulc (State Specialist, Forage Production)
Matthew Schmerge (Educator, Agriculture and Natural Resources)
Mike Estadt (Educator, Agriculture and Natural Resources)
Nick Eckel (Educator, Agriculture and Natural Resources)
Pierce Paul (State Specialist, Corn and Wheat Diseases)
Richard Purdin (Educator, Agriculture and Natural Resources)
Sarah Noggle (Educator, Agriculture and Natural Resources)
Stephanie Karhoff (Educator, Agriculture and Natural Resources)
Ted Wiseman (Educator, Agriculture and Natural Resources)
Tony Nye (Educator, Agriculture and Natural Resources)
Wayne Dellinger, CCA (Educator, Agriculture and Natural Resources)


The information presented here, along with any trade names used, is supplied with the understanding that no discrimination is intended and no endorsement is made by Ohio State University Extension is implied. Although every attempt is made to produce information that is complete, timely, and accurate, the pesticide user bears responsibility of consulting the pesticide label and adhering to those directions.

CFAES provides research and related educational programs to clientele on a nondiscriminatory basis. For more information, visit cfaesdiversity.osu.edu. For an accessible format of this publication, visit cfaes.osu.edu/accessibility.