C.O.R.N. Newsletter : 2019-13

  1. Windows for Planting Expected Next 2-3 Weeks

    Author(s): Jim Noel

    After a wet spring was forecasted since January, it appeared in April that a window would open in May. The rain total window has; however, the frequency window has not. The rainfall the last two weeks in Ohio has averaged 1.5 to 2.5 inches with some streaks above 3 inches and some below 1.5 inches. Normal for this period is 1.5 to 2.0 inches. The reality is the ground is just so wet from the wet period up to May. The other BIG key is the frequency of the wet weather.

    Often times when it is wet in say the eastern U.S., it is dry in the western U.S. The opposite also holds true. However, we have a very active and progressive weather pattern all around the northern hemisphere. This means a lot of weak to moderate storms on a continuous basis. It is not just Ohio either. Boston, MA set a record for most days with measurable rain in the month of April.

    Much of the U.S. is very wet right now.The latest soil moisture rank shows most of the corn and soybean belt is in the top 1-5%. https://www.cpc.ncep.noaa.gov/products/Soilmst_Monitoring/Figures/daily/curr.w.rank.daily.gif

    There are some questions on similarities to past years. Yes, you can see some similarities to 1993 or 1965 or 1948 and 1949 but there is no perfect year. It depends on where you are. From the widespread wetness in the U.S. you have to look at 1948/1949 for a closest fit but even that does not.

    Going forward for the rest of May, we will be seeing increasing temperatures which will lead to increasing evapotranspiration. Hence, like most years, even with some rainfall, the ground will begin to dry in the top layers.

    Up to May 16, temperatures will be below normal. However, starting May 17-May 31 the second half of May will see above normal temperatures and evapotranspiration so things will dry some. Rainfall for the rest of May will average close to normal in the 1.5-3 inch range as seen in this link...https://www.weather.gov/images/ohrfc/dynamic/NAEFS16.apcp.mean.total.png

    Looking ahead to the summer growing season, not much has changed. We expect near to slightly above normal temperatures from June to August. However, due to the wet soils, we expect normal daytime temperatures and above normal nighttime temperatures similar to last summer. Humidity levels will be above normal this summer too with all the evaporation. Therefore, expect increased issues with mold and mildew. As for precipitation, June looks like a variable month with areas of above and below normal precipitation. That could create some early challenges for growing if you get areas of hard ground near the top soil with wet groundneath. As we get into July and August, indications are for a little wetter than normal pattern to resume.


  2. OARDC Branch Station Temperature (Air and Soil) and Precipitation Analysis

    The Ohio Agricultural Research and Development Center (OARDC) Agricultural Research Stations located throughout the state have two and four inch soil temperatures monitored on an hourly basis. This will be the final soil temperature update this season.  

    Figure 1. Average daily air temperature (average of maximum and minimum daily temperatures; red-dashed), two and four inch soil temperatures for spring 2019 (brown and blue-solid, respectively), and two and four inch five-year average soil temperatures (brown and blue-dotted, respectively) for four OARDC stations from around Ohio (Northwest, Wooster, Western, and Piketon; see map insets). Conditions for 2019 are plotted through May 12th.

    Figure 1 shows that while soil temperatures were running close to the five-year averages earlier in the week, they ended on a downturn. All fours stations are currently cooler than their five-year averages. Of note, 2” and 4” soil temperatures at the Northwest station in Custar were 6-8°F below their five-year averages as of Sunday, May 12, 2019. Historically, soil temperatures warm fairly rapidly over the next couple of weeks, and with a warmer air mass set to move into the region by mid- week, soil temperatures should moderate this week.   

    Figure 2. Accumulated precipitation (percent of normal based on 1981-2010 climatological mean) for Ohio for the period January 1-May 12, 2019. Stars designate a selection of OARDC Agricultural Research Stations from around the state. The accumulated precipitation (in inches) is provided in the table on the right, along with number of days with 0.1” of precipitation or greater since April 1. 2019. Figure provided by the Midwest Regional Climate Center (https://mrcc.illinois.edu/).

    Figure 2 shows the updated percent of normal precipitation that has fallen since January 1. The entire state of Ohio is currently running above average, with much of the state between 125-150% above average. Areas across western and southwest Ohio have seen greater than 150% of normal precipitation for the year to date (dark green shaded). The table to the right of the figure indicates the amounts that have fallen at the same selected OARDC sites used for soil temperatures in Figure 1. All of these sites are above average.

    While the period May 2018 – April 2019 was the second wettest May to April period on record since 1895, the amount of precipitation since April 1, 2019 has not set records. However, the frequency of precipitation is high, with many areas across the state having received at least 0.01” or greater of precipitation on more than 50% of days since April 1, 2019. Thus, windows for adequate drying this spring have been limited, preventing the necessary fieldwork and planting.

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

  3. Fertilizer and Manure Application Weather Forecast Tools

    For those of you who sat in our Fertilizer Applicator Certification Training, you already know about using the National Weather Service website to see and capture the seven-day forecast for manure or fertilizer applications. Go to https://www.weather.gov, then select forecast - local - then enter your zip code. View the multi-day forecast report in the lower right corner. Shown here for Marysville – doesn’t look too bad but unfortunately the ground won’t support equipment.

    A couple of other tools can also be used, and have interesting features are: 

    • The Ohio Applicator Forecast from the Ohio Department of Agriculture is designed to help nutrient applicators identify times when weather-risk for applying is low. Visit: https://www.agri.ohio.gov/wps/portal/gov/oda/divisions/plant-health/resources/ohio-applicator-forecast
      • The risk forecast is created by the National Weather Service
      • Takes snow accumulation and melt, soil moisture, and forecast precipitation and temperatures into account.
      • The chances of surface runoff in the next 24 hours are displayed on the overview map of the state.
      • Zoom to street level and 7 days of weather conditions and runoff chances are predicted.
      • Risk is grouped into 3 categories: Low, Medium, and High.
      • When the risk is Medium, it is recommended that the applicator evaluate the situation to determine if there are other locations or later dates when the application could take place.
    • Field Application Resource Monitor from OSU. Visit: https://farm.bpcrc.osu.edu
      • F.A.R.M. allows users to define their location of interest (using Google Maps) and receive 12- and 24-hour precipitation forecasts to aid in the application of fertilizer, manure, and/or pesticides.
      • F.A.R.M. also utilizes a database of historical forecasts allowing users to search previous dates.
      • Gives you a red light or a green light on application.
  4. Applying Manure to Newly Planted Crops

    Author(s): Glen Arnold, CCA

    Livestock producers across the state are dealing with manure storages that are extremely full. Wet weather last fall, poor winter conditions for manure application, and a wet spring will have many livestock producers needing to apply manure and plant crops at the same time when fields become suitable.

    Liquid dairy and swine manure can be applied to both newly planted corn and soybean fields. If applied while the seed is protected by a layer of soil, both corn and soybeans will emerge through surface applied manure.

    Corn is more tolerant of manure than soybeans. In research plots and on-farm trials, we have applied swine and dairy manure to corn using a drag hose from just after planting to the V3 stage of growth. The manure did not seem to hamper corn emergence and growth. The only obvious damage to the emerged corn plants was when the tractor wheels crushed them. These plants are always slightly behind the remainder of the field but still produce ears.

    Soybeans can be easily killed by swine finishing manure when emerging from the soil or already emerged. We have wiped out double-crop soybean stands using swine finishing manure rates of 5,000 gallons per acre. I have had livestock producers tell me they have applied sow manure and nursery manure to soybeans without a problem. Other livestock producers have said they have reduced soybean yields when manure has been applied to established soybeans. Based on one year of data, we know a drag hose (no manure applied) does not damage soybeans enough to reduce yields at stages V1, V3, and V5.

    If you think you will be working with a commercial manure applicator to apply manure to newly planted crops, be sure to contact them well in advance. Commercial applicators I have spoken with are stretched extremely thin with all their regular customers with full manure storage facilities.

    Surface applied manure is at risk to runoff caused by pop-up thunderstorms. Be sure to print out rainfall forecasts when starting the manure application and check with your SWCD office about setbacks from ditches and streams.







  5. Alfalfa Weevil

    Cool weather has slowed everything down including insect growth and development, and we could see problems with alfalfa weevil later than typical this year.   Alfalfa fields should be scouted weekly for weevils until at least the first harvest.  Followup scouting may be needed after harvest in heavily infested fields. 

    Spot problem fields early by checking alfalfa tips for feeding damage – small holes and a tattered appearance. 

    Alfalfa weevils







    Green alfalfa weevil larvae (the main feeding stage) at various growth stages, and brown adults. Photo by Julie Peterson, University of Nebraska.

    Fields that have a south facing slope tend to warm up sooner and need to be checked for weevil earlier.

    Scout for alfalfa weevils by collecting a series of 10 stem samples from various locations.  Place the stems tip down in a bucket. After 10 stems have been collected, shake the stems vigorously shaken into the bucket and count the larvae.  Divide this number by 10 to get the average number of larvae per stem.  Do this procedure at least 3 times (for a grand total of 30 stems, in 10-stem units).  Alfalfa weevil larvae go through four growth stages (called instars).  The shaking will dislodge the late 3rd and 4th instar larvae which cause most of the foliar injury. Close inspection of the stem tips may be needed to detect the early 1st and 2nd instar larvae. Also record the overall height of the alfalfa.  The treatment threshold is based on the number of larvae per stem, the size of the larvae and the height of the alfalfa according to the following table.  When alfalfa is around 12-16 inches in height, growers should consider an early harvest rather than spraying. Over 16 inches, we would always recommend an early cutting. In those fields which are cut early for alfalfa weevil, the regrowth should be checked to make sure weevils that are still alive do not prevent good regrowth.

    Table 1. Action thresholds relevant to stand height, tip feeding, and density of larvae per stem.

    Stand Height Inches

    Indication of Problem % Tip Feeding

    Problem Confirmation Larvae per Stem

    Recommended Action




    Recheck in 7 days



    > 1




    > 2

    Spray or harvest



    > 4

    Harvest early

    When harvested early due to weevil, check within one week for regrowth.

    For more information about alfalfa weevil, visit our factsheet at https://ohioline.osu.edu/factsheet/ENT-32

  6. Managing Big, Wet Cover Crops

    Author(s): Mark Loux

    Managing cover crops in a year like this can challenge even those with the most experience.  A few suggestions regarding termination of covers:

    • Increase glyphosate rates to compensate for larger size, and consider applying alone or just with Sharpen.  Mixing glyphosate with other herbicides or ATS can reduce its activity on grass covers, especially when large.  Herbicides that can antagonize glyphosate include 2,4-D, metribuzin, atrazine, and flumioxazin and sulfentrazone products.  Sharpen has not caused a reduction in glyphosate activity on grass covers in university research.  One approach would be to apply the glyphosate or glyphosate/Sharpen first, wait a few days, and then apply residual herbicides. 
    • For covers that contain legumes, it will be generally still necessary to include with the glyphosate a growth regulator herbicide such as 2,4-D, dicamba, or clopyralid.  Sharpen will not be effective enough unless canola or rapeseed is the cover targeted.  Clopyralid is very effective on alfalfa and clover.  The exception here is hairy vetch which is easily killed by herbicide or even just being run over once it flowers. 
    • Our experience with relatively small (less than 2 feet) covers is that they do not interfere with the activity of residual herbicides.  We are somewhat unsure about the effect of taller covers on residual herbicide activity, but assume it could be reduced.  This may be a situation where the residual could be omitted from the burndown and then included in an early POST treatment.  Some considerations here:
      1. A large dense cover does provide fair to good early-season control of weeds on its own;
      2. We have herbicides in corn and soybeans (depending upon which traits are planted) allowing us to obtain POST control of many weeds, so the residuals could be omitted entirely, but this probably won’t work in nonGMO or Roundup Ready soybeans;
      3. Many covers are variable in size and density, and fields can have areas where the cover is not providing any control of weeds - omitting PRE residual herbicides in these areas can be a mistake;
      4. Most PRE corn herbicides can also be applied early POST, but most PRE soybean herbicides cannot, including anything containing metribuzin, flumixazin, sulfentrazone, or saflufenacil.  Soybean herbicides with substantial residual activity on at least some weeds, which can be applied POST, include Scepter, imazethapyr (Pursuit), FirstRate, metolachlor, Zidua/Anthem, Warrant, and Outlook.  Due to widespread ALS resistance or just a narrow spectrum of broadleaf weed control, none of these have any residual activity on marestail or ragweeds; so
      5. A two POST application approach may be more effective in soybeans than trying to make residual herbicides work.
    • This may be a situation where planting green is better than killing the cover ahead of planting and allowing the cover to start to die and degrade.  Rationale for this is that a live cover can continue to use soil water and help create conditions fit for planting, while a dead cover can trap moisture and prevent soil conditions from drying as fast.  One option here is to delay burndown until the crop has been planted, or even until crop has emerged.  Ability to do this in soybeans would depend upon which herbicide resistance traits were present – more complex trait systems would be more effective.
    • We generally do not recommend using Gramoxone to control large covers or large weeds.  Gramoxone is most effective on small weeds and covers (6 inches tall or less). Where Gramoxone might fit would be in a situation where we are able to spray first with a systemic product like glyphosate, but not able to plant for another week or two, and there is additional weed emergence or an incomplete cover crop termination.  This would create a need for a quick burn down with a second burndown pass just before planting, and Gramoxone could be used in the second burndown (with some metribuzin ideally).   
    • Grass covers that are no completely killed by an initial herbicide applications can be controlled with glyphosate POST.  Planting Enlist or Xtend soybeans will provide for the most effective POST options to control legume covers that escape the initial burndown, although high rates of glyphosate can also work.  Glufosinate also has some activity on legumes but will be more variable – use high rates and spray volumes and take steps to otherwise maximize coverage and activity.


  7. Unexpected Damage on Cry1F by European Corn Borer in Nova Scotia, Canada

    In 2018, our entomologist colleagues confirmed unexpected damage to Cry1F corn by European corn borer (ECB) in a few corn fields in Nova Scotia, Canada.  Corn in these fields were single-traited, i.e. they only expressed the Cry1F toxin. There is no indication that any of the other above-ground traits were compromised. (Note: for a list of Bt traits in hybrids see the Bt trait table at https://lubbock.tamu.edu/files/2018/11/BtTraitTableNov2018.pdf). Monitoring will expand this year to see if these ECBs spread outside of Nova Scotia.

    These observations in Nova Scotia should remind us that insects continuously adapt to control tools, and that good insect resistance management (IRM) practices are necessary to prevent resistance.  While it is not entirely clear what factors led to unexpected damage in this case, they likely involved continuous use of a single trait (as opposed to multiple/pyramided traits), a small isolated population, and a lack of refuge compliance. The good news is that all of the other above-ground traits still work well against ECB. Any hybrids that contain Cry1F with an additional above-ground trait should still control ECB. And in Ohio, we have not seen any cases of unexpected damage by ECB on any traited corn.  Nonetheless, we should continue to remember and use IRM and scouting so that these traits remain effective against this important pest.

    For more information on the ECB resistance story in Nova Scotia, please see: http://fieldcropnews.com/2019/05/european-corn-borer-resistance-to-bt-corn-found-in-canada/


  8. CLIMATE SMART: Farming with Weather Extremes

    Save The Date: Thursday July 18, 2019: The Ohio State University Extension and the State Climate Office of Ohio will be hosting CLIMATE SMART: Farming with Weather Extremes, to be held at Der Dutchman in Plain City, Ohio. Agenda and additional details to follow. For more details on how you can sponsor the event, please contact Amanda Douridas (douridas.9@osu.edu; 937-484-1526) or Aaron Wilson (wilson.1010@osu.edu; 614-292-7930).

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.


Amanda Douridas (Educator, Agriculture and Natural Resources)
Andrew Holden (Educator, Agriculture and Natural Resources)
Anne Dorrance (State Specialist, Soybean Diseases)
Chris Zoller (Educator, Agriculture and Natural Resources)
Dean Kreager (Educator, Agriculture and Natural Resources)
Elizabeth Hawkins (Field Specialist, Agronomic Systems)
Harold Watters, CPAg/CCA (Field Specialist, Agronomic Systems)
Jason Hartschuh, CCA (Educator, Agriculture and Natural Resources)
Jeff Stachler (Educator, Agriculture and Natural Resources)
Lee Beers, CCA (Educator, Agriculture and Natural Resources)
Mark Badertscher (Educator, Agriculture and Natural Resources)
Mike Estadt (Educator, Agriculture and Natural Resources)
Mike Gastier, CCA (Educator, Agriculture and Natural Resources)
Peter Thomison (State Specialist, Corn Production)
Sam Custer (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 (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.