Corn Newsletter : 2016-08

  1. Corn and Soybean: What’s in Store for 2016?

    This “spring,” the weather has gone from snow and 24 degrees to sunny and 80 degrees within one week. This unusual weather leaves many of us wondering what’s in store for the remainder of the growing season.

    In general, unfavorable weather conditions tend to affect soybean yield much less compared to corn yield. In 2012, when we experienced a hot, dry summer, corn yield was reduced by 23% while soybean yield was only reduced by 8% (see the table below). However, under more optimum weather conditions, corn yield gains are much greater compared to soybean. With more ideal weather in 2013 and 2014, corn yield increased 12-14% while soybean yield only increased 2-8%.

    Table 1. Corn and soybean grain yield averages for Ohio compared to the 5-year average (data from USDA National Agricultural Statistics Service).


    Corn (bu/acre)

    Soybean (bu/acre)


    153 (-1%)

    50 (+2%)


    176 (+14%)

    53 (+8%)


    174 (+12%)

    50 (+2%)


    120 (-23%)

    45 (-8%)


    153 (-1%)

    48 (-2%)

    5-Year Ave.



    Soybean Perspective. Despite the weather, the state soybean yield does not tend to fluctuate much. Soybean vegetative and reproductive stages overlap allowing the soybean plant to compensate for short periods of stress (see the figure). In 2012, while plants were stunted and there was an increased number of flower abortion due to hot/dry weather conditions, soybean yield was “saved” in many areas of the state due to rainfall in August and September promoting seed fill.  (This was especially true of our later maturing varieties.)

    Corn Perspective.

    With the weather forecast calling for “slightly-above” normal temperatures and “slightly below precipitation” for the remainder of April and similar conditions for May, this year offers an opportunity to plant corn at optimum calendar dates for yield. The recommended time for planting corns across Ohio is mid-April through about the first week of May. Grain yield and test weight are increased by early plantings, whereas grain moisture is reduced, thereby allowing earlier harvest and reducing drying costs. In central Ohio, yields decline approximately 1 to 1.5 bu/day for planting delayed beyond the first week of May. Early planting generally produces shorter plants with better standability. Delayed planting increases the risk of frost damage to corn and may subject the crop to greater injury from various late insect and disease pest problems, such as European corn borer and gray leaf spot. With earlier planting, vegetative growth is usually complete and pollination initiated prior to the period of greatest moisture stress in July and grain filling occurs during the periods when solar radiation is high which promotes greater accumulation of dry matter in the grain.

    No-tillage corn can be planted at the same time as conventional, if soil conditions permit. In reality, however, planting may often need to be delayed several days to permit extra soil drying. Corn should be planted only when soils are dry enough to support traffic without causing soil compaction. The yield reductions resulting from "mudding the seed in” may be much greater than those resulting from a slight planting delay. Moreover, given the weather projections for drier and warmer conditions than normal, even with such delays, the crop may be planted before the optimum plant date window ends.

    There have been occurrences in past years when early to mid-April planting were adversely affected by an abrupt transition from warm, dry conditions to freezing rains and snow. When dry corn seed absorbs cold water as a result of a cold rain or melting snow, “imbibitional chilling injury” may result. Such injury in corn seed can lead to delayed seedling growth and reduced stands so planting right before such large temperature swings should be avoided.

    Appropriate planting depths for corn vary with soil and weather conditions. There is a perception that shallow planting depths (less than 1.5 inches) are appropriate for early plantings - when soil conditions are usually cool and moist - because seed will emerge more rapidly due to warmer soil temperatures closer to the surface. However, planting shallower than 1.5 inches is generally not recommended at any planting date or in any soil type. Recent Ohio studies that evaluated corn response to seeding depth provide no evidence to support shallow plantings. For normal conditions plant corn at 1.5 to 2-inches deep to provide frost protection and allow for adequate root development. When corn is planted 1.5 to 2 inches deep, the nodal roots develop about 0.5 to 0.75 inches below the soil surface. At planting depths less than 1 inch, the nodal roots develop at or just below the soil surface. Excessively shallow planting can cause slow, uneven emergence due to soil moisture variation, and rootless corn (“floppy corn syndrome”) when hot, dry weather inhibits nodal root development. Shallow plantings increase stress and result in less developed roots, smaller ears and reduced yields.

  2. Warm Weather Hit in a Big Way This Last Week

    Author(s): Jim Noel

    After a cold start to April the warm weather hit in a big way this last week. Temperatures now for Ohio are running 3-5 degrees below normal for April but will likely be down to a degree or two below normal by late this week for April as the warmth cancels out the early April cold. Also, since March first, temperatures are running 2-6 degrees above normal even with that early April cold stretch so this is going down as a WARM spring.

    Rainfall since April 1 is normal to an inch below normal.

    The strong El Nino is quickly fading and will likely be replaced by La Nina this summer. La Nina events usually put stresses on Ohio summer crops so this is worth watching.

    This coming week will remain warm until a storm system brings on average about 0.50 inches of rain late Wednesday into early Friday. If we get far less than 0.50 inches of rain then this could be an early indication of developing dryness. If we get far more than 0.50 inches this could signal continued decent rains into May so this is worth watching closely later this week.

    For the remainder of April temperatures will continue above normal with normal to below normal rainfall. Rainfall averages an inch per week so normal rain is 2 inches. We expect 1-2 inches for the rest of April.

    As for last freeze, as predicted in February and March, it appears the last hard freeze has come about on schedule in April. Indications are we can still expect a few days of frost and light freeze conditions especially north of I-70 but the last hard freeze in the middle 20s and below has probably already occurred.

    Evaporation rates are above normal right now and likely to overall stay above normal into May.

    The outlook for May calls for warmer and drier than normal weather.

    Risk Outlook                       April                       May                       June

    Temperatures                     Slighty Below          Slightly Above        Above

    Rainfall                              Normal                     Below                    Below

    Freeze                              Normal

    4 inch soil                         Normal/Above           Above                     Above

    Evapotranspiration             Normal                     Above                     Above

    The latest outlook for temperatures and precipitation for the region from NOAA/NWS into the end of the month can be seen here and it shows warmer than normal along with wetter in the western corn and soybean areas but normal or drier in eastern areas.


  3. Announcement of Spring/Summer Field Day Dates

    Field days are important learning tools

    Currently 24 field days on a variety of topics are being planned by Agriculture and Natural Resource staff starting June 1 through the fall with locations throughout the state. A complete calendar of dates can be found at Full agendas are still being developed and you will want to check back for registration information along with other details about a month prior to the date.

    An excellent set of field days which include a variety of topics will be presented. Topics include small grains production, hay production, precision agricultural equipment, sprayers, soybean and corn production, modified relay intercropping plus nutrient management which include Fertilizer Applicator Certification Training for several dates.

    The calendar includes a first time event is Ohio. The North American Manure Expo will be held at the Molly Caren Ag/Farm Science Review Site on August 3 & 4. This regionally rotating event is a must attend for those involved with manure spreading and use.

    The field day calendar leads up to the annual Farm Science Review, scheduled for September 20 to 22. As always a variety of displays, demonstration and field activities are being planned.

    These programs are sponsored by Ohio State University Extension and Ohio Agricultural Research and Development Center in the College of Food Agriculture and Environmental Sciences at The Ohio State University.

  4. Time to stock up on nozzles now! But do you know which one to buy?

    Author(s): Erdal Ozkan
    This is the time of the year you must complete shopping for nozzles because the spraying season is just around the corner. Although nozzles are some of the least expensive components of a sprayer, they hold a high value in their ability to influence sprayer performance. Nozzles meter the amount of liquid sprayed per unit area, controlling application rate, as well as variability of spray over the width of the sprayer boom. Nozzles also influence droplet size, affecting both target coverage and spray drift risk. Nozzles come in a wide variety of types and sizes. The best nozzle for a given application will maximize efficacy, minimize spray drift, and allow compliance with label requirements such as application rate (gallons per acre) and spray droplet size. Selecting the best nozzle requires careful consideration of many important factors including: sprayer operation parameters (such as application rate, spray pressure, travel speed); type of chemical sprayed (herbicides, insecticides, fungicides); mode of action of chemicals (systemic, contact); application type (broadcast, band, directed, air assisted); target crop (field crops, vegetables, vineyard, shrubs and trees, etc.); and spray drift risk. A new Ohio State University Extension Publication, entitled “Selecting the Best Nozzle for the Job” gives step-by-step guidelines for selecting the most appropriate spray nozzle for a given application situation. The publication is available online at following web site:

    Which nozzle type is best your situation?

    There is a large type of nozzles to choose from. Each nozzle type is designed for a specific type of target and application. For example, a nozzle designed for broadcast spraying is not good for spraying pesticides over a narrow band. While one nozzle may be best for a given situation, it may be worst choice for another. For example, we at Ohio State University have conducted field experiments to determine which nozzles to choose for two different application situations: soybean diseases such as rust and white mold, and wheat diseases such as head scab and stem rust. We included 6-8 different nozzles in the experiments. We found out that while a twin-fan pattern nozzle was best for controlling wheat head scab, the same nozzle turned out to be the worst choice to protect soybeans against rust and white mold when the soybean canopy is tall and dense. So, before buying the nozzles and putting them on the boom, check the nozzle manufacturers’ catalogs which have charts showing which nozzle type will be best for a specific job. Check the websites of nozzle manufacturers to reach their catalogs.

    Nozzle size

    Once you determine the type of a nozzle you need to buy, you also must buy the right size of that nozzle which will satisfy the application rate (gallons per acre or gpa) you wish to use as you do your spraying at different travel speeds. Nozzle catalogs ar filled with tables and charts showing application rates, given a nozzle’s flow rate (gallons per minute or gpm) delivered at various pressures (psi) and travel speeds (mph). These tables are useful tools for selecting the appropriate nozzles, pressure and speed to spray chemicals at application rates prescribed by product labels. However, the charts are only for a limited number of travel speed and nozzle spacing situations. There may be situations where the charts will not provide information associated with your sprayer setup (nozzle spacing) and operating conditions (travel speed and spray pressure). The Apps developed by most of the major nozzle manufacturers can provide you the exact nozzle flow rate required for any given set of application parameters, and identify a specific set of nozzle recommendations for the given application parameters. To find these Apps, simply visit the App Store in your smart phone or tablet and do a search under “Spray Nozzle Calculator”, or some other key words related to nozzle size selection. You may also want to do a search under the name of the nozzle company from which you are interested in buying the nozzles. However, some Apps are not user friendly and sometimes they do not take into account the droplet size requirements when recommending nozzles. Although the Apps and tables in catalogs may expedite the nozzle size selection process, it is best to understand the procedure and the math nozzle manufacturers use to generate the values listed in tables and to recommend nozzles in their Apps. The procedure used by the nozzle manufacturers to generate numbers in tables and in their Apps is explained below. By following the steps mentioned in the new OSU Extension publication mentioned above (AEX-528) you will be able to determine the exact nozzle flow rate (gpm) required for your spray application parameters. Once the exact nozzle flow rate is determined, you can then look at the catalog to select the nozzle that will provide you the flow rate at a practical pressure setting.

    Keep several types of nozzles on the boom

    Remember that one specific type of nozzle will not be best for all applications. For this reason, it is best to have several types and sizes of nozzles on the boom so that you can switch to the “best” nozzle choice for a given spraying job. As shown in the pictures below, there are various types of sprayer components and setups you can buy to configure your boom so the new set up allows you to easily switch from one nozzle to another instantly.

    Keep spray drift in mind when selecting nozzles

    One of the major problems challenging pesticide applicators is spray drift, which is defined as movement of pesticides by wind from the application site to an off- target site. Drift is influenced by many factors which are discussed in detail in OSU Extension publication Bulletin 816. To find any OSU Extension Publication, go to the following web site, and do a search using some key words, such as “spray drift”, “nozzles”, “calibration”, or my last name “ozkan”:

    Equipment, especially the nozzles, used to spray pesticides play a significant role in generating as well as reducing spray drift. In nozzle catalogs, you can see a number of different nozzles of the same type, in terms of spray pattern. For example, one can find nozzles within the same “flat-fan” category classified as “low-drift.” Research conducted at Ohio State and elsewhere clearly indicate that nozzles labeled as “low-drift” significantly reduce spray drift.  If drift is, or becomes a concern, it may be best to switch from a conventional flat-fan nozzle to a “low-drift” flat-fan nozzle with the same flow rate. Therefore, it is best to have more than one type of a “flat-fan” pattern nozzle on the boom.

    Some final thoughts

    Nozzles are typically the least costly items on a sprayer, but they play a key role in the final outcome from a spraying job: achieving maximum efficacy from the pesticide applied while reducing the off-target (drift) movement of pesticides to minimum. Pesticides work well if the rates on labels are achieved during application. This can be achieved only if the right nozzle type and the proper size of the nozzles are on the sprayer, and the sprayer is operated properly.

    Although the Apps and tables in catalogs may expedite the nozzle size selection process, it is best to understand the process and the math nozzle manufacturers use to generate the values listed in tables, and to generate nozzle recommendations in their Apps. This procedure, explained in this new OSU Extensin Publication (AEX-528) hopefully will help you to determine the exact nozzle flow rate (gpm) required  for your spray application parameters, while highlighting some other important parameters such as spray pressure, droplet size, spray coverage on the target, and drift, all of which should be given serious consideration when selecting the best nozzle for a spraying job.

    Erdal Ozkan, Professor and Extension ag engineer, can be reached at 614-292-3006, or


About the C.O.R.N. Newsletter

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 Bennett (Miami County)
Amanda Douridas (Champaign County)
Andy Michel (State Specialist, Entomology)
Anne Dorrance (State Specialist, Soybean Diseases)
Bruce Clevenger, CCA (Defiance County)
Clifton Martin (Muskingum County)
Debbie Brown, CCA (Shelby County)
Dennis Riethman (Mercer County)
Ed Lentz, CCA (Hancock County)
Eric Richer, CCA (Fulton County)
Flo Chirra (Williams County)
Greg LaBarge, CPAg/CCA (Field Specialist, Agronomic Systems)
Harold Watters, CPAg/CCA (Field Specialist, Agronomic Systems)
Jeff Stachler (Auglaize County)
Lee Beers, CCA (Trumbull County )
Mark Badertscher (Hardin County)
Mark Loux (State Specialist, Weed Science)
Mary Griffith (Madison County)
Mike Gastier, CCA (Huron County)
Pierce Paul (State Specialist, Corn and Wheat Diseases)
Sam Custer (Darke County)
Sarah Noggle (Paulding County)
Steve Culman (State Specialist, Soil Fertility)


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.

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