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Agronomic Crops Network

Ohio State University Extension


C.O.R.N. Newsletter 2013-06

Dates Covered: 
March 26, 2013 - April 1, 2013
Steve Prochaska

Now is the Time to Fine Tune Your Sprayer

Higher pesticide costs and new chemicals designed to be used in lower doses make accurate application more important than ever. There is no better time than early spring to take a closer look at your sprayer. Here are some of the things I would check on a sprayer to achieve efficient and effective application of pesticides:

 •Double-check your sprayer for mechanical problems before you start using it.  You won’t have time to do this when planting is in full swing. 

•Clean the sprayer tank thoroughly and make sure nozzle filters are clean. 

•Clean spray nozzles, check their flow rates, and replace the ones that are spraying more      than 10 percent of the original output. 

•Check the agitator in the tank to make sure it’s working properly. 

•Run water through the spray system to make sure everything is working properly 

•Find out if the sprayer is delivering the proper application rate (gallons per acre).  

One can determine if the chemicals are applied at the proper rate only by carefully calibrating the sprayer. Calibration, perhaps more than anything else, will have a direct impact on achieving effective pest control and the cost of crop production. While applying too little pesticide may result in ineffective pest control, too much pesticide wastes money, may damage the crop and increases the potential risk of contaminating ground water and environment. Results of "Sprayer Calibration Clinics" I participated in Ohio, and data from several other States show that only one out of three to four applicators are applying chemicals at a rate that is within 5 % (plus or minus) of their intended rate (an accuracy level recommended by USDA and EPA). Of those two-thirds of the applicators missing the mark, about half is under spraying while the other half is over spraying. In one particular case, the applicator would be over spraying by as much as 75% had he used the nozzles that he just purchased and installed on the boom.  

Sprayers should be calibrated several times a year. Changes in operating conditions and the type of chemical used require a new calibration. Frequent calibration is even more important with liquid application because nozzles wear out with use, increasing the flow rate. Over a decade ago, my colleagues at University of Nebraska conducted an interesting survey. The survey results revealed that there is a direct positive correlation between application accuracy and the frequency of calibration. Approximately 67 percent of the operators who calibrated before every spray operation had application errors below 5 percent. Only 5 percent of the applicators who calibrated their equipment less than once a year (once every two, three, four years) achieved the same degree of application accuracy.            

There are several ways to calibrate a sprayer. Regardless of which method you choose, it usually doesn’t take more than 30 minutes to calibrate a sprayer, and only three things are needed: a watch or something to count seconds, a measuring tape, and a jar graduated in ounces. I will go over an easy way to calibrate a sprayer in the next issue of the newsletter. In the mean time, you can check the OSU Extension publication on boom sprayer calibration. Here is the URL for this publication:

Here is an Easy Way to Calibrate your Sprayer

This is the time to check the accuracy of your sprayer. One can determine if the chemicals are applied at the proper rate only by carefully calibrating the sprayer. While applying too little pesticide may result in ineffective pest control, too much pesticide wastes money, may damage the crop and increases the potential risk of contaminating ground water and environment. The primary goal with calibration is to determine the actual rate of application in gallons per acre, then to make adjustments if the difference between the actual rate and the intended rate is greater or less than 5% of the intended rate. This is a recommended guideline by USEPA and USDA. 

Calibrating a boom sprayer is not as difficult as it sounds. It usually doesn’t take more than 30 minutes, and only three things are needed: a watch showing seconds, a measuring tape and a jar that measures ounces. 

Before starting calibration, make sure you have a good set of nozzles on the sprayer. Nozzles wear off through extended use causing over application, or some nozzles are plugged. Clean all the plugged nozzles. Check the output of all the nozzles for a given length of time at a given spray pressure. Compare output from each nozzle’s output with the expected output shown in the nozzle catalog for that nozzle at the same pressure. Replace the nozzles showing an output error of more than 10% of the output of the new nozzle. Once you do this, now you are ready to calibrate your sprayer.  

There are several ways to calibrate a sprayer. Regardless of which method you choose, it usually doesn’t take more than 30 minutes, and only three things are needed: a watch showing seconds, a measuring tape, and a jar graduated in ounces. Here, I will describe perhaps the easiest of all the methods to calibrate a sprayer. 

To calibrate a boom sprayer for broadcast applications using this method, follow these steps:

  1.   Fill the sprayer tank (at least half full) with water.

  1. Run the sprayer, inspect it for leaks, and make sure all vital parts function properly.
  2. Measure the distance in inches between the nozzles.
  3. Measure an appropriate travel distance in the field based on this nozzle spacing. The appropriate distances for different nozzle spacing is as follows: 408 ft for a 10-inch spacing, 272 ft for a 15-inch spacing, 204 ft for 20-inch spacing, 136 feet for a 30-inch spacing, and 102 feet for a 40-inch spacing. (See extension publication AEX-520 for travel distances for other spacings, and for an explanation for selection of these specific travel distances for given nozzle spacing (
  4. Drive through the measured distance in the field at your normal spraying speed, and record the travel time in seconds. Repeat this procedure and average the two measurements.
  5. With the sprayer parked, run the sprayer at the same pressure level and catch the output from each nozzle in a measuring jar for the travel time required in step 5 above.
  6. Calculate the average nozzle output by adding the individual outputs and then dividing by the number of nozzles tested. The final average nozzle output in ounces you get is equal to the application rate in gallons per acre. For example, if you catch 15 ounces from a set of nozzles, the actual application rate of the sprayer is equal to 15 gallons per acre.
  7. Compare the actual application rate with the recommended or intended rate. If the actual rate is more than 5 percent higher or lower than the recommended or intended rate, you must make adjustments in either spray pressure or travel speed or in both. For example, to increase the flow rate you will need to either slow down, or increase the spray pressure. The opposite is true when you need to reduce application rate. As you make these changes stay within proper and safe operating condition of the sprayer. Remember increased pressure will result in increasing the number of small, drift-prone droplets. Using the trial-and error method to eventually reach the intended application rate takes some time. If you follow the equations given in Extension Publication AEX-520 on Calibration you can find optimum travel speed and pressure much faster.
  8. Recalibrate the sprayer (repeat steps 5-8 above) until the recommended application error of +5% is achieved.
Asiatic Garden Beetle Asiatic Garden Beetle

Asiatic Garden Beetle

Last year we reported on the first known instance of Asiatic garden beetle grubs causing significant stand losses in corn in northern Ohio just below Lake Erie.  These problems were in corn following soybean, and in fields that had sandier soils.  Further surveying indicated that these stand losses extended from south of the lake westward to northeast Indiana and southwest Michigan, areas of two other states that have experienced similar problems the past few years.  Finally, similar stand losses were found to have been more common the previous 4-5 years.  

At this time, there is not much in the way of sampling available to determine the potential for stand loss except for digging soil prior to planting looking for the presence of these grubs.  Individual grubs are smaller than most other grubs, can be quite active, and possess a whitish globular structure on both sides of its mouth (see photos at and ).  

If numerous grubs are found, or if you have experienced such stand losses in prior years, you might want to consider taking action, although not much information is known on best management practices.  It was obvious from last year that neither transgenic corn hybrids offer control (which was expected) nor seed treatments.  The latter was a disappointment because we would have hoped they would work.  However, all the affected fields were transgenic corn hybrids that all had an insecticide seed treatment already applied; thus, neither of these tactics can be counted on to provide control.

At this time, the best chance of grub management would probably be with a granule or liquid soil insecticides that have grubs on their labels.  There is not much information available on how well these products work on the Asiatic garden beetle, mainly because it is such a new pest and good tests have yet been conducted.  But at this time these soil insecticides at least offer a hope.  We would ask any growers who use them leave some untreated strips in their fields to see how well the products work.  We would love to hear how well the insecticides work in real world conditions.


Protecting Bees during Spring Planting Protecting Bees during Spring Planting

Protecting Bees during Spring Planting

Last year we brought up concerns with possible bee kills from the use of neonicotinoid seed treatments when planting corn.  The neonicotinoids, when applied to the seed, get mixed with the talc that is used to allow seeds to flow more easily in the planters, and then the insecticides plus talc enter the environment during planting or when the seed boxes are cleaned.  This “dust” can settle on flowering plants and weeds that bees will use for forage, or perhaps contact the bees or nearby hives directly resulting in bee mortality.  

Although much work and study is ongoing and still needed on the extent of this problem, there are certain practices that growers can use that can help limit bee exposure to these neonicotinoids.  The following suggestions are those being recommended by numerous groups and people, including Bayer (the manufacturer of clothianidin or Poncho), and from information received from our neighbors to the north in Ontario, Canada.  To see further ideas on limiting bee’s exposure, see Bayer’s Bee Health Care website and read the brochures that are available (   

First, know where beehives are located and remember that bees can forage up to 3 miles from their hive.  Communication among growers, seeders and beekeepers on the timing of planting and the location of hives can help reduce the risk of bee incidents. Such communication can enable beekeepers to confirm that hives are located upwind or in shelter belts and have access to clean water sources. It can also permit beekeepers to temporarily protect or relocate hives where this is feasible. Then, the following are suggestions that growers should consider: 

During Preplant

  • Avoid generating dust when handling treated seed, pouring seeds carefully into the planter in such a way as to avoid the transfer of dust from the seed bag; do not shake any loose material or dust from the seed bag into the planting equipment,
  • Control flowering weeds before planting so that foraging bees are not attracted to the field during planting,
  • Check that treated seed and coating are of high quality; seeds should be clean and the coating should be well-adhered to the seeds,
  • Handle bags with care during transport, loading and unloading in order to reduce abrasion, dust generation and spillage,
  • Use planting equipment that ensures a high degree of incorporation of seed into the soil and that minimizes spillage and dust emission, and where air exhaust is directed into the ground along with the seed, and
  • Because seed flow lubricants may affect the generation of dust during planting; carefully follow use directions 

During Planting

  • Plant in the early morning or in the evening when bees are not foraging,
  • Avoid planting treated seed in windy and/or very dry conditions; consider wind direction and avoiding planting treated seed if bee-attractive flowers are downwind,
  • Make sure seed is placed into the soil and not exposed, especially at row ends and corners 

During Disposal and Cleanup

  • Spilled or exposed seeds and dust should be incorporated into the soil or otherwise cleaned- up from the soil surface,
  • Do not leave empty bags or left-over treated seed in fields or the environment.
  • Do not clean planting equipment near bee colonies, or bee-attractive flowering crops or weeds,
  • Use broom or shop vacuum to properly dispose of any dust or treated seed in planting equipment, and if compressed air is used, take care to minimize dust release
  • Properly dispose of any dust or treated seed remaining in planting equipment, and (for example, empty into a container and vacuum any dust remaining in the hopper).

Cold Extended Weather Forecast

Everything remains on track for the overall colder pattern to remain intact into the first half of April before things moderate. The good news is after the early week snow, temperatures will moderate to normal or slightly warmer than normal for Easter weekend. Highs will reach the 50s and some spots in southern Ohio and Indiana may reach 60. The bad news is it will not last.  A cooler than normal weather pattern will return in early April. The National Weather Service Climate Forecasting System week 1 and week 2 temperatures can be found here:

The Natiional Weather Service Climate Forecasting System week 3 and week 4 temperatures can be found here:

Expect 4 inch soil temperatures to be below normal in April which may delay planting some. Finally, the risk for late season freezes in April is also elevated based on the coldest month of March records.

Ohio No-Till Field Day

The Spring Ohio No-Till Field Day will be held on April 10, 2013, on the David Brandt farm located at 6100 Basil Western Road, Carroll, OH 43112.  This program is presented by: Ohio No-Till Council, Cover Crop Solutions and Walnut Creek Seeds. 

Sponsors for this program  include: OSU Extension and OARDC, NRCS-USDA, Ohio Country Journal, Ohio Corn & Wheat Growers Assoc., and Ohio Soybean Council. Other contributors  of this program include: Bird Hybrid; Suma Grow liquid fertilizer; United Landmark, JD Equipment, Mayer Equipment; Franklin Equipment; and David Mast. 

Registration fee is $35 by April 3 or $50 at the door.  To register and view the program agenda, go to  or call 740-756-4436.  

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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.