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Agronomic Crops Network

Ohio State University Extension


C.O.R.N. Newsletter 2009-05

Dates Covered: 
March 3, 2009 - March 17, 2009
Harold Watters

March blows in

Authors: Jim Noel

March looks to be on track for the typical wild swings. Temperatures this week will start 15-20 degrees below normal with highs in the upper 20s and 30s across the state. By the end of the week and start of the weekend, temperatures will run 15 to 20 degrees above normal with highs from 55-60 northeast to 65-70 southwest. Very limited precipitation is expected this week. From late this weekend into the middle of next week there will be a series of storms that brings an inch to possibly 2 inches of rain. Much colder and drier weather will return later next week into the 3rd week of March with temperatures returning to 5-15 degrees below normal.

Spring is still on track to be slightly cooler and wetter than normal with the greatest chances of wetness in the north part of the state.

Corn Flea Beetle and Stewart’s Bacterial Leaf Blight

Authors: Ron Hammond, Pierce Paul, Andy Michel, Dennis Mills, Bruce Eisley

The bacterium causing Stewart's bacterial leaf blight is carried and spread by the adult corn flea beetles. The beetle over-winters as an adult in the soil near corn fields. Flea beetle adults become active in the spring when the soil temperatures reach 65 F. Adults are most active on sunny, warm, windless days. If the adult fed on diseased corn in the late summer or fall, it may carry the bacterium that causes Stewart's disease of corn in its gut over the winter. In the spring as the corn emerges, the flea beetles feed on the young plants and spread the bacterium which in turn causes seedling wilt and leaf blight. The occurrence of Stewart's bacterial disease is totally dependent on the level of bacteria-carrying flea beetle survival over the winter. For many years the winter temperatures have been used to predict the risk of Stewart's disease because higher populations of the flea beetle survive during mild winters than during cold winters. The 'flea beetle index' is calculated as the sum of the average temperatures (Fahrenheit) of December, January and February.

- Index values less than 90 indicate negligible disease threat,
- 90-95 indicate low to moderate levels,
- 95-100 indicate moderate to severe and
- values over 100 predict severe disease threat.

We checked the average temperature for those months at several locations in Ohio to determine the risk level according to the 'flea beetle index' for 2008. The locations and the corresponding indexes were: Wooster (OARDC), 79.6; Ashtabula, 79.8; Hoytville (Northwest Research Station), 80.0; South Charleston (Western Research Station), 83.7; Jackson, 93.6; and Piketon, 95.1.

Because of a relatively cold January, much colder than normal, the index values are lower than we often see. Thus, these numbers indicate that the risk of Stewart's bacterial leaf blight should be low in much of Ohio, with only southern Ohio considered to have a low to moderate threat.

As always, we would still recommend that growers scout for flea beetles, especially if they have planted a hybrid that is susceptible to Stewart's disease. For growers wishing to take preventive action against flea beetle, a commercially applied insecticide seed treatment such as Cruiser and Poncho are labeled for flea beetles. You can see pictures of flea beetle injury and Stewart’s bacterial blight, and get additional information on Stewart's disease of corn, on the Ohio Field Crop Disease web site at Additional information on the flea beetle can be obtained from OSU Extension Fact Sheet CV-1000-94.

Ohio Wheat Crop Looking Good for February

Authors: Dennis Mills, Pierce Paul, Jim Beuerlein

The 2009 wheat crop got planted in a timely manner last fall and has survived the harsh weather of December-February. When last seen in the fall before the first snow there was no observable disease and the populations were ideal in the fields we visited. The same conditions exist now that the snow has melted which means the yield potential is maximum at this time. However, March is always a very stressful time for wheat due to the rapid changes in air temperatures, potential for soil heaving, flooding, etc. Long term (4 months) weather is not predictable and wheat yields in Ohio are totally a function of the weather because most producers provide all the inputs needed for high yields. Over the past ten years producers have greatly improved their wheat management and the state average yield has jumped ten bushels per acre. Some producers are so excited about the potential for big yields they purchase and apply inputs that are not needed, thus reducing their profits.

In order to maximize profit through adequate input utilization, some producers are interested in using late-winter/early-spring tiller counts to estimate grain yield in an effort to make management decisions. Methods are available that can be used to estimate yield based on early-season tiller counts (, however, these estimates are not very reliable, and are based on several assumptions that are not always accurate. Moreover, methods developed for one location are generally not transferable to another, and as such, may be highly imprecise. For instance, to estimate yield based on the number of tillers per foot of row during early spring, you would need to make assumptions about the number of heads produced per foot of row, the average number of kernels produced per head, and the size (weight) of the kernel. These yield components are difficult to determine early in the season because they vary from one location to another, from one variety to another, and are affected by stresses caused by pests, diseases, and weather conditions. The size of the developing wheat head and the number of spikelets per head are determined shortly after green-up (by Feekes growth stage 5), however, weather and stress conditions during the spring and early summer affect the length of the grain fill period, and as a result, the size of the kernels. Even if nitrogen is applied at the correct rate and time and pests and diseases are controlled, yield may still be low if conditions during grain fill are hot and dry. This makes it difficult to estimate yield based on early-spring stand count.

In general, if 20-30 pounds of nitrogen was applied at planting, then we have till the first of May to make our spring application, thus no need to risk the loss of nitrogen applied in March-early April or the cost of split applications. Nitrogen is very mobile, so we don't need good coverage of the leaf tissue. Applications of 28% should be made with very large flood jets and just enough pressure to produce a good application pattern, which produces a reduced number of very large droplets and reduced leaf burn. Stream bars for 28% application will also greatly reduce crop damage. Urea application rarely causes leaf burn.

There are very few wheat fields in Ohio that will benefit from an application of Sulfur which is recommended only for very coarse textured soil with less than one percent organic matter.

Check fields in early April or prior to the application of spring nitrogen to be sure the crop is in good condition and a keeper. Scout for disease throughout May and for insect during June and apply pesticides if infection thresholds are reached. To get the highest test weights and grain quality, start harvesting when the grain moisture drops below 18 percent and air dry it in a storage bin to preserve the grain test weight and quality.

Sulfur Fertilization of Winter Wheat in Ohio

Authors: Keith Diedrick, Robert Mullen

A lot of us have heard that the atmosphere and subsequent precipitation are suppliers of sulfur, where airborne sulfur dioxide dissolves and falls to the soil surface as sulfate, the form of sulfur preferred by plants. The amount of sulfur deposited on the surface of the Earth has dropped by half in the last 30 years since the adoption of the Clean Air Act, so do we need to supplement sulfur to maintain our crops today?

In short, most likely not at this time. Sulfur deficiencies are most likely to occur in soils that are coarse textured (sandy) with very low organic matter. Sulfur comes from precipitation as mentioned above, but another significant source of sulfate comes from microbial decomposition of organic matter. Observing your crops over the years and performing tissue and soil analysis will aid in determining the need for sulfur.

In replicated research done in Ohio over the years (as well in our neighboring states), wheat grain quality and yield improvements are rarely and inconsistently realized when sulfur (as ammonium sulfate or gypsum) was supplemented in the system. Most yield improvements in wheat seem to be due to using the varieties adapted to your fields, planting date, and nitrogen rates.

In addition to input costs, soil acidification concerns exist with long-term and heavy use of elemental sulfur (the yellow powder), ammonium sulfate, ammonium thiosulfate, and potassium sulfate fertilizers. This is not an issue for our blueberry and azalea producers who use sulfur for this purpose, however, wheat performs best in soils from pH 6.2 to 6.7.

In most Ohio soils, sulfur is in sufficient levels to avoid limitation of yield. Unless you have coarse-textured, very low OM soils where it is economically beneficial, we do not recommend applying sulfur fertilizers to soft red winter wheat in Ohio.


Havlin, J.L., et al. 1999. Soil Fertility and Fertilizers, 6th ed. Prentice-Hall, Upper Saddle River, NJ.

OSU Extension. 2005. Ohio Agronomy Guide 14th ed. Ohio State University Extension, Columbus, OH.

Red Clover Cover Crops – Nitrogen Contributions or Rotational Benefits?

Authors: Robert Mullen, David Henry

Nitrogen prices continue to be matter of discussion these days even though prices have eased since late last summer, but unfortunately corn prices also fell over the same time period. With these higher fertilizer prices, producers may be considering alternative methods such as cover crops for capturing some nitrogen to decrease the need for supplemental commercial fertilizer. As we have written in the past (CORN article), we are still concerned about just how much nitrogen can be captured and subsequently released.

Ohio State University has established field trials that last couple of years to determine just how much nitrogen one might expect from a legume crop established during or after wheat prior to corn planting. Experimental plots have been at OARDC’s Northwest and Western Research Stations. At the Northwest location, red clover has been interseeded at a rate of 10 pounds per acre into an established wheat planting in early/mid March. The red clover stand is terminated in the mid/late fall with either tillage or a herbicide. In 2005, the red clover stand was a complete failure due to the exceptional wheat crop and dry conditions after wheat harvest. In 2007, we observed a significant yield increase due to the presence of the red clover (18 bu/acre with no-till and 26 bu/acre with tillage), but the rate of nitrogen that had to be supplemented was essentially the same between the cover crop and no cover treatments. This illustrates a rotational benefit rather than a nitrogen contribution. In 2008, the tilled red clover treatment showed a slight nitrogen benefit with an increased yield at the check N rate (approximately 20 lb of nitrogen per acre contributed), but the no-till red clover treatment revealed a rotational benefit (10 bu/acre). Based on the information from this location, only 1 out of 2 years when we established red clover did we observe any nitrogen contribution from the red clover treatment, and the N contribution was only noted when the red clover was incorporated with tillage. It should be noted however that in both years (when we got the red clover established) we did observe a rotational benefit of at least 10 bu/acre when red clover was seeded into an established wheat stand.

At the Western location, red clover has been seeded after wheat harvest in early/mid August. The red clover has been allowed to grow through until early spring when the stand is terminated with either a herbicide application or tillage. In 2007, neither a nitrogen contribution nor a rotational could be identified. In 2008, a significant N contribution was noted especially for the no-till red clover treatment (about 60 pounds of N per acre). A nitrogen contribution was also noted for the tilled treatment but the amount of N contributed was not as dramatic. Based on the information collected at this site we observed a nitrogen contribution 1 out of 2 years with the maximum amount being 60 pounds of nitrogen per acre. We did not observe a rotational benefit at this location in either year.

Take home message – our data does not suggest dramatically cutting nitrogen rates when a cover crop is established (perhaps 30 pounds of nitrogen), but we have not identified conditions when the nitrogen contribution is more likely to occur. It does appear that in the poorly drained soils of northwest Ohio that a rotational benefit is likely to be observed when a legume cover crop is planted. These cover crops do not come without a cost. Seeding costs will be incurred as well as herbicide applications will be required to terminate stands. These costs should not be overlooked when considering the use of a cover crop.

Arrested ears and other ear oddities revisited

Authors: Peter Thomison

In 2007, and to a lesser extent 2006, there were localized reports of “arrested ear” development in several Corn Belt states, especially Illinois and Indiana. Arrested ears were characterized by a range of symptoms. Some ears exhibited varying degrees of stunting with limited kernel formation. Some ear shoots carried either no ear or only the short remnant of an ear. Often silks were absent or limited.
Arrested ears usually occurred in fields that had been treated with various fungicides, herbicides, insecticides, foliar nitrogen, and various spray additives. However, some of the most pronounced arrested ear damage was associated with foliar fungicide applications made with ground equipment during the two week period prior to tasseling. In the various postmortem assessments, it was noted that arrested ear injury frequently occurred in fields where the foliar treatments included non-ionic surfactants. Now there is preliminary evidence from evaluations conducted in 2008 that suggests that the cause of some of these arrested ear problems may actually be due more to surfactants than fungicides.

Dr. Bob Nielsen at Purdue University evaluated the effects of a number of pesticides and spray additives on ear development in 2008. Three fungicides, one insecticide, a commercial non-ionic surfactant, crop oil concentrate, glyphosate, ammonium sulfate, and 2,4-D were applied in various combinations over the canopy of corn at approximately the V14 stage of leaf development (approximately 5 ft tall and 1 - 2 weeks prior to tasseling). Dr. Nielsen’s demonstrations revealed that neither fungicides alone or in combination with just an insecticide resulted in any severely arrested ears. The addition of crop oil concentrate or non-ionic surfactant to fungicides alone or fungicide + insecticide resulted in a frequency of severely arrested ears ranging from 3 to 35%. Further addition of glyphosate with a fungicide/insecticide/non-ionic surfactant combination resulted in 60% or greater arrested ears. Reductions in cob length ranged from 6 to 48% with the application of the various foliar pesticide and additive combinations.

Dr. Emerson Nafziger at the University of Illinois performed tests that compared an untreated check with a nonionic surfactant applied at the labeled rate of 0.25% and at 0.5% (2X), Headline fungicide at 6 oz per acre applied by itself and with each of the two non-ionic surfactant rates, and CoRoN foliar N by itself, at 4 gallons per acre. The foliar treatments were applied at V13-14. According to Dr. Nafziger, in plots with damage, symptoms ranged from slight ear size reduction and oddly angled ear shanks to complete loss of ears. Most common damage symptoms included "bouquet" ears formed by small ears trying to develop from the same shank as the main ear. The results showed that most of the damage came from the non-ionic surfactant by itself, and that increasing the concentration increased the amount of damage. Headline fungicide by itself did no injury compared to the untreated check, but adding fungicide to the non-ionic surfactant increased the damage by about 10 percentage points. About 10% of the plants in the 0.5% non-ionic surfactant treatment had no ears at all, regardless of whether Headline was used.

In trials conducted at the OSU Western Agriculture Research Station near S. Charleston we evaluated Headline fungicide applications at various vegetative stages including V12-14. Non-ionic surfactants were not included in these treatments. No ear abnormalities or injury was observed.

Results of the Purdue and Illinois work indicate non-ionic surfactants applied at approximately V13-V14 can adversely affect ear development in corn. For more details and some excellent pictures documenting the injury potential from such pretassel applications check the following:

Nafziger, E. 2008. More ear oddities, and a possible cause. The Bulletin, Univ. of Illinois. [on-line]. Available at
(URL accessed 3/2/09).

Nielsen, R.L., W. Wise, C. Gerber. 2008. Arrested ears resulting from pre-tassel applications of pesticide & spray additive combinations. Corny News Network, Purdue Univ. [on-line]. Available at (URL accessed 3/2/09).

2008 County level NASS yields now available

Authors: Harold Watters

The March reports for county level crop production are now available for the 2008 crop year on the National Agricultural Statistics Service website:

Register now for Ohio's Overholt Drainage School

Authors: Harold Watters, Bruce Clevenger, Gary Wilson

We have had several calls on how to get registered for the Overholt Drainage School. Registration is now open until March 18th for the March 23 - 27 program. Check this website for the agenda ( and registration ( form. The event, being held at the Garden Hilton Inn in Wooster, is a continuing education program for land improvement contractors, soil and water conservation technicians, farmers, engineers, consultants, sanitarians and other individuals interested in advancing their knowledge of basic concepts, principles and skills related to the purpose, design, layout, construction and management of water management systems.

For more information, contact Dr. Larry C. Brown at 614-292-3826 or email at

Private Pesticide License Renewal by March 31st

Authors: Glen Arnold, Harold Watters

As March draws to a close farmers should make certain that they have attended the needed recertification training if their private pesticide applicator license expires on March 31st 2009.

In Ohio we have a two-part system for pesticide license renewal: you pay a fee to the Ohio Department of Agriculture and you receive at least three hours of continuing education every three years from OSU Extension. Several private pesticide recertification opportunities remain available across Ohio, but the dates will pass rapidly. They are listed at the Pesticide Education web site:

Farmers who want add a category, or new applicators, can do so by taking an exam at one of the many Ohio Department of Agriculture (ODA) testing locations listed at the web site: This can also be linked from the OSU Pesticide Education website. You can register on-line or by calling ODA before attending a testing session. Their toll free number is 1.800.282.1955.

Archive Issue Contributors: 

State Specialists: Peter Thomison (Corn Production), Anne Dorrance, Pierce Paul and Dennis Mills (Plant Pathology), Ron Hammond, Andy Michel, and Bruce Eisley (Entomology), Mark Loux (Weed Science), Robert Mullen and Keith Dietrick (Soil Fertility), Jim Beuerlein (Soybean & Small Grain Production), and Jim Noel (NOAA). Extension Educators: Jonah Johnson (Clark), Steve Foster (Darke), Greg LaBarge (Fulton), Roger Bender (Shelby), Harold Watters (Champaign), Todd Mangen (Mercer), Glen Arnold (Putnam), Tim Fine (Miami), Gary Wilson (Hancock), Bruce Clevenger (Defiance), Florian Chirra (Williams) and Wesley Haun (Logan).

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.