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Agronomic Crops Network

Ohio State University Extension


C.O.R.N. Newsletter 2013-31

Dates Covered: 
September 16, 2013 - September 23, 2013
Debbie Brown

Weather Update for Mid/Late September

The overall trend remains in place for above normal temperatures and below normal rainfall for the rest of September.

Temperatures are expected to average 1-5 degrees above normal through late September.  So temperatures will be above normal but not to the extreme levels of earlier this month. Normal highs are 70-75 and normal lows are near 50.

Rainfall will return for the second half of this week with a fairly widespread 0.50 to 1.00 inches across Ohio. Isolated totals will be higher.

After the rain later this week, it appears it will not be until the end of the month before the next rain event.

The latest 16-day rainfall outlook can be found at the NWS Ohio River Forecast Center website:

The Intelligent Sprayer Developed at Ohio State University Making Debut at FSR

The intelligent sprayer, developed by Engineers at the College of Food Agricultural and Environmental Sciences at Ohio State, and engineers at USDA-ARS at Wooster campus of the College (OARDC), is making its début at the Farm Science Review. This is the only sprayer of its kind in the world. It discharges pesticide sprays only when there is a target tree in sight, and it matches the pesticide spray rate to the target tree characteristics (height and leaf density) in real-time. A high speed laser scanner provides canopy characteristics of a tree. The intelligent sprayer is displayed at Farm Science Review, just south of the Farm Science Review Headquarters office.

 Variable-rate applications using this intelligent sprayer can greatly reduce pesticide use and off-target contamination of environment for nursery and orchard growers. Field experiments demonstrated that compared to conventional sprayers, the intelligent sprayer provided more uniform spray coverage and deposition inside canopies with different foliage densities at different growth stages. In addition, the intelligent sprayer reduced spray volume by 47–73% with much less off-target loss on the ground, through tree gaps and in the air.

By accurately targeting spray applications, this new technology will significantly reduce the amount and cost of pesticides for growers, reduce the risk of environmental pollution by pesticides, and provide safer and healthier working conditions for workers.

Advantages of the intelligent sprayer over a conventional sprayer:

● Less chance of over spraying pesticides

● Less variations of spray deposition with growth stages

● More consistent spray deposition uniformity inside canopies at different growth stages

● Better spray trajectory control

● Less spray loss beyond tree canopies (40–87% less loss)

● Less airborne drift (up to 87% less drift)

● Reduction of the spray consumption (47–73% less spray mixture used)

● Less spray loss on the ground (68–93% less loss)

Evaluating Corn Hybrid Demonstration Plots Hybrid demonstration plots

Evaluating Corn Hybrid Demonstration Plots

This is the time of year when many farmers visit and evaluate hybrid demonstration plots planted by seed companies and county Extension personnel, among others. When evaluating these plots, it’s important to keep in mind their relative value and limitations.

Demonstration plots may be useful in providing information on certain hybrid traits that are usually not reported in state corn performance summaries. The following are some traits to consider when examining hybrid demonstration plots.

 PLANT/EAR HEIGHT. Corn reaches it maximum plant height soon after tasseling occurs. Remember that although a big tall hybrid may have a lot of "eye appeal," it may also be more prone to stalk lodging in the fall. Unless your interest is primarily silage production, increasing plant height should not be a major concern. Generally later maturity hybrids are taller than earlier maturity hybrids. Big ears placed head high on a plant translate to a high center of gravity, predisposing a plant to potential lodging. The negative effects of stalk rot on stalk lodging in the fall may be worsened by high ear placement. Plots that have been subjected to early season (V7 or earlier) defoliation caused by hail or frost often have lower than normal ear height.

 STALK SIZE. Generally speaking, a thicker stalk is preferable to a thinner one in terms of overall stalk strength and resistance to stalk lodging. As you inspect a test plot, you will see distinct differences among hybrids for stalk diameter. However, also check that the hybrids are planted at similar populations. As population increases stalk diameter generally decreases. Also keep in mind that uneven emergence and development may make such comparisons difficult because late emerging plants are “spindlier”.

 DISEASES. During the grain fill period, leaf diseases can cause serious yield reductions and predispose corn to stalk rot and lodging problems at maturity. Ear rots can also impact yield and grain quality. The onset of leaf death shortly after pollination can be devastating to potential yield, since maximum photosynthetic leaf surface is needed to optimize grain yield. Hybrids can vary considerably in their ability to resist infection by these diseases. Demonstration plots provide an excellent opportunity to compare differences among hybrids to disease problems that have only occurred on a localized basis. Look for differences in resistance to northern corn leaf blight, gray leaf spot, and diplodia ear rot. Symptoms of these diseases and others are available online at the OSU Field Crop Disease Website (

Check to see if foliar fungicides have been applied and what crop rotation has been followed. Typically you’ll encounter more severe foliar disease problems in no-till, continuous corn.

STALK ROTS. Hybrids will likely differ widely when faced with strong stalk rot pressure. Begin checking plants about 6 weeks after pollination (at about black layer) by pinching lower stalk internodes with your thumb and forefinger. Stalks that collapse easily are a sure indicator of stalk rot. Remember that hybrids with thicker stalks may be in plots having thin stands.

LODGING. Perhaps as important as stalk rot resistance is the stalk strength characteristics of a hybrid. Sometimes, superior stalk strength will limit the adverse effects of stalk rot. If your variety plot is affected by stalk rot in late August and early September, evaluate stalk lodging of the different hybrids. Most agronomists characterize plants with stalks broken below the ear as ‘stalk lodged’ plants. In contrast, corn stalks leaning 30 degrees or more from the center are generally described as ‘root lodged’ plants; broken stalks are usually not involved. Root lodging can occur as early as the mid-to- late vegetative stages (as it did this year) and as late as harvest maturity (remember the damage from hurricane “Ike” in 2008?). Both stalk and root lodging can be affected by hybrid susceptibility, environmental stress (drought), insect and disease injury. Root lodging may be associated with western corn rootworm injury. However, much root lodging in Ohio occurs as the result of other factors, i.e. when a hybrid susceptible to root lodging is hit by a severe windstorm, like those we experienced in July 10. A hybrid may be particularly sensitive to root lodging yet very resistant to stalk lodging. A cornfield may exhibit extensive root lodging in July but show little or no evidence of root lodging at harvest maturity in September (except for a slight “goose necking” at the base of the plant). In recent OSU tests evaluating hybrid by plant population interactions, we have observed less recovery in certain hybrids when plant populations exceeded 34-35,000 plants/A.

GREEN SNAP (aka "brittle snap") is pre-tassel stalk brakeage caused by wind. The problem has become more common in Ohio in recent years because of the greater frequency of severe wind storms in late June and mid-July. Vulnerability to green snap damage varies among hybrids. Breaks in the stalk usually occur at nodes (along nodal plates) below the ear.

 TRANSGENIC TRAITS: Because damage from European corn borer (ECB) and western corn rootworm (RW) can be very localized, strip plot demonstrations may be one of the best ways to assess the advantages of ECB Bt and RW Bt corns. The potential benefit of the ECB Bt trait is likely to be most evident in plots planted very early or very late; the potential benefit of the RW Bt trait is likely to be most evident in plots planted following corn or in a field where the western corn rootworm variant is present.

 HUSK COVERAGE/EAR ANGLE. Hybrids will vary for completeness of husk coverage on the ear as well as tightness of the husk leaves around the ear. Ears protruding from the husk leaves are susceptible to insect and bird feeding. Husks that remain tight around the ear delay field drydown of the grain. Hybrids with upright ears are often associated with short shanks that may be more prone to ear and kernel rots than those ears that point down after maturity. This relationship received considerable attention in 2009 when Gibberella ear rot problems were widespread across the Eastern Corn Belt. However, we’ve observed that differences in ear “orientation” among hybrids can be strongly influenced by growing season and plant density. Also, under certain environmental conditions, some hybrids are more prone to drop ears, a major problem if harvesting is delayed.


The following are some additional points to consider during your plot evaluations:

 1. Field variability alone can easily account for differences of 10 to 50 bushels per acre. Be extremely wary of strip plots that are not replicated, or only have "check" or "tester" hybrids inserted between every 5 to 10 hybrids. The best test plots are replicated (with all hybrids replicated at least three times).

 2. Don't put much stock in results from ONE LOCATION AND ONE YEAR, even if the trial is well run and reliable. Don't overemphasize results from ONE TYPE OF TRIAL. Use data and observations from multiple university trials, local demonstration plots, and then your own on-farm trials to look for consistent trends.

 3. Initial appearances can be deceiving, especially visual assessments! Use field days to make careful observations and ask questions, but reserve decisions concerning hybrid selection until you've seen performance results.

 4. Walk into plots and check plant populations. Hybrids with large ears or two ears/plant may have thin stands.

 5. Break ears in two to check relative kernel development of different hybrids. Use kernel milk line development to compare relative maturity of hybrids if hybrids have not yet reached black layer. Hybrids that look most healthy and green may be more immature than others. Don't confuse good late season plant health ("stay green") with late maturity.

 6. Differences in standability will not show up until later in the season and/or until after a windstorm. Pinch or split the lower stalk to see whether the stalk pith is beginning to rot.

 7. Visual observations of kernel set, ear-tip fill, ear length, number of kernel rows and kernel depth, etc. may provide some approximate basis for comparisons among hybrids but may not indicate much about actual yield potential. This year we’ve seen differences in tip kernel abortion (“tip dieback” or “tip-back”) among hybrids and heard reports of “zipper ears” (missing kernel rows). Even if corn ear tips are not filled completely, due to poor pollination or kernel abortion, yield potential may not be affected significantly, if at all, because the numbers of kernels per row may still be above normal.

 8. Find out if the seed treatments (seed applied fungicides and insecticides) applied varied among hybrids planted, e.g. were the hybrids treated with the same seed applied insecticide at the same rate? Differences in treatments may affect final stand and injury caused by insects and diseases.

Corn Ears Showing Stink Bug Injury Stink bugs on corn

Corn Ears Showing Stink Bug Injury

Stink bug damage in soybeans is well documented in Ohio. However farmers may be surprised to learn that stink bug injury can also be seen in corn. Usually the damage in field corn is localized to “scarring on kernels” or causing a “mottled” appearance near the tip of the ear but severe injury has been observed (see photo).  Sweet corn is particularly susceptible to stink bugs, with similar damage symptoms.

Kernel damage from stink bug feeding

Last week we saw stink bug injury at the Northwest Branch near Hoytville and the Waterman Farm in Columbus. At Waterman, the damage was associated with brown marmorated stink bugs, but green stink bugs were more common at NW Branch. Damage was evident on husks where stink bugs appeared to be feeding (see photo). In the southern states, stink bugs cause significant losses in field corn. When stink bugs pierce through the husk and feed on the ear during early development, the cob will not develop on that side, but continue growing on the back side giving the ear a characteristic banana shaped appearance. The shuck will also stop developing, exposing the grain to bird and insect damage. Injury also includes shrunken and/or missing kernels. Heavy stink bug populations can reduce not only yields but also the quality of the grain.  While we have not seen any economic losses from stink bugs in field corn, growers should be aware of their presence and the damage they can cause.

Modified Relay Intercropping – Getting Started

Modified Relay Intercropping (MRI) is the planting of soybeans into headed wheat that may occur up to 6 weeks prior to wheat harvest.   MRI is system where two crops, wheat and soybeans can be harvested in the same growing season.

1.  To determine equipment suitability for modified relay intercropping;  begin in fall by running wheat drill/planter set to appropriate row spacing  in fallow ground and then ‘soybean seeder’  to evaluate where tractor tires, planting equipment tires and openers will fit in wheat rows. Plan for a tram line and also make wheat row spreaders for tractor tires and planting equipment to move wheat out of row when planting.

2.  Wheat Row spacing may range from 10 to 20 inches Wheat rows beyond greater than 10 inches may experience a small yield drop.  The drop in yield is relatively small up to 15 inches (from 5 to 7%) over various studies.

3.  Plant seed to achieve 1.6 to 2.2 million seeds/acre or if in 15 inch rows not more than 25 seeds per foot of row.

4.  Attempt to sow wheat by Oct. 5 in North Central Ohio for best results ( ie must use appropriate soybean variety that will come off to permit timely wheat harvest).  There is not any merit to planting prior to Hessian Fly free Data (  for example: Sept. 26 in Crawford County). 

5.  Select wheat varieties that are:  High yielding; disease resistant; early maturing and short  if possible.  Be sure seed is treated with appropriate fungicides.  Go to http://agcrops/ and check wheat variety performance trials and 15 inch row trial.

6.  Incorporate a tram line for sprayer and tractor tires as this will greatly aid in management and precision soybean interseeding.

7.  Apply fertilize appropriate for wheat production and 30 bu/soybeans (our  approximate long term average).     

8.  Control marestail and other weeds prior to planting wheat either with appropriate tillage (not vertical tillage) or glyphosate + Sharpen.

8. Grow the best wheat you can grow ( ie:  an appropriate spring nitrogen rate applied, disease control as needed as needed and 2,4-D applied on wheat in the spring prior to  wheat jointing or at   Feekes GS 6.)

9.  Interseed soybeans about 30 to 40 days prior to wheat harvest at 225,000 + seeds/acre ( ie if wheat harvest is expected June 25,  may start interseeding  around  May 25).   The fall wheat planting date, variety, weather and wheat row spacing selected will influence the interseeding date.  May use up to 3.5 maturity  soybean in North Central Ohio ( later maturity  soybeans may allow later pods to develop with late season rains).  Wheat will often be in flower when interseeding.  This will not harm wheat as long as it is not run down.   MRI system works because wheat is flexible, tough adaptable plant.  The larger the soybeans are at wheat harvest; the more susceptible to combine wheel damage.  Can lose significant soybean stand – larger the header; less soybean stand loss. 

10.  Harvest wheat early as can be threshed,   if possible at 20% moisture and dry.

11.  Cut wheat at top of soybeans.

12.  Aggressively chop and evenly spread wheat wheat residue.

13.  Control weeds; remember marestail must be controlled in the wheat.

14.  Scout for defoliators/pod feeders in late July and early August– may damage interseeded or double crops beans heavily.

For more information on the Modified Relay Intercropping go to:




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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.