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Agronomic Crops Network

Ohio State University Extension


C.O.R.N. Newsletter 2008-30

Dates Covered: 
September 8, 2008 - September 16, 2008
Wesley Haun

Field Drying and Corn Harvest Timing

Authors: Peter Thomison

There are plenty of corn fields that are green with kernels in the late dough and early to dent stages in parts of Ohio that received timely rains and where corn was planted late. However, near drought conditions and recent dry weather in much of the state have accelerated maturation in many corn fields. Corn will normally dry approximately 3/4 to 1% per day during favorable drying weather (sunny and breezy) during the early warmer part of the harvest season from mid September through late September. By early to mid October, dry-down rates will usually drop to ½ to 3/4% per day. By late October to early November, field dry down rates will usually drop to 1/4 to 1/2% per day and by mid November, probably 0 1/4% per day. By late November, drying rates will be negligible.

Estimating dry down rates can also be considered in terms of growing degree days (GDDs). Generally, it takes 30 GDDs to lower grain moisture each point from 30% down to 25%. Drying from 25 to 20 percent requires about 45 GDDs per point of moisture. In September we average about 10 to15 GDDs per day. In October (as weather cools) the rate drops to 5 10 GDDs per day. However, note that the above estimates are based on generalizations, and it is likely that some hybrids vary from this pattern of drydown. Dr. Bob Nielsen at Purdue has written an excellent overview of grain drying (referenced below) that includes a discussion of hybrid characteristics that influence the rate of grain drying.

Agronomists generally recommend that harvesting corn for dry grain storage should begin at about 23 to 25% grain moisture. Allowing corn to field dry below 20% risks yield losses from stalk lodging, ear rots, and insect feeding damage. Growers this year should be prepared for stalk lodging problems (associated with drought stress) that may slow harvest and contribute to yield losses. The loss of one "normal" sized ear per 100 feet of row translates into a loss of more than one bushel/acre. In fact, an average harvest loss of 2 kernels per square foot is about 1 bu/acre! According to an OSU ag engineering study, most harvest losses occur at the gathering unit with 80% of the machine loss caused by corn never getting into the combine. Growers need to consider the impact of premature plant death on corn maturation. Within fields, significant variation in grain moisture may exist among plants that died prematurely and those that matured more normally.
Nielsen, R.L. (Bob). 2008. Field drydown of mature corn grain. Corny News Network, Purdue Univ. [On-Line].

Harvesting Drought Stressed Corn

Authors: Peter Thomison

Drought stress, combined with uneven emergence and development problems, has resulted in smaller than normal ears, and a greater percentage of "nubbin" ears in many Ohio corn fields. In some fields, plants are shorter than normal with reduced ear heights. Stress conditions may have also predisposed the corn crop to more stalk rot and greater potential for stalk lodging. Corn root worm injury in localized areas has resulted in root lodging. As a result of these conditions, some combine and harvesting adjustments may be necessary.

The following are management suggestions from ag engineers and equipment specialists on harvesting drought damaged crops.

1. Review the operator's manual for suggestions on harvesting a "light crop".

2. With short or lodged corn, run the gathering snouts and chains low. Watch for stones, logs and other debris, and be sure stone protective devises are working.

3. Drive carefully and at normal speeds to avoid excessive harvest loss and machine damage from stones.

4. For small ears, set stalk rolls and snapping plates closer than normal to snap off a higher percentage of ears. Do not attempt to snap off barren cobs.

5. If clean shelling is a problem, increase cylinder speed slightly, and if necessary, decrease concave clearance. With a rotary machine, check rotary concave clearance. Avoid excessive damage to kernels from good ears.

6. If cleaning losses are high, open the chaffer and chaffer extension slightly.

7. Initially decrease the amount of air from the cleaning fan. If cleaning becomes a problem, increase the fan blast, and close the lower sieve slightly.

8. Be alert to changes in weather and crop conditions, and make adjustments as necessary

Effect of August Drought on Soybean Yields

Authors: Jim Beuerlein

A wet spring and dry fall is the worst possible combination for good soybean yields. Wet springs result in small, shallow root systems, the infection and development of root rot diseases, reduced plant growth due to reduced nutrient uptake, and reduced nitrogen fixation by rhizobium bacteria. The smaller plant size results in fewer nodes where pods can form. Dry weather in August reduces the rate of photosynthesis and thus the production rate of grain. The lack of adequate water causes plants to shorten the grain filling period and mature earlier than normal.

Some fields in Ohio have had adequate rainfall for an average yield, but most have endured extensive dry weather and plants started dropping leaves in late August rather than late September, cutting their grain fill period in half. Although the soybean crop often surprises us with its productivity under stress conditions, there won’t be many nice surprises this year. Generally, we have some lost acreage due to flooding, we have lower plant populations and smaller plants than normal, we have poor pod set in many areas of the state, and the grain will be much smaller than normal due to the shortened grain fill period.

Rainfall in early September will greatly benefit late planted or late maturing crops assuming they are active when rain comes. Double crop and relay crops both had good soil moisture at the start, and could produce extremely good yields if they get rain in early September. I am expecting a state average yield in the high 30’s, but hope we are all pleasantly surprised with our yields.

Important Management Guidelines for Ohio Wheat Production

Authors: Dennis Mills, Ron Hammond, Pierce Paul, Edwin Lentz, Jim Beuerlein

The 2008/2009 winter wheat season is fast approaching and as growers make preparation for planting, we would like to remind them of a few important management decisions that are important for a successful crop. Nearly every farm in Ohio has a field or two that could benefit from planting wheat, if for no other reason than to help reduce problems associated with continuous planting of soybeans and corn. Consistent high yields can be achieved by following a few important management guidelines. Below are listed the most important management decisions that Ohio wheat producers need to make at fall planting time to produce a crop with satisfactory economic returns.

1) Select the right variety. Select high-yielding varieties with high test weight, good straw strength and adequate disease resistance. Do not jeopardize your investment by planting anything but the best yielding varieties that also have resistance to powdery mildew, Stagonospora leaf blotch, and/or leaf rust. Avoid varieties with susceptibility to Fusarium head scab. Plant seed that has been treated with a fungicide seed treatment to control seed-borne diseases. The 2008 Ohio Wheat performance trial results can be found at

2) Plant at the right time. Plant wheat after the Hessian Fly Safe date for your county. This date varies between September 22 for northern counties and October 5 for the southern-most counties. Planting within the first 10 days after this date insures the proper planting time to avoid serious insect and disease problems including Hessian Fly, aphids carrying Barley Yellow Dwarf Virus, and several foliar diseases. Planting before this date has lowered yield by 7 to 20% in research trials due to disease and insect problems. On the other hand, planting late (generally after Oct 20 in northern Ohio) can reduce the number of primary tillers that develop in the fall and increases the risk of cold temperature injury. The Hessian Fly free dates can be found at

3) Use the correct seeding rate. Optimum seeding rates are between 1.2 and 1.6 million seeds per acre. For drills with 7.5 inch row spacing, this is about 18 to 24 seeds per foot of row with normal sized seed. When wheat is planted on time, actual seeding rate has little effect on yield, but high seeding rates (above 30 seeds per foot of row) increase lodging. There is no evidence that more seed is better, it only costs more money.

4) Plant seeds at the right depth. Planting depth is critical for tiller development and winter survival. Plant seed 1.5 inches deep and make sure planting depth is uniform across the field. No-till wheat into soybean stubble is ideal, but make sure the soybean residue is uniformly spread over the surface of the ground. Shallow planting is the main cause of low tiller numbers and poor over-winter survival due to heaving and freezing injury. Remember, you can not compensate for a poor planting job by planting more seeds; it’s just more expensive.

5) Apply 20 to 30 lb of actual nitrogen per acre at planting to promote fall tiller development. Wheat also requires higher levels of available soil phosphorus as compared to corn and soybeans. Soil potassium should be maintained at appropriate levels based on soil CEC. Refer to the Tri-State Fertilizer Recommendations for Corn, Soybeans, Wheat, and Alfalfa: Extension Bulletin E-2567 to match your soil fertility requirements. In Ohio, limed soils usually have adequate calcium, magnesium and sulfur for wheat. Soil pH should be between 6.5 and 7.0.

The key to a successful wheat crop is adequate and timely management. The above recommendations are guidelines that may be fine-tuned by you to fit your farming operation and soils. They also assume that you are planting wheat in fields that are adequately drained. You can review more details on these, and other, research-based wheat management recommendations on-line at

Wheat-Soybean Relay Intercropping

Authors: Jim Beuerlein

Relay cropping enables the production of a soybean crop after wheat harvest in central and northern Ohio where there is not adequate time for double cropping. There are two primary requirements for profitable relay cropping: 1) There must be adequate time for the production of a second crop, & 2) There must be adequate water to produce two crops, whether from stored soil moisture, rainfall, or irrigation.
Timeliness of operations, and selection of appropriate varieties and cultural practices are crucial for success as follows:
1) Select a wheat variety of medium to early maturity with medium height and an erect growth habit. Examples are:
Ohio Public Certified: Bravo, Hopewell, Roane, Sunburst;
Steyer Seeds: Geary, Lantz;
Seed Consultants: SC 1339;
AgriPro COKER: Cooper;
Mich. Crop Impro. Assoc: Red Ruby;
AGI: AGI 104;
Virginia. Tech: VA03-409
2) Plant the wheat no-till, in 15-inch rows at the rate of 20-25 seeds per foot of row as soon as possible after the fly-safe date. DO NOT over seed, as lodging must not be allowed.
3) Broadcast 20-30 pounds of Nitrogen at planting along with the phosphate and potash that will be needed for both the wheat and soybeans.
4) Apply herbicides as needed to control weeds in the spring.
5) Apply spring nitrogen between mid-March and early-May at one pound of Nitrogen per bushel of anticipated yield. Urea and 28% solutions are acceptable before mid-April, but urea is preferable after mid-April. DO NOT apply excess nitrogen, as lodging must not be allowed.
6) No-till plant a tall, full season, glyphosate-tolerant soybean variety between the wheat rows during very late May to very early June at a rate of 6 seeds per foot of row.
7) Combine tires should run on wheat rows when harvesting wheat and not on soybean rows.
8) Start wheat harvest as soon as grain moisture reaches 20 percent if using a grain table and at 25 percent if using a stripper head. Air-dry grain in storage.
9) Windrow straw for immediate bailing or chop and spread as widely as possible if not bailed.
10) Apply glyphosate for soybean weed control following wheat harvest.
Additional detailed information about relay cropping is available in Chapter 8 of the Ohio Agronomy Guide, 14th edition. Weed control information is available at

Bean Leaf Beetles on Late Maturing Soybeans

Authors: Ron Hammond, Andy Michel, Bruce Eisley

Although we mentioned this a few weeks ago, a reminder is in order. We have received a few reports of heavy pod feeding by the bean leaf beetle. Growers should remember to scout late-planted soybeans that will remain green for an extra few weeks. These fields might receive many of the bean leaf beetle adults that are now leaving yellowing, maturing fields, resulting in significant pod feeding in fields that are still green. This would include late planting regular soybeans, double-cropped soybeans, and relay intercropped soybeans.

Weather update

Authors: Jim Noel

Some rain will occur especially in northern Ohio Monday night and Tuesday, expecting less than 0.50 inch. The main focus will be on Ike and how it may affect Ohio later this week and into next week. There is potential for some heavy rain in Ohio as a front stalls in Ohio and waits for Ike to move up the Ohio Valley. However, there is still uncertainty on the track Ike will lead; therefore, the potential for a limited amount of rain. Keep an eye on this: If Ike tracks toward Louisiana or northeast Texas; it probably will come this way. If it takes a westward path across Texas, we will receive very little rain. Ike could break the dry trend or will reinforce the current pattern, so this one is worth watching.

Agronomic Crops Team at FSR September 16, 17 & 18

Authors: Harold Watters

The OSU Extension Agronomic Crops Team will be staffing the Ag Crops counter and Diagnostic desk at the corner of Kottman and Friday Streets in OSU Central during the OSU Farm Science Review.

State specialists, along with county professionals who specialize in agronomic crops, will be available to answer questions, discuss information from the C.O.R.N. newsletter and provide opinions on this years corn, soybean, wheat and forage crops. These are the folks who provide you the Crop Observation and Recommendation Network newsletter throughout the year, provide scouting reports and conduct research.

Also this year we have added some crop management demonstrations in the Demonstration area between the parking lot and the Exhibit area, just to the east of the Gate C entrance. Stop to view our comparisons on Weed Management, Fungicides on Corn, Antique Corn demonstrations and Forage plots.

Archive Issue Contributors: 

State Specialists: Ann Dorrance, Pierce Paul, and Dennis Mills (Plant Pathology), Ron Hammond, Andy Michel, and Bruce Eisley (Entomology), Mark Loux (Weed Science), Peter Thomison, (Corn Production), Jim Beuerlein (Soybean and Wheat Production) James Noel (NOAA/NWS/OHRFC). Extension Associates and Agents: Roger Bender (Shelby), Harold Watters (Champaign), Mike Gastier (Huron), Tim Fine (Miami), Gary Wilson (Hancock), Glen Arnold (Putman), Greg LaBarge (Fulton), Howard Siegrist (Licking), Les Ober (Geauga), Marissa Mullett (Coshocton), Suzanne Mills-Wasniak (Montgomery), Wesley Haun (Logan), Ed Lentz (Seneca), Steve Bartels (Butler), Steve Foster (Darke).

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.