C.O.R.N. Newsletter 2007-31

Dates Covered: 
September 17, 2007 - September 24, 2007
Andy Kleinschmidt

Fertilizing Established Alfalfa Stands This Fall

Authors: Mark Sulc, Robert Mullen

As final harvests of alfalfa are collected, fertilization of potassium should be considered if it is not a part of your program. Alfalfa that has adequate levels of potassium accumulates more carbohydrates in their root system which improves their over-wintering ability and vigor early the next spring. Fall fertilization should be done as soon as possible so that the plant can take advantage of the added nutrients before the onset of winter.

Application of potassium should be considered if soil test levels are less than 300 lb/acre. Potassium application rates can be determined by computing how much potassium next year’s crop will remove (base it on this year’s yield or a known “average”). Generally, for every ton of alfalfa forage removed approximately 50 lb of K2O is removed. Thus a 6 ton/acre crop will remove 300 lb K2O/acre. If you wish to maintain current potassium levels, add 300 lb K2O/acre.

Application can be split between this fall and after the first harvest in the spring (applying half in the fall and half in the spring will minimize luxurious uptake of potassium by the crop early next year). The earlier potassium is applied this fall the greater the opportunity for the crop to take it up and prepare for the winter. Soil test values well above 300 lb/acre probably do not warrant any application at all. Check soil test levels next fall to monitor potassium needs for the next year.

Phosphorus can also be applied in the fall after the final cutting. If soil test levels are below 100 lb P/acre, apply additional phospohrus. Crop removal can also be used to determine the rate of application (a ton of alfalfa removes approximately 13 lbs P2O5). If the soil test value is well above 100 then additional phosphorus is not necessary. Providing adequate nutrition for your alfalfa crop will pay dividends next year and extend the life of the stand.

Evaluating Corn Hybrid Demonstration Plots in 2007

Authors: Peter Thomison

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 checking out 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, especially those that are usually not reported in state corn performance summaries. The following are some hybrid characteristics to consider while checking out hybrid demo 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.

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, which affected many corn fields this year, 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 Plant Pathology website (http://www.oardc.ohio-state.edu/ohiofieldcropdisease/corn/corn2.htm). 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 in late August or about 6 weeks after pollination 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 overcome the effects of stalk rot. If your variety plot is affected by stalk rot in late August and early September, be certain to evaluate the stalk lodging resistance 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 not involved. Root lodging can occur as early as the late vegetative stages and as late as harvest maturity. Both stalk and root lodging can be affected by hybrid susceptibility, environmental stress (drought), insect and disease injury.

Root lodging is frequently attributed to 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. 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).

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 protrude 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 often associated with short shanks may be more prone to ear and kernel rots that those ears that point down after maturity. 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. This is especially important this year given the tremendous variability in growing conditions and crop performance across the state. Don't overemphasize results from ONE TYPE OF TRIAL. Use data and observations from 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 ("tip dieback"), 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 more ear stunting (aka “beer can” ears than normal); some hybrids express this disorder more than others. The appearance of this ear anomaly is relatively rare and seems associated with specific environmental conditions. Usually the problem is very limited in occurrence across a field, but if growers have experienced perennial ear stunting problems, they may want to ask their seedsman for advice in selecting hybrids less prone to the problem.

8. Find out if the seed treatments (seed applied fungicides and insecticides) used 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.

Prepare Grain Bins and Harvesting Equipment Now for Fall Harvest

Authors: Curtis Young

We are now half way through the month of September, and corn and soybeans are maturing rapidly in the fields. The harvest season will soon be upon us. Now is time to prepare storage facilities and harvest equipment for the coming corn and soybeans, before things get too busy. No one needs the added stress of equipment breakdowns or messes to clean-up once harvest begins. There are several suggested measures one should take to reduce slow-downs during harvest, protect personal safety, and prepare the storage facility to maintain as high a grain quality as possible. These measures include: facility inspection and repair, sanitation, and empty-bin insecticide treatments.

Storage facilities should be inspected closely for signs of deterioration, especially for leaks and holes through which insects, birds or rodents can gain easy access to the stored grain or rain and snow can drip or blow in onto the grain to produce wet spots that can lead to mold growth. While inspecting for physical problems, one should also test aeration fans and driers for functionality. Check belts, bearings and gear boxes for wear and proper lubrication. Check electrical systems for corroded connections and frayed wiring before harvest. Mice like to nest inside electrical boxes where they are safe from predators. They will strip insulation from wires for nesting material and their urine causes corrosion. While inspecting control boxes, be sure to seal any openings where mice could get in. Be sure that guards and safety shields are in place over belts, chains and intakes. Seal all leaks and make repairs to the equipment before you need them to manage the grain.

Sanitation can prove to be a very valuable tool in reducing the potential of new grain coming into contact with grain that may be infested with grain damaging and contaminating insects. Grain that accumulated or got stuck in equipment and stayed there throughout the summer months had a great potential of becoming infested with several species of insects. Pieces of equipment that need to be cleaned thoroughly before they are used again include the combine, truck beds, grain wagons, augers, bucket lifts, and grain dumps. Other sources of grain infesting insects include livestock feeds, old seed bags, spilled grain, old contaminated grain that was not disposed of properly and other cereal products. And the number one rule in grain storage is, NEVER LOAD NEW GRAIN INTO A BIN ON TOP OF OLD GRAIN.

Another area of sanitation that is frequently overlooked is the clearing of all vegetation growing around the bases of storage bins. This vegetation can harbor grain infesting insects and provide concealment for rodents. It is advisable to clear all vegetation within 10 feet of the bases of the bins. It would be even more preferable to have the whole storage area cleared of vegetation and be covered with gravel. Follow up the vegetation removal with a residual herbicide application to the cleared area to prevent regrowth. Removal of unwanted vegetation will also improve visibility of obstructions on the ground that could be trip hazards.

The interiors of the storage bins should be thoroughly cleaned. Walls, ceilings, ledges, rafters, braces, ladder wrongs and handling equipment should be swept, brushed or vacuumed clean of all debris, dust and grain. Fans, aeration ducts, exhausts and when possible, beneath slotted floors should be cleared of debris as well. Dispose of all debris in a lawful manner and away from the storage facility. Once all cleaning has been completed, an empty-bin application of an appropriately labeled insecticide is advisable, especially in bins with difficult to clean areas and/or in bins with a history of insect problems. For empty-bin insecticide treatments that are applied as a liquid, allow a minimum of 24 hours for the sprays to dry before loading grain into the bin. It is preferable to have empty-bin treatments applied a least two weeks prior to harvest.

Registered empty-bin insecticides include: Diacon II (methoprene- which is an insect growth regulator that only impacts immature insects), Tempo (cyfluthrin), Storcide II (chlorpyrifos methyl plus deltamethrin), and Insecto, Protect-It, Perma-Guard and others (diatomaceous earth and/or silicon dioxide). Refer to the individual product labels for lists of insects controlled and application directions. If a bin is known to be heavily infested with insects, an empty-bin fumigation may be required to knock down insect populations before applying one of the above insecticides. The most readily available product for this purpose is phosphine gas producing materials such as aluminum phosphide and magnesium phosphide sold under a wide variety of trade names. Phosphine is an extremely toxic material and fumigations should be conducted by trained, experienced, licensed applicators.

Another measure one might take to reduce the chance of insect infestation is to apply a perimeter spray around the base and up the outside walls of the bin about 15 feet. This may only be necessary in areas where grain infesting insect movement has been observed on the outsides of the storage bins. There are several synthetic pyrethroids (cyfluthrin, deltamethrin, permethrin, resmethrin, etc.) that can be used for this purpose as long as they do not come in contact with the grain.

Last but not least, review your safety procedures for working with flowing grain, grain harvesting and handling equipment, and personal protection. Anyone who works around the bins and grain handling equipment should know where to find shut-off switches, fire extinguishers, and emergency phone numbers. Being prepared for harvest will reduce the risk of accidents, and knowing how to react in an emergency can save lives.

Modified Relay Intercropping of Soybeans into Wheat

Authors: Steve Prochaska

Wheat is a flexible, adaptable plant with a growing season that starts with planting in the fall and ends with harvest in the early summer. This adaptability allows farmers to capture some 66% of the traditional growing season — May 20 to September 30 — to produce a second crop through the interplanting of soybeans into wheat in late May or early June. This practice is known as Modified Relay Intercropping (MRI).

In the MRI system, two crops — wheat and soybeans — are harvested in the same year. However, because of the difference in crop growth requirements and grain markets, farmers can effectively hedge production and price risk in an MRI system in most years. Producers considering using an MRI system should plan to grow wheat in such a manner (wheat rows 15 inches or less in width) that yield is not significantly reduced from wheat grown in a conventional system.

Long-term research at The Ohio State University's Ohio Agricultural Research and Development Center, in Crawford County and locations in Indiana has shown that MRI or Relay Intercropped wheat will yield about 90 percent of conventional wheat.

Soybean production in an MRI system is more speculative than wheat production due to the need for adequate rainfall in July and August. Thus, MRI should only be done on soils with good water holding capacity.

Different wheat row spacing has been used successfully in MRI. Wheat is a very adaptable plant and will compensate for different row spacing by tillering. Wheat row spacing may range from two rows of wheat planted about 6 inches apart (with a 14 inch open space for soybean planting) to even row spacing of 10 to 15 inches. Wheat must be planted to accommodate soybean planting equipment. A tram line is essential to this system to allow for the tractor and planter or drill to run through the wheat with minimal damage. Row spreaders are also needed on the tractor and drill to move plants out of the row middle when interseeding. Other wheat row spacing configuration is possible; however, production factors such as soybean planting date and weed control programs will need to be considered.

It should be remembered that sunlight is the energy source responsible for wheat and soybean production. Thus, a primary goal of MRI is to capture and utilize as much sunlight as possible. Light, or the lack of it, has a profound effect on the growth of intercropped soybeans. Planting date for wheat and soybeans does matter. Wheat should be planted on or soon after the Hessian Fly Free date for the county to facilitate early wheat harvest the following summer. Soybeans can be planted too early into wheat with little light available to support plant growth particularly in narrow row MRI systems (10 inches).

Wheat varietal selection is important in this system. See the following article for information on possible varieties http://corn.osu.edu/story.php?setissueID=196&storyID=1207.

Finally, for a more thorough overview of this system go to the following pages for more information; http://ohioline.osu.edu/agf-fact/0504.html and http://ohioline.osu.edu/agf-fact/0106.html

Agronomic Crops Team at the Farm Science Review

Authors: Harold Watters

The OSU Extension Agronomic Crops Team along with several Purdue University Agronomists will be staffing the AgCrops counter and Diagnostic desk at the corner of Kottman and Friday Streets in OSU Central during the Farm Science Review.

State specialists, along with county educators who specialize in agronomic crops, will be available to answer questions, discuss information in 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. Attending the Farm Science Review and having a one-on-one discussion with anyone in this group is a great way the end the crop year and get a head start on next year.

Those staffing the Diagnostic side of the tent encourage you to bring in weeds, disease and insect pests you may have questions about to the Farm Science Review. They plan to do as much diagnostic work during the Review as they do during a normal week in the OSU Plant Pest Diagnostic Clinic.

State specialists planning to attend and staff the Agronomic Crops and Diagnostic Clinic Tent are: Anne Dorrance, Mark Loux, Jim Beuerlein, Nancy Taylor, Barb Bloetscher along with many others.

A full listing of activities at Farm Science Review can be found at http://fsr.osu.edu/.


Archive Issue Contributors: 

State Specialists: Ann Dorrance, Pierce Paul and Dennis Mills (Plant Pathology), Robert Mullen (Soil Fertility), Ron Hammond and Bruce Eisley (Entomology), Mark Sulc (Forages), and Peter Thomison (Corn Production) Extension Educators: Harold Watters (Champaign), Steve Prochaska (Crawford), Howard Siegrist (Licking), Steve Bartels (Butler), Jonah Johnson (Clark), Roger Bender (Shelby), Steve Foster (Darke), Mike Gastier (Huron), Alan Sundermeier (Wood), Bruce Clevenger (Defiance), Greg La Barge (Fulton), Curtis Young (Allen), and Todd Mangen (Mercer).

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.