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Ohio State University Extension


C.O.R.N. Newsletter 2009-08

Dates Covered: 
April 7, 2009 - April 14, 2009
Steve Prochaska

Corn Planter Adjustment - Last Minute Tips

Authors: Peter Thomison, Greg LaBarge

Corn sometimes emerges unevenly because of environmental conditions beyond the control of growers. However, timely planter servicing and adjustment, as well as appropriate management practices, can help prevent many stand uniformity problems. The following are some tips for improving the uniformity of seed placement during planting.
1. Keep the planting speed within the range specified in the planter's manual.
2. Match the seed grade with the planter plate.
3. Check planters with finger pickups for wear on the back plate and brush (use a feeler gauge to check tension on the fingers, and then tighten them correctly).
4. Check for wear on double-disc openers and seed tubes.
5. Make sure the sprocket settings on the planter transmission are correct.
6. Check for worn chains, stiff chain links, and improper tire pressure.
7. Make sure seed drop tubes are clean and clear of any obstructions.
8. Clean seed tube sensors if a planter monitor is being used.
9. Make sure coulters and disc openers are aligned.
10. Match the air pressure to the weight of the seed being planted.
11. Make planter adjustments and follow lubricant recommendations when using seed-applied insecticides (e.g. Poncho and Cruiser)
Uneven corn emergence generally has a greater impact on grain yield than uneven plant spacing. Uneven emergence affects corn performance because competition from larger, early-emerging plants decreases the yield from smaller, later-emerging plants. If the delay in emergence is less than two weeks, replanting increases yields less than 5 percent, regardless of the pattern of unevenness. However, if one-half or more of the plants in the stand emerge three weeks late or later, then replanting may increase yields up to 10 percent. Emergence delays of 10 days or more usually translate to growth stage differences of two leaves or more. When two plants differ by two leaves or more, the younger, smaller plant is more likely to be barren or produce nubbin ears. Weeds also tend to be a greater problem in those areas of a field characterized by skips and gaps in the corn rows, and slow, erratic corn emergence.

For more information on planter adjustments to improve stand establishment in corn, consult: "Tips to Reduce Planter Performance Effects on Corn Yield" OSU Extension Fact Sheet AGF-150-01

Dr. Bob Nielsen at Purdue University has a good article entitled “Planter Maintenance: Less Down Time, More Yield ” (Chat 'n Chew Café, 21 Feb 2005). It includes links to the service support Web pages at Case-IH, Deere, and Kinze and is accessible online at

An article from the University of Nebraska has a good discussion of seed tube maintenance and other key points can be found at:

Soybean Aphids in 2009?

Authors: Ron Hammond, Andy Michel, Bruce Eisley

As we start getting into the planting season, we thought it appropriate to discuss our thoughts for soybean aphid for the coming year. The question is whether the aphid will continue its two-year cycle in Ohio, becoming a problem this year, following an extremely low aphid year in 2008. Based on information collected during the fall of 2008, we think the chances are good that the two-cycle will continue, and thus, are predicting the soybean aphid to become a significant problem in Ohio in 2009.

The main criteria we are basing this on are the fall collections of winged aphids in suction traps in neighboring states to our west and north. In a number of these traps, fall collections were high. These numbers had followed a summer when suction trap collections in these same sites were very low. This scenario, low summer captures followed by high fall collections, has usually been the determining factor when making our “aphid prediction”. While not all collection in neighboring states showed this pattern, a number of them did. See for a list of sites and the numbers.

The only caveat to this prediction is that we did not find any aphid colonies or eggs on the few buckthorn plants that we sample in the fall in Ohio. However, because most of our aphid problems “migrate” from the north, we do not think that the lack of over wintering aphids in our state should be a determining factor. As always, we could be wrong in our prediction, but we have called it correctly for the past 6 out of 7 years! On the plus side, if we are wrong, at least it will be to the growers' benefit.

As we have discussed throughout the winter and in past newsletters, we recommend taking an IPM approach to aphid management. While seed treatments will control early season aphid populations, they will not have any impact in mid-summer when aphids arrive in large numbers from areas to our north. Thus, we do not recommend seed treatment insecticides for aphid control. What we do recommend is scouting your soybeans from early July through August, and using the 250 aphids per plant threshold with a rising population density to determine the need for treatment. Follow the C.O.R.N. newsletter for updates on the soybean aphid situation throughout the summer.

A Brief Review of 2,4-D Ester Use and Labels

Authors: Mark Loux

The herbicide 2,4-D remains an extremely important component of weed management programs in corn, soybeans, and wheat, especially in no-tillage production systems.

We cannot emphasize enough the importance of a “clean” start in no-till fields. The most effective weed control and highest yield potential results from using fall or spring burndown herbicides, and establishing the crop under weed free conditions. Failure to use an effective burndown treatment that includes several different herbicide sites of action also increases the risk of herbicide resistance. The inclusion of 2,4-D ester in burndown programs can help control a number of large or tough winter weeds, including marestail, dandelion, wild carrot, poison hemlock, mustards, etc. Adding 2,4-D to glyphosate-based burndown programs also greatly reduces the selection for glyphosate resistance in early-emerging summer annuals, including marestail, lambsquarters, and giant and common ragweed. Populations of these weeds have already developed resistance to glyphosate in some Ohio fields, and some of the glyphosate-resistant ragweed populations have resistance to ALS-inhibiting herbicides also. Our research shows that control of resistant populations in soybeans can be almost impossible unless the field is weed-free at the time of planting, and use of 2,4-D ester is required to achieve this where glyphosate resistance has developed. Some additional information on 2,4-D use and restrictions:

1. 2,4-D is labeled for preplant application to soybeans, and preplant or preemergence in corn. There is some risk of injury with this type of use, although soybeans are much more sensitive to 2,4-D than corn. However, risk of injury is low as long as guidelines for use on herbicide labels are followed.

2. Labels vary with regard to specific recommendations on timing of application in corn. Labels for some products recommend that 2,4-D be applied either 7 to 14 days before planting or 3 to 5 days after planting before the corn has emerged, while others specify application any time after planting. 2,4-D can be applied early postemergence to corn also. Apply broadcast up to 8-inch corn, and as a directed spray using drop nozzles to taller corn.

3. Applications of 2,4-D around the time of planting can injure corn. This is more likely to occur in coarse-textured soils with low organic matter content, and when above-average rainfall and prolonged soil moisture occur within a week after planting. Injury may be more severe when 2,4-D is applied with chloracetamide herbicides.

4. Many 2,4-D products are labeled for use in the spring prior to no-till soybean planting. OSU recommends the use of only 2,4-D low-volatile ester (LVE) or similar products for this application. 2,4-D amine products are more water-soluble and may leach into the seed zone. For 2,4-D ester, rates up to 0.5 lb active ingredient per acre must be applied at least 7 days before soybean planting. Application rates of more than 0.5 lb up to 1.0 lb active ingredient per acre generally must be applied at least 30 days before planting. Several 2,4-D ester products, including E-99, Salvo, and Weedone 650, can be applied at a rate of 1.0 lb ai/A up to 15 days before planting. Using rates higher than 0.5 lb can improve control of dandelion, dock species, wild carrot, and swamp smartweed, and also marestail plants that have initiated stem elongation.

5. Aside from waiting the required amount of time between application and planting, other keys to avoiding 2,4-D injury include making sure that seeds are well covered with soil and that the planting furrow seals. In addition, fields that have been treated with 2,4-D ester should not be tilled prior to planting. The exception to this rule would be where 2,4-D ester was applied very early in spring, and there has been adequate time for degradation. When 2,4-D is applied before planting, avoidance of crop injury is based on the fairly rapid degradation in soil and the relative immobility of the ester formulation on the soil surface (e.g. its tendency not to readily move below the soil surface unless much rain occurs). Tilling the soil after 2,4-D application can move it down into the seed germination zone, which increases the risk of uptake by seed, leading to germination and emergence problems.

6. 2,4-D labels vary also with regard to the timing of postemergence applications to wheat. Some labels specify that application must occur before jointing, while others allow application after jointing but before early boot. In our limited research with wheat, we have not observed yield loss from 2,4-D even when applied in nitrogen fertilizer solution, as long as it was applied before early boot. Some generally recommendations to minimize the risk of injury to wheat that has jointed: use an amine formulation instead of an ester; apply in water instead of fertilizer solution; and do not apply more than 0.25 lb ai/A of ester or 0.5 lb ai/A of amine.

April Weather Forecast

Authors: Jim Noel

March was a mild month compared to a normal March across Ohio. It was wetter than normal in the north and drier than average in the central and south. In the far north and northwest, rainfall was 100-200% of normal while in the south and east it was 50 to 75% of normal. Temperatures were some 3 to 6 degrees above normal.

It appears April will not be as mild with temperatures averaging near normal and precipitation near normal. However, there will be some big swings in both.

Week 1 - This week
It will be cold with some snow showers through Tuesday. Freezing temperatures for low can be expected through Wednesday AM. More rain is on tap by the end of the week with temperatures returning to near normal.

Week 2 - Next week
Expect temperatures to average below normal with some early week rains.

Week 3 - Week of Apr 19-25
Expect near to below normal temperatures with some light rainfall.

We can not rule out some late freezing temperatures in Ohio as some large high pressure systems may come down from Canada in Week 2 and 3. The best chances will be in valley areas and north of I-70.

Also, Ohio is split on rainfall, too wet in the far north and northwest and turning too dry in east and southern sections. Right now, it looks like the wettest areas of the state for April will be the west and driest areas will be in the east. This will have to be watched as a drought has developed east of Ohio. However, there is no indication right now of a big drought for Ohio as the weather patterns look rather active this month for rain events.

Soybean Rust 2009 – What Happened This Winter and How Are We Going to Scout For It

Authors: Anne Dorrance

Well it is after April 1 and it is time to take a look at what has been happening in the southern US. Soybean rust did over winter this year and rust was found on kudzu in Georgia and Alabama. Check out rust locations at the public website found at: . Soybean Rust sentinel plots are now being planted across the south for future monitoring this summer. In our view, it is not time to buy rust fungicides, but it is time to become familiar with the public website.

The next critical time for Ohio soybean producers to check this website will be after the July 4th weekend. This will be the time when our soybean crop goes into flower and will determine if rust has jumped to Ohio soybeans in the south. If the southern US counties have been turned red on the above mentioned web site (from Northern Georgia across Mississippi and Louisiana), then our risk becomes moderate. Note that it will only take one pustule on one leaf to turn a county red.

Commentaries are important to read to see what the specialist are advising growers in the south. To do this, click on the maps on the side panel where states are different shades of blue. From here, click on each state to view their assessment of soybean rust risk.

Once our risk becomes moderate when a high level of rust inoculant is present in the southern US. We then will begin to monitor the storms, hurricanes and how many weeks it takes for rust to begin to be identified in Kentucky, Tennessee, Southern Illinois and Virginia. We have two major routes, the old blue mold pathway from Georgia and North Carolina as well as up the Mississippi and Ohio River Valleys. If it is a hot dry year, it took 4 to 6 weeks for rust to move which is too slow to impact Ohio soybeans. If it is wet and cool and big storms move in; it may be 3 weeks or less to jump from state to state. We will have to monitor the weather and conditions that influence infection.

For 2009, we are reducing the number of Ohio plots that will be sampled each week. Ten soybean sentinel plots will be planted across the state and will be scouted on a weekly basis. The funding was cut in half for the sentinel plot system and we will become more efficient at soybean rust monitoring and detection. As such, we will be participating in soybean rust trapping projects plus augmenting this with some additional traps that will be screened with the rust antibody that we helped develop here at OSU. When rust traps of the experimental models indicate that a spore deposition may have occurred, we will do more mobile scouting. So if you see a red truck parked on the side of the road with state plates that begin with the number 30 – that is what we are doing in the soybean field – looking and searching for rust.

A little bit more on the funding, the Risk Management Agency (USDA) was crucial along with the soybean check-off to develop and fund the first 3 years of this rust monitoring project. It is expected that once a system is up and running that other funds will be found. We (soybean specialists) are still investigating and wish not to put this on the back of the soybean check-off. We are making sure that our colleagues in the southern states get the funding they need. Many of us in the north scrimped and prepared for this year in order to fund the southern folks through this season. The build-up of rust in the southern US basically determines our risk. Scouting for rust in the southern US has been an adventure. Amy Fahnestock wrote an article for CropLife about the adventures of my southern colleagues for soybean rust in the March 2009 issue. The link is at . After you read this, I think you will agree, we need more dollars from somewhere put into this effort!

Non-traditional Fertilizer Products, How Can You Evaluate Their Usefulness?

Authors: Robert Mullen, Edwin Lentz

Many products are frequently marketed as the latest and greatest technology that will improve agronomic productivity of all major crops in Ohio. The question is which ones are legitimate and which ones are wastes of money? Here are a few simple ways to evaluate whether or not what you are being sold is real or bogus.

1.If it sounds too good to be true, it probably is. This old adage is almost always true. So if something is promising tremendous yield improvements by supplying adequate nutrition, suppressing weeds, improving soil health with a small application rate, it is most likely not going to deliver the desired benefits.

2.Take a lesson from the first law of thermodynamics (that states that energy can neither be created nor destroyed – it simply changes form). In our case nutrients can neither be created nor destroyed, they can only be shuttled between different pools. So if a product states that application of this material is equal to 50 pounds of phosphorus per acre, and the material fertilizer analysis (required on the bag by law) has 20% phosphorus and the application rate is not 250 pounds per acre, you are not supplying the same amount of nutrients at a rate of 50 pounds per acre. The maximum efficiency of any system is 100%, so how can this product magically supply more than is being applied?

3.Look for un-biased research results. Many products are vetted through land-grant universities to determine their potential usefulness. Just because a product works at some remote location does not necessarily mean it will work on your farm (this is why land-grant universities conduct field research). If the individual selling you the product is also the individual conducting the research be wary.

4.Before completely adopting an alternative product to be used on the entire farm, evaluate the product on a limited basis and make simple comparisons to current practices. If you see no yield advantages, you have your answer.

Remembering these simple rules can help you separate good products from bad.

In addition, university research and extension soil fertility specialists in the Corn Belt also maintain a data base on non-traditional ag products (Ohio State University participates with this committee). The criteria to be included in the data base follows these guidelines: 1) at least two site-years of research, with multiple crops or varieties substituting for a site-year; 2) authors listed; 3) replicated with statistical analysis; 4) reasonably applicable to north central USA crop production; 5) reference source available; and 6) author permission. These are also good guidelines for a producer to consider for legitimacy of a non-traditional product. The web site is located at . Please contact Ed Lentz or Robert Mullen for more information about this committee. If you would like to evaluate a non-traditional product, contact your county Extension Agriculture Educator to set up an on-farm experiment.

Archive Issue Contributors: 

State Specialists: Peter Thomison (Corn Production), Anne Dorrance, Pierce Paul and Dennis Mills (Plant Pathology), Ron Hammond and Andy Michel (Entomology), Mark Loux (Weed Science), Robert Mullen, (Soil Fertility). County Extension Professionals: Jonah Johnson (Clark), Roger Bender (Shelby), Harold Watters (Champaign), Les Ober (Geauga), Steve Foster (Darke), Greg LaBarge (Fulton), Tim Fine (Miami), Flo Chirra (Williams), Wesley Haun (Logan), Bruce Clevenger (Defiance), Howard Siegrist (Licking), Ed Lentz (Seneca), Marissa Mullet (Coshocton), Suzanne Mills-Wasniak (Montgomery) and Steve Prochaska (Crawford)

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.