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Ohio State University Extension


C.O.R.N. Newsletter 2005-24

Dates Covered: 
August 1, 2005 - August 9, 2005
Harold Watters

Soybean Rust Update – August 1

Authors: Anne Dorrance

NO soybean rust was found again last week in Ohio’s sentinel plots. Due to the heat – plots were sampled and leaves were examined with dissecting scopes (high magnification) for rust and none was found. Good news. More soybean rust was found in Georgia and Mississippi last week, but that is a very long ways from Ohio and levels are still very, very low. It looks like we are just about out-of-the-woods for soybean rust here in Ohio.

What to do with the triazoles or Section 18 products – to quote an old show from the 60’s (yes I am that old) – “sit on it fellas!”. EPA has never in their history granted a Section 18 request like this before - -this took a lot of good faith on their part that these fungicides would not be abused. So if there is no rust – then don’t use them. If you have been talked into trying the “plant health” effect applications, then stick to the Section 3 labeled compounds of Quadris and Headline and not the combination products. Remember applications in strips across fields will provide a much better read on these products and if you are getting a true effect. I know too many of you that like to try things on the better ground. Remember to take the yield of each strip and then take the AVERAGE of each treatment to make your comparisons. The trick is to make the spray swaths wider than your combine. Then when you run your combine – go up the middle of the spray swath. Bicycle flags will stick up above the canopy if you need to have something to put your sights on as you drive across the fields.

The next article has some tips I’ve pulled from a number of sources for fungicide storage, some are especially pertinent for farms – keep in mind your water sources.

Fungicide/Pesticide Storage

Authors: Anne Dorrance

It appears that there maybe some fungicide storage issues for this winter in light of the fact that soybean rust may not be an issue for the 2005 season. Here are some tips from Cornell, Ohio State University and North Carolina State University.

From the Pesticide Management Education Program at Cornell University (

The following are some suggestions for safe storage:
1. Be sure that caps are tightened securely on all bottles and cans. Eliminate leaky containers.
2. Do not store weed killers close to other materials such as wettable powders, dust formulations or granular insecticides. Some weed killers such as 2,4-D and 2,4,5-T are highly volatile substances and can contaminate other materials especially when confined in close quarters.
3. Store wettable powders, dusts and granules of pesticide products in a cool, dry place.
4. Do not store liquid pesticides in a place where the temperature will fall below 40 degrees f. Too low temperature may result in a breakdown of liquid material, and if the liquid should freeze, there is the danger that the containers will break.
5. Do not carry over pesticide products whose labels have been lost or are not complete and legible.
6. Above all, keep pesticide materials in a locked room or cabinet and out of reach of children and animals.
7. Always purchase pesticides in a container size small enough to be used up within a season or less. This is the best method for reducing storage problems. Although this method may seem somewhat uneconomical, in the long run, it may prove to be a great savings when one looks at the previous six suggestions. Source: J. Capizzi, OPEW (Vol. XI, No. 3)

From Ohio State University Bulletin 745 from 1987, all of these guides are important for today: Storing Pesticides for Next Season

Growers storing pesticides should always consider safety and product quality, whether storage is for a few weeks or a year or more. It is best not to have leftover pesticides. However, there are usually surplus pesticides left over at the end of the season and preseason purchases often are very economical.

The following points should be followed:
1. Read the label. Certain formulations or products have special storage requirements. Those restrictions or directions will be printed on the label.
2. Make certain that the label is in good condition (readable) in order to know what is in the container and have directions for safe, effective and legal use.
3. Write down the purchase or delivery date on the label. Use older or opened products first. Products several years old may not be effective.
4. Keep an up-to-date inventory of pesticides to assist in purchase decisions and in case of emergency.
5. Usually storage temperatures should not go below freezing nor above 100 degrees F. Ventilation is important for storage of most pesticides. Keep pesticides dry and out of direct sunlight.
6. Store insecticides away from herbicides to prevent use mixup, contamination and possible plant damage. Never store pesticides with feed and seed.
7. Pesticide storage areas should be placarded and locked away from children, irresponsible adults and animals.

From North Carolina State ( – this fact sheet focuses on storage and handling facilities – on farm – primarily related to protected farm water sources (wells). In addition, they outline the following:

Pesticides should always be stored in sound, properly labeled, original containers. Each container should be labeled with the following:
1. Common chemical name,
2. Percentage of each active ingredient,
3. U.S. Environmental Protection Agency (EPA) registration number,
4. Signal word, and
5. Classification of uses (restricted use or general use).

Sound containers are your first defense against a spill or leak. If a container is accidentally ripped open or knocked off a shelf, the spill should be confined to the immediate area and cleaned up promptly.

Steel shelves are easier to clean than wood if a spill occurs. Shelves for smaller containers should have a lip to keep the containers from sliding off.

Store dry products above liquids to prevent wetting from spills. Provide pallets to keep large drums or bags off the floor.

Keep pesticides separate to prevent cross-contamination. Herbicides, insecticides, and fungicides should be kept on separate shelves or areas.

Pesticide storage areas must be kept free from combustible materials (such as petroleum products) or other operations that present a fire
hazard (such as welding).

A pesticide storage area cannot be closer than 50 feet to a private well and 100 feet to a public well.

Soybean Aphid Update August 1

Authors: Ron Hammond, Bruce Eisley

Much of northern OH is continuing to have soybean aphid problems. Numerous questions have come up about its life cycle, control issues, and what is happening in the field. Growers need to remember that this insect is still a relatively very new pest, having only been in soybeans for 5-6 years based on our experience. Thus, we still have much to learn about it to come up with answers to many of these questions.

Although significant problems are not being reported the farther south you go into Ohio, remember that we are only in the first week of August. In 2003, many of the problems we experienced did not occur until the second and third weeks of the month. For growers in more central Ohio, pay particular attention to later planted soybean fields that are in late R2 and R3 with succulent soybean leaves still present. These fields are probably more at risk than early planted fields. However, growers are advised to continue to monitor all their fields. All growers should remember: This is Not Over Yet.

We are in the middle of changing populations. Growers are reporting seeing numerous winged aphids, and wondering whether they are coming or going. The only way to possibly know this is to have an idea of what the populations have done over the past few weeks. Having had a rising population would suggest the winged aphids are new and will be leaving. Having had a much lower population and then winged adults would suggest they are new to the field from either more northern areas or nearby fields. Growers are seeing many new “baby” aphids, whitish in color throughout the canopy, and wondering how they should be dealt with. Again, we need to know if these aphid populations are continuing to increase in size, are they holding steady, or are numbers falling off. If they grow into adults and begin producing more aphids, we need to spray and put a stop to it. If they do not increase in size or density, perhaps being preyed upon, then we could wait and put off spraying for a while. Again, is the population increasing in size?

Questions are coming in regarding soybean growth stage. We recommend spraying at the 250 aphids PER PLANT threshold at least through the R5 stage, and perhaps in the R6 stage if populations are still increasing and plants are under stress. Yield losses have been documented at both those stages under certain circumstances. Variable control has been reported for various materials. Remember that for all these insecticides, good coverage is essential, and that includes higher spray pressure, higher volume, and small droplet sizes. You need to get the spray well into the plant canopy. Perhaps after this summer we might be able to start differentiating which materials do a better job.

And finally, for those fields that are still flowering that need to be sprayed, remember the need to contact registered apiaries that are within a half of mile of your field. This might be true for soybean fields that were later planted, such as double-cropped soybeans. The following had been printed in the C.O.R.N. 2005-19:

If applications are made to flowering soybeans, growers must take care because bees might be actively working a soybean field. Although bees are not usually associated with soybeans, they do forage in soybeans and problems could occur if hives are nearby. Label directions pertaining to most of the insecticides and state regulations state that the insecticide should NOT be applied to blooming or flowering crops if bees are actively working in the target area. Thus, most materials for soybean aphid control should be applied in early morning or late day when bees would not be active in fields.

Ohio regulations state in 901:5-11-02 (Trained Servicepersons, Safety and Restrictions) of the Ohio Administrative Code " No person shall: (15) Apply or cause to be applied any pesticide that is required to carry a special warning on its label indicating that it is toxic to honey bees, over an area of one-half acre or more in which the crop-plant is in flower unless the owner or caretaker of any apiary located within one-half mile of the treatment site has been notified by the person no less than twenty-four hours in advance of the intended treatment; provided the apiary is registered and identified as required by section 909.02 of the Revised Code of Ohio, and that the apiary has been posted with the name and telephone number of the owner or responsible caretaker. (16) Apply pesticides which are hazardous to honey bees at times when pollinating insects are actively working in the target area, however, application of calyx sprays on fruits and other similar applications may be made." The names and addresses of registered apiaries are available at the Ohio Department of Agriculture at 1-614-728-6270 (Division of Plant Industry – Apiaries). Growers or applicators should contact this number as early as possible prior to a potential treatment to give them enough lead time to respond to your requests. Growers should be advised to follow all label directions and state regulations; it is the soybean grower's responsibility.

Orthene Labeled for Soybean Aphid Control

Authors: Ron Hammond, Bruce Eisley

Orthene 90 S has received a section 2(ee) recommendation for soybean aphid control on soybeans in Ohio. Orthene is labeled at rates of 0.56 to 1.1 lbs per acre, with a 14 day preharvest interval. Growers should read the 2(ee) label for regarding its use. It is a non-restricted insecticide. At this time, we have not examined this material in trials against this aphid; however, we are currently testing it in our trials. On the other hand, from experience on other crops, Orthene is known to be an effective material against aphids, partially because of its systemic activity.

Preharvest Intervals and Soybean Insects

Authors: Bruce Eisley, Ron Hammond

Now that we are getting in August, growers should be aware of the time periods required between insecticide application and harvest, the PHI = Preharvest interval (the waiting period required before harvest), when it comes to making a selection for either soybean aphid or two spotted spider mite control (this would be important for spraying any soybean insect problem in late summer). The following is a list of insecticides that are labeled for the two pests and their PHI:

Insecticide PHI (in days)
Asana* 21
Baythroid 45
Furadan* 21
Lannate* 14
Lorsban* 28
Mustang* 21
Orthene 14
Penncap-M* 20
Warrior* 45

These two materials are labeled for two spotted spider mites:

Insecticide PHI (in days)
Lorsban* 28
Dimethoate 21

* restricted use insecticide.


Estimating Yield Losses in Drought Damaged Corn Fields

Authors: Peter Thomison

Corn growers with drought damaged fields may want to predict grain yields prior to harvest in order to help develop grain marketing plans.

Two procedures, which are widely used for estimating corn grain yields prior to harvest, are the YIELD COMPONENT METHOD (also referred to as the "slide rule" or corn yield calculator) and the EAR WEIGHT METHOD. Each method will often produce yield estimates that are within 20 bu/ac of actual yield. Such estimates can be helpful for general planning purposes.

THE YIELD COMPONENT METHOD was developed by the Agricultural Engineering Department at the University of Illinois. The principle advantage to this method is that it can be used as early as the milk stage of kernel development. The yield component method involves use of a numerical constant for kernel weight which is figured into an equation in order to calculate grain yield. This numerical constant is sometimes referred to as a "fudge factor" since it is based on a predetermined average kernel weight. Since weight per kernel will vary depending on hybrid and environment, the yield component method should be used only to estimate relative grain yields, i.e. "ballpark" grain yields.

When below normal rainfall occurs during grain fill (resulting in low kernel weights), the yield component method will OVERESTIMATE yields. In a year with good grain fill conditions (resulting in high kernel weights) the method will underestimate grain yields.

Step 1. Count the number of harvestable ears in a length of row equivalent to 1/1000th acre. For 30 inch rows, this would be 17 ft. 5 in.

Step 2. On every fifth ear, count the number of kernel rows per ear and determine the average.

Step 3. On each of these ears count the number of kernels per row and determine the average. (Do not count kernels on either the butt or tip of the ear that are less than half the size of normal size kernels.)

Step 4. Yield (bushels per acre) equals (ear #) x (avg. row #) x (avg. kernel #) divided by 90.

Step 5. Repeat the procedure for at least four additional sites across the field.

Example: You are evaluating a field with 30 inch rows. You counted 24 ears (per 17' 5" = row section). Sampling every fifth ear resulted in an average row number of 16 and an average number of kernels per row of 30. The estimated yield for that site in the field would be (24 x 16 x 30) divided by 90, which equals 128 bu/acre.

THE EAR WEIGHT METHOD can only be used after the grain is physiologically mature (black layer), which occurs at about 30 35% grain moisture. Since this method is based on actual ear weight, it should be somewhat more accurate than the yield component method above. However, there still is a fudge factor in the formula to account for average shellout percentage.

Sample several sites in the field. At each site, measure off a length of row equal to 1/1000th acre. Count the number of harvestable ears in the 1/1000th acre. Weigh every fifth ear and calculate the average ear weight (pounds) for the site. Hand shell the same ears, mix the grain well, and determine an average percent grain moisture with a portable moisture tester.

Calculate estimated grain yield as follows:

Step A) Multiply ear number by average ear weight.

Step B) Multiply average grain moisture by 1.411.

Step C) Add 46.2 to the result from step B.

Step D) Divide the result from step A by the result from step C.

Step E) Multiply the result from step D by 1,000.

Example: You are evaluating a field with 30 inch rows. You counted 24 ears (per 17 ft. 5 in. section). Sampling every fifth ear resulted in an average ear weight of 1/2 pound. The average grain moisture was 30 percent. Estimated yield would be [(24 x 0.5) / ((1.411 x 30) + 46.2)] x 1,000, which equals 135 bu/acre.

Because it can be used at a relatively early stage of kernel development, the Yield Component Method may be of greater assistance to farmers trying to make a decision about whether to harvest their corn for grain or silage. Since drought stress conditions in some fields may result in poorly filled small ears, there may be mechanical difficulties with sheller or picker efficiency which need to be considered. Since it will probably be cheaper to buy corn for grain than to buy hay for roughage (because of the likely forage deficit), there will be greater benefit in harvesting fields with marginal corn grain yield potential for silage.

Western Ohio Agronomy Field Day - August 10th (6-9 p.m.)

The field day will be held at the Darke County Research Farm located at 5105 County Home Rd. Greenville, Ohio (the farm is located at the southwest corner of St. Rt.127 and St. Rt. 49, just south of the Darke County Jail). Register by calling the OSU Extension Office at 937 548-5215 or email: .

The program will start at 6:00 p.m. with a tour of the research test-plot that includes: Twin-row high population corn study, Twin-row corn silage study and the Soybean Rust Sentinel plot. In addition, a first year corn rootworm survey study will be on going, participants will be able to observe the procedures for monitoring the corn rootworm in soybean fields and to discuss the economic importance of such a survey.

Presentations will also be given on the following topics:
- Crop Insect Up-date, Bruce Eisley, IPM Research Associate, OSU Extension.
- Weed Control Up-date, Jeff Stachler, Weed Science Specialist, OSU Extension.
- Soybean Rust and other Disease Up-date, Anne Dorrance, Soybean Disease Extension Specialist.

CCA credits for Certified Crop Advisors and Pesticide Applicator credits (category 1) will also be provided. For more information contact the Darke County OSU Extension office at (937) 548-5215 or email .

Southwest Ohio Corn Growers Field Day August 16th

Authors: John Yost

The Southwest Ohio Corn Growers and Fayette County Agronomy Committee will hold their annual field day on August 16th, from 9:30 AM to 3:00 PM, at the Fayette County Demonstration Farm near Washington Courthouse, Ohio. This year’s featured speaker will be Floyd D. Gaibler, US Under Secretary for Farm and Foreign Agriculture Services. As deputy, Gaibler provides leadership to agencies and programs administered by the FFAS mission. He offers general direction to programs administered by the Farm Service Agency and the Commodity Credit Corporation, the Risk Management Agency and the Federal Crop Insurance Corporation, and the Foreign Agricultural Service. Deputy Gaibler will discuss the 2007 Farm Bill, CAFTA, and the Demeter LLC Ethanol Plant intended for Bloomingburg, Oh.

The lunchtime program will also feature Ohio Department of Agriculture Director Fred Dailey, Ohio Corn Growers Executive Director Dwayne Seikman, and Dave Link, (Greater Ohio Farm Service Group Leader) to give a brief overview and update on the Demeter Enterprises LLC Ethanol Plant in Bloomingburg, Oh. Dayton Power and Light Company will host an electrical safety demonstration following the lunch program.

In addition to the lunch program there will be wagon tour stops covering Precision Agriculture, Disease Resistance in Corn Hybrids, Planter Unit Calibration, Nitrogen Management, and Tillage effects on soil density and root structure. As always, the field day will provide commercial exhibits, corn hybrid show plots, health screenings by the Fayette County Health Department, and Fayette County Master Gardener and Farmer’s Market Displays.

The Ohio Department of Agriculture will host a pesticide pickup at the field day. Farmers are welcome to bring their unwanted and/or unused chemicals to the program for disposal free of charge.

This program is free to the public. Lunch will be provided by the Southwest Ohio Corn Growers Association. If you have questions about this program contact John Yost ( or 740-335-1150).

Archive Issue Contributors: 

Anne Dorrance and Dennis Mills (Plant Pathology), Peter Thomison (Corn Production), Jeff Stachler (Weed Science), Ron Hammond and Bruce Eisley (Entomology). Extension Agents: Steve Foster (Darke), Roger Bender (Shelby), Dusty Sonnenberg (Henry), Keith Diedrick (Wayne), Harold Watters (Champaign), Glen Arnold (Putnam), Bruce Clevenger (Defiance), Howard Siegrist (Licking), Alan Sundermeier (Wood), Mark Koenig (Sandusky), Ed Lentz (Seneca) and John Yost (Fayette).

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.