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Agronomic Crops Network

Ohio State University Extension


C.O.R.N. Newsletter 2010-29

Dates Covered: 
September 7, 2010 - September 13, 2010
Wes Haun

Weather Update

The weather trend will be near normal temperatures and below normal rainfall in September. No changes from previous reports.

This week will turn cooler with limited rainfall. There will be a few showers Tuesday then again at the end of the week as the remains of Hermine passes mainly to the south and west of Ohio; although, southwestern Ohio has a low probability of some rain with Hermine. Another front will bring some showers this weekend and another front about the middle of next week. However, it appears rainfall amounts will be limited with most of these systems. Temperatures will rebound to above normal readings next week after cooling off this week.

This pattern could linger into October before breaking for a somewhat wetter pattern.

Hay Field with Spotted Knapweed

Spotted knapweed is an aggressive perennial weed that impacts hay and pasture fields in Ohio. The western United States has struggled with this weed for many years. The plant is attractive and flowers resemble those of red clover. It is 1 to 3 feet tall at this time of the year. This weed can produce as much as 1000 seeds per plant. The problem with this weed is that it can completely take over hay fields and pasture land, as indicated by the photo (a hay field near Quaker City). Livestock avoid eating the plant, and it crowds out desirable grasses and legumes.

Seeds of this weed can be spread through the actions of hay hauling and mowing. It is also likely vehicles venturing into infested areas have contributed to plant distribution. The best knapweed control program is early detection and eradication. Avoid spreading this weed seed on farm machinery. Avoid purchase of seed containing knapweeds and utilize only certified seed when planting. Manage hayfields and pastures to promote dense grass growth, which will help reduce the establishment of knapweed. Other recommendations for control:

- control the plant as soon as you see it. In small areas around the house you can pull it up and burn it. It may also be spot-treated using a glyphosate product such as Roundup or one of the many other products containing this active ingredient.

- For pasture and grass hay fields there are several broadleaf herbicide options depending on knapweed state of maturity and use of the forage. At the current state of knapweed development, Milestone at 5-7 oz/Acre or ForeFront at 2-2.6 pt/Acre can provide effective control. Other possible options include dicamba (1-2 lbs ai/A) or Curtail (4-6 pts/A). Treatment with 2,4-D (2 lbs ai/A) can be effective when plants are in the rosette stage in fall or early spring.

- Refer to product labels for herbicide use restrictions regarding grazing, hay harvest, and replanting. The application of broadleaf herbicides will injure legumes such as clover and alfalfa.


Late Season Diseases are Pushing the Crop Along Cyst Females on Roots

Late Season Diseases are Pushing the Crop Along

A number of late season diseases are pushing this crop to maturity as plants continue to die, even through the drought. One of these diseases, charcoal rot, is much more common in western states but we are finding it more frequently in Ohio, especially southern Ohio. This is a fungal disease caused by Macrophomina phaseolina. It survives in the soil as microsclerotia and infections occur during wet periods in the spring. The fungus colonizes the roots, but if there are no stresses, such as drought then very little happens. When conditions of stress occur, like we are having this summer, then the disease becomes very visible and yield losses can result.

This fungus colonizes the roots and tap roots of the plant. If you take a knife (carefully) and scrape away at the side, you will see “pepper granules” embedded in the tissue. These are the survival structures or microsclerotia of the fungus in the soybean stems.

Since we have no control over when and where hot, dry growing conditions appear, there are other strategies to put in place for management of charcoal rot. Maintain good fertility for the crop, too little or too much will add stress. Avoid water stress when possible, manage fields to manage the moisture. Many of our fields have conditions of either too much or too little moisture. For fields where this is a recurring problem, one recommendation that has been effective is reduced plant population per acre. During periods of low water, there will be more water per plant than at higher plant populations, thus alleviating the stress from that point. Several states are looking at resistance to this pathogen where it occurs on an annual basis. For more information there is a very nice piece on charcoal rot from Kansas State University

Soybean cyst nematode is pushing maturity as well. In the past 3 seasons, we have participated in a north central soybean research project with looked at the changes in SCN population over the growing season when susceptible, PI88788 resistance, Peking resistance and Hartwig (CystX) resistance was planted. In all of these years, where SCN populations were high, that area of the field matured first. Turning bright yellow and dying early. At the time the leaves were still on the plants, we can see the cyst females on the roots.

If you have patches of early dying plants, check out the roots. Can you see SCN females on the roots in the above photo?

Corn Harvest Schedules and Dry Down Rates

Don’t plan your harvest strategies this year based on average calendar dates for corn maturity from past years. Grain moistures may be considerably lower than you might expect. In test plots planted April 29 at the Western Agricultural Research Station near S. Charleston, grain moisture levels as of Sept. 3 ranged from 21 to 24% for 108 day and 110 day hybrids. High temperatures during grainfill and recent dry weather have accelerated maturation in many corn fields.

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. In some areas, growers this year should be prepared for stalk lodging (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.

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 things cool down) 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 article on grain drying (referenced below) that also identifies hybrid characteristics that influence drying rates.

Past Ohio research evaluating corn drydown provides insight on effects of weather conditions on grain drying. During a warm, dry fall, grain moisture loss per day ranged from 0.76 to 0.92%. During a cool, wet fall, grain moisture loss per day ranged from 0.32 to 0.35%. Grain moisture losses based on GDDs ranged from 24 to 29 GDDs per percentage point of moisture (i.e. a loss of one percentage point of grain moisture per 24 to 29 GDD) under warm dry fall conditions, whereas under cool wet fall conditions, moisture loss ranged from 20 to 22 GDD. The number of GDDs associated with grain moisture loss was lower under cool, wet conditions than under warm, dry conditions.


Nielsen, R.L. (Bob). 2008. Field drydown of mature corn grain. Corny News Network, Purdue Univ. [On-Line]. Available at [URL accessed 9/7/10].


Plan to Attend the Farm Science Review AgAnswers Booth at FSR

Plan to Attend the Farm Science Review

The growing season has been rough for some of us in 2010, but the crew and the grounds are ready for Ohio State University’s annual fall farm show at their site on the grounds of the Molly Caren Ag Center at the intersection of US 40 and SR 38 just north of London. Crops look very good and as of today harvest has started – yield expectations are above average.

Tickets are available now for the 2010 Farm Science Review – to be held on September 21, 22 & 23 in London Ohio – All Extension offices in Ohio and many agricultural businesses have the tickets for sale at $5 each. Tickets at the gate are $8.

Agronomic Crops Team at the Review

We have added a number of field demonstration plots to the Farm Science Review exhibit area for this year. We will again have the “antique corn” plots and will also have discussion plots on managing corn and soybeans for higher yield. We have education plots on cover crops in conjunction with the Ohio NoTill Council and “bio-energy” crops, too. We think it is time to at least think about adding another agronomic crop to your enterprise – and that may be an energy crop. Stop by and get a tour from an Agronomic Crops Team member as you make your way from the parking lot to the exhibit area.

The Agronomic Crops Team will also be in the EERT – that’s the Extension, Education & Research Tent at OSU Central on the southeast corner of Friday and Kottman in the center of the Farm Science Review exhibit area.

Also in the show tent:

• Forages Team

• AgAnswers

• Purdue Extension

• Low Temperature Grain Drying

• Hydroponics

• OPDN – Ohio’s Plant Diagnostic Network

• AgCrops displays

• Weed Management

• Nutrient Management

• BioEnergy Crops

For spring 2010 the Agronomic Crops Team developed a new website ( and updated the C.O.R.N. newsletter, stop by to share your comments on what you think of it and subscribe if you are not already a user.

New this year will be the sale of Extension publications at the Review. Look for home tree planting, soybean production, weed control and the brand new field guide - Corn, Soybean, Wheat and Forage Guide, as well as many other publications all at OSU Central.

Golf Cart Use

As the Farm Science is a pedestrian show, it is important to limit the use of golf carts to those individuals who require this type of vehicle for use at the show. An expressed need for the use of a special need vehicle should be apparent, whether the vehicle is rented or brought by the individual. It is also the policy of the Farm Science Review to limit all vehicular traffic inside the exhibit area to a minimum and to maintain the area as a primary pedestrian facility.

Golf cart, electric scooter, segway or approved disabled unit will be the only mode of transportation allowed for the 2010 FSR visitor. No other types of vehicles will be allowed into the FSR exhibit area.

The use of a motorized vehicle is a privilege provided to the user. The abuse of this privilege will result in the revoking of the issued Special Needs Vehicle Permit and the removal from the grounds of the Molly Caren Ag Center of the vehicle and the individual(s) to whom the Permit was issued. For more information on cart use see the FSR special needs policy:

2010 Farm Science Review features

• This is the 48th Farm Science Review, the 28th at the Molly Caren Agricultural Center.

• Hundreds of demonstration plots and several million dollars worth of machinery.

• Twenty-first year of inductions into the Farm Science Review Hall of Fame.

• Ohio Farmer Conservation Awards; Thursday at 11:30.

• OSU Central, featuring demonstrations and displays from OSU colleges and departments.

• Lots of farm safety, home safety and health information.

• Global Positioning Systems (GPS) hands-on demonstrations in the demonstration fields.

• Expanded programs on conservation practices in the Gwynne Conservation Area.

• An arts and crafts exhibit tent.

• Permanent washroom facilities with diaper changing stations.



Archive Issue Contributors: 
  • Glen Arnold
  • Roger Bender
  • Bruce Clevenger
  • Matt Davis
  • Mike Gastier
  • Mark Koenig
  • Ed Lentz
  • Les Ober
  • Steve Prochaska
  • Jon Rausch
  • Alan Sundermeier
  • Ron Hammond
  • Pierce Paul
Archive Issue Authors: 

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.