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Agronomic Crops Network

Ohio State University Extension


C.O.R.N. Newsletter 2008-23

Dates Covered: 
July 21, 2008 - July 29, 2008
Howard J. Siegrist

July 2008 Weather Report Update

Authors: Jim Noel

Last week: It was mainly a hot and dry week.

This week: Some showers and storms will occur Monday and Tuesday with most places getting 0.10 to 0.25 inches with isolated 1-3 inch rains mainly in the south. Drier and cooler weather return for the second half of the week. Very low relative humidity is expected later in the week.

Next week: Slightly warmer than average with near to slightly below normal rainfall.

August: Near normal rainfall and temperatures.

Developing: We might be setting up a pattern for August and September of slightly drier than normal, we will monitor this development. The tropics will have something to say about this.

Heat: It does not look like this summer will be a hot one. In fact, it might be one of the cooler ones when it comes to 90 degree days. We do not see any long stretches of 90 degree weather into August at this point. We will see some but they will not last long as the core of heat is in the western half of the U.S. this year and not that impressive.

Fungicide Restrictions on Corn Silage and Soybean Forage

Authors: Pierce Paul, Anne Dorrance, Dennis Mills

Foliar fungicides have been and will be applied to corn and soybeans. There are feeding restrictions with some fungicides. Below is a brief list according to the current label. As always double check the label to be sure there are no restrictions.

Domark (tetraconazole) 12 hour REI (restricted entry interval)
Corn - Not labeled
Soybeans - Do not apply after R5. Do not graze or feed soybean forage or hay to livestock.

Headline (pyraclostrobin) 12 hour REI
Corn - 7 day phi. No livestock feeding restrictions
Soybeans - 21 day phi. Soybean forage may be fed no sooner than 14 days after last application.

Proline (prothioconazole) 48 hour REI
Soybeans – 21 day phi. No feeding restrictions.

Quadris (azoxystrobin) 4 hour REI
Corn - 7 day phi
Soybeans - 14 day phi. May be applied the day of harvest to soybean forage and hay.

Quilt (azoxystrobin + propiconazole) 12 hour REI
Corn - 30 day phi for forage, grain and stover
Soybeans - Do not apply within 21 days of harvest for seed and 0 days for forage and hay.

Stratego (propiconazole + trifloxystrobin) 24 hour REI
Corn - 30 day phi. Do not apply after silking. Do not graze or harvest for forage within 30 days of application.
Soybeans - 21 day phi. Do not feed hay.

Corn Insect Update: Western Bean Cutworm & First-Year Corn Rootworm

Authors: Bruce Eisley, Ron Hammond, Andy Michel

Last week, we mentioned two important corn pests that are worth scouting for: western bean cutworm and first-year corn rootworm. Based on observations and reports from growers and extension educators this past week, the timing seemed very appropriate.

First is an update on western bean cutworm. Trap catches by various extension educators increased during last week. We now have a total of 44 moths from across parts of northwest, west central, and central Ohio. This is higher than in previous years, and we have more counties reporting multiple catches in traps. Why the higher numbers this year? There are at least two possible reasons. One is that we have more traps placed around this state this year, and this increases the chance of catching moths. The other, more probable reason might be related to high number of storms in the past few weeks. Western bean cutworm moths likely travel with moving weather fronts, and we have seen storm after storm this year. The more important question is: can we expect any damage this year? We still think the chances of seeing large scale damage is very minimal. Remember, individual trap counts routinely reach 100 to 1,000 in Iowa where the pest can cause serious problems. However, we do recommend scouting for the presence of eggs or larvae, especially in corn at the late-stage whorl to VT stages. Eggs are laid on the upper leaf surface in masses of 5-200 and change color from white to tan to purple. Larvae are ¼ to 1 ½ inches long and have a tan to brownish color as they mature. Larvae will feed on pollen before moving to the ears. If you see any eggs or larvae, please contact entomology specialists or your extension educator.

Second is an update on the first-year corn rootworm variant and corn rootworm in general. We mentioned last week about scouting corn fields for root feeding as well as to begin planning to scout for the variant, which lays eggs in soybean fields and will feed on first-year corn. We have received reports of significant root lodging in first year corn in various locations around the state. As we wait for adult emergence, which should begin any time, now is the right time to inspect for any feeding and lodging and trap for the variant to help make decisions on managing corn rootworm next year. Please contact entomology specialists or your extension educator if you have lodging in first year corn anywhere in the state as we are trying to determine the extent of the problem. Our variant trapping across the state will begin next week and we will provide updates in future CORN newsletters.

Western Corn Rootworm and Japanese Beetle Adults in Corn

Authors: Bruce Eisley, Andy Michel, Ron Hammond

Western corn rootworm adults, along with Japanese beetles, are beginning to show up in corn fields. With corn silks emerging, we expect to begin seeing silk clipping by both these insects. Because of the potential for uneven silking with the variation in corn growth within many fields, there may be only a small portion of the field that has fresh silks at any one time. In these cases, the beetles will congregate on those emerged silks, and thus, insect populations per plant may be larger than if the whole field had silked at the same time. As more plants silk, populations may become dispersed throughout the field and reduce the beetle numbers per plant and thus, perhaps the need for treatment.

Rescue treatment for rootworm beetle silk clipping is warranted if 5 or more rootworm beetles are found per silk mass, 75% of the plants have silked, and silk clipping to 1/4 inch or less is observed. For Japanese beetles, rescue treatment is warranted if there are 3 or more beetles per silk mass and pollination has not occurred. See and for a list of insecticides for corn rootworm adults and Japanese beetle adults, respectively.

Soybean Aphid Update

Authors: Bruce Eisley, Andy Michel, Ron Hammond

We finally found soybean aphids in Ohio from northern counties. They probably also exist in other fields, but continue to be in extremely low numbers. Of more importance is that states and areas to our north have yet to find large aphid populations. This is important because economic populations in Ohio originate from the aphids that migrate into our state from northern locations after having built to large densities, including Michigan and Ontario, and as we saw last year, Quebec (see the aphid PIPE system at ). Adding to this is that the last two weeks in July is the time period when we usually will see the large aphid migration during an outbreak year. Thus, the next 2-3 weeks is critical for the soybean aphid situation. If, as expected, we do not see a large migration from the north, we should be free of a major aphid outbreak (as we had predicted), although isolated problems might still occur.

Growers should plan on scouting their fields closely over the next 3 weeks, initially for the presence of winged aphids suggesting the migration has occurred, followed by the presence of unwinged aphids which will be the offspring of the winged migrants.

Remember that the threshold for treatment remains an average of 250 aphids per plant, with an increasing population throughout the field. Spraying low aphid populations for “insurance” purposes could lead to more problems than it solves if you manage to kill off beneficial insects that are helping out. If large populations are found, please contact your local extension educator so they can make us aware of the aphid’s presence. However, at the current time, it is looking good that we will not have a major problem with the aphid this year. But do not let your guard down until we get well into August and soybean pod-filling growth stages.

Ohio State University's Annual Field Crops Day - July 24

Authors: Alan Sundermeier

Ohio State University’s Annual Field Crops Day takes place from 9-11:30 a.m. on Thursday, July 24, at the Northwest Agricultural Research Station in Wood County. The station is located at 4240 Range Line Road, one-half mile northeast of Hoytville at the corner of Oil Center and Range Line roads.

This free public program features talks on research and recommendations. Ohio State University Extension specialists and scientists with the university’s Ohio Agricultural Research and Development Center (OARDC) will speak. OSU Extension and OARDC, of which the station is a part, are the sponsors. No registration is required. Refreshments will be provided.

For more information, contact Mr. Davis at (419) 257-2060 or

The presentations include:

•“Corn Diseases: Best Management Practices,” Dennis Mills, Plant Pathology, OARDC and OSU Extension.

•“Weed Resistance Management,” Harold Watters, OSU Extension, Champaign County, and co-coordinator, OSU Extension Agronomic Crops Team.

•“Insect Concerns for the 2008 Season,” Andy Michel, Entomology, OARDC and OSU Extension.

•“Different Aspects of Nitrogen Management,” Robert Mullen, School of Environment and Natural Resources, OARDC and OSU Extension.

Farm Focus Hosts 2008 Field Day on July 29

The field day will be held at the Marsh Foundation Farm on Old Lincoln Highway in Van Wert. Registration will begin at 8 a.m. The last shuttle will leave by 8:30 for the field demonstrations and sessions.

This field day offers 4.0 hours of Certified Crop Advisor CEU’s, 1.0 hour in Nutrient Management, 1.0 hour in Soil & Water, 1.0 hour in Crop Management and 1.0 hour in Professional Development for those that attend the full four sessions.

For more information, contact Gary Prill, Farm Focus/OSU Extension-Van Wert County at 419.238.1214 or visit the website: . If rain interferes with the Tuesday, July 29 planned activities, a rain date of Thursday, July 31 has been reserved with the same schedule for the day.

Archive Issue Contributors: 

Specialists: Pierce Paul, Anne Dorrance, and Dennis Mills (Plant Pathology), Ron Hammond, Andy Michel, and Bruce Eisley (Entomology), Peter Thomison (Corn Production), Jim Noel (NOAA/NWS/OHRFC). Extension Educators and Associates: Steve Bartels (Butler), Harold Watters (Champaign), Jonah T. Johnson (Clark), Marissa Mullett (Coshocton), Bruce Clevenger (Defiance), Greg LaBarge (Fulton), Les Ober (Geauga), Gary Wilson (Hancock), Mike Gastier (Huron), Howard Siegrist (Licking), Wesley Haun (Logan), Todd Mangen (Mercer), Tim Fine (Miami) Suzanne Mills-Wasniak (Montgomery), Glen Arnold (Putnam), Mark Koenig (Sandusky), Ed Lentz (Seneca), Roger Bender (Shelby), and Alan Sundermeier (Wood).

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.