CORN
Crop Observation and Recommendation Network

July 6 to July 11, 1999
C.O.R.N. 99-16

In This Issue:

A) Field Crop Pest Activity
B) Drought Conditions Persist
C) Forage Species For Supplemental Emergency Forage
D) Last Minute Reminder About OSU Weed Day
E) Double Crop Buckwheat

A) Field Crop Pest Activity - Bruce Eisley - Ron Hammond CORN Questions

Western Corn Rootworm Adults Emerging (Bruce Eisley)

Western corn rootworm beetles are emerging at this time. Beetles have been found in corn fields in all parts of Ohio. The beetles will feed on the corn leaves until the silks and tassels emerge.

The next couple of weeks is a good time to inspect corn fields for rootworm damage. Fields treated with a soil insecticide and first year corn fields (particularly in those areas where adult counts were high in soybeans last year)are field that may need to be inspected. If fields are not inspected soon after larval feeding is complete, the root system will begin to regenerate and rootworm damage will be difficult to see. Plants to be inspected should be dug (dont't pull) from the field and the dirt washed from the root system. Larval damage can be identified by slight feeding on the root tips, tunneling of the roots or roots chewed back to the base of the plant. Determine the amount of feeding on the roots and use this to evaluate the soil insecticide (if one was used) performance or to determine if rootworm damage is occurring in a field year corn field.

We would like to know if you are finding problems in first year corn fields. You can either contact us by calling the IPM Office at (614) 292-8358 or by e-mailing me at eisley.1@osu.edu.

European Corn Borer (Bruce Eisley)

Ron Becker, OSU Extension Wayne County, reports finding several fields that have gone over the 50% infestation level for European corn borer. This is the first report of fields with this high rate of infestation. Reports and observations prior to this have found European corn borer numbers in fields either at 0 levels or less than 5% infestation.

Japanese Beetles In Large Numbers (Bruce Eisley)

Curtis Young, IPM Specialist in NW Ohio, reports finding large numbers of Japanese beetles emerging in corn fields. The numbers seem to be much larger this year than last. They will feed on corn leaves and could move to the silks as they emerge and cause problems with pollination. They may also move to soybeans and begin feeding. In areas where mites are building in soybean fields or where Mexican bean beetle or bean leaf beetles are present, the addition of Japanese beetles to the soybeans may cause the field to go over threshold sooner than expected.

Mexican Bean Beetle In Soybeans (Bruce Eisley)

Every year we receive a few calls about Mexican bean beetle in soybeans in some area of the state. The first report this year is from a consultant in the Coshocton County area. The beetles are beginning to build and may cause problems later on in the season. The adults should be out at this time with eggs being laid and some larvae in the field. Most soybeans are beginning to bloom and so soybeans can only lose 15% of their foliage before economic damage occurs.

Potato Leafhopper (Bruce Eisley)

Potato leafhopper numbers remain high in many fields and are increasing in other fields throughout the state. For areas that did not receive any or very little rain in the past couple of weeks, the economic threshold in these areas for potato leafhoppers may need to be lowered. Last week's newsletter had a table that adjusted the threshold levels for less than ideal conditions.

Green Cloverworm (Ron Hammond)

Ron Hammond, Research Entomologist at OARDC, reports finding a soybean field in Wayne County with a large population of green Cloverworm feeding on foliage. This is the first generation from adults that migrated in from the south this spring. Ron reports that the worms are large and ready to pupate and the percent defoliation is less than the 15% threshold. He suggests that we watch for this insect and be aware that the next generation may cause economic damage.

B) Drought Conditions Persist - Peter Thomison CORN Questions

Although rains last week helped reduce moisture stress in many corn fields, the effects are likely too short-lived. According the National Weather Service "the 6 to 10 day outlook for the period from July 6 through July 10 calls for much above normal temperatures and below normal precipitation for Ohio. If this pattern persists, a continued increase in the severity of the drought can be expected." The Weather Service has concluded that moderate to severe meteorological drought conditions continue across much of Ohio and has indicated that dry conditions are becoming critical in central and south central Ohio.

The determination for the drought condition is based on the Palmer Drought Severity Index for the period ending June 26th. The Palmer Drought Severity Index depicts long term abnormal dryness or wetness, but only accounts for rainfall and temperatures and does not account for river levels or the amount of water stored in reservoirs.

The Palmer Index is used to measure effects of prolonged dry or wet conditions, and reflects the general long term status of water supplies. The categories for drought are near normal (1.9 to +1.9) moderate (2.0 to 2.9) severe (3.0 to 3.9) and extreme (4.0 or less). Below is specific information concerning the Palmer Drought Index per region:

For more details for drought conditions and the Palmer Drought Index, consult the following web sites.

http://www.nws.noaa.gov./oh/hic/current/drought/iln.htm
http://www.cpc.noaa.gov/products/analysis_monitoring/regional_monitoring/palmer.gif

C) Forage Species For Supplemental Emergency Forage - Mark Sulc CORN Questions

Many Ohio livestock producers are faced with or may soon face a need for supplemental forage to offset lost production from drought stressed forage stands. Our options for planting supplemental forage are limited to the summer annual grasses and legumes. Below is a brief description of these forage species to consider. Refer to the Ohio Agronomy Guide, 13th Edition, for more information on establishment and management of these crops. Feeding these forages should be based on forage quality analyses and ration balancing to meet the herd's nutritional and energy requirements.

Corn silage provides the highest yield potential and feeding value of all annual forages grown in Ohio. Yield potential and feeding value are still higher than for the summer annual grasses. If forage is needed before the ear is formed, corn can be green chopped. Without the ear, feeding value of corn will be at least equal to that of the other summer annual grasses, and forage dry matter yields are likely to be higher with corn. Nitrate toxicity is a potential problem with drought stressed corn, so be prepared to test for nitrates if the drought persists and limits corn growth.

Summer-annual grasses include sudangrass, sorghum x sudangrass hybrids, pearl millet and other millet species, and forage sorghum. These grasses grow rapidly, and when managed properly can provide forage of good quality. Summer-annual grasses are a good double-crop option when planted after a small grain crop. All these species can be planted up to July 15, and will produce a good crop assuming sufficient moisture is present for emergence and growth in the latter half of the summer. Pearl millet is essentially free of prussic acid poisoning potential, and the sorghum species vary in degree of prussic acid poisoning potential. Nitrate toxicity is possible with all summer annual grasses. Refer to the Agronomy Guide for how to reduce these risks.

Mixtures of summer-annual grasses and legumes such as field peas and soybeans are being marketed by some seed dealers. The legumes generally improve protein content compared with summer-annual grasses grown alone. The annual legumes included in these mixtures would be present in the first growth only.

Soybean can be grown for forage, although corn silage should be the first choice. Use of herbicide-treated soybeans for forage or hay is allowed for only a few herbicides, so check the label before using herbicides on soybeans to be used for forage. Harvest soybeans for hay to optimize yield and quality when seeds are filling the pods and the lower leaves of the plant are just beginning to turn yellow. If harvested for silage at this stage, soybeans should be mixed with corn in the silo to achieve acceptable fermentation. Mix one part soybean with two or more parts of corn in the silo. Soybean forage should comprise no more than 30 to 40% of the dry matter intake of the animal, because of its high oil content (assuming it was harvested when seeds were formed). This level will not be exceeded when soybean and corn silage are ensiled together in the proportions described above.

Brassica crops such as turnip and rape are fast-growing crops that are good options for grazing, especially for sheep and beef cattle. These crops are highly productive, and can be grazed from 80 to 90 days after seeding. These crops must be treated more like "concentrates" than "forage" in nutritional planning for livestock because of their high digestibility and low fiber content. They are seldom used as dairy feed because they can cause an off-flavor in milk. Additional information is provided in the Ohio Agronomy Guide.

D) Last Minute Reminder About OSU Weed Day - Jeff M. Stachler   CORN Questions

Don't forget that the 1999 OSU Weed Science Field Day will be held on July 7, 1999. We will start at 9:00 at the OARDC Western Branch, break for lunch at noon, and resume the tour in the afternoon at Farm Science Review. A lunch will be available at Western Branch at a cost of approximately $10 per person. Reservations are not required, but we would appreciate a phone call to let us know how many in your organization are attending so we can plan for lunch. Call Jeff Stachler or Tony Dobbels at (614) 292-1393 or send an e-mail to stachler.1@osu.edu.

The OARDC Western Branch is located about 5 miles south of I70 on SR 41. Our plot area at Farm Science Review is located north of I70 on SR 38, directly across SR 38 from the large red storage shed (about 1 mile north of the I70 overpass, and after the road makes two sweeping turns). There is no exit from I70 for SR 38 you must exit I70 at SR 29 and go west to SR 38, or you can exit at SR 42 or 56 and take SR 40 to SR 38.

E) Double Crop Buckwheat  - Dave Jones  CORN Questions

Glenn Arnold, Extension Agent Putnam County reports lots of interest in his County on double cropping Buckwheat behind Wheat. Buckwheat should not be considered without a contract as nearly all the Buckwheat grown in northwest Ohio is grown under contract. Buckwheat can be seeded beginning in May and some varieties as late as July 20th. Buckwheat matures about 10 weeks after germination. Normal yields are 20 to 40 bushels (48 lbs/bu) per acre. Seeding rates are between 36 and 72 lbs/acre which is 8 to 10 seeds per foot of row in 7 inch rows spacing. Seeding depth is 1 to 1.5 inches. 100 lbs of 19-19-19 fertilizer is considered adequate. See the Ohio Agronomy Guide, bulletin 472, for more information on Buckwheat.

Readers can subscribe electronically to this newsletter by sending an e-mail message to: corn-out-on@postoffice.ag.ohio-state.edu. A successful subscription message will receive by an automatic reply from the listserv. Contact your local Ohio State University Extension Office or e-mail labarge.1@osu.edu if you have problems subscribing.

Past versions of C.O.R.N. can be found on the World Wide Web at: http:/www.ag.ohio-state.edu/~corn/archive/

C.O.R.N. is a summary of crop observations, related information, and appropriate recommendations for Ohio Crop Producers and Industry. C.O.R.N. is produced by the Ohio State University Extension Agronomy Team, State Specialists at The Ohio State University and Ohio Agricultural Research and Development Center. C.O.R.N. Questions are directed to State Specialists, Extension Associates, and Agents associated with Ohio State University Extension and the Ohio Agricultural Research and Development Center at The Ohio State University.

Contributors to C.O.R.N. this week include:
State Specialists: Peter Thomison (Corn Production) Bruce Eisley, Hal Willson, & Ron Hammond (Entomology), Jeff M. Stachler (Weed Science), and Mark Sulc (Forages); Extension Agents: Dave Jones (Allen), Barry Ward (Champaign), Steve Prochaska (Crawford), Dennis Baker (Darke), Larry Lotz (Fayette), Clark Hutson (Seneca), and Roger Bender(Shelby)

Editor: David A. Jones         Web Editor: Steve Lichtensteiger

Information presented above and where trade names are used, they are supplied with the understanding that no discrimination is intended and no endorsement by Ohio State University Extension is implied. Although every attempt is made to produce information that is complete, timely, and accurate, the pesticide user bears responsibility of consulting the pesticide label and adhering to those directions.

All educational programs conducted by Ohio State University Extension are available to clientele on a nondiscriminatory basis without regard to race, color, creed, religion, sexual orientation, national origin, gender, age, disability or Vietnam-era veteran status.

Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, Keith L. Smith, Director, Ohio State University Extension.

TDD # 1 (800) 589-8292 (Ohio only) or (614) 292-1868

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