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November 25-December 9, 2002
C.O.R.N. 2002-39
In This Issue:
A) 2002 Ohio Corn Performance Test Results Available
B) Cca And Pat Credits Available At Regional Agronomy Meetings
C) Put Our Pocket Field Guide On Your Wish List
D) Ohio Now Has Glyphosate Resistant Marestail!
E) Comparing Corn Seed Treatments
F) 2002 Ohio Corn Performance Test: An Overview
Results of the 2002 Ohio Corn Performance Test are available on-line at http://www.oardc.ohio-state.edu/corn2002/. Since assessment of hybrid performance is enhanced by using a number of test sites, farmers along Ohio's border with neighboring states may also want to consider checking results of the Purdue, Kentucky, Michigan State, Pennsylvania, and West Virginia Corn Test results. An on-line version of the 2002 Indiana corn test results is available at http://www.agry.purdue.edu/ext/variety.htm. Growers interested in results of corn hybrid silage trails should consult the Michigan State University and Pennsylvania corn hybrid tests that include silage yields. The North Central Crop Evaluation Committee web site http://www.ksu.edu/kscpt/nccec/ provides links to corn hybrid test results from state universities across the Corn Belt.
December 16, 2002
Trumbull County - Warren at Trumbull Career and Technical Center, 330-675-2595
December 17, 2002
Wyandot County - Sycamore at Sycamore Community Center, 419-447-9722
December 18, 2002
Henry County - Deshler at Bavarian Haus, 419-354-9050
December 19, 2002
Darke County - Versailles at K of C Hall, 937-548-5215
A complete agenda listing and approved credits for CCA and Pesticide Applicator Training for each location can be found at http://corn.osu.edu/Education/index.html.
Looking for a handy pocket size (6 inch by 3.25 inch) guide to identify pests in your corn, soybean, wheat and alfalfa fields? The perfect fit is the Corn, Soybean, Wheat and Alfalfa Field Guide, Bulletin 827 developed by OSU Extension. The guide was revised in February 2002 with colored pictures for identification and information about the common pests (diseases, insects & weeds) that are found on field crops. The guide also contains information on fertility, herbicide, insecticide and fungicide use on these crops.
Single copies of the guide can be purchased from OSU Extension County Offices and bulk quantities copies of the guide can be purchased through OSU Extension Communication & Technology Phone at 614-292-1607.
Marestail/horseweed in three Ohio and two Indiana fields
have been confirmed to be glyphosate-resistant in OSU greenhouse testing. Plants
from these populations survived glyphosate rates up to 3.0 pounds acid equivalent
per acre (88 oz/A Roundup WeatherMax or 128 oz/A of all other formulations).
The three Ohio populations are from west central Brown County between Mt. Orab
and Georgetown. The two Indiana populations are from Jackson County, southwest
of Seymour and west of Interstate 65. The Indiana populations are almost directly
west of the Ohio populations, and we assume that many fields between these two
areas are likely to have glyphosate-resistant marestail populations also. We
are in the process of testing additional marestail populations from Clermont,
Clinton, and Highland Counties, and will have the results within several weeks.
Many of these fields have been continuous no-tillage soybeans and planted with
Roundup Ready soybeans for at least the previous five years, with two or more
applications of glyphosate per year. Fields with glyphosate-resistant marestail
are likely to have a combination of dead, severely injured, and slightly injured
plants occurring in patches at the time of harvest.
Further greenhouse studies will be conducted to determine if these populations are also ALS-resistant. However, based upon previous greenhouse research and the fact that some of these fields were treated with a mixture of FirstRate plus glyphosate, these populations are most likely resistant to both glyphosate and ALS inhibitors. If these populations have multiple resistance, then herbicide control options become very limited in soybeans. It will be very important to use 2,4-D before soybean planting wherever possible. 2,4-D is most effective when applied before marestail plants begin to bolt (produce a stem). More information about controlling resistant marestail populations will be made available after additional research is completed.
Farmers understand the importance of establishing an adequate plant stand for the economic production of corn. The corn plant has a remarkable ability to compensate for a minimum of missing plants in the spring if the weather conditions are favorable for growth and grain production throughout the growing season. However, when stand is reduced in such a way that larger distances occur between plants, yield can be affected. Most stand loss is associated with weather and/or planting conditions that affect the growth and survival of seed, seedlings and young plants. Weather conditions that lead to excessive stand loss generally increase production costs requiring replanting or accepting lower plant populations and lower yield. Most producers rely on planting fungicide treated seed and increased seeding rates to compensate for potential stand losses. Generally growers plant 10% more seed than necessary to achieve optimum stand. Stand losses can be attributed to various environmental conditions as well as seed and seedling diseases, insect damage and planter malfunctions.
Several different fungi can cause seed and seedling diseases of corn, but various species of Pythium and Fusarium are the most common. In spring, field conditions that influence soil warming and the moisture holding capacity of the soil affect development of seedling diseases. No tillage and reduced tillage fields, with significant layers of crop residue insulating the soil, will prevent warming and help maintain moisture near the soil surface where seeds are placed during planting. Additionally, soil that is not tilled is likely to hold more moisture longer into the planting season and it generally takes less volume of rain to saturate non-tilled than tilled soil during a rain event. Saturated conditions prevent the young seedlings from obtaining adequate oxygen by seedling roots for respiration needed for growth and the water-filled soil pore spaces help to create avenues for swimming zoospores of some Pythium species to find and infect corn roots.
Because little genetic resistance is available in corn to Pythium and Fusarium, especially in young seedlings, management of seedling diseases has been through the use of seed treatment fungicides and cultural practices that help to reduce environmental conditions that favor disease development. Over the past several years there has been a significant change in the fungicides used on corn seed. Most corn seed planted in 2002 was treated with Maxim XL, a combination of fludioxonil and mefenoxam from Syngenta. A few companies have used the Corn Treatment System (CTS) from Gustafson, Inc., that contains captan, metalaxyl and a polymer to reduce dust. Both combinations include a broad-spectrum fungicide (fludioxonil or captan) to control Fusarium, Rhizoctonia and other fungi, along with a narrow-spectrum fungicide (metalaxyl or mefenoxam) to improve control of Pythium.
How do the seed treatment products compare?
The introduction of metalaxyl (Allegiance) and mefenoxam (Apron XL) onto the corn seed treatment market has brought new levels of efficacy against Pythium to the field. These products have made it possible for corn to be planted earlier into cooler soils and into seed beds that are less favorable for corn seedling growth (i.e. no-tillage) without excessive stand losses to soil borne diseases. However, growers should realize that failure to control seedling diseases may occur under environmental conditions highly unfavorable for seedling growth. Growers should not expect miracles in contrary planting seasons.
Evaluation of seed treatment research trials across the US Midwest for the past three years has indicated no real difference in efficacy of Allegiance plus captan (CTS) and Maxim XL (Maxim + Apron XL). Generally, these studies look at seedling emergence (stand) and final grain yield. Some years in some locations the Allegiance plus captan (CTS) has statistically higher stand or higher yield than the Maxim XL treatment, but in other years or locations the opposite is true. Many times there are no statistical differences in stand or yield between the fungicide treatments, just the statistically significant improvement in stand or yield over the untreated control treatment. Little is known as to why one treatment may perform better than another under certain circumstances and there is no substantial reason to assume one will consistently out perform the other for disease control.
Planter box treatments:
There are several planter-box treatments available for corn that can be used in addition to the commercially applied fungicides. Most planter-box treatments are a combination of an insecticide and a fungicide. These products include Kernel Guard Supreme, Germate Plus, Agrox and others. The additional fungicide can sometimes improve stand, but usually this effect is not statistically significant. Their best use is for control of wireworms and seed corn maggots.
Ways to reduce seedling stand losses:
Seed corn is expensive. Farmers should expect to buy the highest quality seed possible. This includes seed that has been harvested, dried, conditioned and handled properly to reduce injury to the seed coats. Because corn seed is expensive, it is a definite advantage to treat the seed with a seed treatment fungicide to help protect the germinating seed and seedlings through the first week or so of growth. The few dollars cost for the seed treatment of a unit of seed averaged over the acres the unit will plant represents a good investment especially when weather conditions are unpredictable. Crop rotation is important for corn. Tillage can improve soil drainage in poorly drained soils and tillage can reduce the amount of residue over the seed row. Plant when soil conditions are right. Do not 'mud in' corn seed early in the season, but wait a few extra days for soil moisture to get to a reasonable level. You will likely pay for compacted soils two ways; poor seedling emergence and lower yield from plants that survive. Additionally, wait until the soil temperature is above 50o F. Monitor the soil temperature in fields to be planted to reduce chances of stand establishment problems.
In 2002, 236 corn hybrids representing 38 commercial brands were evaluated in the Ohio Corn Performance Test. Testing was conducted in three regions of Ohio, Southwestern/West Central (SW/WC); Northwestern (NW); and North Central/Northeastern (NC/NE), with three test sites established within each region. Testing was also conducted at two other Ohio sites that have unique production environments (Coshocton and Piketon). Entries in the regional tests were planted in either an early or full season maturity trial. These 11 test sites provided a range of growing conditions and production environments.
Environmental conditions varied greatly across Ohio during the 2002 growing season, especially with regard to the amount and distribution of precipitation. Cool, rainy weather delayed planting, and wet soil conditions during emergence and early vegetative growth resulted in restricted, shallow root systems. These factors combined with a drought that began in mid June severely reduced yields, especially at test sites in the Northeast and Northwest. Rainfall deficits were most pronounced at Upper Sandusky in the NW region and Wooster in the NE/NC region, and results from these two sites were not published because of field variability and very low yield levels.
For early maturity corn SW/WC averaged 155 bushels per acre with a range of 80-193, NW averaged 76 with a range of 61-87 and NE/NC averaged 129 with a range of 67-164. For full season corn SW/WC averaged 151 bushels per acre with a range of 79-194, NW averaged 77 with a range of 65-91 and NE/NC averaged 130 with a range of 63-173. Yields, averaged across the three tests site within a region, were highest in the SW/WC region and lowest in the NW region. Complete tables with grain yield and other measures of agronomic performance are indicated for can be found Table 1 below.
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.
State Specialists: Pat Lipps, Anne Dorrance, & Dennis Mills (Plant Pathology), Peter Thomison (Corn Specialist), Jeff Stachler (Weed Science), Bruce Eisley (IPM) and Ron Hammond (Entomology) District Specialists: Ed Lentz (Agronomy) Extension Agents: Roger Bender (Shelby), Mark Koenig (Sandusky), Howard Siegrist (Licking), Barry Ward (Champaign) and Harold Watters (Miami)Editor: Greg LaBarge Web Editor: Tom Rosati
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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