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March 4-17, 2003
C.O.R.N. 2003-5
In This Issue:
A) Nitrogen Management for Wheat
B) Early Spring Weed Control in Wheat
C) Establishing a Healthy, Vigorous2003 Soybean Crop
D) Predicting Flea Beetle Activity & Stewart's Disease
on Corn
E) Twin-Row Corn: An Alternative to Narrow Row Corn?
F) Popcorn Production Information Available Online
G) Monsanto's Rootworm-Protected Biotech Corn Receives Final
Clearance
H) Mustang MAX Labeled
I) 2003 Virgil Overholt Drainage School
As soon as the snow melts in many areas it will be time to apply nitrogen (N) to wheat. Producers should consider three important management decisions for wheat production: N rate, application time, and N source. A brief discussion follows for each of these decisions.
Nitrogen rate. The Ohio State University considers yield goals, or yield potential, in their nitrogen recommendations. Thus, a realistic yield goal is needed to determine the optimum nitrogen rate. Once the yield goal is determined, the recommendation may be based on the following equation for mineral soils, which have both 1 to 5% organic matter and adequate drainage:
40 + [1.75 x (yield potential - 50)]
If =20 lb/A of N was applied in the fall, the spring rate should be reduced by 20 lb/A.
Spring Application Time. If the crop received fall N, spring N may be applied between late February and early April. Application should be made before early stem elongation (our research has shown significant yield losses if the first spring application occurs after Feekes GS 7). If no fall N has been applied, the application should be made at greenup.
In most years, yield gains from a split application have not been large enough to offset the cost of a second trip across a field. A split spring application program may be a benefit in poorly drained fields that are prone to N loss, and also in years that the potential for N loss is great. Years that have a potential for N loss generally have a warmer than normal winter followed by a warm and wet April. This pattern has only occurred once in the past five years (2002). For split programs, our research would recommend a small N rate at greenup with the largest rate applied at initial stem elongation.
Another approach in years of potential N loss is to delay the Spring N application to Feekes GS 5 or early GS 6. Over the past three years, our research has shown similar yields or slightly better yields for single applications at initial stem elongation (Feekes GS 6) compared to initial greenup. The number of heads was not reduced by the application delay. This option should only be considered when some N has been applied in the fall. A producer also runs the risk of not getting adequate N on timely if fields are unsuitable for application at the later stages.
Nitrogen Sources. Most N sources are satisfactory for wheat, but price and
availability may limit some products in a given year. Urea, urea-ammonium nitrate
solutions (UAN), and ammonium sulfate are often the most common. Our research
has shown similar yields among these three sources except in years of N loss.
Urea-ammonium nitrate solutions have the greatest potential for loss, then urea,
and ammonium sulfate the least.
Many wheat herbicides have some activity on Canada thistle and can suppress it enough to prevent harvest problems. Effectiveness often depends upon the size of the thistle at the time of application - regrowth is more likely when thistles are very small at time of application. Best products for thistle control are Stinger, Curtail, and Express. Best products for wild garlic are Harmony Extra, Harmony GT, and Peak, which should be applied when garlic has 2 to 4 inches of new growth but is less than 12 inches tall. Dandelion is most effectively controlled/suppressed with Curtail, but can also be suppressed with mixtures of Express plus 2,4-D or 2,4-D plus dicamba.
When wheat has not yet reached the jointing stage, any herbicide labeled can be safely applied. As wheat growth stage advances past jointing, and then past boot stage, herbicide choices become much more limited. Most herbicides can be applied in nitrogen fertilizer solution when the wheat is top-dressed. This may increase injury somewhat, and some labels recommend adjusting surfactant rates to minimize injury. Where nitrogen is split-applied, risk of herbicide injury may be reduced if applied in a mix of nitrogen solution and water. Some key herbicide limitations are listed below - these are also shown in a figure on page 109 of the 2003 OSU Weed Control Guide and in the text on pages 101-107 or http://ohioline.ag.ohio-state.edu/b789/index.html.
2,4-D: all 2,4-D products are labeled for application before jointing. A few are labeled up to early boot stage. 2,4-D is generally safe up to early boot, but the risk of injury increases after jointing. 2,4-D will not control chickweed or henbit, and can be weak on smartweed and deadnettle. MCPA products have characteristics and labeling similar to 2,4-D products.
Banvel/dicamba: Apply before jointing. Rate labeled for wheat is low, and will be most effective in a tank-mix or premix with another herbicide (e.g WeedMaster is a premix of 2,4-D amine plus dicamba). Not as effective as 2,4-D on mustard species, but more effective on smartweed. Weak on chickweed, deadnettle, henbit, and wild garlic.
Buctril/Moxy: Apply before the boot stage. Applying in fertilizer solution increases leaf burn. Weak on most winter annuals, dandelion, and wild garlic. For best results apply before weeds reach the 4-leaf stage or a height of 2 inches.
Curtail: premix of 2,4-D plus Stinger. Apply up to 2 pints before jointing, and up to 1.5 pints before boot stage. Excellent control of ragweeds and Canada thistle, and most effective wheat herbicide on dandelion. Weak on chickweed, henbit, and wild garlic. Do not plant double crop soybeans in fields treated with Curtail.
Harmony Extra: Apply before flag leaf is visible and when weeds are less than 4 inches tall or across (rosette). Apply with nonionic surfactant. Effective for wild garlic (at high rates) and most winter annuals. Weak on ragweeds and ALS-resistant marestail.
Harmony GT: Similar to Harmony Extra, but less effective on Canada thistle, chickweed, and a few other winter annuals. Apply with nonionic surfactant.
Express: Apply before the flag leaf is visible when weeds are less than 4 inches tall or across (rosette). Not as broad spectrum as Harmony Extra, but more effective on Canada thistle and dandelion. Apply with nonionic surfactant.
Peak: Apply before 2nd node is detectable in wheat stem elongation, and when
weeds are 1 to 3 inches tall. Do not plant double crop soybeans in fields treated
with Peak. Apply with crop oil concentrate or nonionic surfactant.
Getting a crop off to a good start and keeping it healthy and growing fast will almost always result in high yields baring a catastrophe. When soybean seed is dropped from the planter into the soil and covered, the potential yield for that crop is at its maximum. Yield potential decreases daily if growth conditions are less than ideal or if stresses caused by disease or insects slow plant growth. Good crop management is protecting the crop from stress and the resulting yield reduction. Because soybeans are grown in short crop rotations there are many stresses that must be managed. Everyone is aware of the need to provide adequate nutrition and control weeds for the crop since failing to do so becomes obvious early in the season and is paid for with a reduced harvest. Few producers eliminate or adequately control the stress caused by disease and insects.
During the last five years we have seen a general decline in the ability of the Phytophthora genes to adequately control that disease due to the evolution of the pathogen to produce new races that can defeat the resistance genes. The Phytophthora resistance genes currently available are effective in less than half of our soybean fields. The level of partial resistance, which is effective against all races of Phytophthora, is present in cultivars at much lower levels than a few years ago. Therefore, it is now easier for Phytophthora to cause serious yield reductions than in the past. Seed treatment fungicides will help control Phytophthora and other root and stem rot diseases and allow the crop to get off to a better start.
Seed companies sometime tell customers that the quality of their seed is very high and fungicides are not needed. Seed quality and disease susceptibility are two different factors. No matter how good the seed quality, if a variety is susceptible to a disease and the proper environmental conditions exist, it will become diseased and lower yields will be harvested. Seed treatment fungicides can't provide season long control of disease, but they will help the crop get off to a healthier start so it will be better able to fight off disease if it occurs later in the season.
Do fungicide seed treatments pay? The answer from ten years of testing fungicide seed treatments on soybeans is both yes and no. Most root rot diseases can infect the crop anytime throughout the season if conditions are suitable for infection. Generally, the later in the season an infection occurs, the lower the yield losses. In years with dry soil conditions during and after planting there is little disease development early in the season and the beneficial effect of fungicide seed treatment is reduced. When the soil becomes saturated for a couple days following planting, the seed treatment fungicides pay large dividends. When plants become infected, they don't grow or produce well even though we may not see symptoms of the disease. By the time we can see disease symptoms, the yield has already been reduced by 10 percent. Replanting will cost a minimum of $80 per acre due to lost production, the purchase of more seed and replanting. Over our ten years of testing, the use of fungicide seed treatments has increased income by 3.5 times more than the treatment cost. Over time, it pays to use a fungicide seed treatment on soybean seed regardless of variety, crop rotation, tillage, soil type, soil drainage or planting date.
Several fungicides can control some of the root rot diseases, but only two, Allegiance and Apron XL, are effective against Phytophthora root rot. Most seed companies do not use the "full labeled rate" of these materials when treating seed. Where severe Phytophthora exist, full label rates are needed for control. Most seed companies will add extra Allegiance or ApronXL when requested.
For the latest information and tables showing the efficacy of several seed
treatment fungicides on four soybean diseases go to the online version of corn
at: http://corn.osu.edu/library/articles/cornfungicide.html.
Stewart's bacterial leaf blight was severe in much of Ohio in 2002. The bacterium causing this disease is carried and spread by the Flea Beetle. During years with mild winter temperatures the flea beetle adults overwinter in large numbers. In the spring, as corn emerges from the ground, the flea beetles feed on the young plants and spread the bacterium which in turn causes seedling wilt and leaf blight. The incidence of Stewart's disease is related to the ability of the flea beetle to overwinter. More complete information on the disease is available on the Ohio Field Crop Disease web site http://www.oardc.ohio-state.edu/ohiofieldcropdisease/corn/stewarts.htm.
Flea beetle adults become active in the spring when soil temperatures reach 65 F. Adults are most active on sunny, warm, windless days. They hide in cracks in the soil during windy, cool or cloudy periods. After feeding and mating, adult females lay eggs at the base of the corn plants. Larvae feed on corn roots and are full grown in about two weeks. There are at least two generations per year in Ohio. The beetle overwinters as an adult in the soil near corn fields. It prefers bluegrass sod, but may be found in fencerows, roadsides, and woods. Additional information in flea beetles is available at: http://ohioline.osu.edu/b545/b545_14.html.
The occurrence of Stewart's bacterial disease is totally dependent on the level
of flea beetle survival over winter. For many years, winter temperatures have
been used to predict the severity of Stewart's disease because higher populations
of the flea beetle survive during mild winters than during cold winters. The
'flea beetle index' is calculated as the sum of the average temperatures (Fahrenheit)
of December, January and February. Index values of less than 90 indicate negligible
disease threat, 90-95 indicate low to moderate levels, 95-100 indicate moderate
to severe and values over 100 predict severe disease. The 2003 flea beetle index
and predicted incidence levels for several locations in Ohio are:
Wood Co. = 71.5; Negligible
Wooster, Wayne Co. = 76.1; Negligible
South Charleston, Clark Co. = 76.3; Negligible
Piketon, Pike Co. = 91.4; Low to Moderate
These numbers indicate that flea beetle populations should be very low in Ohio
and that Stewart's bacterial disease should not be severe. Time will tell if
this prediction is correct. Although the flea beetle index has been a relatively
good predictor over the years, we would still recommend that growers scout their
corn fields for the presence of flea beetles. Growers should watch this CORN
newsletter for up-dated information as the spring progresses.
I've received several inquiries recently concerning the yield potential of "twin-row" corn plantings. There have been reports suggesting that twin rows may offer the same yield increases associated with narrow row corn. Narrow row corn production is usually associated with row spacings of 22-inches or less. In a typical twin row system two rows are placed 7-inches apart on 30-inch centers, although other twin row configurations are used. Twin rows make it possible to create narrow rows without changing the row configuration of other equipment, and to avoid costs associated with equipment conversion to a narrow row system. Staying on 30-inch centers allows growers to use the same corn header and tractor tire spacing used in 30-inch corn production.
We conducted a study comparing a 15-inch/30-inch twin row system with 30- and 15-inch row spacings at Washington Courthouse in 1996-1998. This was a collaborative effort involving Larry Lotz, former ag science extension agent in Fayette Co., and Mark Loux, state specialist in weed control. The three row spacing were planted at conventional and high seeding rates (29000 vs. 39000 seeds/A). Over the course of the three years, the twin row system performed as well or better than the 30- and 15-inch row spacings (the yield advantage over 30-inch rows was 15% in 1996 and 4% in 1998.) Population effects on yield were negligible and we didn't observe consistent differences in row spacing response to population. Results of other twin row corn studies have been mixed (see below). More work is needed to determine the role of hybrid, seeding rate, and production environment on twin row corn yield potential.
The following is some additional information on twin rows that's available on-line.
Evaluation of Twin- and Narrow-row Corn and Soybean 2001 - Research Summary
University of Missouri (note: this study evaluated the potential use of the
Great Plains 1510P Precision Seeding System™ in establishing twin rows)
http://aes.missouri.edu/greenley/research/cornsoy.stm
Evaluating Twin-Row Corn Planting Systems, Kansas State University http://www.oznet.ksu.edu/neao/twin_row.htm
Twin-Row Corn, Ontario http://www.gocorn.net/Planting6.html
While the acreage of some specialty corns has declined sharply in recent years, at least one, popcorn, appears to be doing well. Recent acreage estimates suggest that popcorn production may be increasing in Ohio. However popcorn acreage is limited (35,000 to 60,000 A?) and localized. According to a recent report, Ohio ranks fourth in the U.S. in popcorn production behind Nebraska, Indiana, and Iowa.
Popcorn is a special kind of flint corn (vs. the dent types used in commodity grain production). Popcorn yields are measured in pounds of shelled corn per acre. Popcorn hybrids generally yield less than half as much as dent corn hybrids.
The following is some information on popcorn production from extension and university sources that is available online. Most popcorn in the U.S. is grown under contract for processors and companies such as Vogel, Weaver, Wanberg, and Metzger. Growers producing popcorn commercially generally follow cultural practices, plant popcorn hybrids, etc. which are specified by these companies.
NCH-5, Popcorn Production and Marketing:
http://www.agcom.purdue.edu/AgCom/Pubs/NCH/NCH-5.html
Popcorn and Ornamental Corn, Oregon State University: http://oregonstate.edu/Dept/NWREC/popcorn.html
Popcorn Production, University of Nebraska: http://www.ianr.unl.edu/pubs/fieldcrops/g426.htm
Alternative Field Crops Manual, Popcorn, University of Wisconsin: http://www.hort.purdue.edu/newcrop/afcm/popcorn.html
Agricultural Marketing Research Center - Popcorn: http://www.agmrc.org/corn/pc.html
Monsanto Company announced last week that it had received registration from the US EPA for is new YieldGard Rootworm insect protect corn technology. The YieldGard Corn contains a protein from Bacillus thuringiensis (Bt) allowing the corn plant to protect its roots against corn rootworm larvae. This is the first time that a biotechnology product (Bt) has been designed to protect corn against corn rootworm larvae.
Monsanto says that the YieldGard Rootworm trait will be available in 2003 in corn hybrids sold by DEKALB and Asgrow as well as through licensed, independent seed companies.
As part of the registration, EPA requires the use of an insect resistance management (IRM) practices to delay the potential development of resistance by target pests. The IRM for YieldGard Rootworm corn requires growers to plant a 20 percent refuge of non-YieldGard Rootworm corn adjacent to or within the YieldGard Rootworm cornfield.
OSU Entomologists have conducted corn rootworm trials using the YieldGard Rootworm
technology for the past several years. Based on root ratings, the YieldGard
Rootworm technology performed as good as or better than the granular soil insecticides
that are commonly used for rootworm control.
FMC has informed us that Mustang MAX has received label approval for use on corn, soybean, wheat and alfalfa. The chemical in Mustang MAX is the same as that in Mustang, zeta-cypermethrin, but the pounds active ingredient in Mustang MAX is less than in Mustang, 0.8 lb/gallon vs 1.5 lb/gallon. The chemical is labeled for the same insects that Mustang is labeled for and includes most of the common pests that we have in Ohio. Rate per acre is almost the same with Mustang MAX as with Mustang but the active ingredient per acre will be less with Mustang MAX.
The Virgil Overholt Drainage School will be held on March 17-21, 2003 at the Fayette County Agricultural Service Center. This program is designed to promote effective "Agricultural Water Management Systems that Balance Food Production and Environmental Objectives."
The Overholt Drainage School provides continuing education for land improvement contractors, sanitarians, soil and water conservation technicians, farmers, consultants, and others interested in advancing their knowledge of basic concepts, principles, and skills related to the purpose, design, layout, construction, and management of Soil and Water Conservation Systems, with emphasis on Water Management and Water Quality.
2003 sessions include:
Laser Surveying and Topographic Mapping
Subsurface Drainage Design
Subsurface Drainage System Installation: Considerations Using Pull-Behind Plows
Waterway Design Concepts, Layout, Construction and Contractor Checkout
Surveys and Measurements for Drainage Channel Restoration
Program is presented by the Overholt Drainage Education and Research Program (ODERP), Department of Food, Agricultural, and Biological Engineering (FABE), Ohio State University Extension, and Ohio Agricultural Research and Development Center (OARDC), at The Ohio State University, in cooperation with the USDA-Natural Resources Conservation Service (NRCS), the USDA-Agricultural Research Service (ARS) - Soil Drainage Research Unit, the Ohio Land Improvement Contractors' Association (OLICA), and others. Instructors include Land-Grant University Faculty and Staff, NRCS engineers and technicians, ARS engineers and scientists, and experienced OLICA contractors. The Overholt Drainage School Program is funded in part by donations made to the ODERP Endowment, Dept. FABE at The Ohio State University.
For additional information and registration forms please use the following link to the Virgil Overholt Drainage School Website: http://www.ag.ohio-state.edu/~agwatmgt/2003_Overholt.htm
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: Mark Loux and Jeff Stachler (Weed Science), Pat Lipps, Anne Dorrance and Dennis Mills (Plant Pathology), Jim Beuerlein (Soybean & Small Grain Production), Peter Thomison and Allen Geyer (Corn Production), Bruce Eisley (IPM) and Ron Hammond (Entomology); District Specialists: Ed Lentz (Agronomy); Extension Agents: Steve Foster (Darke), Howard Siegrist (Licking), Glen Arnold (Putnam), Clark Hutson (Seneca) and Roger Bender (Shelby)Editor: Clark Hutson Web Editor: Nathan Watermeier
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.
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