C.O.R.N. Newsletter 2006-27

Helpful Tips As We Get Ready to Plant Wheat

Authors: Dennis Mills, Pierce Paul

The 2006/2007 winter wheat season is fast approaching and as growers make preparation for planting, we would like to remind them of a few important management decisions that are important for a successful crop.

1- Variety selection: Select high-yielding varieties with good test weight, straw strength and disease resistance. Since no single variety is equally resistant to all diseases, select those that are resistant to the disease most damaging and common in your region of the state. When choosing between varieties with moderate resistance to wheat scab and those with resistance to foliar diseases, give first preference to wheat scab resistance. In any given year, scab may result in more yield and quality losses that any other disease. Management options for scab are limited and fungicides are not very effective. Foliar diseases can be managed successfully with fungicides. For a list of wheat varieties and their disease resistance and agronomic trails refer to the 2006 Wheat Performance Trial (http://www.oardc.ohio-state.edu/wheat2006/). For growers interested in varieties suitable for relay intercropping, refer to a recent C.O.R.N article by Jim Beuerlein and Rich Minyo (http://corn.osu.edu/story.php?setissueID=145&storyID=864) for a list of those varieties.

2- Seed preparation and planting: Plant seeds that have been properly cleaned to remove shriveled kernels and treat all seeds with a fungicide to control soil- and seed-borne diseases. Due to rain-related harvest delay, sprouting occurred in some locations. Since sprouting affects seed viability and vigor, growers are advised against planting seeds harvested from fields with sprouting problems. If it is absolutely necessary to plant seeds from such fields, make sure you do a germination test.

Plant after the Hessian Fly Safe date for your county to avoid insect and disease problems. This date varies between September 22 for northern counties to October 5 for the southern-most counties. On the other hand, planting too late (generally after Oct 20 in northern Ohio) can reduce the number of primary tillers that develop in the fall and increases the risk of cold temperature injury.

Plant seeds at a rate of 1.2 to 1.6 million seeds per acre. For drills with 7.5 inch row spacing, this is about 18 to 24 seeds per foot of row with normal sized seed.

Plant seed 1.5 inches deep and make sure planting depth is uniform across the field. No-till wheat into soybean stubble is ideal, but make sure the soybean residue is uniformly spread over the surface of the ground. Shallow planting is the main cause of low tiller numbers and poor over-winter survival due to heaving and freezing injury.

3- Fertilizer application. Apply 20 to 30 lb of actual nitrogen per acre at planting to promote fall tiller development. Wheat also requires at least 45 ppm of available phosphorus per acre in the soil to produce really good grain yields. If the soil test indicates less than 40 ppm, then apply 80 to 100 pounds of P2O5 at planting. Soil potassium should be maintained at levels of 135, 165 and 185 ppm for soils with cation exchange capacities for 10, 20, or 30, respectively. If potassium levels are low, apply 60 to 100 pounds of K2O at planting. In Ohio, limed soils usually have adequate calcium, magnesium and sulfur for wheat. Soil pH should be between 6.5 and 7.0 for eastern Ohio (6.0 and 7.0 for western Ohio).

For more on wheat management guidelines, seeding rates and fungicide seed treatments visit:
http://corn.osu.edu/story.php?setissueID=104&storyID=618
http://corn.osu.edu/story.php?setissueID=102&storyID=605
http://www.oardc.ohio-state.edu/ohiofieldcropdisease/corn/seedtreatmentefficacy.htm

The Importance of the Preemergence Glyphosate Application in No-till Wheat

Authors: Mark Loux

In the past few years, dandelions, winter annual grass species, such as downy brome, cheat, and annual bluegrass, and winter annual broadleaf species, such as common chickweed, purple deadnettle, marestail/horseweed, and cressleaf groundsel, have become more prevalent in no-till winter wheat. Many of these weeds can be effectively managed with a preplant/preemergence application of glyphosate. This is often a more effective treatment for winter annuals, compared to the herbicides that can be applied broadcast to wheat in late fall or early spring. A dense population of winter annuals or dandelion may have already suppressed wheat growth by the time a fall or spring treatment can be applied. The preplant glyphosate application is also the most effective and least expensive tool to control dandelions and winter annual grasses.

We suggest a glyphosate rate of at least 0.75 lb of glyphosate acid per acre in any field that contains dandelion. Include ammonium sulfate in glyphosate treatments, and the appropriate amount of surfactant if specified by the product label. The activity of herbicides on dandelions may be reduced where fall dandelion growth has been less than vigorous as a result of dry conditions. Also, the preplant herbicide application timing for wheat is somewhat earlier than the optimum timing for fall dandelion control. However, we believe the control attained by a glyphosate application makes it worth the effort even if dandelions are not in the optimum condition. It is possible that increasing the glyphosate rate to 1.1 or 1.5 lbs of glyphosate acid per acre may improve dandelion control prior to wheat planting, but we have not conducted research to verify whether this is the case.

We usually receive questions in early fall about the safety and legality of 2,4-D applied prior to wheat planting. As far as we know, no 2,4-D product label supports this use of 2,4-D. There is some risk of stand reduction and injury to wheat from preplant applications of 2,4-D. We question why producers would want to use 2,4-D, when glyphosate can be applied for about the same cost to provide a similar level of weed control (better on some species). One argument in favor of the use of 2,4-D would be to avoid overuse of glyphosate and slow the development of herbicide resistance. However, 2,4-D can be used with glyphosate in fall and spring herbicide treatments prior to corn and soybean planting, and would probably be best avoided prior to wheat planting.

Producers who have applied glyphosate at the time of no-till wheat planting report that their fields have been relatively free of winter annuals in the spring. However, producers also indicate that they often do not have time to make the application, given the time required to harvest corn and soybeans and plant wheat. Consider having the glyphosate custom applied where time is a limiting factor, especially in fields where winter weeds are evident. Where possible, apply the glyphosate several days before tillage or planting. Otherwise, be sure to apply before the wheat emerges!

Weed Control Observations in Soybean Fields

We have noticed weeds extending above the soybean canopy in many fields in the last two weeks, especially giant ragweed, marestail/horseweed, velvetleaf, common lambsquarters, and annual grasses. On three different trips through parts of Champaign, Darke, Fayette, Madison, and Miami Counties, we determined the percentage of fields where giant ragweed and marestail were evident. If more than two giant ragweed or marestail plants were present in a field and there presence did not appear to be due to a skip in the herbicide application, the field was noted as having escapes of these two weeds. We walked some of the fields and spoke with producers, finding that both non-GMO and Roundup Ready soybeans were present in these areas. We walked these fields to determine if plants had regrown following a herbicide application or whether new germination occurred after the herbicide application. In most of the fields, giant ragweed had regrown following a postemergence herbicide application (regardless of the type of soybean planted), and new germination had also occurred.

Based on our scouting, approximately 33% of the soybean fields in Madison County had giant ragweed plants surviving postemergence herbicide application. In Fayette County, 54% of the soybean fields had marestail plants surviving and evident above the soybean canopy. In the other counties, giant ragweed and marestail appeared to be surviving herbicide applications in approximately 16 to 23% and 11 to 46% of the soybean fields, respectively.

Take the opportunity now and at harvest to make a note of weeds that are escaping weed control programs. Ideally, you should take the time to determine why weeds are escaping (regrowth from postemergence herbicides or emergence after herbicide applications). Examine spray records from this year for fields where problems occurred, and then determine how future weed control programs can be adjusted to prevent the same problem from occurring.

Central Ohio Agronomy Show September 7th

Authors: Howard Siegrist

The Central Ohio Agronomy Show runs from 1:30 p.m. to 7:30 p.m. on Thursday, September 7th at Kilbarger Farms 11895 Shell Beach Road, Thornville, OH.

The event will feature presentations by top industry and educational representatives including Ken Ferrie, Field Agronomist for Farm Journal Magazine. Ferrie will present research and field observations on vertical tillage management and the keys to successful strip tillage and planting.

Bob Neilson, Purdue University's corn specialist will discuss the merits of twin row corn production in Ohio and the stresses of a hot and sometimes dry summer on the corn crop as it approaches maturity.

Anne Dorrance, OSU Soybean Plant Pathologist will share information on foliar diseases in soybeans in the absence of soybean rust and when it is wise to consider fungicide use.

Nathan Watermeier, Precision Agriculture Specialist with OSU Extension will present programs on RTK auto steer and variable rate technologies. He will be assisted by other university and industry representatives.

Field comparisons of harvest efficiencies of combines in harvest of soybeans will be demonstrated and tips maximizing harvest efficiency will be presented by industry representatives.

Winter annual weed control in row crop production will be addressed by Mark Loux, OSU Weed Specialist.

Ohio's new nitrogen recommendations and how to make the wisest choice in nitrogen rates will be presented by Robert Mullen, OSU Soil Fertility Specialist.

The program offers CCA continuing education credits in soil and water management, crop management, nutrient management and pest management. Certified crop advisors are also encouraged to attend the "Corn College in the Field" earlier the same day at the same location where 3 CEU's of CCA credit will be available.

The cost for the Central Ohio Agronomy Show is $5.00 which includes supper. Pesticide applicator credits will also be available to private and commercial license holders. No reservations are needed.

Questions may be directed to the Licking County Extension office (740) 670-5315. The event is sponsored by the OSU Extension offices in Fairfield, Pickaway, Perry and Licking Counties.