C.O.R.N. Newsletter 2007-36

Dates Covered: 
October 22, 2007 - October 29, 2007
Editor: 
Curtis E. Young

The Status of Ohio Winter Wheat - Should We be Concern about the Lush Growth?

Authors: Pierce Paul, Jim Beuerlein

We are receiving many questions and concerns about the greater-than-normal vegetative growth of wheat. The warm weather and delayed killing frost has allowed wheat and winter annual weeds to grow well this year. Generally, it is almost impossible to get too much wheat growth in the fall in Ohio, and that has not happened since 1970 when I first came to Ohio. Winter wheat cannot joint until after vernalization brought on by cold winter temperatures, so all the fall growth is tillers and leaves. More growth in the fall is good in that tillering is completed before dormancy and the plants are ready to start reproductive growth as soon as spring temperatures allow. More fall growth improves the winter hardiness and decreases the potential for heaving next spring. Increased fall growth does not make the heads more subject to freeze injury next spring because that damage happens as a result of unusually cold weather later in the spring than usual which happens somewhere in Ohio every few years. More fall growth is associated with increased yield potential because the factory is ready to start production as soon as spring breaks. Historically, we rarely get enough fall growth, so the extra growth we see now is unusual. As long as the plants in 7.5-inch rows don't get more than 12 inches tall, there are no concerns. We need not worry about plant size in 15-inch rows, regardless of its height.

In addition, growers are concerned that delayed killing frost could lead to more damage by aphids and fall development of diseases such as leaf rust and viruses. However, recent surveys of wheat fields have shown no evidence of rust or other disease development. In addition, the number of aphids being found in most fields is well below the treatment threshold of 50 aphids per linear foot of row (http://corn.osu.edu/#B), suggestions that fall transmission of viruses such as BYDV will also be very low.

All things considered, the crop is off to a great start and with a high yield potential. We need to keep scouting the crop and control any problems that can lower the high yield potential we have at mid-October. If we are successful in doing so, and the weather in April through June is ideal for wheat, we could see yields in excess of 130 bushels per acre as the yield potential of most of the varieties we grow is far greater.

Transgenic Corn and Refuges

Authors: Bruce Eisley, Andy Michel, Ron Hammond

Knowing that Ohio growers will in all likelihood be planting more Bt transgenic corn hybrids next spring, we continue to remind growers about Insect Resistant Management (IRM) requirements. The purpose of employing these practices is to help prevent insects from developing resistant to the Bt gene. These are government regulations that must be followed. Growers who fail to follow IRM requirements risk losing access to Bt corn technology.

There are two different Bt types that could be used, Bt for corn borer and Bt for corn rootworms, with three different families of transgenic hybrids available with the different Bt genes alone or in different stacked configurations (YieldGard, Herculex, and Agrisure). There are some similarities and some differences in the requirements for the two Bt types.

First, and foremost, is the need to plant a 20% refuge area to non-Bt corn. A refuge is simply a block or strip of corn planted with a hybrid that does not have the Bt gene for controlling the target insects. The primary purpose is to maintain a pest population that is not exposed to the Bt toxin, allowing susceptible insects to remain alive in the population to mate with any resistant insects that survive in the transgenic area. This allows any offspring to remain susceptible to the Bt. In terms of the distance of the refuge from the Bt corn, there is a major difference between transgenic hybrids for corn borer and rootworm. For corn borer, the non-Bt refuge can be within, adjacent, or near the Bt field, but has to be within 1/2 mile, preferably within 1/4 mile. For corn rootworm, the non-Bt refuge has to be within the same field as the Bt corn, or adjacent to it. When adjacent, it can be separated at most by a ditch or a road, but not by another field. When planting the refuge, there are various plantings options, including a separate field refuge (mainly for corn borer), an adjacent field, a separate but adjacent block next to the Bt, a block refuge within the Bt field, the refuge planted along the perimeter, or a split-planter refuge. If planting the refuge using a split planter, the strip width must be at least 4 rows for corn borer (6 preferred) and corn rootworm.

There are other guidelines related to IRM, including management of the Bt field and non-Bt refuge, and use of other insecticides. Both the transgenic and non-transgenic areas should be managed in a similar manner. Growers should plant both hybrids close to or at same time, and select Bt and non-Bt hybrids that have similar growth and development characteristics. If planting a refuge for rootworm, the cropping history must be the same (i.e., if the Bt is planted following corn then the refuge must be planted following corn). Reducing inputs or placing the refuge on marginal land can reduce the effectiveness of the refuge. In terms of insecticides, there are procedures for controlling the target insect (corn borer or corn rootworm) and secondary insects in both the Bt corn and in the refuge. The major ones are, for European corn borer, the non-Bt corn refuge may be treated with conventional insecticides only if the target pest reaches economic threshold. However, a foliar Bt-based insecticide cannot be used within the refuge. For rootworms, a soil-, seed-, or foliar-applied insecticide for control of rootworm larvae and other soil pests is allowed in refuge. If an aerial insecticide is applied to the refuge for control of rootworm adults, the same treatment must be applied at same time to Bt corn. Regarding the use of rotations with Bt-rootworm hybrids, if the refuge is planted on rotated grown, the Bt field must also be on rotated ground. However, if the refuge is corn following corn, than the Bt field can be planted on either a continuous or rotated field.

If growers are planting a stacked hybrid containing both types of Bt, they have two approaches on how to manage their refuge. The first choice is planting separate refuges for each target pest. However, we recommend the second choice, the common refuge approach where corn without any Bt technology is planted. The common refuge, also 20%, must be within or adjacent to the transgenic field, as is the case with Bt-rootworm transgenic corn. A common refuge can be treated with soil insecticides or seed treatments for rootworms, and also non-Bt foliar insecticides for control of late season pests. If rootworm adults are present at that time, than the Bt stacked hybrid must also be treated in a similar manner. Growers should seed their seed dealer for any additional IRM requirements related to the use of stacked traits.

It is of extreme importance that growers follow these guidelines. Not only are we concerned about preventing resistance to the Bt technology, but also to make sure growers do not loose the ability to use this technology because of making wrong decisions.

There is another suggestion to mention to growers, especially those planning on using transgenic rootworm corn in first year corn. If possible, plan on leaving a strip in your corn without any protection from rootworm to determine if the first year rootworm variant is REALLY a problem in your field next year. Leaving an untreated strip (no soil insecticide nor seed treatment) will be the only way to determine if the variant was actually present AND an economic problem. Corn in these untreated strips should have their roots dug and rated next July to determine the level of rootworm injury.

Correcting 2006 Compaction Problems - Randall Reeder

Authors: Randall Reeder

Last fall at this time farmers were trying to harvest crops in the wettest fall in at least fifty years. Severe compaction was a common result. Then the wet fall was followed by a wet winter and a wet spring leaving little or no chance to do anything to correct compaction problems before planting.

For many Ohio farmers, now is the time to consider compaction solutions. If the yield monitor confirmed your worst fears about compaction, conditions this fall seem to be ideal for subsoiling. Deep tillage can help increase water infiltration and improve soil structure. However our research at OARDC Northwest Experiment Station indicates that subsoiling does not immediately return soil to its “pre-compaction” state. And be cautious of heavy axle loads on the field in the year or two following subsoiling.

From a crop residue management standpoint the best subsoiler is one that simply slices through the soil with little surface disturbance. This design is often preferred because crop residue will protect against erosion and the field may be smooth enough to plant without additional tillage. Try to till no deeper than the compaction zone. And if the shanks are 24 to 30 inches apart the undisturbed soil between them will support heavy loads better than with a typical V-ripper which usually tills the whole area.

For those without compaction problems, but still not quite ready for continuous no-till, there are several options for light shallow tillage. The goal should be to do the least amount of tillage necessary to create conditions for a good crop. Strip-till can be a good choice, especially for farmers with a precise auto-steering system.

Comprehensive Nutrient Management Plan Provider Workshop

Authors: Greg LaBarge

The Comprehensive Nutrient Management Planners Workshop early registration deadline is a postmark of October 23rd for the $375 workshop rate. After this date the registration is $450. There is no at the door registration. The program has been approved for a total of 15 hours of Certified Crop Advisor Credit with 6.5 hours of nutrient management and 8.5 hours of soil and water credit. The program will be held at The Centre at Bluffton, 601 Main St., Bluffton, OH 45817.

The session lays the ground work for Technical Service Providers, NRCS and SWCD to provide Comprehensive Nutrient Management Plans for farmer clientele. The program is approved for those who wish to do plans for farmers in Ohio, Michigan and Indiana. Sessions will highlight the information that goes into development of a CNMP and software that is available to do the work necessary to complete a plan.

A listing of the process to become certified can be found state at the following websites: Ohio (http://www.oh.nrcs.usda.gov/technical/cnmp.html), Michigan (http://www.maeap.org/modules.php?name=DocReader&op=showCat&cid=79&mt=2) and Indiana (http://www.in.nrcs.usda.gov/tsp.html).

Participants will need to do additional work beyond the course above and complete a approved plan to reach full certification status. By participation in this workshop, potential plan providers can map out an individualized plan to reach full certification.

A complete copy of the agenda can be found and registration material can be found at: https://agcrops.osu.edu/calendar/ For more information contact Greg LaBarge, Extension Educator OSU Extension-Fulton County at 419-337-9210 or labarge.1@osu.edu.

The National No-Till Conference

Authors: Randall Reeder

The National No-Till Conference is returning to Cincinnati, January 9-12. This annual meeting rotates among four Midwest locations and draws about 700 farmers and crop consultants.

The early bird registration deadline for the 16th National No-Tillage Conference is October 31. Register today for only $217 for the first attendee and $187 for each additional member of your family or farm. This is a $30 discount off the regular price. Plus, this year, your registration includes a 1-year subscription to No-Till Farmer. There are several ways to register. Call (866) 839-8455 or (262) 432-0388. Fax your registration to (262) 786-5564. Register online at: http://www.lesspub.com/cgi-bin/site.pl?ntf/ntfConf or mail: National No-Tillage Conference, P.O. Box 624, Brookfield, WI 53008-0624.

New Field Crop Entomologist on Board

Andy Michel is our newest addition to the entomology specialist team. He has long been interested in entomology since his undergraduate in the Department of Entomology at Purdue University. There, he worked with a few systems, such as examining genetics of Hessian fly resistance to wheat, biological control of a potato beetle, and the establishment of the soybean aphid in Indiana during 2001. At the University of Notre Dame, he completed a Ph.D. studying insect population genetics and adaptation in mosquitoes, specifically an African malaria vector. He has just finished a 2-year post-doctoral study on a major pest of apples, the apple maggot fly Rhagoletis pomonella. For the apple maggot fly, Andy studied how the native population that infests hawthorn trees has shifted hosts to attack apples. Andy’s larger research goals are to understand the genetic underpinnings involved in how insect pest species adapt to the changing agricultural landscape. For example, what genetic changes occurred within western corn rootworm for it to infest first year corn? How fast will this adaptation migrate? He is also interested in how insect populations migrate, establish populations, and exchange genes. In this manner, he hopes to have better predictions of increasing pest populations. He also hopes to be able to contribute to the transgenic/refuge debate - how much refuge is necessary, does placement and configuration change the number of refuge populations are refuge populations mating with any potential Bt survivors? As our methods of agriculture adapt, so will insect pests. Tracking and understanding these adaptations will be key to the management of pests. Andy is eager to be working with the Agronomic Crops Team and with all the growers in the state of Ohio. (He will also easily forgo his allegiances to the Boilermakers and the Irish and is very happy to be rooting for the Buckeyes!)

Archive Issue Contributors: 

State Specialists: Ann Dorrance, Pierce Paul and Denis Mills (Plant Pathology), Ron Hammond, Andy Michel and Bruce Eisley (Entomology), Mark Loux and Jeff Stachler (Weed Science), Randall Reeder (Agricultural Engineer), and Jim Beuerlein (Small Grains). Extension Educators: Harold Watters (Champaign), Howard Siegrist (Licking), Roger Bender (Shelby), Glen Arnold (Putnam), Wes Haun (Logan), Mike Gastier (Huron), Steve Foster (Darke), Gary Wilson (Hancock), Greg LaBarge (Fulton), and Curtis Young (Allen).

About the C.O.R.N. Newsletter

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.