C.O.R.N. Newsletter 2006-37

Dates Covered: 
October 31, 2006 - November 6, 2006
Editor: 
Curtis E. Young

How to Save Treated Wheat Seed from 2006 for Fall 2007 Planting

Authors: Jim Beuerlein, Pierce Paul

Because of late soybean harvest and poor planting conditions, some Ohio growers may not be planting wheat in 2006. Unwilling to face the risks of greater winter kills and poor tiller development associated with late planted wheat, some growers are thinking about saving their treated seed for the fall 2007 planting. The dilemma then is what is the best way to maintain treated wheat seed (under less than optimum storage conditions) until next fall to maximize germination?

Storage to maximize quality until next fall would be cold conditions; 40-60 F would be perfect. However, these conditions are not available to most growers. So, try to keep seeds as cool as possible and in as low a humidity environment as possible. Actually wheat is fairly easy to maintain for a year or so. However, growers will still need to check their germination and vigor next September to be sure they have good seed and to adjust seeding rate to ensure desired plant population. Contact Central Ohio Seed Testing, 614-792-0334 for sample bags and sampling instructions.

To prevent any accidental introduction of treated seeds into the marketplace, seed and storage facility should be clearly labeled that the seed is treated.

Late Planted Wheat and Tillering

Authors: Robert Mullen, Edwin Lentz

Due to delayed soybean harvest this fall, some producers have gotten their wheat in the ground rather late (in fact, some still have not planted wheat). So naturally, the question is how do you promote tillering? Well, unfortunately there is very little that can be done this fall due to the onset of cold weather. So what about next spring, can you apply some early spring nitrogen to promote tillering before stem elongation?

Other states such as Kentucky and Virginia recommend some nitrogen be applied to fields that did not see much tillering in the fall. The rates of nitrogen are relatively low (60 pounds per acre or less), and the universities recommend that nitrogen be split applied (late winter and early spring) (http://www.ca.uky.edu/agc/pubs/id/id125/05.pdf). But can information from lower latitudes be applied in Ohio?

Our spring growing conditions are considerably different than Kentucky and Virginia and the proposition of spring tillering is much less here due to fewer growing degree days. Research has been conducted the last two years at the Western and Northwest Research Stations to determine the impact of nitrogen timing on wheat grain yield. Nitrogen was either supplied at initial greenup or delayed until Feekes 6. Over the four site-years of the study, nitrogen timing did not affect wheat head counts, and wheat yield was actually increased 2 out of 4 site-years by delaying nitrogen application until Feekes 6 (the other two site-years did not show a difference in yield due to timing of application). Granted some nitrogen was applied in the fall and wheat was planted timely, but the take home message is that spring nitrogen did not significantly promote spring tillering. If nitrogen is applied earlier in the spring, recognize that the potential for loss is also greater.

Soybean Seed Quality

Authors: Anne Dorrance, Dennis Mills

Phomopsis seed rot can occur in Ohio when susceptible varieties are planted and rains are above normal during pod development and filling stages. This disease can be caused by three different fungi all of which can survive on soybean residue. Seed which is infected is cracked, shriveled and chalky white (http://www.oardc.ohio-state.edu/ohiofieldcropdisease/soybeans/phomopsis.htm). Seed that is heavily infected will not germinate. Seed where the fungus is only on the outside of the seed will be fine if it remains dry. We have seen germination increase on some seed lots over the winter when it is maintained in cool dry conditions. The fungus does not survive very well on the outside of the seed. The challenge is for seed that is still in the field and Phomopsis has started to invade the pod. Under wet conditions, more seed will become colonized in those pods and those that are colonized the fungus will become firmly established. On the outside of the plant, linear rows of small black fruiting bodies form on the stems and over the surface of the pods. These are what will aide in the survival of the fungus in the field. Fields with high levels of Phomopsis should be harvested early, to reduce the severity of infections that may occur and consider tillage to bury the residue to reduce survival. As always, when disease levels are high, crop rotation is essential especially on no or reduced tillage fields.

Split Fields: The Bane of On-Farm Research

Authors: Robert Mullen, Edwin Lentz

Last winter we had a series of CORN Newsletter articles discussing the importance of statistics to agricultural research (Newsletter 2005-39 (http://corn.osu.edu/story.php?setissueID=117&storyID=657), 2005-40 (http://corn.osu.edu/story.php?setissueID=118&storyID=659), and 2006-02(http://corn.osu.edu/story.php?setissueID=121&storyID=691)). A point was made then that simply splitting fields may cause a producer, consultant, or retailer to conclude that the difference between the two areas of the field were due to a treatment (application of fungicide, insecticide, non-traditional fertilizer, etc.). This may or may not be true, but because we have no estimate of error (both within treatments and among treatments) we cannot definitively say why they were different. The purpose of this article is to shed light on the fact that there are a few major things that can affect the information you get from split field information.

First we will tackle the concept of error. Any measurement has a level of error associated with it even something as simple as using a tape measure to determine the length of a board. Error simply refers to the uncertainty of the measurement. In agricultural research, we measure yield levels from treatments to determine if the treatment improved crop productivity, but there may be underlying unknown causes that influenced yield more than the treatment. Here is an example of data collected from an experiment at the Northwest Research Station evaluating lime applications in corn. Corn yield without any lime added from four replications: 146, 139, 161, and 161 bushels per acre. Corn yield with lime added at a rate of 1.25 tons per acre from four replications: 153, 152, 150, and 148 bushels per acre. If you simply compared the 139 bushel yield to the 153 bushel yield you would conclude that application of 1.25 tons of lime per acre could increase yield 14 bushels per acre. If you look at the average of each treatment the yield levels are nearly identical 152 and 151 bushels per acre. The yield differences between the four replications represents the error associated with conducting the research in this field.

Assume we have a field that was split into two. One side (west) received a fungicide application, and the other side (east) did not receive the application. The west side yielded 10 more bushels per acre. Here are just a couple of reasons yields could have been different.

a) Soil differences
Large source of error. The soil located in a large field (even small fields) is unlikely to be uniform (just check the soil survey). Soil from the west side of the field could have been well drained while the east side was generally poorly drained. This could easily account for the difference in yield. Differences attributed to a treatment may in fact be due to differences in drainage, soil texture, topography, soil chemical properties, etc.

b) Management differences
Large source of error. Fields will often have different historical rotations. The west side may have been rotated to wheat and other grass crops in the past while the east side was not. This could easily account for yield differences. Historical management can have a large impact of soil productivity.

c) Mistake in area estimate
Potentially large source of error. Perhaps the area estimates for the two halves of the field were incorrect. In the above scenario, the west side actually had more acreage than the untreated, so the total weight was greater. Area estimates can be incorrect and greatly influence observations.

Be careful when drawing conclusions from split-field data. What you attribute a yield increase to may have nothing to do with the treatment. This is why replication and randomization are critical!!

Bt Corn Refuge Requirement Update

Authors: Ron Hammond, Bruce Eisley

It was called to our attention that the article in the CORN newsletter a few weeks ago on refuge requirements was incorrect regarding the number of rows needed when planting non-Bt corn in strips, whether within the field or as a perimeter planting. We had stated that 4 rows were needed when planting Bt corn borer, but 6 rows for Bt corn rootworm. Upon looking at some literature and numerous web sites, it became clear that there is much misleading information still out there. We contacted representatives from the seed companies to get things straightened up. As of now, the strip requirement for all Bt corn, whether for borer corn (YieldGard Corn Borer, Herculex I, and Agrisure CB), rootworm (YieldGard Rootworm, Herculex RW, and Agrisure RW), or their available stacked traits is a minimum of 4 rows of non-Bt corn with 6 row being preferred.

Archive Issue Contributors: 

State Specialists: Ann Dorrance, Pierce Paul and Dennis Mills (Plant Pathology), Ron Hammond and Bruce Eisley (Entomology), Jim Beuerlein (Small Grain Production), Mark Loux (Weed Science) and Robert Mullen (Soil Fertility). Extension Educators: Howard Seigrist (Licking), Roger Bender (Shelby), Harold Watters (Champaign), Keith Diedrick (Wayne), Curtis Young (Allen), Gary Wilson (Hancock), Glen Arnold (Putnam), Bruce Clevenger (Defiance), Mike Gastier (Huron), Ed Lentz (Seneca), Stephen Foster (Darke), Steve Prochaska (Crawford), and Jonah Johnson (Clark).

About the C.O.R.N. Newsletter

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.