CORN
Crop Observation and Recommendation Network

October 27 - November 9, 2003
C.O.R.N. 2003-37

In This Issue:

A) Status of First Year Corn Rootworm in Ohio
B) On-Farm Gypsum Research Results
C) Harvest Delays Increase Potential for Yield Losses
D) Corn Stalk Quality Becoming an Issue In Ohio

A) Status of First Year Corn Rootworm in Ohio - Eisley & Hammond CORN Questions

A preliminary report about the 2003 western corn rootworm trapping program in Ohio soybeans was included in an earlier newsletter. The final data from the 2003 rootworm trapping program have been assembled and are available on the WEB at http://ipm.osu.edu/fycr/fycr.htm. This is an overview of the results from that survey.

Sampling was done using Pherocon® AM yellow sticky traps placed in 89 fields in 22 counties. Six traps were placed in the soybeans on metal posts at canopy height and located at least 100 feet from the field edge and evenly spaced in the field. The traps were placed in the field at the end of July and changed weekly for six weeks until the early part of September. Each week the old traps were removed from the posts, the WCRA were counted and recorded and new traps placed on the posts. After each trapping week, the number of beetles collected were summed and divided by the number of days the traps were in the field resulting in the average number of beetles collected per trap per day. Research indicates that catches in soybean of 5 or more beetles/trap/day during any trapping week indicates a potential problem with rootworm in the field the following year.

Based on the potential treatment level of 5 beetles/trap/day during any trapping week, the trapping data from 2003 had the following results:
One field had an average > 3 beetles/trap/day
Three fields had an average > 2 beetles/trap/day
Twenty-six fields had an average > 1 beetle/trap/day
Fifty-nine fields had an average < 1 beetle/trap/day
None of the fields went over the threshold of 5 beetles/trap/day.

Based on these data, if any of these fields are planted to corn in 2004, a treatment (either insecticide or plant resistance) should not be needed for rootworm. These data do not mean that other fields in a county, that were not sampled, do not need treatment but it does give information about the fields that were sampled and about the abundance of the beetles this year.

B) On-Farm Gypsum Research Results - Lentz CORN Questions

On-farm research was completed this past growing season to observe potential yield benefits from gypsum applied to corn and wheat. Neither study showed a benefit. The corn study was completed on Dean Koehler's farm in Wyandot County, where 1000 and 4000 lb/acre of gypsum were applied in early January. Yield means were 204.5 bu/A for the zero check, 205.6 bu/A for the 1000 lb treatments, and 205.3 bu/A for the 4000 lb treatments. No statistical differences were detected among comparisons. The wheat study was completed on Dave Lotz's farm in Hardin County, where 100 and 200 lb/A of gypsum were applied soon after greenup. Yield means were 67.8 bu/A for the zero check, 66.4 bu/A for the 100 lb treatment, and 67.1 bu/A for the 200 lb treatment. No statistical differences were detected among comparisons. In addition, yields were not affected by the supplemental sulfur, since gypsum provides calcium and sulfur to the soil. Both of these studies were replicated 4 to 5 times. More detailed information may be found in the Agronomic Crops Team On-Farm Research Bulletin to be published early next year. On-farm gypsum studies will be continued in the future. This past year, The Ohio State University has also initiated a study to investigate the relationship between gypsum and soil quality. Special thanks to Chris Bruynis and Gene McCluer, OSU Agricultural & Natural Resources Extension Agents, and Farmers Commission, Inc.for their assistance in these studies.

C) Harvest Delays Increase Potential for Yield Losses - Thomison CORN Questions

Despite the cool weather, late crop maturation, and an earlier than normal frost, corn grain moisture may lower than you would expect. At two of our hybrid performance test sites in NW Ohio (Van Wert and Hoytville) harvested last week, grain moisture of entries ranged from about 16 to 25%. Moreover, these test sites were planted relatively late (May 22, 2003). Because the potential for stalk rot is widespread this year, the yield potential of many corn fields could drop considerably if harvesting is delayed much beyond maturity. Ear drop may also increase in some locales due to European corn borer damage. Ear damage by corn borers and other insects may also increase the potential for grain quality problems caused by ear molds.

In 2002 we initiated a study to evaluate effects of delayed harvests on corn hybrids differing in maturity and stalk quality. At the S. Charleston test site, corn was harvested on three dates: Oct.2, Nov. 1, and Dec.3. Grain moisture, averaged across hybrids, decreased from 23.3% on the first harvest date to 17.1% on the second harvest to 15.8% on third harvest date. Between the first harvest date and later harvests in early Nov. and Dec., stalk lodging increased from less 6% to over 25% while grain yield (which averaged more than 170 bu/A on the first harvest date) decreased 30%.

The stalk lodging and ear drop associated with weathering can result in significant yield losses. The loss of one "normal" sized ear per 100 feet of row translates into a loss of more than one bushel/acre. An average harvest loss of 2 kernels per square foot is about 1 bu/acre. Keep in mind that most harvest losses occur at the gathering unit. The table below shows the range of visible corn harvesting losses by source. Average gathering unit losses accounted for about a 1.2 bu/acre loss out of the total 1.5 bu/acre machine loss. The results indicate that approximately 80% of the total machine loss is caused by corn never getting into the combine.

CORN HARVEST LOSSES BY SOURCE, BU/ACRE

From Gliem, J.A., R.G. Holmes, and R.K. Wood. 1989. Current utilization and optimization of existing machinery technology when harvesting feed grains. The Farm Income Enhancement Program. OSU Dept. of Agric. Econ. and Rural Sociology.

The ideal kernel moisture level to harvest corn at for dry grain storage is about 25%. There may be a strong temptation to allow grain to dry in the field to moisture levels in the low 20's or high teens before harvest so as to decrease grain drying costs. However, field drying diminishes significantly as the weather cools and essentially stops by mid to late November. When deciding whether to delay harvest to save fuel consider that an increase of about 2% in field losses is equal to the cost of the extra fuel needed to dry wet corn from 25% to 20% moisture. To save on drying fuel costs you may risk appreciable increases in field losses. Harvesting corn wetter than normal to minimize field losses may end up costing you less than the yield losses that can occur with field drying.

D) Corn Stalk Quality Becoming an Issue In Ohio - Pat Lipps CORN Questions

The harvest season has been somewhat of a challenge for most farmers in Ohio this year and it will continue to be challenging as the season progresses. Soybean harvest has progressed slowly due to the late maturing bean crop and occasional rain showers. With a slow soybean harvest and a later than normal wheat planting season following the harvested bean crop, the corn crop is in need of attention. Within the last week corn moistures have dried to a level that corn harvest should be going rapidly. Unfortunately, we are now beginning to get reports of harvest problems from lodging.

There are a couple of issues that could lead to lodged corn plants. First is the very poor root systems that have developed on corn plants in fields with poor drainage. These plants may have a reasonable brace root systems but little roots below ground due to root rot that occurred earlier in the season. If the soil becomes saturated and significant wind occurs these plants would be easily blown over and 'root lodged'.

The second problem is stalk rots cause by root and stalk infecting fungi. It is now late October and corn plants have been dead for several weeks. Early harvest estimates indicate that yields have been good. This means that the crop in the field consists of dead, rapidly decomposing stalks holding up at least normal to above normal weight in grain. The wet conditions over the past week in many locations in the state have given several stalk rotting fungi the opportunity to degrade stalk tissues to the level that standability has become a problem. The fungi causing anthracnose stalk rot and Gibberella stalk rot are common in fields. These fungi continue to grow and colonize stalk tissues as long as moisture and temperatures permit. In particular, Gibberella and Fusarium fungi are capable of rapidly decomposing stalk tissues to the point of causing severe lodging in some fields. Very wet weather and relatively warm temperatures will favor rapid decay of stalk tissues over the next few weeks.

It may be wise to visit fields during times when it is too wet to harvest to examine stalks for stalk rot in individual fields. Examination of stalks can be done rapidly by squeezing stalks above the brace roots to determine if they are easily crushed between the thumb and fingers. Fields that have higher percentage of crushable stalks, or have plants beginning to lodge should be scheduled for harvest as soon as possible. This would also be a good time to evaluate differences in hybrids and their ability to stand until harvested. Hybrids that tend to fall down before grain moistures are at the level they can be harvested should be eliminated from your production program for next year.

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.

Editor: Barry Ward        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.

TDD # 1 (800) 589-8292 (Ohio only) or (614) 292-1868

  | C.O.R.N. | Newsletter | Archive | Search | Questions? | Ohioline | Publications |