Vol. 5 No. 4 April 25, 1997

Weekly Crop Update

University of Delaware Cooperative Extension

Volume 5, Issue 26

September 25, 1997

Field Crops:

Understanding OptimumŽ High-Oil Corn: Part 4--Premium vs Added Costs

Richard W. Taylor, Extension Agronomist


Bob Uniatowski, Extension Associate - Field Crops



In 1997 on Delmarva, the reported premium or bonus for OptimumŽ high-oil corn was reported to be as follows: $0.30/bu for 7.5 percent oil (dry matter basis); $0.25/bu for 7.0 percent oil; $0.20/bu for 6.5 percent oil; and downward in 5 cent increments for each one-half percent reduction in oil content.


In future years, other incentives may also be available to growers that must be taken into account when deciding the profitability of Optimum high-oil corn. Also, as breeding advances eliminate the need to plant higher populations and transform the best and newest corn hybrids, the premiums paid for Optimum high-oil corn will flow directly into the grower's bottom line.


The following table is taken from information presented by Dr. Peter Thomison at the Joint Meeting of the Northeastern Branch of the American Society of Agronomy and Eastern Forage Improvement Conference held at the University of Maryland, College Park, Md., on July 13 to 16, 1997. Dr. Thomison and his co-authors work on high-oil corn (both TC Blends and conventionally bred high-oil hybrids) at the Ohio State University in Columbus, Ohio. The table should provide you with a rough guideline when evaluating the economics of Optimum high-oil corn.


Table 1. Premium needed to cover extra production, handling and storage costs for high-oil corn assuming corn price is $2.50 per bushel; an extra $12 per acre in costs.


Conventional Corn Yield



Yield Reduction




















Small Grain Planting Window -

Richard W. Taylor, Extension Agronomist


Bob Uniatowski, Extension Associate - Field Crops



In a three-year study, we found that barley planted in late-September has about a 10 percent lower yield potential than when planted the first week to 10 days of October. Delaying barley planting until mid-October also reduced yields by 10 percent. Planting in late October reduced yield by another 10 percent. Planting in early November decreased yield potential an additional 20 percent.


Can I Plant Late, but Increase my Seeding Rate?

We found that it didn’t help. Compared with seeding barley at 2 bu/A, increasing the seeding rate up to 3 bu/A did not change yields. This was true with a September planting date as well as a mid-November planting date. In a few years of our four year study, a seeding rate of 1.5 bu/A did reduce yields (3 to 5 bu/A) compared to the 2 bu/A rate, but the difference was not significant averaged across years.


For wheat, we found that winter weather conditions significantly impact planting date differences. Ideally, wheat should be planted during the two week period following Hessian fly-free date. Delayed planting until mid-to-late November decreased yield potential an average of 19 bu/A (about a 25 percent yield reduction). This varied by year as follows: 7.5 bu/A (<10 percent) in 1992, 41 bu/A (50 percent) in 1993 (a very harsh winter), 13.5 bu/A (15 percent) in 1995, 21 bu/A (25 percent) in 1996, and 10.2 bu/A (12 percent) in 1997.


As with barley, increasing the seeding rate with late planted wheat did not increase the yield potential. Seeding rates of 20, 30, or 40 seeds per row foot on 7 inch rows produced equal yields (77 to 78 bu/A averaged across 5 years, six varieties, and two early and late planting dates). A seeding rate of 10 seeds per row foot produced an average of 70.5 bu/A or about a 9 percent reduction in yield. For October versus late-November planting dates, average yields (5 years and 6 varieties) were:



Seeding Rate

(seeds/row ft.)




Late November















Did You Over-Plant Sorghum?

Richard W. Taylor, Extension Agronomist



While driving by a number of grain sorghum fields in both Delaware and Maryland yesterday, I noted areas in many of the fields where the plants are only just recently headed out and bloomed. After inspecting some of these areas, I think you may be able to use them to identify fields that in future years will yield better if you could reduce the seeding rate. The remainder of the field had mature grain on the seed heads. Try spending a few minutes driving by your sorghum fields to see if they show this type of heading activity. If they do, it’s a good bet that you could reasonably reduce your seeding rate, maintain overall yield potential and improve the drought resistance of the crop especially on the sandier areas of the field.


Will you hurt your yield potential if you decrease your seeding rate? In sorghum studies that Bob Uniatowski and I conducted, we found that severely decreasing plant populations reduced yields by only 8 percent (for example, going from 5 plants per row foot down to 1 plant per row foot on 30 inch rows). Drought stress will decrease yields by much larger amounts and too high a population certainly increase the chance for drought stress. The other key to maintaining maximum yield potential is to obtain as uniform spacing within the row as possible. This also helps maintain sorghum’s drought tolerance.



Field Crop Diseases -

Bob Mulrooney, Extension Plant Pathologist



Corn Ear Rots.

Now that corn harvest is underway, be on the lookout for corn ear rots. The most common ones we see here on Delmarva are Diplodia ear rot, Giberella ear rot, and both Penicillium and Aspergillus ear rot. Diplodia is favored by dry conditions early and wet before and after pollination. It produces a white mold between the kernels starting at the base of the ear and progressing toward the tip. It is one of the most common here in Delaware. Little can be done in the field, but hybrids differ in susceptibility to Diplodia. Grain should be dried to 14% moisture to prevent further growth in storage. Ear rots by Penicillium and Aspergillus can increase after drought stress and insect or mechanical damage to the ear tips.


To minimize possible mycotoxin problems after harvest from ear infections by certain species of Fusarium, Aspergillus and Penicillium fungi, (1) harvest as soon as the moisture content allows minimum grain damage, (2) adjust the harvesting equipment for minimum kernel damage and

maximum cleaning. (3) If you store corn, dry the shelled corn to at least 15% moisture as rapidly as possible, but not longer than 24 to 48 hours after harvest. Safe long term storage can be achieved at a uniform moisture of 13%. (4) Cool the grain after drying and maintain dry storage

conditions. (5) Be sure to store the grain in clean, insect and rodent-free structures. (6) Continue periodic aeration and probing for hot spots at periodic intervals during storage. (7)Consider treating high moisture corn with organic acids to prevent mold growth during storage.



With the dry weather and mite problems that growers experienced this season in many areas it is easy to overlook possible damage from the soybean cyst nematode. SCN infestations can look like drought or mite damage. So unless you have checked and know for certain that SCN was not involved in the stunted, poor growth I would highly recommend that you soil sample to see if SCN is present and at what level. Growers and commercial reps are urged to soil test for SCN this fall especially where SCN susceptible varieties were grown or plan to be grown next season. Remember that you cannot presume that a rotation plan or growing resistant

varieties for any length of time will reduce cysts to safe levels for susceptible soybeans without first taking a soil test. Fall is the best time for nematode sampling. Sample after fall harvest but before any fall tillage. Soil cores should be taken in the root zone of the harvested crop. Soil test bags and nematode sampling instructions are available from the Extension offices in each county.



Vegetable Crops:


1997 Variety Trial Results for Processing Peas and Sweet Corn are Available

The 1997 Delaware Pea Variety Trial Results are now available from the Sussex County Extension Office. Results this year include a 37 variety processing pea variety trial, a pea plant population and nitrogen fertility trial, and an evaluation of poultry manure as a nutrient source for peas.


The results of the 1997 Processing Sweet Corn Variety Trial are also available at the Sussex County Office. The trial included Standard, Sugar Enhanced and Supersweet varieties for processing. If you would like a copy of either of these result books, please contact the University of Delaware Research & Education Center at 302-856-7303. Office hours are 8 a.m. to 4:30 p.m., but you may leave a message on voice mail before or after office hours. Please be sure to leave your compete mailing address or a phone number so that we may get your copy to you as soon as possible. Thanks!



This is the last edition of the Weekly Crop Update for 1997. I hope that the information provided this year has been relevant, helpful and informative. A special thank you goes out to those individuals who contribute to the newsletter each week. It is a big commitment, especially during the crop season, and I appreciate their cooperation and efforts. In the next few months we will be evaluating our programs for the year and making plans for 1998. In an effort to improve the Weekly Crop Update, we will be asking you for input. We hope you will be frank and let us know what you like about the newsletter and what you don’t like about it. You will be receiving a request for input in the mail next week. (For Internet users, a form is available on our website) I hope you will take a moment to look it over and respond. Thank you in advance for your input. Weekly Crop Update will begin again in April 1998.

Best Wishes for a profitable 1997 harvest season!


 S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S



Weather Summary

University of Delaware,



Week of September 19 to September 25, 1997



0.02 inches: September 19

0.40 inches: September 21

Readings taken for the previous 24 hours at 8 a.m.





Ranged from 91 F on September 21 to 62 F on September 25.



Ranged from 62 F on September 20 to 42 F on September 24.


Soil Temperature:


64 F. Average for the week.


Compiled & Edited By:

Tracy Wootten

Extension Associate - Vegetable Crops




Cooperative Extension Education in Agriculture and Home Economics, University of Delaware, Delaware State College and the United States Department of Agriculture cooperating, John C. Nye, Dean and Director. Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. It is the policy of the Delaware Cooperative Extension System that no person shall be subjected to discrimination on the grounds of race, color, sex, disability, age or national origin.