When one uses a soil insecticide it is important to remember that protection of the primary portion of the root system from economic attack by larvae is the goal. Also, one needs to understand that products do not provide 100% control and occasionally some economic damage may occur depending on the larval population, weather, product performance, planting date, plant development, and time of larval hatch. All of these factors can ultimately impact product performance and must be considered when using a soil insecticide. The important thing for producers to understand is the positive and negative aspects of each product, and determine which one(s) fits best under their farming system. Also, one needs to understand what the warrantee for each product really means. Additionally, it makes sense to have untreated check strips in fields to gauge the performance and economics of using the product.
The following guidelines, formulated from 2000 research and observations, should be taken into consideration when making rootworm management decisions for corn following last year’s soybean. If a soil insecticide is needed, see the table below for performance data that may assist you in product selection.
Northern Indiana (approx. north of Interstate 70):
Southern Indiana (approx. south of Interstate 70):
The above discussion is based on assessment of risk of damage from corn rootworm. An insecticide may be needed if other soil insect pests are present in economic numbers. Whenever soil insecticides are used, we encourage producers to leave untreated strips in order to evaluate product performance and the economics of using insecticides.
There will be two new active ingredients on the market for the 2001 growing season. In addition, there will be several new formulations and/or co-packs of existing herbicides. It is anticipated that several new glyphosate (the active ingredient in Roundup products) formulations and/or premixes will be marketed as well. With this in mind, be particularly cautious to avoid misapplications or drifting of glyphosate-containing products to non-Roundup Ready crops. Some of the following herbicides were labeled for the 2000 season. Federal approval of others in this list is anticipated before the start of the growing season.
Balance Pro – new liquid formulation of Balance
Define – Co-marketed with Bayer
Outlook – active isomer of Frontier
Ultra Blazer – new formulation of Blazer
Celebrity Plus – Accent + Distinct
Extreme and Backdraft – Use NIS instead of COC or MSO
Laddok S-12 – to be marketed by Sipcam Agro USA in 2001
Steel – No longer marketed
Hornet WDG – new potassium salt formulation
Acetochlor products – acquired from Zeneca
Canopy XL and Express – Fall application for soybeans
Basis – Fall application for corn
Canopy – No longer manufactured
Command Xtra – Command + Authority
Gauntlet – Authority + FirstRate
Aim – labeled for soybeans
Roundup UltraMax – 5 lb ai/gal formulation of glyphosate
Degree - For use in corn
Degree Extra – For use in corn
Touchdown – New 4 lb ai/gal formulation
Boundary – s-metolachlor and metribuzin
Expert – s-metolachlor, atrazine and glyphosate
Gramoxone Max 3L –
Callisto – New broadleaf MOA in corn
Dual II - No longer manufactured
United Ag. Products
Mirage – 4 lb ai/gal formulation of glyphosate
Valor – New preemergence broadleaf MOA in soybeans
Soybean seed quality in the eastern corn-belt, though not perfect, is considerably better than that available for the 2000 growing season. The germination of soybean seed this year, prior to cleaning, is in the range of 85 to 87%. Some seed lots have suffered from mechanical damage, but the extent of the problem is much lower than last year. Because of wet conditions in some areas prior to harvest, pod and stem blight is present in some seed lots. In most cases, these seed lots can be identified but if needed, the seed can be treated with a fungicide to prevent rotting of the seed prior to germination.
Much of the soybean seed produced in Iowa and Nebraska in 2000 is of poor quality as a result of the late summer dry weather conditions in the area. Because of the poor seed quality in the western corn-belt, supplies of the more popular varieties will be very tight since seed from the eastern corn-belt will be needed to fill this shortfall.
Size of the soybean seed for the 2001 growing season will be near normal with a few seed lots with smaller seed than normal. Always check the seed tag for the percent germination and the number of seeds per pound before calibrating drills and planters. Proper calibration of planting equipment to prevent over planting is an area where farmers can save some money. Purdue recommends seeding rates of 200,000, 165,000 and 130,000 seeds per acre for 7.5, 15 and 30 inch rows respectively. This recommendation is based on seed with a germination of at least 90% and that 90% of those seeds will emerge and become established as normal plants.
Nitrogen fertilizer will likely remain high-priced and in questionable supply for the upcoming 2001 corn cropping year in Indiana and other parts of the U.S. Midwest. While some farmers may opt for switching a portion of their intended corn acreage to soybean in response to the nitrogen issue, most will likely ‘ride it out’ as best they can.
As with most cropping decisions, there is no single best answer for how to manage these uncertainties of N price and supply. The suggestions offered in this article will help farmers fine-tune their N application rate calculations and maximize the crop’s N use efficiency.
Nitrogen Rate Recommendations
Yield Goal. Nitrogen fertilizer rate recommendations are typically based strongly on the yield goal determined for the field in question. It is imperative that the yield goal be realistic and not ‘pie-in-the-sky.’ Given that any year’s crop yield will be determined primarily by the weather, it is not unreasonable to use the average three- to five-year yield for a field as the yield goal for 2001. For the typical corn/soy crop rotation, this obviously requires field crop records for the past six to ten years.
Timing of N Applications. Pre-plant applications of N fertilizer are typically less efficient than sidedress N applications, meaning that there are more opportunities for N loss to occur during the time from pre-plant to crop uptake as compared to the time from sidedress to crop uptake. Consequently, sidedress N fertilizer rates can be decreased in recognition of its greater N use efficiency.
Credits For Existing Nitrogen. Previously grown legume crops (soybean) or applications of organic wastes (manures, biosolids) may contribute nitrogen to the following corn crop. Such contributions are typically taken into account when making N fertilizer rate recommendations.
Pre-Sidedress Nitrate Test (PSNT). The PSNT is a soil test procedure that is valid for organic soils (20% OM or greater) or where organic wastes have been applied to the field (manures, biosolids). The results of this test can be used to modify sidedress N rate recommendations based on the predicted availability of mineralized nitrogen from the organic components of the soil. In some situations, the PSNT may indicate no need for additional sidedress N applications.
Nitrogen Use Efficiency
Know Your Nitrogen Sources. Part of the challenge facing corn growers in 2001 will be that their nitrogen source of choice may simply not be available and so will be forced into using a nitrogen source with which they are not familiar. Recognize that the corn crop could care less which fertilizer source of nitrogen is used. The agronomic differences among N fertilizer sources lie mainly in their relative risk for nitrogen losses due to leaching, denitrification and volatilization.
Nitrate-containing fertilizers (UAN liquids, ammonium nitrate) are susceptible to leaching and denitrification nitrate losses from the day they are applied to the field. Urea-based fertilizers (urea, UAN liquids) convert relatively quickly to nitrate forms of nitrogen and are subsequently susceptible to the same N loss mechanisms. Consequently, these forms of fertilizer N are not well suited to early pre-plant applications, but rather to later pre-plant or sidedress applications.
Urea-based fertilizers are also vulnerable to volatilization losses when surface-applied and not incorporated into the soil, especially so in high-residue tillage systems. Part of the conversion of urea to nitrate involves the formation of ammonia, which is very volatile. When this conversion occurs on the surface, quite a bit of the nitrogen may ‘disappear into thin air’ and not be available to the developing crop. Such surface-applied N is also used by microbes for the decomposition of plant residue and may not become available to the crop until later in the season. For these two reasons, urea-based fertilizers should be injected below the surface trash or at least applied in concentrated bands over the surface as opposed to broadcast surface applications in high-residue tillage systems.
Anhydrous ammonia eventually converts to nitrate also, but the process is much lengthier than other forms of N. Consequently, anhydrous ammonia is typically better suited for early pre-plant applications than other forms of N.
For more details about nitrogen fertilizer decision-making for 2001, obtain a copy of the following Purdue publication from your local county Extension educator or from the Web address listed.
Sylvie Brouder, Brad Joern, Tony Vyn, and Bob Nielsen. Feb. 2001. Nitrogen Decision$ 2001: The Soil Fertility Perspective. Purdue University, Agronomy Dept. AGRY-01-01. <http://www.agry.purdue.edu/ext/pubs/agry0101.pdf>
You can also read what our colleagues in adjacent states are saying about this year’s nitrogen issues by browsing the following Web articles:
Don’t forget, this and other timely information about corn can be viewed at the Chat ‘n Chew Café on the World Wide Web at <http://www.kingcorn.org/cafe>. For other information about corn, take a look at the Corn Growers’ Guidebook on the World Wide Web at <http://www.kingcorn.org/>
In general, the 2000-01 Indiana wheat crop went into dormancy in good condition. The November and December temperatures were lower than normal, which resulted in very few fields with excessive top growth. In mid December, snow fall of 1 inch or more was recorded across the entire state and remained for about one month. This snow cover was sufficient to protect the wheat crop from the sub zero temperatures that occurred during the last two weeks of December. Since the snow has melted, temperatures have dipped to single digits on only two or three occasions. In the Lafayette area, the wheat crop looks good but temperatures have not yet been warm enough for wheat to break dormancy and begin to grow. In the southern one-third of Indiana, temperatures have warmed to the point where some fields have broken dormancy and are beginning to grow very slowly.
If you are curious whether your wheat has broken dormancy, there are two ways of making this determination when examining wheat plants. First, carefully wash the roots of a wheat plant and look for new root growth from the crown area of the plant. These roots should be snow white and may be very short (1/4 to 1/2 inch) if the plant has just broken dormancy. Secondly, look closely at the top two leaves of the plant. You should be able to see a line across the leaf at the point where the leaf was covered by the leaf sheath. The area below the line is the new growth and can be characterized by a brighter or shiny appearance when compared with the area above the line.
To date, it is our opinion that the Indiana wheat crop has not suffered any injury. However, each time wheat breaks dormancy and grows for a short period of time before re-entering dormancy, root reserves are lowered and therefore the vigor of the plant declines making it vulnerable to winter decline and perhaps death as a result of Rhizoctonia. The intermittent freezing and thawing that has occurred the past week can result in severe heaving of the plants on wet, poorly drained or heavy soils.
As the wheat begins to break dormancy, it is time to top-dress with nitrogen as soon as soil conditions permit. Assuming that 20 pounds of nitrogen were applied at seeding time, the rate of top-dress nitrogen is directly related to yield potential. With a yield potential of 50 bushels per acre, we recommend 40 lbs. of N as a top- dress, at 70 bu/ac we recommend 60 lbs. of N and at 90 bu/ac, 90 lbs. of N. On soils with a cation exchange capacity less than 10, the N rate may need to be increased by 10-15 lbs./ac. When top dressing, we recommend the use of dry materials or the use of streamer bars when using liquid materials. Every effort should be made to keep as much of the nitrogen fertilizer off the wheat leaves as possible. Nitrogen fertilizer applied to a plant with lowered vigor and dead leaf tissue could cause a significant Rhizoctonia problem.
Farmers can get expert crop management advice for the 2001 season and peer over the horizon to what may lie ahead for agriculture, at a Purdue University conference.
“Farming Today for Food Tomorrow” offers daylong seminars on corn and soybean management, site-specific farming and forages. The conference runs on Thursday, March 1, from 9:30 a.m. to 5 p.m. at the Old Lakeville School Project, located six miles south of South Bend, Ind., on U.S. 31.
General sessions on genetically modified foods and forages for horses follow the crop seminars, from 7-9 p.m. Producers should benefit from a wealth of crop seminar information, says Tony Vyn, a Purdue cropping systems agronomist and conference coordinator.
Seminars will cover such topics as CystX, the soybean variety resistant to soybean cyst nematode; corn rootworm management; strip-till options; site-specific equipment and yield monitors; site-specific weed management; hay management; producing and marketing hay; pasture management; and getting water to livestock.
“Also, we’ll have a session on marketing concerns with GMO crops,”Vyn says. “And Jess Lowenberg-DeBoer, director of Purdue’s Site-Specific Management Center, will look at the economics of site-specific farming. That session will answer the question, ‘Should we, in these times of low commodity prices, even consider investing in precision agriculture tools?’”
Another conference highlight is a session on planting second-year soybeans and the risk of diseases and lower yields, presented by Greg Shaner, Purdue Extension plant pathologist.
The focus will shift from the present to the future during a luncheon address by Joseph Pearson, Indiana’s assistant commissioner of agriculture. Pearson will discuss what the next 30 years may have in store for Hoosier farmers, and what role biotechnology could play.
Those attending the crop sessions can earn Certified Crop Adviser continuing education units and Commercial Pesticide Applicator continuing certification hours.
Registration for “Farming Today for Food Tomorrow” is $20 at the door and includes proceedings and lunch. Registration begins at 9 a.m. A 4:15 p.m. session on spray drift management costs an additional $10 for those applying for the Private Applicator Recertification Program. The evening sessions on GMOs and forages for horses are free.
For more information and a conference brochure, contact Vyn at (765) 496-3757 or Phil Sutton at (219) 235-9604.