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1992

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Articles 31 - 60 of 2016

Full-Text Articles in Life Sciences

Effect Of N Rate And Time Of Application On Corn Grain Yield And N Recovery, Randy Killom, Regis Voss, Joyce Hornstein Dec 1992

Effect Of N Rate And Time Of Application On Corn Grain Yield And N Recovery, Randy Killom, Regis Voss, Joyce Hornstein

Proceedings of the Integrated Crop Management Conference

Iowa crop producers purchase and apply 7.6% of all the nitrogen (N) fertilizer used in the United States to support production of com, small grains, and pasture on nearly twenty million acres annually (Hargett and Berry, 1990). The annual cost of the nitrogen fertilizer (1.5 million tons in 1990) exceeds $300 million.


Seed Quality Evaluation Methods, Tim J. Gutormson Dec 1992

Seed Quality Evaluation Methods, Tim J. Gutormson

Proceedings of the Integrated Crop Management Conference

Seed quality evaluation methods will be discussed during a tour of the I.S.U. Seed Testing Laboratory. The following discussion of seed quality is provided as background or reference information. The importance of quality seed stocks is often taken for granted in U.S. agriculture. High quality seed supplies of the major crops have evolved through the competitive nature of the U.S. seed industry. However, occasionally an emergence, contamination, or seed quality question arises. To help answer these seed quality questions it is useful to understand seed evaluation methods and labeling requirements.


Digital Soil Maps For Iowa, Gerald A. Miller, Robert C. Mortensen Dec 1992

Digital Soil Maps For Iowa, Gerald A. Miller, Robert C. Mortensen

Proceedings of the Integrated Crop Management Conference

The Iowa Cooperative Soil Survey (ICSS) initiated a program in 1987 to transfer printed soil maps in each county soil survey report to an electronic database. The purpose of this cooperative project is to provide a computerized database of the county soil maps to support federal, state, local and private sector decision-making concerning use and management of Iowa's soil resources.


Waste Corn As A Source Of Inoculum Of Aspergillus Flavus, The Cause Of Aflatoxin, D. C. Mcgee, O. M. Olanya, L. H. Tiffany Dec 1992

Waste Corn As A Source Of Inoculum Of Aspergillus Flavus, The Cause Of Aflatoxin, D. C. Mcgee, O. M. Olanya, L. H. Tiffany

Proceedings of the Integrated Crop Management Conference

Aspergillus Flavus occurs worldwide in diverse habitats on a variety of plant and animal substrates. In the United States, contamination of susceptible crops particularly maize, peanuts, cottonseed, and tree nuts has become a major health concern because of the development of the carcinogen, aflatoxin. Extensive research into all aspects of the biology of A. flavus over the past twenty years still has left many unanswered but very basic questions about the ecology of this important organism.


Evaluating Weed Management Programs For The Development Of Herbicide Resistance, Bob Hartzler Dec 1992

Evaluating Weed Management Programs For The Development Of Herbicide Resistance, Bob Hartzler

Proceedings of the Integrated Crop Management Conference

The phenomena of herbicide resistance is not a new concern; triazine resistant weeds were first reported in the late 1960's. Since then, resistance has developed to many other important classes of herbicides. Although there are isolated infestations of triazine resistant weeds across Iowa, these weeds are not considered a major problem in the state. Recent shifts in herbicide use patterns has increased the potential for the development of resistant biotypes. This paper will describe factors which influence the development of resistance and how weed management programs can be manipulated to minimize the potential for resistance.


Understanding And Reducing Pesticide Losses, James Baker, Ed Adcock, Gerald Miller Dec 1992

Understanding And Reducing Pesticide Losses, James Baker, Ed Adcock, Gerald Miller

Proceedings of the Integrated Crop Management Conference

A small portion of pesticides applied on farms inadvertently reaches surface and groundwater. The amount varies from nearly zero to sometimes more than 5 percent of the amount applied, depending on several factors discussed below. That may not seem like much, but a 1 percent loss of a 1-pound-per-acre pesticide application can contaminate all of the drainage from a field in a normal year at 5 parts per billion (ppb). This level can be of concern if the drainage water enters drinking water supplies. The U.S. Environmental Protection Agency has established Health Advisory Levels for most pesticides in drinking ...


Phosphorus And Potassium Fertilization Of Corn And Soybean, Antonio P. Mallarino Dec 1992

Phosphorus And Potassium Fertilization Of Corn And Soybean, Antonio P. Mallarino

Proceedings of the Integrated Crop Management Conference

Fertilization practices for phosphorus (P) and potassium (K) during the last three decades have increased soil-test P (STP) values and soil-test K (STK) values of most agricultural soils in Iowa. This tendency for soil-test values to increase with time generally has been considered a desirable consequence of fertilization. This was especially true about 30 or 40 years ago when many Iowa soils tested very low or low in STP and STK. Recent soil-test summaries (Killom, Voss, and Eik, 1990) and surveys (Blackmer and Mallarino, unpublished), however, indicate that more than 70% of Iowa soils test high or very high in ...


What Is The Best Soybean Row Width? A U.S. Perspective, Richard Johnson, D. E. Green, C. W. Jordan Dec 1992

What Is The Best Soybean Row Width? A U.S. Perspective, Richard Johnson, D. E. Green, C. W. Jordan

Proceedings of the Integrated Crop Management Conference

What is the "best" row width for soybeans? That seemingly simple question has been the subject of debate and research for about 80 years - ever since people stopped thinking of soybeans as a hay crop and started considering it a grain crop.


Subsurface Flow Barriers To Reduce Nitrate Leaching, R. Horton, T. C. Kaspar, J. L. Baker, M. Kiuchi Dec 1992

Subsurface Flow Barriers To Reduce Nitrate Leaching, R. Horton, T. C. Kaspar, J. L. Baker, M. Kiuchi

Proceedings of the Integrated Crop Management Conference

Groundwater is a very important natural resource which directly affects many human lives. In the United States, groundwater is the source of about 22 percent of the freshwater used. About 53 percent of the total population and 97 percent of the rural population use groundwater supplies for their drinking water (Moody, 1990). Although contamination of groundwater can occur naturally, agriculture is considered to be one of the most widespread nonprofit sources of groundwater contamination. Among agricultural chemicals, nitrogen-fertilizer has been used most extensively, especially by com producers. About one million tons of nitrogen-fertilizer are used annually in Iowa. In some ...


Refinement Of Rootworm Thresholds For New, Commercially-Available Sticky Traps, Jon J. Tollefson Dec 1992

Refinement Of Rootworm Thresholds For New, Commercially-Available Sticky Traps, Jon J. Tollefson

Proceedings of the Integrated Crop Management Conference

Sampling adult com rootworms is a proven method of gathering information about the insect population to assist com growers in managing this pest. Specifically, if the adult population reaches a prescribed density, a com grower should consider rotating to a crop other than com or apply a rootworm insecticide if planting com the following spring. Conversely, if the adult population fails to reach this density, a com grower can forego a control option without expecting to suffer economic yield losses.


Residue Management With Chisel-Type Implements, Richard Johnson Dec 1992

Residue Management With Chisel-Type Implements, Richard Johnson

Proceedings of the Integrated Crop Management Conference

Where chisels are improperly used, it may be difficult to end up with 30% surface cover. But by considering one or more of the following, 30 to 50% surface cover after planting should be possible:


Tillage Equipment Adjustment For Surface Residue, Mark Hanna Dec 1992

Tillage Equipment Adjustment For Surface Residue, Mark Hanna

Proceedings of the Integrated Crop Management Conference

Crop producers are increasingly interested in methods to manage higher levels of surface residue. Both economics and soil conservation are responsible for this attention. Six million additional Iowa acres will be shifted to a conservation tillage system during 1992-94 to comply with soil loss goals of the Food Security Act according to plans filed with the Soil Conservation Service. From a production cost viewpoint, fewer machine operations on the land lower input costs and increase net profit if output can be maintained.


Improving Soybean Profits With Management, Edward S. Oplinger Dec 1992

Improving Soybean Profits With Management, Edward S. Oplinger

Proceedings of the Integrated Crop Management Conference

Reduced and no-tillage systems for crop production are increasing in importance as part of soil conservation programs throughout most of the USA. Some of the current interest is the result of the Federal Farm Program and the need to be in compliance with farm plans. For some soybean producers, adoption of some form of reduced tillage will be the only way they can continue to raise soybean on certain fields. Some growers are also adopting reduced tillage as a soil stewardship practice and also as a means of reducing equipment and labor costs and to improve profits. This new method ...


Common Corn Diseases, C. A. Martinson Dec 1992

Common Corn Diseases, C. A. Martinson

Proceedings of the Integrated Crop Management Conference

The causes of root and stalk rots of com commonly observed in Iowa are primarily fungal pathogens. In some instances the pathogen causes both root rot and stalk rot and some pathogens are associated with only one or the other.


The Research Basis For Wisconsin's Legume Nitrogen Credits, K. A. Kelling, L. G. Bundy, R. P. Wolkowski Dec 1992

The Research Basis For Wisconsin's Legume Nitrogen Credits, K. A. Kelling, L. G. Bundy, R. P. Wolkowski

Proceedings of the Integrated Crop Management Conference

The ability of legumes to supply nitrogen to succeeding crops has been recognized for many years. The amount of actual N available will depend on the amount of N in the alfalfa and its availability, and any additional soil N that may be released due to the growth of the legume. From a practical standpoint, however, it is not the amount of N added to the system that is of primary importance. Much more important is the amount of N not needed by the com when the com is grown following the legume. This approach, commonly called the nitrogen fertilizer ...


The Insects Of 1992: A Review Of Problems And Management Strategies, Marlin E. Rice Dec 1992

The Insects Of 1992: A Review Of Problems And Management Strategies, Marlin E. Rice

Proceedings of the Integrated Crop Management Conference

Each growing season seems to be unique when we reflect back on the insects that captured our attention. This year, com rootworms grabbed the limelight as probably the most economically destructive insect of the year. Com flea beetles were early season problems in the southeastern region of the state, while thistle caterpillars fascinated us with their destructive potential on small soybeans.


European Corn Borer: Pest Management By Integrating Scouting Computer Software, And Insecticides, Marlin E. Rice Dec 1992

European Corn Borer: Pest Management By Integrating Scouting Computer Software, And Insecticides, Marlin E. Rice

Proceedings of the Integrated Crop Management Conference

A computer program, known as the European com borer – phenology and management software, was recently developed for use in Iowa. The software is designed to perform three different operations: 1) to analyze the costs of an insecticide application for first generation European com borer control and determine if this management activity is potentially profitable, 2) to predict the dates when second generation European com borer eggs will be laid and suggest a time period for scouting, and 3) to compare the economic costs versus the benefits of making an insecticide application for control of second generation European com borers. The ...


Spray-Wind-Inversion, S. Elwynn Taylor Dec 1992

Spray-Wind-Inversion, S. Elwynn Taylor

Proceedings of the Integrated Crop Management Conference

Wind, clouds, humidity, stability--there are numerous properties of the atmosphere that influence effective application of agricultural chemicals. Whenever a material is dispersed in the atmosphere, some of it will, inevitably not reach the intended target. The responsibility of the applicator is to minimize drift that is to apply at a time and in a manner that will not result in the movement of significant concentrations of material away from the target zone: Drift can result from wind carry, from high concentrations of fine mist suspended in the air, and from vapor drift. Drift may be hazardous to nontarget crops, to ...


Soybean Cyst Nematode- Biology And Management, Gregory L. Tylka Dec 1992

Soybean Cyst Nematode- Biology And Management, Gregory L. Tylka

Proceedings of the Integrated Crop Management Conference

The soybean cyst nematode, Heterodera glycines, is a small, unsegmented plant-parasitic roundworm that attacks the roots of soybeans. While many plant-parasitic nematodes are believed to be endemic or native to the United States, the soybean cyst nematode was apparently introduced from Japan. Soybean cyst nematode was first discovered in the United States in 1954 in North Carolina (Winstead et al., 1955). It has since spread to 28 additional states in the Southeast and Midwest (Noel, 1992). It was first discovered in Iowa in Winnebago County in 1978. The presence of soybean cyst nematode has been confirmed in 54 counties within ...


Soybean Cyst Nematode- Identification And Extraction Techniques, Gregory L. Tylka Dec 1992

Soybean Cyst Nematode- Identification And Extraction Techniques, Gregory L. Tylka

Proceedings of the Integrated Crop Management Conference

A major factor limiting soybean production in Iowa is parasitism by the soybean cyst nematode, Heterodera glycines. Soybean cyst nematode is now known to be present in 54 counties within Iowa. It is very likely that the nematode is present in many other counties as well, but the nonspecific nature of the above-ground symptoms of soybean cyst nematode damage makes early identification or diagnosis of infestations difficult.


Theory And Practice: Weed Management In No Tillage Soybeans, Micheal D. K. Owen Dec 1992

Theory And Practice: Weed Management In No Tillage Soybeans, Micheal D. K. Owen

Proceedings of the Integrated Crop Management Conference

Recent changes in government policy and concerns for soil conservation have resulted in considerable interest in no tillage soybean production. Further, there has been a coincidental shift in narrow row production. These efforts represent an interest to increase the amount of plant residue left intact on the soil surface after planting thus reducing soil erosion and an attempt to manipulate row spacing to improve soybean yield potential. However, growers intuitively recognize that weed management becomes increasingly challenging as the amount of soil disturbance is decreased. The difficulty in weed management when seed bed preparation tillage is eliminated is the result ...


Factors Affecting Postemergence Herbicide Activity, Bob Hartzler Dec 1992

Factors Affecting Postemergence Herbicide Activity, Bob Hartzler

Proceedings of the Integrated Crop Management Conference

Postemergence herbicides have become an increasingly important tool in weed management systems. Reasons for this increase include the introduction of new products, environmental concerns, and changes in production practices. Several factors influence the performance of postemergence herbicides, including timing of application, environmental conditions, spray additives, and method of application. This paper will focus on specific aspects concerning postemergence herbicide use that have been the focus of recent questions.


Agricultural Contribution Of Nitrate-N To The Des Moines River: 1945 Vs. 1980, Dennis R. Keeney, Thomas H. Deluca Dec 1992

Agricultural Contribution Of Nitrate-N To The Des Moines River: 1945 Vs. 1980, Dennis R. Keeney, Thomas H. Deluca

Proceedings of the Integrated Crop Management Conference

Recently, intensive water quality monitoring has demonstrated the presence of nitrate (N03-N) in surface and groundwater throughout the Midwestern U.S. (Hallberg, 1989).


Beneficial Microorganisms In Low-Input Agriculture, Thomas E. Loynachan Dec 1992

Beneficial Microorganisms In Low-Input Agriculture, Thomas E. Loynachan

Proceedings of the Integrated Crop Management Conference

The overall involvement of microorganisms in crop production still remains much of a mystery. Because of their distribution and size, most studies have been done in the laboratory and the implications of these studies referred back to the field. With this approach, unfortunately, much remains unknown, not only about the growth of individual organisms, but certainly the interactions of organisms in nature. Several "nontraditional" soil amendments have been marketed over the years that capitalize on our lack of understanding of soil microbial processes. Terms such as soil activators, soil enhancers, and enzyme stimulators have been used, claiming to improve soil ...


1992- Another Unusual Crop Season, Garren O. Benson Dec 1992

1992- Another Unusual Crop Season, Garren O. Benson

Proceedings of the Integrated Crop Management Conference

According to the October Crop Report the 1992 Iowa com and soybean yields are estimated at 135 and 42 bulac, respectively. These numbers may change somewhat in the November and January crop reports; however, there is little question that the crop is a big one. The main concern as of mid-October was getting com dry enough so that harvest can proceed. As the crop matured 10 to 20 days late, it is not surprising that wet grain would be a problem. Ear and stalk rots and grain physical quality problems could also be concerns. With the small acreage set-aside (5 ...


Disease.Pro: A Computerized Disease Assessment Training Program, Forrest W. Nutter Dec 1992

Disease.Pro: A Computerized Disease Assessment Training Program, Forrest W. Nutter

Proceedings of the Integrated Crop Management Conference

Disease.Pro is a computerized disease assessment training program designed to help people working in the agricultural sciences improve their ability to estimate disease proportion.


"The Right Stuff", Farming By Location, Tom Colvin, Jack Ambuel, Kandiah Jeyapalan Dec 1992

"The Right Stuff", Farming By Location, Tom Colvin, Jack Ambuel, Kandiah Jeyapalan

Proceedings of the Integrated Crop Management Conference

A satellite-based positioning system is being developed to determine the location of farm equipment while working in the field. A satellite receiver mounted in a moving tractor or combine calculates position coordinates based on signals received from a selection of satellites in the Department of Defense Global Positioning System (GPS). The position coordinates are retrieved from the receiver by a computer and combined in a common data base with additional information collected by the computer such as yield, soil fertility, soil moisture, temperature, implement draft, and fuel consumption. There are a number of possible applications for this system. One is ...


Application Of Chromosome Maps To Soybean Improvements, Lisa Lorenzen, Randy Shoemaker, Sam Boutin, Nevin Young Dec 1992

Application Of Chromosome Maps To Soybean Improvements, Lisa Lorenzen, Randy Shoemaker, Sam Boutin, Nevin Young

Proceedings of the Integrated Crop Management Conference

The mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by the United Sates Department of Agriculture or Iowa State University and does not imply its approval to the exclusion of other products that may be suitable.


Economic Comparison Of Biological Control And Insecticidal Control Of The European Corn Borer, David B. Orr, Leslie C. Lewis, John J. Obrycki, Marlin E. Rice Dec 1992

Economic Comparison Of Biological Control And Insecticidal Control Of The European Corn Borer, David B. Orr, Leslie C. Lewis, John J. Obrycki, Marlin E. Rice

Proceedings of the Integrated Crop Management Conference

The European com borer has been considered a damaging pest of com in Iowa since its arrival in 1942 (Harris & Brindley 1942). Estimates of annual losses to this pest in Iowa alone range from 100 to 500 million dollars (Bergman et al. 1985). Damage by this insect can be either direct or indirect. Direct damage to grain yield results when com borer feeding occurs on the grain itself, or when feeding in the stalk or shank causes breakage below the ear resulting in loss of the entire ear. Indirect losses are usually more important, and result from leaf and stalk feeding which reduces the amount of nutrients directed to the ear; this has also been referred to as "physiological loss" (Showers et al. 1989).


Crop Residue Management- Part Of Farming In The Future, Jeffrey J. Zimprich Dec 1992

Crop Residue Management- Part Of Farming In The Future, Jeffrey J. Zimprich

Proceedings of the Integrated Crop Management Conference

Farming systems that manage crop residue are becoming more and more popular today. Interest and enthusiasm in crop residue management indicates that these farming practices will be part of farming in the future. Profit and conservation are driving these upward trends.