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What To Do With Failed Seedings Of Alfalfa, Dan Undersander Dec 1993

What To Do With Failed Seedings Of Alfalfa, Dan Undersander

Proceedings of the Integrated Crop Management Conference

Because of the wet and cloudy conditions in 1993, many alfalfa seedings either had excessive seedling death to result in thin stands or remained stunted with little growth and forage yield.


Effect Of '93 On 1994 Soil Fertility Decisions, Regis D. Voss Dec 1993

Effect Of '93 On 1994 Soil Fertility Decisions, Regis D. Voss

Proceedings of the Integrated Crop Management Conference

Because Iowa soils were saturated frequently and some were flooded for various lengths of time, questions arise on whether fertilizer practices should be adjusted in 1994 for these situations. These questions deal with nitrogen fertilizer rates and time of application, potential changes in soil test values, and potential fallow syndrome on soils that were flooded.


Post Anthesis Nitrogen Loss From Corn, Dennis Francis, James Schepers Dec 1993

Post Anthesis Nitrogen Loss From Corn, Dennis Francis, James Schepers

Proceedings of the Integrated Crop Management Conference

Nitrogen (N) management practices of corn producers have been called into question because of nitrate contamination problems in surface and ground water. Fertilizer N has been strongly implicated as the major source of much of the nitrate that now exists in our water resources. Cultural practices used in corn production lend themselves to possible nitrate leaching because practical limitations require a majority of the fertilizer N to be applied well ahead of when it can be used by the crop. Nitrogen uptake by corn is anything but uniform throughout the growing season. Little N is used by a corn crop ...


Soybean Cyst Nematode Identification And Extraction Techniques, Gregory L. Tylka Dec 1993

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 57 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. Above-ground symptoms of soybean cyst nematode damage often do not appear consistently, and may be absent for several years following initial infestation. The primary above-ground symptoms of soybean cyst nematode damage are chlorosis ...


Impact Of Excess Water On N Loss, Robert G. Hoeft Dec 1993

Impact Of Excess Water On N Loss, Robert G. Hoeft

Proceedings of the Integrated Crop Management Conference

Experience in 1993 as well as many other years has clearly shown that unpredictable, but frequently occurring heavy rains will result in significant N loss through denitrification or leaching. In those years, farmers and their advisers often wonder how much loss has occurred and whether or not it would be beneficial to apply more N late in the season. In order to answer that question, one needs to first be able to predict a) how much of the applied N was present as N03-N, b) what portion of that N was lost, and c) whether or not it would be ...


Relay Intercropping Wheat And Soybean, Keith Whigham Dec 1993

Relay Intercropping Wheat And Soybean, Keith Whigham

Proceedings of the Integrated Crop Management Conference

Relay intercropping is defined as growing two or more crops simultaneously during part of the life cycle of each (Andrews and Kassam, 1976). That is contrasted to the practice of sole cropping where most midwest farmers plant one crop per field per season. In other words, corn is planted in May and harvested in October. Why would farmers be interested in trying relay intercropping when they are already acquainted and efficient in sole cropping systems? The answer is the potential to increase total production per unit area of land during one cropping season and the potential to conserve soil from ...


Monitoring Nitrogen Status Of Corn, James Schepers, Tracy Blackmer Dec 1993

Monitoring Nitrogen Status Of Corn, James Schepers, Tracy Blackmer

Proceedings of the Integrated Crop Management Conference

The strong relationship between nitrogen (N) availability in soil and crop yields makes N management a primary concern of producers. Over the past several decades, a majority of corn producers have come to regard fertilizer N as the primary source of N nutrition. Most producers acknowledge other sources of N such as manure, legumes, nitrate in water used for irrigation and mineralization of organic matter (microbial conversion of organic N to inorganic N as ammonium and nitrate). Giving credit for non-fertilizer sources of N is a common practice, but the amount of credit is usually conservative because producers are uncertain ...


Relative Hybrid Maturity: Are Gdd Ratings Better Than 'Days To Maturity'?, R. L. Nielsen Dec 1993

Relative Hybrid Maturity: Are Gdd Ratings Better Than 'Days To Maturity'?, R. L. Nielsen

Proceedings of the Integrated Crop Management Conference

It's no great secret that corn hybrids vary for the length of growi.ng season required to successfully grow, develop, and mature. We talk about 'early' and 'late' corns as well as 'short' and 'full' season corns. We also talk about 'days to maturity', as in '112' day corn or '102' day corn. Why all the interest in wanting to accurately distinguish among hybrid maturities?


Effect Of Tillage And Other Management Strategies On Plant Diseases, Wayne L. Pedersen Dec 1993

Effect Of Tillage And Other Management Strategies On Plant Diseases, Wayne L. Pedersen

Proceedings of the Integrated Crop Management Conference

When the Southern Corn Leaf Blight (Bipolaris maydis race T = Helminthosporium maydis) epidemic devastated the corn crop throughout the Corn Belt in 1971, plant pathologists scrambled for information on the survival of this pathogen. Little information was available, but the standard answer was very simple and effective, "Plow your corn ground and rotate to another crop" (R. R. Nelson- 1971 on the Today Show). The rapid transition from "T" male sterile cytoplasm to normal cytoplasm eliminated the very susceptible host, but sanitation (plowing) and crop rotation are two of the most effective means of controlling plant diseases. If disease control ...


Meeting Agriculture's Environmental Challenges: Agribusiness's Role, Jeffrey J. Zimprich Dec 1993

Meeting Agriculture's Environmental Challenges: Agribusiness's Role, Jeffrey J. Zimprich

Proceedings of the Integrated Crop Management Conference

Agriculture has always been a business full of challenges and gambles. A look at today's producers and the choices they have with new technology, unknowns in the weather, etc., quickly points out that the questions are not becoming fewer or any easier to answer. At the same time producers try to make the correct production and marketing decisions, most try to balance these economic interests with environmental and farm improvement goals. Today's Iowa farmers have environmental issues facing them related to the 1985 and 1990 Farm Bills, the Clean Water Act, etc.. Presently, Americans of all walks of ...


Management Of Urea Containing Fertilizers, Robert G. Hoeft Dec 1993

Management Of Urea Containing Fertilizers, Robert G. Hoeft

Proceedings of the Integrated Crop Management Conference

Direct application of urea containing fertilizers (dry urea and UAN solutions) has increased markedly over the past two decades throughout Illinois, Iowa, and Minnesota (Fig.l). They now account for about 35% of the total N market (Fig.2). In that same time period, ammonium nitrate has decreased from 10 to less than 1 percent and anhydrous ammonia from approximately 80 to 65 percent of the market in Iowa, Illinois, and Indiana.


Corn Leaf Diseases And Their Control, C. A. Martinson Dec 1993

Corn Leaf Diseases And Their Control, C. A. Martinson

Proceedings of the Integrated Crop Management Conference

The 1993 growing season was another unusual year for leaf diseases of corn. Some diseases went rampant and other diseases, which were expected because of the wet weather, did not develop on corn leaves. The various diseases will be discussed.


Tillage Systems And Weed Population Dynamics, Douglas D. Buhler Dec 1993

Tillage Systems And Weed Population Dynamics, Douglas D. Buhler

Proceedings of the Integrated Crop Management Conference

Conservation tillage (CT) has had more impact on weed control in row crop production than any other recent change in management practices. In conventional tillage systems, moldboard plowing and secondary tillage just before planting help crop seedlings get an equal start with weed seedlings. In CT systems, herbicides are used to substitute for some or all of this tillage.


Corn Ear Rots, Storage Molds, And Associated Hazards, Gary P. Munvkvold Dec 1993

Corn Ear Rots, Storage Molds, And Associated Hazards, Gary P. Munvkvold

Proceedings of the Integrated Crop Management Conference

Ear rots and storage molds occur every year on corn throughout the Midwest. These diseases are serious concerns in corn production because they cause losses in grain yield and quality, and pose potential hazards in harvesting, handling, and feeding grain. Harvesting and handling hazards are generally related to respiratory problems with inhalation of mold spores, while the hazards of feeding moldy grain are generally related to the presence of toxic chemicals (mycotoxins) produced by the fungi. Particularly because of the possibility of mycotoxin production, it is important to recognize ear rots and storage molds and be aware of their toxigenic ...


The Iowa State Corn Yield Test, Kenneth E. Ziegler Dec 1993

The Iowa State Corn Yield Test, Kenneth E. Ziegler

Proceedings of the Integrated Crop Management Conference

The seventy-fourth year for the test was completed in 1993. For each of those 74 years Iowa State University has provided Iowa corn growers with performance evaluation data on varieties and hybrids of corn available for them to grow. Over the course of the past 74 years, the program has changed a lot. For a description of the early history of the Corn Yield Test see Chapter 8 in the book "The Iowa Crop Improvement Association" by JoeL. Robinson and Oliver A. Knott, Iowa Crop Improvement Association, Ames, IA 50011, 1963. Mention of other early historical events of the Iowa ...


Stand Establishment Variability In Corn, R. L. Nielsen Dec 1993

Stand Establishment Variability In Corn, R. L. Nielsen

Proceedings of the Integrated Crop Management Conference

A wise agriculturalist once told me that "the sins of planting will haunt you all season." By that he meant that mistakes made during the planting operation are usually permanent, unless you decide to replant the field at a later date. Uneven stand establishment can reduce the yield potential of a field before the plants have hardly begun to grow.


Soybean Cyst Nematode- Biology And Management, Gregory L. Tylka Dec 1993

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, 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), and has since spread to 25 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 57 counties within Iowa ...


Diagnostic Tools For Weed Science, Robert G. Hartzler Dec 1993

Diagnostic Tools For Weed Science, Robert G. Hartzler

Proceedings of the Integrated Crop Management Conference

Persons involved in production agriculture have a wide array of new technology available to help make management decisions. This paper will discuss two diagnostic tests that may have practical use now or sometime in the future.


Dna Fingerprinting Of Crop Germplasm, Michael Lee Dec 1993

Dna Fingerprinting Of Crop Germplasm, Michael Lee

Proceedings of the Integrated Crop Management Conference

Selection of crop cultivars is one of the most important aspects of crop production. For any given crop, a farmer often grows more than one elite cultivar in a season to take advantage of genetic differences among cultivars for various traits such as stress tolerance and maturity. This is a sound management practice: farmers are using genetics to minimize the risks of crop production while maximizing the yield potential of their crop. Unfortunately this management decision often may be based on very limited genetic information leading to a faulty conclusion. Recent developments in DNA fmgerprinting techniques for cop species have ...


Crop Yields And Weather: Events, Seasonal Trends, Long Range Indicators, And Variability, Elwynn Taylor Dec 1993

Crop Yields And Weather: Events, Seasonal Trends, Long Range Indicators, And Variability, Elwynn Taylor

Proceedings of the Integrated Crop Management Conference

Crop yield is ultimately dependent upon weather events. Soil moisture, soil temperature, insect damage, disease development, and weed competition are each directly influenced by the meteorological environment. Crops are directly impacted by freezing events, which may have wide area impact, and by localized events such as hail storms. The weekly monitoring of meteorological events is crucial to evaluation of crop condition and development. To the extent that events may be anticipated, production and marketing strategies may be adjusted to manage the risk associated with an agronomic system.


Alternative Forage Crops, Dan Undersander Dec 1993

Alternative Forage Crops, Dan Undersander

Proceedings of the Integrated Crop Management Conference

Farmers this year have two reasons for asking about alternate crops. The first is for use as an emergency forage when stands or new seedings of perennial forages fail and the second is as a long term alternative to alfalfa. Before beginning this paper, we should put things into perspective by stating that alfalfa is still the best choice, in most cases, for long term production of high quality, high tonnage harvested forage. We also expect to see increased use of corn silage, where topography and farm plans permit in dairy rations, in the alfalfa-based rations.


1993! A Year To Forget - Lessons For 1994, Garren O. Benson Dec 1993

1993! A Year To Forget - Lessons For 1994, Garren O. Benson

Proceedings of the Integrated Crop Management Conference

The October 1 Crop Report forecast 1993 Iowa corn and soybean yields at 105 and 34 bu/ac, respectively. What will the November and January reports indicate? Based on observations as of October 20, with 80% of corn yet to be harvested, 105 bu/ac appears very optimistic. The need for good weather for both in-field drying and corn harvest are paramount at this time. The oat crop was the worst in recent history and problems with 1993 forage crops have been well documented.


The End-Of-Season Cornstalk Test For Excess Nitrogen, A. M. Blackmer, T. F. Morris, A. P. Mallarino Dec 1993

The End-Of-Season Cornstalk Test For Excess Nitrogen, A. M. Blackmer, T. F. Morris, A. P. Mallarino

Proceedings of the Integrated Crop Management Conference

Recent studies have shown that the N status of a corn crop can be assessed by measuring nitrate concentrations in the lower portion of cornstalks at the end of the growing season. This finding lead to the development of a new tissue test that can be used to evaluate N management practices used in any field in any year. This evaluation gives feedback that can be used to improve N management. The test is called the "end-of-season cornstalk test". It is a management tool that should be of interest to all corn producers and all who advise corn producers. The ...


Improvement Of Corn Germplasm, Arnel R. Hallauer Dec 1993

Improvement Of Corn Germplasm, Arnel R. Hallauer

Proceedings of the Integrated Crop Management Conference

Corn is the most widely and intensively grown crop species in the world and ranks third in the world, behind rice and wheat, in total production. Corn originated in southern Mexico or northern Guatemala 5,000 to 10,000 years ago. Corn is extremely variable genetically, and selection pressures were effective in developing corn strains to meet the needs of the native inhabitants. Most of the genetic variability in corn was present before the European colonists arrived in the Western Hemisphere. Native Americans had developed races that were being grown in present-day southern Canada, the United States, Mexico, Central America ...


Residue And Compaction Management, Tom Kaspar Dec 1993

Residue And Compaction Management, Tom Kaspar

Proceedings of the Integrated Crop Management Conference

No-till is becoming more popular because it reduces soil erosion, improves water conservation, and decreases labor requirements. Unfortunately, the crop residues that protect the soil surface from erosion in no-till systems may reduce com yields by slowing soil warming in the spring. One way to solve this problem may be to clear residues from the seed row, while leaving the rest of the soil surface residue covered.


Flow Cytometric Analysis And Sorting Of Heterodera Glycines Eggs, G. L. Tylka, T. L. Niblack, T. C. Walk, K. R. Harkins, L. Barnett, N. K. Baker Dec 1993

Flow Cytometric Analysis And Sorting Of Heterodera Glycines Eggs, G. L. Tylka, T. L. Niblack, T. C. Walk, K. R. Harkins, L. Barnett, N. K. Baker

Plant Pathology and Microbiology Publications

A nondestructive technique was developed to characterize and separate eggs of soybean cyst nematode, Heterodera glycines, by developmental stage using flow cytometry. Eggs from cysts cultured on susceptible soybean roots were suspended in 0.1% xanthan gum or 59% sucrose and loaded into either a Coulter EPICS 752 or EPICS 753 flow cytometer. Eggs were analyzed and sorted according to forward angle and 90º light scatter, flow cytometric parameters that are relative measures of object size and granularity, respectively. Mature eggs containing vermiform juveniles were less granular and slightly larger than eggs in earlier stages of embryogeny, allowing for separation ...


Effects Of Eight Herbicides On In Vitro Hatching Of Heterodera Glycines, A. T. S. Wong, G. L. Tylka, R. G. Hartzler Dec 1993

Effects Of Eight Herbicides On In Vitro Hatching Of Heterodera Glycines, A. T. S. Wong, G. L. Tylka, R. G. Hartzler

Plant Pathology and Microbiology Publications

Laboratory studies were conducted to evaluate effects of selected herbicides on hatching of free eggs of the soybean cyst nematode, Heterodera glycines. The herbicides used were Atrazine (atrazine), Basagran (bentazon), Bladex (cyanazine), Blazer (acifluorfen), Command (clomazone), Lasso (alachlor), Sonalan (ethalfluralin), and Treflan (trifluralin). Treatments comprised two concentrations of commercial herbicide formulations and deionized water and 3.14 mM zinc sulfate as negative and positive controls, respectively. Eggs were extracted from females and cysts, surface disinfested, and incubated in herbicide or control solutions at 25 ± 2 C in darkness. Hatched second-stage juveniles were counted every other day for 24 days. Hatching ...


Atrazine And Water Quality: An Evaluation Of Restricting Atrazine Use On Corn And Sorghum To Postemergent Applications, Aziz Bouzaher, Derald J. Holtkamp, P. G. Lakshminarayan, Philip W. Gassman, Randall A. Reese, Todd Campbell, Marc Ribaudo, Andrew Manale, Robert Taylor Dec 1993

Atrazine And Water Quality: An Evaluation Of Restricting Atrazine Use On Corn And Sorghum To Postemergent Applications, Aziz Bouzaher, Derald J. Holtkamp, P. G. Lakshminarayan, Philip W. Gassman, Randall A. Reese, Todd Campbell, Marc Ribaudo, Andrew Manale, Robert Taylor

CARD Staff Reports

Atrazine is the most widely used herbicide for corn and sorghum and the most commonly encountered in ground and surface water. In addition to water quality problems, atrazine poses hazards through atmospheric transport, food residues, and exposure of applications and wildlife. If atrazine use is restricted, substitute herbicides will come into wider use, increasing the likelihood of occurrence of their own sets of potentially undesirable side effects and imposing cost or efficacy penalties.


Toxicity Of Fusarium Proliferatum-Fermented Nixtamalized Corn-Based Diets Fed To Rats: Effect Of Nutritional Status, Suzanne Hendrich, Kathrine A. Miller, Terrance M. Wilson, Patricia A. Murphy Oct 1993

Toxicity Of Fusarium Proliferatum-Fermented Nixtamalized Corn-Based Diets Fed To Rats: Effect Of Nutritional Status, Suzanne Hendrich, Kathrine A. Miller, Terrance M. Wilson, Patricia A. Murphy

Food Science and Human Nutrition Publications

Male F344/ N rats were fed corn, nixtamalized corn, Fusarium proli feratum- fermented (FP) corn to provide 50 mg/kg fumonisin B1 (FB1), or nixtamalized FP corn (NFP), with and without supplemented nutrients. Nixtamalization of FP corn almost completely hydrolyzed FB1 and produced 7-10 mg/kg hydrolyzed fumonisin (HFB1). Relative liver weight was significantly increased in nutrient-supplemented rats fed FP or NFP corn. Plasma cholesterol increased in rats fed FP or NFP corn. Plasma glutamate­ pyruvate transaminase was elevated in allrats fed FP corn and in nutrient-supplemented rats fed NFP corn. All rats fed FP corn and nutrient-supplemented rats fed ...


Nuclear Size And Dna Content Of The Embryo And Endosperm During Their Initial Stages Of Development In Glycine Max (Fabaceae), Mark A. Chamberlin, Harry T. Horner, Reid G. Palmer Oct 1993

Nuclear Size And Dna Content Of The Embryo And Endosperm During Their Initial Stages Of Development In Glycine Max (Fabaceae), Mark A. Chamberlin, Harry T. Horner, Reid G. Palmer

Botany Publication and Papers

A technique was developed for isolating embryo sacs from ovules of soybean and for separating embryo from endosperm. Image analysis and cytophotometry were used to determine the relative mass of DNA and size of nuclei of endosperm and embryo cells. Analyses were done at the globular through late heart-shaped embryo stages to correlate ploidy level or nuclear size, and differentiation in these tissues. Mean size of embryo nuclei was fairly constant through all stages studied. Ploidy condition of the embryo was stable, 950/o99% of the nuclei were distributed in a bipolar pattern by relative mass at 2C and 4C ...