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Iowa State University

Plant Sciences

Proceedings of the Integrated Crop Management Conference

1996

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Biotechnology For The Control Of Soybean Diseases, Randy C. Shoemaker, Laura Frederick Marek Nov 1996

Biotechnology For The Control Of Soybean Diseases, Randy C. Shoemaker, Laura Frederick Marek

Proceedings of the Integrated Crop Management Conference

Approximately 80% of the total soybean production in the United States occurs in the North Central States. Ten of the 12 most productive states are located in this region (Doupnik 1993). During a three-year period (1989- 1991) soybean production and disease loss for the North Central States was estimated at 13.17% or 236,730,000 bu (Doupnik 1993). At the current price of$7.00/bu that level of loss corresponds to a loss to the North Central States soybean growers of $552,370,000 per year! Soybean cyst nematode and Phytophthora root and stem rot are two major ...


The Role Of Transgenes In Hybrid Development, Rita Hogan Mumm Nov 1996

The Role Of Transgenes In Hybrid Development, Rita Hogan Mumm

Proceedings of the Integrated Crop Management Conference

Transformation has been a major breakthrough in crop improvement, enabling the transfer of useful genes from virtually any species (Kung and Wu, 1993). Crops with dramatic levels of insect resistance, for example, have been developed through the transfer of genes from soil bacteria. These products have armed growers with the means to protect their crops against pests in a way not previously available through conventional breeding. Likewise, transgenic introductions have offered growers additional options in weed control. Products with novel herbicide resistances have offered opportunities to save on crop inputs and to protect the environment. On the horizon, transgenic crops ...


How Much Nitrogen Do Soybeans Leave For Corn?, Alfred M. Blackmer Nov 1996

How Much Nitrogen Do Soybeans Leave For Corn?, Alfred M. Blackmer

Proceedings of the Integrated Crop Management Conference

Many studies in Iowa have shown that the optimal rates of N fertilization for com following soybean tend to be less than the optimal rates for com following com. This conclusion is supported by data presented in Figure 1, which summarizes the results of 35 pairs of N-response trials having 10 rates of fertilizer N applied. Quadratic-plateau yield response curves were fit to the data from each site and analyzed to determine economic optimum rates of fertilization. The mean economic optimum rates of fertilization were 103lb N/acre for com following soybean and 163lb N/acre for com following com.


Soybean Cyst Nematode - Biology And Management, Gregory L. Tylka Nov 1996

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

Proceedings of the Integrated Crop Management Conference

Soybean cyst nematode, Heterodera glycines, is a small, unsegmented plant-parasitic roundworm that attacks the roots of soybeans. Many plant-parasitic nematodes are believed to be endemic or native to the United States, but soybean cyst nematode likely was introduced from Japan. Soybean cyst nematode was first discovered in the United States in 1954 in North Carolina (Winstead et al., 1955), and since has spread to 27 additional -states in the Southeast and Midwest (Noel, 1992). It was first discovered in Iowa in Winnebago County in 1978. In 1996, soybean cyst nematode was identified for the first time in Grundy, Mahaska, and ...


The 1996 Growing Season: A Season Of Inordinate Variability, Dale E. Farnham Nov 1996

The 1996 Growing Season: A Season Of Inordinate Variability, Dale E. Farnham

Proceedings of the Integrated Crop Management Conference

The October Crop Report estimated Iowa com and soybean yields at 135 and 44 bu/ac, respectively. One can expect these numbers to be adjusted somewhat by subsequent reports. The yield relationship between com and soybean varies between regions and is a reflection of the variation in growing season in the different parts of the state. Yield estimates, as of October 11, are presented by Crop Reporting District in Table 1. Yield variability is the result of many factors. The major negative factors in 1996 were too much rain, late planting, too little rain, cool conditions throughout the growing season ...


1996 Results And Future Outlook, Jack T. Bernens Nov 1996

1996 Results And Future Outlook, Jack T. Bernens

Proceedings of the Integrated Crop Management Conference

The objective of this presentation is to share the results of our wide scale farmer strip trials conducted in 1995 and 1996 seasons. In 1995 Northrup King had over 400 farmer strip trial locations and each location was ranked by independent third party crop scouts for level of European Com Borer infestation (None, Low, Moderate, Severe). In 1996 we expect to harvest over 700 locations and will rank these locations using the same scale. At the time of this writing, we still have many of these locations to harvest and the compilation of ranking etc. still needs to be accomplished ...


Soybean Cyst Nematode - Identification And Extraction Techniques, Gregory L. Tylka Nov 1996

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 was identified in Grundy, Mahaska, and Ringgold Counties for the first time in 1996 and is now known to be present in 72 Iowa counties. It is very likely that the nematode is present in many other counties as well, but the nonspecific nature of the aboveground symptoms of soybean cyst nematode damage makes early identification or diagnosis of infestations difficult.


A Review Of Chemical Seed Treatments For Control Of Seed And Soil Borne Diseases, Vince Morton Nov 1996

A Review Of Chemical Seed Treatments For Control Of Seed And Soil Borne Diseases, Vince Morton

Proceedings of the Integrated Crop Management Conference

The objective of a soybean producer at planting is to establish a plant population that is adequate for maximum yield. The final plant population is determined by:


Crop Responses To Herbicides, Bob Hartzler Nov 1996

Crop Responses To Herbicides, Bob Hartzler

Proceedings of the Integrated Crop Management Conference

Selective herbicides have become an integral component of modem crop production systems. These herbicides are selected for their ability to control important weeds without causing significant injury to the crop. Although the margin of crop safety varies widely among products on the market, it has generally been accepted that these products will not impact crop yield potential when used according to label and under 'favorable' environmental conditions. However, increasing numbers of persons are beginning to question the validity of this assumption. Several factors are responsible for these concerns, including changes in herbicide use patterns, introduction of herbicide resistant crops that ...


Losses Of Fall-Applied Nitrogen, Alfred M. Blackmer Nov 1996

Losses Of Fall-Applied Nitrogen, Alfred M. Blackmer

Proceedings of the Integrated Crop Management Conference

Applying N fertilizer to some fields in the fall instead of the spring offers several benefits to com producers and fertilizer suppliers. Benefits for producers often include paying less for fertilizer, reducing the amount of field work that must be accomplished in the spring, and avoiding soil compaction associated with application of fertilizer on wet soils in the spring. Benefits for suppliers include more time for movement of fertilizer materials from the manufacturers to the producers and more acres per year covered by each fertilizer applicator.


Phosphorus And Potassium Placement For No-Till Corn, Antonio P. Mallarino, Jose M. Bordoli, R. Borges Nov 1996

Phosphorus And Potassium Placement For No-Till Corn, Antonio P. Mallarino, Jose M. Bordoli, R. Borges

Proceedings of the Integrated Crop Management Conference

The information presented is part of ongoing research to identify effective fertilizer placement methods and diagnostic tools for phosphorus (P) and potassium (K) in no-till and ridge-till corn and soybean. Results for no-till cornfields will be emphasized here. There is uncertainty about soil test interpretations and cost-effective methods of fertilizer application for the no-till system. Moreover, producers are uncertain about the value of soil testing in conservation tillage because of large variability and lack of knowledge concerning techniques for collection of samples. Broadcast placements are less costly than banded placements but they seem inefficient for no-till fields because fertilizers are ...


Crop Diseases In 1996 - Review And Update, Gary P. Munkvold Nov 1996

Crop Diseases In 1996 - Review And Update, Gary P. Munkvold

Proceedings of the Integrated Crop Management Conference

Diseases cause losses to our crops every year, and 1996 was no exception. Many of the disease problems this year were associated with the wet spring. Cooler-than-normal summer temperatures also influenced diseases, some positively, some negatively. In com, the most troubling disease problems were seedling diseases and early-season crown rot. Some foliar diseases appeared late in the season, causing losses in some fields. Gray leaf spot did not develop into a widespread problem as it did in 1994 and 1995, but this disease remains an important issue. Common rust and Stewart's wilt reached damaging levels in some fields. There ...


Questionnaire Responses In The Agricultural Health Study By Private Versus Commerical Applicators From Iowa, Charles F. Lynch, Nyla Logsden-Sackett Nov 1996

Questionnaire Responses In The Agricultural Health Study By Private Versus Commerical Applicators From Iowa, Charles F. Lynch, Nyla Logsden-Sackett

Proceedings of the Integrated Crop Management Conference

The Agricultural Health Study (AHS) is a large epidemiologic study of registered pesticide applicators and their spouses in Iowa and North Carolina (Alavanja, Sandler et al., 1996). A goal of this study is to enroll 75,000 of these individuals and follow them for at least the next 10 years to evaluate the role of agricultural exposures in the development of cancer and other diseases. Enrollment began in December 1993. As of October 1996, 73,500 individuals had enrolled with 46,000 coming from Iowa and consisting of 5,400 commercial pesticide applicators, 26,100 private applicators, and 14,500 ...


Weather And Yield Trends, S. Elwynn Taylor, Richard E. Carlson Nov 1996

Weather And Yield Trends, S. Elwynn Taylor, Richard E. Carlson

Proceedings of the Integrated Crop Management Conference

Yield trends and yield variability are strongly influenced by weather. It is extraordinary for a statewide corn yield to exceed the established trend by more than 10%. It is not uncommon for yields to be diminished by more than 10% of the trend. Geographically, yields are differentially influenced by the ENSO (EI Nino/Southern Oscillation). Differential influences appear to have a lesser yield reducing impact in the eastern portion of the corn belt. Climate dynamics appear to be impeding the rate of yield increase in the central U.S. Advancements in long-lead forecasting are beginning to benefit efforts to assessment ...


Spatial Variability Analysis: A First Step In Site-Specific Management, C. A. Cambardella, T. S. Colvin, D. B. Jaynes, D. L. Karlen Nov 1996

Spatial Variability Analysis: A First Step In Site-Specific Management, C. A. Cambardella, T. S. Colvin, D. B. Jaynes, D. L. Karlen

Proceedings of the Integrated Crop Management Conference

Small-scale spatial variability of selected soil-test parameters in two adjacent central Iowa fields is discussed. We used semivariance analysis to detect the distance to which parameters were correlated and to estimate the strength of each correlation. Distinct differences in spatial dependence patterns were observed for the two farming systems.


Riparian Management To Protect Water Quality, Richard C. Schultz, Thomas M. Isenhart Nov 1996

Riparian Management To Protect Water Quality, Richard C. Schultz, Thomas M. Isenhart

Proceedings of the Integrated Crop Management Conference

The agricultural landscape has four major sources of non-point source (NPS) pollutants. These are: 1) surface and subsurface runoff which carry sediment and agricultural chemicals to streams; 2) eroding streambanks which can contribute more than fifty percent of the sediment load to the stream; 3) field tile drains which contribute the highest concentrations of soluble agricultural chemicals to streams; and 4) livestock grazing of streamside or riparian areas which contribute to bank instability and add animal waste and pathogens to the water. Maintaining or establishing a forested or prairie buffer along streams and rivers provides more than just a beautiful ...


Relative Emergence Of Weeds And Corn And Soybean, Douglas D. Buhler, Robert G. Hartzler, Frank Forcella, Jeffery L. Gunsolus Nov 1996

Relative Emergence Of Weeds And Corn And Soybean, Douglas D. Buhler, Robert G. Hartzler, Frank Forcella, Jeffery L. Gunsolus

Proceedings of the Integrated Crop Management Conference

The success of integrated weed management relies on matching control strategies to the specific weed problem in a field. This requires information not only on what weed species and how many of these weeds are present in a field, but also knowledge of the distribution of the weeds throughout the field and the stage of development of these weeds. Weed control recommendations typically provide information on appropriate tillage methods and herbicide selection. The information concerning weed infestations used to base these recommendations typically is not of sufficient detail to optimize the efficiency of these strategies. Information on weed populations can ...


Clarion Composting Project, Donald Wetterauer Nov 1996

Clarion Composting Project, Donald Wetterauer

Proceedings of the Integrated Crop Management Conference

In Iowa and other parts of the U.S. the number of animals raised in livestock confinement facilities continues to increase. Residents in many rural areas are concerned about the quantities of manure that will be generated at these facilities and how this will affect their quality of life. Land application of the manure is currently the primary method of using the manure. However, environmental concerns may impose regulations that limit how the manure is applied. Alternative methods of manure utilization are needed.


Weed Management Update, Micheal D. K. Owen Nov 1996

Weed Management Update, Micheal D. K. Owen

Proceedings of the Integrated Crop Management Conference

Generally, the 1996 crop year was better than early indications suggested. However, there were numerous problems, concerns, and management decisions that, if resolved or improved would have dramatically improved crop health and weed management in specific fields. Also of importance are new products that may be available for weed management in 1997. Finally, some aspects of weed management, specific weeds, and application problems will likely be significant problems in 1997. This paper will describe these situations and provide some discussion concerning strategies to resolve the problems.


Effects Of Water Quality On Hypoxia In The Gulf Of Mexico, Paul V. Zimba Nov 1996

Effects Of Water Quality On Hypoxia In The Gulf Of Mexico, Paul V. Zimba

Proceedings of the Integrated Crop Management Conference

In many aquatic systems, incidences of low oxygen (hypoxia) waters have been causally linked to increased nutrient concentrations. The Mississippi River accounts for approximately 80-90% of the freshwater inflow to the Gulf of Mexico; water quality in the Mississippi River should serve as a indicator of conditions in the Gulf. Near its mouth, the Mississippi River splits, with approximately one-third of its discharge diverted into the Atchafalaya River. A review of the literature (primarily peer reviewed journals and technical publications) suggests that the Mississippi River waters enriches the Gulf of Mexico and this enrichment has increased in recent years. However ...


Pasture Renovation - When Changes Are Needed, Stephen K. Barnhart Nov 1996

Pasture Renovation - When Changes Are Needed, Stephen K. Barnhart

Proceedings of the Integrated Crop Management Conference

Pasture improvement is often considered to include liming, fertilization, weed control and seeding as required to establish desirable forage plants. The degree of suppression or sod destruction and seeding depends upon whether the objective of the improvement is to: a) "repair", b) add to or c) replace the existing vegetation. The latter two of these strategies are often referred to as pasture renovation.


Management Of Soybean White Mold, X. B. Yang, Peter Lundeen Nov 1996

Management Of Soybean White Mold, X. B. Yang, Peter Lundeen

Proceedings of the Integrated Crop Management Conference

In the 1996 field season, white mold was prevalent in many Iowa soybean fields at much greater levels than in 1992 and 1994. This outbreak may be attributed to the high moisture (rain and heavy dew) and cool temperature in August. Compared with 1994, the disease differences were 1) a greater number of severely infested fields with sizes ranging from 50 to 100 acres have been observed, and 2) the disease occurred further south. Although the disease was observed in counties as far south as hwy 34 in 1994, no severe damage was reported. This year severe infestation occurred in ...


Maximizer Hybrid Corn: Performance Update, David L. Dornbos Jr. Nov 1996

Maximizer Hybrid Corn: Performance Update, David L. Dornbos Jr.

Proceedings of the Integrated Crop Management Conference

Results of 1996 field tests with Maximizerâ„¢ hybrid com confirm the results from the previous two years, indicating that these products offer an innovative solution to growers, enabling them to maximize grain yield, test weight, standability, and performance consistency in spite of damage otherwise caused by the European com borer (ECB). Responses from the approximately 9,000 growers who had the opportunity to plant the 135,000 units available in 1996 are overwhelmingly positive. In addition, feedback supporting rapid market growth of this technology is being received from 800-plus on-farm company-sponsored tests, and those from university and USDA researchers. Rapid ...