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Asian Soybean Rust And Common Soybean Leaf Diseases, Alison Robertson, Greg Tylka 2017 Iowa State University

Asian Soybean Rust And Common Soybean Leaf Diseases, Alison Robertson, Greg Tylka

Alison Robertson

Asian soybean rust was found in several southern states in November 2004. The fungus is expected to overwinter on weed hosts in southern Florida and the southern tip of Texas. Rust outbreaks in Iowa will depend on the northward seasonal dispersal of rust spores from these overwintering areas.


Early Season Disease Management In Soybeans, Sarah Cerra, Alison Robertson, Silvia Cianzio 2017 Iowa State University

Early Season Disease Management In Soybeans, Sarah Cerra, Alison Robertson, Silvia Cianzio

Alison Robertson

Damping off and seed rot, caused by Phytophthora sojae, is an important early season disease of soybean in Iowa. The disease is favored by warm (>60 F), wet soil conditions. P. sojae is an oomycete that survives in the soil as thick-walled oospores. When soil conditions are warm and wet, the oospores germinate, producing sporangia, which in turn produce many zoospores. These spores have flagella that enable them to swim in freestanding water. The zoospores are attracted to soybean roots by root exudates, where they infect seedling roots and cause disease. Thus, wet soils are essential for infection by P ...


Understanding The Fungicides That Will Kill Asian Soybean Rust, Alison Robertson 2017 Iowa State University

Understanding The Fungicides That Will Kill Asian Soybean Rust, Alison Robertson

Alison Robertson

Most of the fungicides approved for Asian soybean rust management in Iowa, and the United States, belong to either the chloronitrile, strobilurin, or triazole chemical groups. These groups all have different effects and modes of action; therefore, it is essential to understand how each group functions to protect soybean crops from infection by Phakopsora pachyrhizi and subsequent Asian soybean rust disease development.


Using Fungicides Effectively, Alison Robertson 2017 Iowa State University

Using Fungicides Effectively, Alison Robertson

Alison Robertson

For a fungicide to be effective, three rules must be followed:


Building The "Rust Fast Track System" For Identifying Asian Soybean Rust In Iowa, Alison Robertson, Gregory L. Tylka 2017 Iowa State University

Building The "Rust Fast Track System" For Identifying Asian Soybean Rust In Iowa, Alison Robertson, Gregory L. Tylka

Alison Robertson

Asian soybean rust is a serious soybean leaf disease not yet discovered in Iowa. There are common soybean leaf diseases that may be confused with Asian soybean rust. To achieve accurate and prompt identification of Asian soybean rust throughout the state, the Iowa Soybean Rust Fast Track system was created. This unique system makes use of hundreds of private agricultural professionals throughout Iowa and 40 Iowa State University Extension field personnel to filter out suspected soybean rust samples that are common soybean leaf diseases, thereby ensuring that the ISU Plant Disease clinic is not inundated with minor diseases of soybean.


Pesticide Sprays To Control Botrytis Rot, Anthracnose, And Tarnished Plant Bug In Day-Neutral Strawberries, 1992, M. L. Gleason, G. R. Nonnecke, D. R. Lewis 2017 Iowa State University

Pesticide Sprays To Control Botrytis Rot, Anthracnose, And Tarnished Plant Bug In Day-Neutral Strawberries, 1992, M. L. Gleason, G. R. Nonnecke, D. R. Lewis

Donald Lewis

The trial was held at the Iowa State University Horticulture Farm. Day-neutral strawberries planted into plastic mulch in May 1992 on sandy loam soil (fine, loamy, mixed mesic, Typic Hapludoll) were arranged in a randomized complete block design with five treatments and four replications. Each block consisted of five 20-ft-long double rows of plants with 12-in spacing between plants in the double rows, and each 20-ft segment was a treatment subplot. In three treatments ("post-infection"), timing of fungicide sprays was based on a leaf wetness-temperature model proposed by M. Ellis (pers. comm., Department of Plant Pathology, OARDC, Wooster, OH, and ...


Spray Timing To Control Botrytis Fruit Rot And Tarnished Plant Bug In Day-Neutral Strawberries, 1991i, M. Gleason, G. Nonnecke, D. Lewis, S. Parker 2017 Iowa State University

Spray Timing To Control Botrytis Fruit Rot And Tarnished Plant Bug In Day-Neutral Strawberries, 1991i, M. Gleason, G. Nonnecke, D. Lewis, S. Parker

Donald Lewis

The trial was held at the Iowa State University Horticulture Farm in 1991. Day-neutral strawberries planted in May 1991 on sand loam (fine, loamy, mixed mesic, Typic Halpudoll) soil were arranged in a randomized complete block design with five replications and 3 treatments. Each block was a 100-ft-long double row of plants with 12-in. spacing between plants, and treatment subplots within blocks were 20-ft segments of the double row. Data were taken only from the center 15 ft of each subplot. Timing of fungicide sprays for Botrytis fruit rot in the "model-driven" treatment was based on a leaf wetness-temperature model ...


Evaluation Of Provisia Rice In Arkansas Rice Production Systems, Zachary Lancaster 2017 University of Arkansas, Fayetteville

Evaluation Of Provisia Rice In Arkansas Rice Production Systems, Zachary Lancaster

Theses and Dissertations

With the continued evolution of herbicide resistance, it is becoming more difficult to achieve adequate weed control in Arkansas rice production systems. Thus, new technologies are needed to combat these troublesome weeds. A new non-GMO, herbicide-resistant rice type is under development that is resistant to quizalofop, an acetyl coenzyme A carboxylase (ACCase)-inhibiting herbicide that will allow for selective grass weed control in rice. With the commercialization of this technology by 2018, research was conducted to determine the best fit for quizalofop-resistant rice in current production systems. Experiments included evaluation of off-target movement of quizalofop, determination of plant-back risk from ...


Validation Of A Hairy Roots System To Study Soybean-Soybean Aphid Interactions, Stephanie C. Morriss, Matthew E. Studham, Gregory L. Tylka, Gustavo C. Macintosh 2017 Iowa State University

Validation Of A Hairy Roots System To Study Soybean-Soybean Aphid Interactions, Stephanie C. Morriss, Matthew E. Studham, Gregory L. Tylka, Gustavo C. Macintosh

Gregory Tylka

The soybean aphid (Aphis glycines) is one of the main insect pests of soybean (Glycine max) worldwide. Genomics approaches have provided important data on transcriptome changes, both in the insect and in the plant, in response to the plant-aphid interaction. However, the difficulties to transform soybean and to rear soybean aphid on artificial media have hindered our ability to systematically test the function of genes identified by those analyses as mediators of plant resistance to the insect. An efficient approach to produce transgenic soybean material is the production of transformed hairy roots using Agrobacterium rhizogenes; however, soybean aphids colonize leaves ...


Now’S The Time To Scout For Scn, Greg Tylka 2017 Iowa State University

Now’S The Time To Scout For Scn, Greg Tylka

Gregory Tylka

Soybean cyst nematode (SCN) is an important, widespread soybean pest in Iowa that often goes undetected. To date, the nematode has been discovered in all but Adams, Allamakee, Ida, and Lyon counties in Iowa. The only consistent and reliable sign of an SCN infestation in the field during the growing season is the presence of adult SCN females and cysts (dead females) on the roots of infected soybean plants. Adult SCN females and cysts are small, round, and white to yellow, each approximately the size of a period at the end of a sentence.


Fusarium Root Rot Of Soybean—Occurrence, Impact, And Relationship With Soybean Cyst Nematode, Mercedes Diaz Arias, Gregory L. Tylka, Alison Robertson, Leonor Leandro 2017 Iowa State University

Fusarium Root Rot Of Soybean—Occurrence, Impact, And Relationship With Soybean Cyst Nematode, Mercedes Diaz Arias, Gregory L. Tylka, Alison Robertson, Leonor Leandro

Gregory Tylka

Fusarium species are ubiquitous soilborne pathogens that can cause devastating and difficult-to-manage damping-off, root rot, wilt, or sudden death syndrome (SDS) in soybeans (Armstrong, 1950; French and Kennedy, 1963; Rupe, 1989). At least 12 different species of Fusarium have been reported to be associated with soybean roots (McGee, 1992); among these species and the diseases they cause, the economic impact is widely recognized only for SDS; economic impacts of Fusarium wilt and root rot are much less well documented. Fusarium root rot is widespread in US (Yang and Feng, 2001). F. oxysporum complex and F. solani complex are generally believed ...


Asian Soybean Rust And Common Soybean Leaf Diseases, Alison Robertson, Greg Tylka 2017 Iowa State University

Asian Soybean Rust And Common Soybean Leaf Diseases, Alison Robertson, Greg Tylka

Gregory Tylka

Asian soybean rust was found in several southern states in November 2004. The fungus is expected to overwinter on weed hosts in southern Florida and the southern tip of Texas. Rust outbreaks in Iowa will depend on the northward seasonal dispersal of rust spores from these overwintering areas.


Corn Nematodes And Soybean Cyst Nematode: Basic Facts And Prospects For 2010, Gregory L. Tylka 2017 Iowa State University

Corn Nematodes And Soybean Cyst Nematode: Basic Facts And Prospects For 2010, Gregory L. Tylka

Gregory Tylka

Nematodes are microscopic worms. Many nematode species live in the soil, and some soil-dwelling nematodes feed on plant roots. These plant-parasitic nematodes can cause considerable damage and yield loss when population densities (numbers) become high.


Fall Is Prime Time To Sample Fields For Scn, Greg Tylka 2017 Iowa State University

Fall Is Prime Time To Sample Fields For Scn, Greg Tylka

Gregory Tylka

The soybean cyst nematode (SCN) is an extremely damaging and widespread pest of soybean in Iowa. The nematode infests more than 70 percent of the fields statewide. However, SCN usually causes no obvious aboveground symptoms for many years after being introduced into a field. Consequently, many SCN-infested fields in Iowa have not been diagnosed. The lack of symptoms and subsequent missed diagnosis are unfortunate because the key to effective management of SCN is early detection, before large nematode population densities develop. Large nematode population densities can cause severe damage to soybean crops, especially in very dry years, a situation that ...


Soybean Cyst Nematode Will Cause Early Senescence Of Soybeans, Greg Tylka 2017 Iowa State University

Soybean Cyst Nematode Will Cause Early Senescence Of Soybeans, Greg Tylka

Gregory Tylka

Soybean cyst nematode is a widespread and serious pest of soybeans in Iowa. But many fields that are infested with the pest go undiagnosed because the nematode often does not cause obvious aboveground symptoms, at least not until population densities become extremely high.


Fall Nematode Sampling Considerations, Greg Tylka 2017 Iowa State University

Fall Nematode Sampling Considerations, Greg Tylka

Gregory Tylka

As we near the last part of the growing season, there are a few important pieces of information to remember concerning sampling Iowa fields for plant-parasitic nematodes.


Introduction, Greg Tylka, David Wright 2017 Iowa State University

Introduction, Greg Tylka, David Wright

Gregory Tylka

On behalf of the Iowa Soybean Rust Team, we would like to welcome you to this special Asian soybean rust issue of the Integrated Crop Management Newsletter.


Nematodes That Feed On Corn—What To Make Of It All, Gregory L. Tylka 2017 Iowa State University

Nematodes That Feed On Corn—What To Make Of It All, Gregory L. Tylka

Gregory Tylka

Nematodes are microscopic worms that live in soil and water. Many nematode species feed on decaying organic matter, bacteria, fungi, and even other nematodes. But some nematodes, including many that live in the soil, feed on plants and are called plant-parasitic nematodes.


Choosing An Scn-Resistant Soybean Variety: It’S Not Just About Yield, Greg Tylka 2017 Iowa State University

Choosing An Scn-Resistant Soybean Variety: It’S Not Just About Yield, Greg Tylka

Gregory Tylka

Resistant soybean varieties are a very effective strategy for managing the soybean cyst nematode (SCN), producing acceptable yields and suppressing reproduction of the nematode. The number of soybean varieties with genetic resistance to SCN in maturity groups I, II, and III has increased dramatically, from a few dozen in the early 1990s to more than 600 currently. Today, most soybean seed companies have SCN-resistant soybean varieties available for Iowa growers, and yield results of soybean variety trials conducted by private testing programs and universities have begun to be released in the past few weeks.


The Increase In Scn Reproduction On Resistant Soybean Varieties—What Does It Mean?, Gregory L. Tylka 2017 Iowa State University

The Increase In Scn Reproduction On Resistant Soybean Varieties—What Does It Mean?, Gregory L. Tylka

Gregory Tylka

The soybean cyst nematode (SCN), Heterodera glycines, is a consistent threat to profitable soybean production in the Midwest each year. In years of adequate to excess rainfall, like 2010 in Iowa, the short-term effect of SCN on soybean yields may be reduction of only a few bushels per acre. But in hot, dry years, yield loss can approach 50 percent or more. And no matter the extent of yield loss, SCN population densities (numbers) can increase dramatically during a growing season if susceptible soybean varieties are grown. And high SCN population densities increase the chances of soybean yields being greatly ...


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