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Soybean Rust: Are We Out Of The Woods?, X. B. Yang Dec 2005

Soybean Rust: Are We Out Of The Woods?, X. B. Yang

Integrated Crop Management News

In the discussion board portion of a website, I recently read a message with a similar subject title by a producer. This question is also one producers in the North Central Region are asking because of the light occurrence of soybean rust this past season. Development of the disease was surprisingly slower than most of us had anticipated. In this article, I will address the questions raised by producers by reviewing what we learned this past growing season, which was summarized during the National Soybean Rust Symposium held last month.


Choosing An Scn-Resistant Soybean Variety: It's Not Just About Yield, Gregory L. Tylka Nov 2005

Choosing An Scn-Resistant Soybean Variety: It's Not Just About Yield, Gregory L. Tylka

Integrated Crop Management News

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.


Fall Is Prime Time To Sample Fields For Scn, Gregory L. Tylka Oct 2005

Fall Is Prime Time To Sample Fields For Scn, Gregory L. Tylka

Integrated Crop Management News

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 ...


Tillage Considerations For Disease Management, X. B. Yang Oct 2005

Tillage Considerations For Disease Management, X. B. Yang

Integrated Crop Management News

In the 2005 growing season, we observed different soybean diseases, and no single soybean disease became a major problem for yield losses. Most diseases were prevalent with a low level of infestation. In corn, the single most significant disease was corn ear rot caused by Aspergillus flavus, a fungus producing alfatoxin. Often, tillage would be considered as a major management option to reduce the disease risk for the next crop. Because of the lack of precipitation this summer in some areas, especially eastern Iowa, use of tillage may not be a good practice in terms of preserving soil moisture.


Soybean Cyst Nematode Will Cause Early Senescence Of Soybeans, Gregory L. Tylka Sep 2005

Soybean Cyst Nematode Will Cause Early Senescence Of Soybeans, Gregory L. Tylka

Integrated Crop Management News

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 above-ground symptoms, at least not until population densities become extremely high. One fairly consistent, albeit somewhat indirect, symptom of SCN parasitism that is apparent at this time of the year is early senescence of the soybeans.


Risk Of Aflatoxin Contamination Increases With Hot And Dry Growing Conditions, Alison E. Robertson Sep 2005

Risk Of Aflatoxin Contamination Increases With Hot And Dry Growing Conditions, Alison E. Robertson

Integrated Crop Management News

Aspergillus ear rot in corn fields has been reported by Iowa State University Extension field crop specialists in southeast and south central Iowa. The concern with this disease is the production of aflatoxins, which are extremely toxic chemicals produced by two molds Aspergillus parasiticus and Aspergillus flavus. Aflatoxin accumulation is usually associated with poor storage conditions. However, hot, dry conditions during grain fill increase the risk of Aspergillus infection and aflatoxin contamination in the field.


Sentinel Plots: The End Of The Season, X. B. Yang, Ralph Von Qualen Sep 2005

Sentinel Plots: The End Of The Season, X. B. Yang, Ralph Von Qualen

Integrated Crop Management News

During the past few weeks we have heard much about being prepared for when bad things happen--bad things like devastating natural events. For Iowa soybean producers, one bad thing we knew was a possibility in 2005 was Asian soybean rust (ASR). Numerous meetings and publications provided information for getting producers prepared should this disease become a problem. Happily, as the season progresses toward its end, ASR is still far from Iowa.


Storing Fungicides Safely, Alison E. Robertson, Richard O. Pope Aug 2005

Storing Fungicides Safely, Alison E. Robertson, Richard O. Pope

Integrated Crop Management News

Growers who stocked up on fungicides for the 2005 growing season due to the threat of Asian soybean rust will likely be facing fungicide storage issues this winter, especially since it is likely that most products cannot be returned. The good news is that most fungicides have a shelf life of at least two years--and probably longer--assuming they are stored correctly. Optimum storage conditions are cool, dry conditions, away from sunlight. Storage temperatures should not go below freezing; however, if a fungicide does freeze, then slowly thaw it out at room temperature.


Soybean Rust Update -- August 2005, X. B. Yang Aug 2005

Soybean Rust Update -- August 2005, X. B. Yang

Integrated Crop Management News

As of today, soybean rust has been found in only five southern states: Alabama, Florida, Georgia, Mississippi, and South Carolina. The disease was found in sentinel plots, commercial production fields, and kudzu plants (see table below). In regions beyond these states, spores that look like spores of soybean rust have been detected by a spore-monitoring project led by the University of Arkansas. A lot more such spores have recently been found in many southern states. In Iowa, no soybean rust has been found in our latest scouting, both in sentinel plots and some production fields.


Scn Could Be Responsible For Yellow Soybean Fields, Gregory L. Tylka Jul 2005

Scn Could Be Responsible For Yellow Soybean Fields, Gregory L. Tylka

Integrated Crop Management News

In the next few weeks, areas of many soybean fields throughout Iowa will likely turn yellow. In several of these fields, the yellowing is caused by feeding by the soybean cyst nematode (SCN). SCN usually is present in fields for many years before population densities increase to a level that causes visible stunting or yellowing. When yellowing occurs, it generally appears in late July or early August. The yellowing often fades after rainfall.


Soybean Rust Outlook--July 18, 2005, Emerson M. Del Ponte, X. B. Yang, Kwang-Soo Kim, Zaitao Pan Jul 2005

Soybean Rust Outlook--July 18, 2005, Emerson M. Del Ponte, X. B. Yang, Kwang-Soo Kim, Zaitao Pan

Integrated Crop Management News

During the past week, soybean rust was found for the first time infecting a commercial soybean field in southern Alabama, 1 mile northwest of a sentinel plot that was found to be infected three weeks earlier. Earlier this week, it was confirmed in a sentinel plot in George County, southeastern Mississippi, at very low levels. In the Alabama field, the disease level was also at very low levels, and the farmer has sprayed the field during the past weekend. The disease was also found in a second sentinel plot in Georgia.


Can We Spray Section 18 Fungicides In Iowa?, Alison E. Robertson, Chuck Eckermann, Robin Pruisner Jul 2005

Can We Spray Section 18 Fungicides In Iowa?, Alison E. Robertson, Chuck Eckermann, Robin Pruisner

Integrated Crop Management News

Over the past couple of weeks, a number of phone calls have been received asking if Section 18 (emergency exemption) fungicides can be sprayed in Iowa. The answer is "yes," Section 18 fungicides may be used in Iowa; however, the Section 18 label clearly states that the products only are approved for the management of Asian soybean rust (ASR). That is, they are not approved for control of other foliar diseases if rust is not present or conditions do not favor ASR development.


Soybean Rust Outlook - June 30, X. B. Yang, Emerson M. Del Ponte, Kwang-Soo Kim, Zaitao Pan Jul 2005

Soybean Rust Outlook - June 30, X. B. Yang, Emerson M. Del Ponte, Kwang-Soo Kim, Zaitao Pan

Integrated Crop Management News

During this past week, we have seen an increase of soybean rust reported in Florida and adjacent states. The disease was found in sentinel plots located in Florida and southeastern Alabama. The disease also was found in another Florida county on kudzu plants. Although the disease has been found in two other states besides Florida, the new findings are around the Florida Panhandle. The increased activities were predicted by computer models during the last two weeks; more findings are predicted because the weather has been suitable for soybean rust development there.


Now's The Time To Scout For Soybean Cyst Nematode, Gregory L. Tylka Jun 2005

Now's The Time To Scout For Soybean Cyst Nematode, Gregory L. Tylka

Integrated Crop Management News

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.


Nematodes Damage Corn, Gregory L. Tylka Jun 2005

Nematodes Damage Corn, Gregory L. Tylka

Integrated Crop Management News

Plant-parasitic nematodes can cause serious damage to corn. There are numerous species that occur in Iowa, including the dagger, lance, lesion, needle, stubby-root, and stunt nematodes. Symptoms of nematode damage on corn include stunting and/or yellowing of foliage and stunting, swelling, and/or browning of roots. In the past few weeks, the Iowa State University Plant Disease Clinic has received samples from fields in southeastern Iowa with corn damaged by the needle nematode.


General Tips For Submitting Plant Samples* To The Plant Disease Clinic, Paula Flynn, Christine Engelbrecht Jun 2005

General Tips For Submitting Plant Samples* To The Plant Disease Clinic, Paula Flynn, Christine Engelbrecht

Integrated Crop Management News

A $10 fee is charged for plant samples. Soil samples (to check for soybean cyst nematode or complete nematode counts, including corn nematodes) cost $15 for Iowa residents and $20 for out-of-state residents. Checks should be made payable to Iowa State University. *When herbicide injury is suspected, the samples should go to the extension weed specialists (see the Weed ID and Herbicide Injury DIagnosis form).


Update On Soybean Rust And Sentinel Plots, X. B. Yang, Ralph Von Qualen, Emerson M. Del Ponte Jun 2005

Update On Soybean Rust And Sentinel Plots, X. B. Yang, Ralph Von Qualen, Emerson M. Del Ponte

Integrated Crop Management News

Soybean rust has still not been detected beyond southern Georgia. Last week, soybean rust was found on kudzu plants in the fifth Florida county, Jefferson. With development this slow, our previous outlook has not changed; the occurrence of soybean rust in Iowa and surrounding states (excluding Missouri and southern Illinois) before the end of July is not great. The first detection date could be even later if no new development of this disease is reported before the end of June.


Soybean Rust Outlook - June 13, X. B. Yang, Emerson M. Del Ponte, Kwang-Soo Kim, Zaitao Pan Jun 2005

Soybean Rust Outlook - June 13, X. B. Yang, Emerson M. Del Ponte, Kwang-Soo Kim, Zaitao Pan

Integrated Crop Management News

This year's hurricane season started early and the arrival of Tropical Storm Arlene has raised some concerns regarding the risk of soybean rust (SBR) this season. The early start of the hurricane season reflects some similarities between the soybean rust situation and the southern corn leaf blight epidemic in 1970. In that epidemic, one major condition was an unusual tropical storm that occurred in June, which facilitated the spread of the southern corn leaf blight (SCL) pathogen from southern Mississippi and Alabama to the northern Corn Belt.


Soybean Rust Outlook - June 5, X. B. Yang, Emerson M. Del Ponte, Kwang-Soo Kim, Zaitao Pan Jun 2005

Soybean Rust Outlook - June 5, X. B. Yang, Emerson M. Del Ponte, Kwang-Soo Kim, Zaitao Pan

Integrated Crop Management News

In last week's sentinel plot teleconference, no new detections of soybean rust were reported in the South. Extensive survey and monitoring efforts have been carried out on soybean and kudzu plants and results suggest that the disease is still limited to Florida and southern Georgia. Computer models continue to show decreased northward movement of spores produced now in Florida compared with late April and early May.


Soybean Rust Weekly Outlook- May 23, X. B. Yang, Emerson M. Del Ponte, Kwang-Soo Kim, Zaitao Pan May 2005

Soybean Rust Weekly Outlook- May 23, X. B. Yang, Emerson M. Del Ponte, Kwang-Soo Kim, Zaitao Pan

Integrated Crop Management News

No other detection has been reported during the past three weeks. The volunteer soybeans found infected in Seminole County of southern Georgia were removed. Sustained, coordinated, and quality monitoring activities have been carried out in southern states, according to southern region coordinator Don Hershman, extension plant pathologist at the University of Kentucky. Soybeans in sentinel plots in Florida are at flowering stage, but no rust has been reported in soybean plants there.


Iowa Soybean Rust Team Tests Fast Track System, Forrest W. Nutter Jr., Alison E. Robertson May 2005

Iowa Soybean Rust Team Tests Fast Track System, Forrest W. Nutter Jr., Alison E. Robertson

Integrated Crop Management News

A "test" of the Asian Soybean Fast Track System (Figure 1) was conducted in late April by randomly selecting 40 of the nearly 500 Iowa First Detectors (www.plantpath.iastate.edu/soybeanrust/firstdetectors) and sending these individuals color images of soybean leaves with symptoms of Asian soybean rust. "This exercise (test) was of critical importance to ensure effective and timely communication among key participants in the Fast Track System, namely the Iowa First Detectors, Triage Team members (who are mostly ISU Extension specialists), and the Iowa State University Plant Disease Clinic," stated David Wright, Director of Production Technology, Iowa Soybean ...


Soybean Rust Weekly Outlook: May 15, 2005, X. B. Yang, E. M. Del Ponte, Kwang Soo Kim, Zaitao Pan May 2005

Soybean Rust Weekly Outlook: May 15, 2005, X. B. Yang, E. M. Del Ponte, Kwang Soo Kim, Zaitao Pan

Integrated Crop Management News

As of May 15, no new development of soybean rust has been observed since the detection of soybean rust in volunteer soybeans in Seminole County in southern Georgia. Potential pathway from known source areas. We used historical weather data to assess the potential spore deposition areas from central Florida where soybean rust has been detected. For modeling proposes, a large quantity of spores was assumed, although in reality, spore production so far is limited.


After-Freeze Update On Sentinel Plots, X. B. Yang, Ralph Von Qualen May 2005

After-Freeze Update On Sentinel Plots, X. B. Yang, Ralph Von Qualen

Integrated Crop Management News

The record low temperatures last Monday, May 2, have caused significant damage to corn plants and early-planted soybeans in Iowa. It also affected a few of the sentinel plots in which plants emerged early. Plants in seven plots emerged before the freeze, and we were able to protect some by covering them with plastic sheets. Our collaborators at the West Central Coop at Jefferson protected their sentinel plot with hay. However, two plots were frozen and were immediately replanted last week.


Soybean Rust Weekly Outlook: May 8, 2005, X. B. Yang, Kwang-Soo Kim, Emerson M. Del Ponte, Zaitao Pan May 2005

Soybean Rust Weekly Outlook: May 8, 2005, X. B. Yang, Kwang-Soo Kim, Emerson M. Del Ponte, Zaitao Pan

Integrated Crop Management News

Last week we stated that knowing whether soybean rust occurs in Alabama, Mississippi, and/or Louisiana in May is critical to better determine the risk of epidemics of this disease in the northern soybean production region. We intend to provide weekly outlooks of this disease from the analysis of updated information of disease occurrence in the southern states and computer modeling results.


Three New Products Receive Section 18 Labels For Asian Soybean Rust Management, Alison E. Robertson, Kristine J. P. Schaefer May 2005

Three New Products Receive Section 18 Labels For Asian Soybean Rust Management, Alison E. Robertson, Kristine J. P. Schaefer

Integrated Crop Management News

Three new fungicides have been given Section 18 labels for use against Asian soybean rust in Iowa (Table 1—please note, this table is based on the latest information available as of May 2, 2005). They are:

  • Headline® SBR, a co-pack of pyraclostrobinand tebuconazole;
  • Orius™ 3.6F, which contains the active ingredient tebuconazole; and
  • Quilt™, a premix of azoxystrobin and propiconazole.


Cool Temperatures Favor Corn Seedling Diseases, Alison E. Robertson May 2005

Cool Temperatures Favor Corn Seedling Diseases, Alison E. Robertson

Integrated Crop Management News

Corn planting is well underway and estimates from Iowa State University Extension field crop specialists suggest 50 to 80 percent of the crop has been planted in most areas. Although some of the corn is beginning to emerge, the cold, wet weather that has occurred over the past 10 days has slowed emergence. These weather conditions can increase the prevalence of corn seedling diseases; one of the many problems that can result in reduced stands.


Progress In Soybean Rust Sentinel Plots, Ralph Von Qualen, X. B. Yang May 2005

Progress In Soybean Rust Sentinel Plots, Ralph Von Qualen, X. B. Yang

Integrated Crop Management News

Our cooperators have worked hard to establish sentinel plots across Iowa. As of May 1, we have 25 of the 30 plots sown and five plots have begun to emerge. Cool temperatures have temporarily halted plant development. We are thankful that, to date, we have lost no plots to frost. Our objective with these plots is to have an early warning should soybean rust reach Iowa. Our strategy for detecting rust early is to have known areas where the host and environment will allow disease development and to closely monitor these areas.


Bean Leaf Beetle And Bean Pod Mottle Virus Management: An Integrated Approach, Marlin E. Rice, Jeffrey Bradshaw, John H. Hill May 2005

Bean Leaf Beetle And Bean Pod Mottle Virus Management: An Integrated Approach, Marlin E. Rice, Jeffrey Bradshaw, John H. Hill

Integrated Crop Management News

Growing soybean in Iowa has become a more complicated task in recent years. One early-season dilemma for growers is which management plan to implement for a pest complex of bean leaf beetles and bean pod mottle virus. We have developed a decision guide for the management of these two pests. The decision guide is based on new research and presents a grower with two management plans: one for managing both the beetle and the virus, or one for managing only the beetle. Ultimately, these management guidelines require knowledge of the soybean field's pest history.


Corn Flea Beetles And Stewart's Disease Risk For 2005, Marlin E. Rice, Richard O. Pope, Alison E. Robertson, Forrest W. Nutter Jr., Paul Esker Apr 2005

Corn Flea Beetles And Stewart's Disease Risk For 2005, Marlin E. Rice, Richard O. Pope, Alison E. Robertson, Forrest W. Nutter Jr., Paul Esker

Integrated Crop Management News

Stewart's disease (also called Stewart's wilt) is a bacterial disease of corn caused by Pantoea (Erwinia) stewartii. The bacterium survives the winter in the gut of hibernating corn flea beetles. In the spring, adult flea beetles transmit the bacterium while feeding on corn. The bacteria are unable to spread from plant to plant without the beetle. Field corn inbreds and sweet corn are particularly susceptible to this disease. Therefore, seed producers in moderate- to high-risk areas should scout for early season flea beetle populations because, if left unchecked, substantial leaf damage during grain fill and yield loss can ...


Sentinel Plots For Controlling Soybean Rust, X. B. Yang, Ralph Von Qualen, Frederico Ribeiro, Emerson M. Del Ponte Apr 2005

Sentinel Plots For Controlling Soybean Rust, X. B. Yang, Ralph Von Qualen, Frederico Ribeiro, Emerson M. Del Ponte

Integrated Crop Management News

Timely application of fungicides is the only way to effectively and efficiently protect soybean crops from soybean rust infections. Because we do not know when and where the disease outbreaks will occur in the coming season, early detection of soybean rust during the growing season is key for timely applications. Over the past few years in other countries, sentinel plots have been effective in detecting the disease early and guiding producers in making better spray decisions.