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Field Testing Of N-Hibit™ Seed Treatment In 2007 For Management Of Scn In Iowa, Gregory L. Tylka, Christopher C. Marett Dec 2007

Field Testing Of N-Hibit™ Seed Treatment In 2007 For Management Of Scn In Iowa, Gregory L. Tylka, Christopher C. Marett

Integrated Crop Management News

N-Hibit™ is a seed-treatment that contains harpin protein, a compound that can stimulate plant defense responses. N-Hibit™ is now being sold in the United States for management of the soybean cyst nematode (SCN). Iowa State University evaluated the effects of N-Hibit™ seed treatment on soybean yield and SCN population densities in experiments at nine locations throughout Iowa. Experiments were conducted in Albert City, Mason City, and Manchester in northern Iowa; Cambridge, Farnhamville, and Urbana in central Iowa; and Council Bluffs, Crawfordsville, and Melrose in southern Iowa. The work was supported by the soybean checkoff through funds from the Iowa Soybean ...


Yield Responsiveness Of Corn To Foliar Fungicide Application In Iowa, Alison E. Robertson, Lori Abendroth, Roger W. Elmore Dec 2007

Yield Responsiveness Of Corn To Foliar Fungicide Application In Iowa, Alison E. Robertson, Lori Abendroth, Roger W. Elmore

Integrated Crop Management News

An estimated three million acres of corn in Iowa were sprayed mid-season with fungicides (strobilurin or a strobilurin/triazole combination) in 2007. Reasons for spraying vary and include the high price of corn, potential to control diseases, and a possibility of improved yield from "plant health" benefits. Until this year, fungicide applications to production corn fields were rarely practiced in Iowa because they were not profitable. In addition, many of the hybrids grown today have good overall tolerance to foliar diseases.


Surveying Iowa For Scn, Gregory L. Tylka, Alison E. Robertson Dec 2007

Surveying Iowa For Scn, Gregory L. Tylka, Alison E. Robertson

Integrated Crop Management News

Most crop professionals in the Midwest recognize the soybean cyst nematode (SCN) as a widespread, yield-limiting factor. But until the mid-1990s, little was known about the actual distribution of SCN throughout the region. In 1995 and 1996, Iowa State University plant pathologists collaborated with the USDA National Agricultural Statistics Service (NASS) personnel to collect samples from hundreds of randomly selected fields in Minnesota, Iowa, Missouri, Illinois, Indiana, and Ohio. The work was supported by the soybean checkoff through funds from the North Central Soybean Research Program.


Soybean Rust: A Year In Review, Daren S. Mueller Dec 2007

Soybean Rust: A Year In Review, Daren S. Mueller

Integrated Crop Management News

During the 2005 and 2006 growing seasons, soybean rust was not a threat for Iowa soybean growers. This year was a different story, as soybean rust was established fairly early in the season in Texas and Louisiana creating the potential for soybean rust to get to Iowa during the growing season. Thankfully, soybean rust was not found while soybean plants were in a vulnerable stage; however, soybean rust was found in a field in Dallas County, Iowa, on Tuesday, September 25, 2007. Since the initial find, soybean rust was confirmed in 13 additional counties in Iowa (Figure 1).


Fungicides For Soybean: Considerations For 2008, Daren S. Mueller Dec 2007

Fungicides For Soybean: Considerations For 2008, Daren S. Mueller

Integrated Crop Management News

Even though soybean rust was found in Iowa in 2007, the pathogen cannot survive in Iowa. The pathogen can only survive on living plant tissue of susceptible plants. Likely overwintering sites are in Florida and Texas on kudzu and in Central America on legumes, such as jicama and soybean. This means the risk of rust getting to Iowa in 2008 is the same as it was at the beginning of past years. For rust to get to Iowa, it will need to successfully overwinter somewhere in the South and retrace the path it traveled in 2007.


Results Of Scn-Resistant Soybean Variety Testing Become Available, Gregory L. Tylka Nov 2007

Results Of Scn-Resistant Soybean Variety Testing Become Available, Gregory L. Tylka

Integrated Crop Management News

There are hundreds of resistant soybean varieties available for use in managing the soybean cyst nematode (SCN), a serious yield-limiting pest of soybeans. SCN-resistant soybean varieties are not immune; they can allow up to 10 percent SCN reproduction. Allowing 10 percent or less reproduction means the soybean varieties are providing 90 percent control.


A New Take On Soil Sampling Fields For Scn, Gregory L. Tylka Nov 2007

A New Take On Soil Sampling Fields For Scn, Gregory L. Tylka

Integrated Crop Management News

Growers and those who advise them receive annual prompting to consider collecting soil samples from Iowa fields in the fall to test for the presence of the soybean cyst nematode (SCN). The nematode often causes no obvious aboveground symptoms for many years after being introduced, so many SCN-infested fields can go undiagnosed. The key to effective SCN management is discovering infestations when the nematode population densities are low.


Soybean Rust Found In An Iowa Field, Daren S. Mueller Oct 2007

Soybean Rust Found In An Iowa Field, Daren S. Mueller

Integrated Crop Management News

Soybean rust was found in a field in Dallas County, Iowa, on Tuesday, September 25, 2007. The soybean rust infection initially was identified via visual observation. On Wednesday, three Iowa State University plant pathologists visited the field and collected additional leaves, and we observed newly formed soybean rust pustules and spores on those leaves to confirm the infection.


Sample Fields This Fall For Scn To Figure Out 2007 Or Plan For 2008, Gregory L. Tylka Oct 2007

Sample Fields This Fall For Scn To Figure Out 2007 Or Plan For 2008, Gregory L. Tylka

Integrated Crop Management News

The soybean cyst nematode (SCN) is a serious, widespread pest of soybean in Iowa and most soybean-producing areas of the Midwest. The nematode infests more than 70 percent of the fields in Iowa. However, SCN usually causes no obvious aboveground symptoms for many years after being introduced into a field. Consequently, many SCN-infested fields in Iowa may go undiagnosed. 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. It is much easier to keep low population densities low than to drive high ...


Top Dieback In Corn: Is Anthracnose The Cause?, Alison E. Robertson Sep 2007

Top Dieback In Corn: Is Anthracnose The Cause?, Alison E. Robertson

Integrated Crop Management News

Over the past week, I have had calls and e-mails regarding anthracnose top dieback in corn. First, a word of caution: Not all top dieback is caused by the anthracnose pathogen. Death of top leaves may be due to one or more of several factors that include hybrid characteristics, environmental stress, and corn borer damage. Bob Nielsen at Purdue University discusses these various factors in an article titled Top Leaf Death in Corn.


Outbreak Of Southern Rust On Corn, Alison E. Robertson Sep 2007

Outbreak Of Southern Rust On Corn, Alison E. Robertson

Integrated Crop Management News

Over the past two weeks, severe leaf blighting due to southern rust has occurred throughout central and southern Iowa. The last severe outbreak of southern rust in Iowa was in 1999. This disease was reported in Nebraska and Kansas earlier in the growing season; however, it was only in mid- to late August that we started to notice a few lesions in our field trials. Temperatures and precipitation in Iowa throughout August were well above normal and thus highly favorable for southern rust.


Warm With Some Concerns, Richard O. Pope Aug 2007

Warm With Some Concerns, Richard O. Pope

Integrated Crop Management News

Iowa crop producers enter August with crop conditions on the edge. Rain in the first week of August has helped in many areas, but the warm weather can hasten crop development. Accumulations of degree days over the normal during grain fill tend to shorten the fill period, which generally limits grain yield.


Summer Scouting In Soybean: Top Dieback And Other Diseases, Xiao-Bing Yang, Alison E. Robertson Aug 2007

Summer Scouting In Soybean: Top Dieback And Other Diseases, Xiao-Bing Yang, Alison E. Robertson

Integrated Crop Management News

This summer in Iowa, we have seen a mixed bag of soybean diseases during our scouting, probably because of climate patterns that have differed from other seasons and because of the very different weather that has occurred in various regions across the state. In eastern Iowa, Iowa State University field agronomists reported the occurrence of white mold, sudden death syndrome, frogeye leaf spot, and top dieback. In southern Iowa, downy mildew was reported. Bacterial blight and brown spot are common across most of the state.


The Dog Days Of Summer, Richard O. Pope Jul 2007

The Dog Days Of Summer, Richard O. Pope

Integrated Crop Management News

The third week of July produced slightly above average temperatures in the northwest two-thirds of Iowa, with southeast Iowa right on average. We are now entering the second part of the traditional dog days of summer, a period from July 3 to about August 11. It is named for the astronomical pairing of the sun with the dog star, Sirius, the brightest star in the northern hemisphere. Ancients thought the dog star added to the heat of the sun and attributed the star with oppressive summer heat.


New Cyst Nematode Species On Corn, Gregory L. Tylka Jul 2007

New Cyst Nematode Species On Corn, Gregory L. Tylka

Integrated Crop Management News

Iowa crop producers and agronomists are well aware of soybean cyst nematode (SCN), the plant-parasitic nematode that is widespread through the Midwest and can seriously reduce soybean yields. And many people are aware of other plant-parasitic nematodes that can cause significant yield reductions on corn. But most crop professionals probably are unaware that there is a corn cyst nematode that has been in the northeastern United States since 1981. And just recently, a new cyst nematode species that reproduces on corn was discovered in Tennessee.


A Potpourri Of Weather, Richard O. Pope Jul 2007

A Potpourri Of Weather, Richard O. Pope

Integrated Crop Management News

Iowans have experienced a range of weather conditions that cover most bases so far in 2007. If you want an excessively wet spring followed by a remarkably dry June and early July--try southwest Iowa. So you say you want a dry spring coupled with excessive rainfall in mid-season? Then east-central Iowa might be your cup of tea. And if you want dry followed by more dry--northwest Iowa can offer that. The rest of the state falls somewhere in the great in-between.


Soybean Rust Update And Outlook, Xiao-Bing Yang, Zaitao Pan Jul 2007

Soybean Rust Update And Outlook, Xiao-Bing Yang, Zaitao Pan

Integrated Crop Management News

During the last two seasons, we projected that the risk of soybean rust (SBR) was no longer a concern when June ended. This season is different from last year because we received more rain early in the growing season, and the disease progressed much faster in the South than during the last two years. Below is an update on the movement of SBR in the two northward pathways and an outlook for the rest of the growing season.


One-Stop Shop: Newly Integrated Plant And Insect Diagnostic Clinic, Christine Engelbrecht, Laura C.H. Jesse Jul 2007

One-Stop Shop: Newly Integrated Plant And Insect Diagnostic Clinic, Christine Engelbrecht, Laura C.H. Jesse

Integrated Crop Management News

Do you have problems with soybeans turning yellow or insects in your alfalfa? Pernicious weeds that you don't recognize? Don't know what to do or who to ask for help? Iowa State University Extension's new Plant and Insect Diagnostic Clinic staff can assist in answering your questions. The Plant and Insect Diagnostic Clinic can diagnose plant health problems caused by diseases, insects, herbicides, or the environment. The clinic also can identify insects, weeds, and fungi. Once they have diagnosed your disease or identified your insect pest, they can advise you on the best course of action to ...


Pollen Shed!, Richard O. Pope Jul 2007

Pollen Shed!, Richard O. Pope

Integrated Crop Management News

Corn has been shedding pollen in all parts of Iowa, meaning that we are in the critical pollination/grain set phase of the season. As I wrote last week, "Thankfully, Iowa farmers in most places started the growing season with ample soil moisture reserves. As the month progresses, rain stress, especially if it is exacerbated by above-average temperatures, will be a continuing concern." We did have a slightly cooler than average week, which helps--but with only very scattered rainfall. Soybean fields in many areas are slow to close the rows, and rain would help there as well.


July Soybean Disease Scouting, Xiao-Bing Yang Jul 2007

July Soybean Disease Scouting, Xiao-Bing Yang

Integrated Crop Management News

Each season in Iowa is different and different seasons have different diseases. After soybean passed the flowering stages, soybean root and foliar diseases began showing up. First, came the report of viral disease being found in the last week of June, which was much earlier than in the past. Then, Fusarium wilt showed up. With weather like we're experiencing, this season appears to be a mixed bag of soybean diseases. This article discusses some soybean diseases that occur in Iowa and that you may see while scouting in July.


Sample Now For Most Corn Nematodes, Gregory L. Tylka Jul 2007

Sample Now For Most Corn Nematodes, Gregory L. Tylka

Integrated Crop Management News

There are many different species of plant-parasitic nematodes that feed on corn, and the different species vary greatly in their ability to cause damage. For example, the damage threshold for spiral nematode (Helicotylenchus) on corn is greater than 1,000 per 100 cc (a little less than a half cup) of soil, but only one needle nematode (Longidorus) per 100 cc soil can be damaging. Also, some nematodes that feed on corn are endoparasites--that is, they feed from within the root tissue. But most corn nematode species are ectoparasites, living in the soil and feeding from outside roots.


July Starts Warm And Dry, Richard O. Pope Jul 2007

July Starts Warm And Dry, Richard O. Pope

Integrated Crop Management News

The first week of July brought temperatures slightly above long-term averages, particularly in northwest and west-central Iowa. Unfortunately, these are exactly the parts of the state where moisture shortages are becoming a bit of a concern. As always, conditions can vary greatly within a local area, depending on soils and where and when the rain falls.


Blooming Time In Iowa, Richard O. Pope Jul 2007

Blooming Time In Iowa, Richard O. Pope

Integrated Crop Management News

July dawns with some corn starting to tassel. Corn is a dioecious plant; that is, the male and female flowers are borne in separate structures with the male flowers in the tassel and female flowers in the ears. This process increases the chances that the plants will crossbreed. Pollen (male) is shed to the wind, landing on silks (female) to achieve pollination. The separation of the flowers, and also in timing—the tassels generally shed pollen one to a few days before the female silks are receptive—increases the chances of natural interbreeding. However, in many modern hybrids, male and ...


Before Applying Fungicides To Corn: Stop! Look! Consider!, Alison E. Robertson, Daren S. Mueller Jul 2007

Before Applying Fungicides To Corn: Stop! Look! Consider!, Alison E. Robertson, Daren S. Mueller

Integrated Crop Management News

There is considerable interest across Iowa and the whole Corn Belt in applying fungicides to field corn. In the past when corn prices were down below $2 a bushel, the decision to apply a fungicide was easy--no. This growing season, the high price of corn and increased disease risk due to increased corn-after-corn acreage has many producers considering fungicide applications as a means to increase yields.


Bean Leaf Beetle: Predicted Peak First-Generation Dates, Marlin E. Rice, Richard O. Pope Jul 2007

Bean Leaf Beetle: Predicted Peak First-Generation Dates, Marlin E. Rice, Richard O. Pope

Integrated Crop Management News

Bean leaf beetle feeding on soybean pods can lead to significant reductions in seed quality and yield. Management during the pod setting and filling stages can be frustrating because beetles may feed on pods for a couple of weeks before the population reaches the economic threshold. In this situation, some loss in seed quality and quantity occurs before an insecticide application can be economically justified. Several years ago, Larry Pedigo and his students in the Department of Entomology developed research-based information to help make a management decision for second-generation bean leaf beetles based upon the population size of the first-generation ...


Soybean Rust Update And Outlook - July 2, 2007, Xiao-Bing Yang Jul 2007

Soybean Rust Update And Outlook - July 2, 2007, Xiao-Bing Yang

Integrated Crop Management News

Since May, Louisiana and southern Texas are considered important source areas of soybean rust spores to northern soybean production. In Louisiana, the disease was found in kudzu plants near New Orleans earlier in the spring. Latest reports indicate that the disease is developing locally with increased severity. Because the wind in June was not suitable to northward movement, limited northward spore movement occurred as indicated by modeling results. On June 20, the disease was found in central Louisiana in sentinel soybean plots and a production field. The finding in central Louisiana is about 10 days earlier than the detection last ...


Safety, Restrictions, And Precautions For Spraying Fungicides On Corn, Daren S. Mueller, Alison E. Robertson Jul 2007

Safety, Restrictions, And Precautions For Spraying Fungicides On Corn, Daren S. Mueller, Alison E. Robertson

Integrated Crop Management News

In the next month, there may be an unprecedented amount of fungicides being applied to field corn in Iowa. While herbicides and insecticides are commonly used by Iowa farmers, fungicides are not. Like herbicide and insecticide labels, reading through a fungicide label will give you most of the needed information concerning safety for both yourself and others while spraying field crops.


Warm Temperatures = Rapid Growth, Richard O. Pope Jun 2007

Warm Temperatures = Rapid Growth, Richard O. Pope

Integrated Crop Management News

The third week of June brought warm and humid weather, spiked with local severe thunderstorms and some areas of heavy rain, especially in southeastern Iowa. Uneven stands are quite common, particularly in corn fields planted into less than ideal seedbeds. Some of that unevenness has been corrected by active growth the past week. Subtle variation in soil conditions, especially due to wheel tracks created during spring tillage, is apparent in some areas.


Fungicide Applications In Corn May Be Increasing, Alison E. Robertson, Daren S. Mueller, Carol Pilcher, Kristine J. P. Schaefer Jun 2007

Fungicide Applications In Corn May Be Increasing, Alison E. Robertson, Daren S. Mueller, Carol Pilcher, Kristine J. P. Schaefer

Integrated Crop Management News

In the past, fungicide applications on hybrid corn were mostly regarded as uneconomical. The increased corn-following-corn acres and associated increased disease risk, together with the higher price of corn and fungicide marketing, are responsible for changes in corn production practices. As a result, fungicide applications on corn may be more common in 2007. It is anticipated that most of these foliar fungicide applications will occur during corn tasseling stage and will be aerial applications.


Another Fungicide Approved For Soybean Rust In Iowa, Daren S. Mueller, Chuck Eckermann Jun 2007

Another Fungicide Approved For Soybean Rust In Iowa, Daren S. Mueller, Chuck Eckermann

Integrated Crop Management News

There has been some activity by the EPA concerning fungicides for soybean rust. The fungicide Caramba™ (metconazole), manufactured by BASF Corp., has been approved as a Section 18 fungicide in Iowa, effective on June 15, 2007. The exemption will expire on April 19, 2009. Caramba is a systemic, triazole fungicide with early infection and protectant activity. A second fungicide, Headline-Caramba™ copack, has been withdrawn by BASF and will not be available.