Open Access. Powered by Scholars. Published by Universities.®

Life Sciences Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 30 of 33

Full-Text Articles in Life Sciences

New Scn Slide Set Available, Gregory L. Tylka Dec 1998

New Scn Slide Set Available, Gregory L. Tylka

Integrated Crop Management News

A new slide set describing the biology, symptoms, and management of soybean cyst nematode (SCN) in the Midwest is available from Iowa State University Extension. The slide set, titled "The SCN Coalition Leader's Guide for SCN Management Training," is organized in a three-ring binder and includes an illustrated script to accompany the slides. Three separate sections describing SCN biology (17 slides), symptoms and scouting (23 slides), and management (17 slides) are included in the slide set, and a fourth section (47 slides) contains an integrated presentation of all aspects of SCN biology, scouting, and management.


Stalk Rots And Corn Lodging, Gary P. Munkvold Nov 1998

Stalk Rots And Corn Lodging, Gary P. Munkvold

Integrated Crop Management News

Iowa has experienced two consecutive years with conditions very favorable for stalk rot development. Some producers have been realizing this over the last few weeks as they struggle to harvest fields that lodged due to stalk rot. The good news is that lodging is not as widespread this year as it was last year. According to Iowa Agricultural Statistics reports, about 19 percent of the acreage has moderate to severe lodging this year compared with last year when about 39 percent of the acres was reported to have moderate to severe lodging. This improvement, however, is probably not related to ...


Discolored Soybean Seeds, X. B. Yang Oct 1998

Discolored Soybean Seeds, X. B. Yang

Integrated Crop Management News

When growers start to combine, pathologists start to receive questions about discolored soybean seeds. For the last two years, we have received numerous reports of discolored seeds from producers, especially in southwestern and western Iowa. Areas where this problem was prevalent last year appear to have the problem again this year. Growers are concerned about the effect of discoloration on seed quality. A few common diseases that are causing seed discoloration this season are discussed in the following paragraphs.


New Prices For Scn Soil Analysis, Paula Flynn, Gregory L. Tylka Oct 1998

New Prices For Scn Soil Analysis, Paula Flynn, Gregory L. Tylka

Integrated Crop Management News

As of October 1, 1998, there is a price discount for multiple soil samples submitted to the ISU Plant Disease Clinic (515-294-1160) for analysis for the soybean cyst nematode (SCN). The cost for processing five samples or fewer will remain at $15 per sample. The new processing prices for six to 10 samples is $12 per sample; analysis of 11 or more samples costs $10 per sample.


Sds Is Spreading In Iowa, X. B. Yang Sep 1998

Sds Is Spreading In Iowa, X. B. Yang

Integrated Crop Management News

For the last two years, sudden death syndrome (SDS) has been spreading across Iowa rapidly. Last year, the disease occurred in many soybean fields in southeastern Iowa. This year it has been found in several soybean fields in central, eastern, and southeastern Iowa, and in one northern Iowa field. In Illinois this disease causes production problems, and colleagues there have reported SDS epidemics this year.


Corn Plants Dying Prematurely, Gary P. Munkvold Sep 1998

Corn Plants Dying Prematurely, Gary P. Munkvold

Integrated Crop Management News

During the last 2 weeks, the appearance of many cornfields has begun to deteriorate, and many plants are now dead. Although we expect plants to be maturing about this time of year, clearly some plants are dying early. Statewide, we reached 50 percent silking by about July 19, which means theoretically, the average corn plant should reach physiological maturity by about September 14. We are well ahead of that pace for a number of reasons, but regardless of the reason, when corn plants don't live for the full season, they don't achieve maximum potential yields. Even though the ...


Quick Scn Info On New Web Site, Gregory L. Tylka Sep 1998

Quick Scn Info On New Web Site, Gregory L. Tylka

Integrated Crop Management News

Information about soybean cyst nematode (SCN) can be accessed at a new Iowa State University Web site called Quick SCN Info. This site is part of the Tylka nematology laboratory's web site. Quick SCN Info contains current SCN management recommendations, commonly asked questions and answers about SCN, links to most of the ISU Extension SCN publications available on the Web, and links to many other Web sites containing SCN information. Among the publications accessible through this site are the 1996 and 1997 SCN Variety Trial results and the most current list of public and private disease-resistant soybean varieties. Be ...


Soybean Stem Diseases In Midsummer, X. B. Yang Jul 1998

Soybean Stem Diseases In Midsummer, X. B. Yang

Integrated Crop Management News

Many of the soybean samples that have been submitted to the ISU Plant Disease Clinic show signs of hail injury, due to the severe storms and associated hail damage earlier this summer. Disease scouting in late July and August may reveal more stem diseases than usual in fields that had hail injury because wounds from the hail are ideal entryways for some pathogens. Stem canker is one stem disease to be concerned with after such weather conditions.


Gray Leaf Spot Is On The Move, Gary P. Munkvold Jul 1998

Gray Leaf Spot Is On The Move, Gary P. Munkvold

Integrated Crop Management News

Reports of gray leaf spot have been numerous this week, after apparently little activity in the previous weeks. The disease has been observed throughout southern Iowa and as far north as Grundy County. Although it is not yet severe in most fields, the warm, humid weather and frequent rain are ideal for the disease this year, and I expect that it will be worse than in the past two years.


New Soybean Disease Information, X. B. Yang Jul 1998

New Soybean Disease Information, X. B. Yang

Integrated Crop Management News

Two updated soybean disease fact sheets are available: Phytophthora Root and Stem Rot of Soybeans(Pm 914) and Soybean Sudden Death Syndrome (Pm 1570). These revised versions have several new color photos that will help with disease identification. Disease management information also is updated, especially with regard to conservation tillage. The Phytophthora fact sheet adds resistance selection information based on results from a recent survey of Phytophthora races in Iowa.


White Mold Mushroom Hunt, X. B. Yang Jul 1998

White Mold Mushroom Hunt, X. B. Yang

Integrated Crop Management News

The wet soil this summer has raised some concerns about soybean white mold. After soybean canopies, white mold fungus produces apothecia, tiny mushroomlike structures that produce spores to infect soybean. In recent extension activities such as Iowa State University (ISU) field days, producers wanted information on white mold risk this season and how to scout for apothecia. Some of the more common questions asked are presented below.


Wet-Weather Issues Relating To Scn, Gregory L. Tylka Jul 1998

Wet-Weather Issues Relating To Scn, Gregory L. Tylka

Integrated Crop Management News

In the June 29 issue of the ICM newsletter, XB Yang discussed the effects of the wet 1998 growing season on fungal soybean diseases. Growers and agribusiness also should be aware of two issues concerning the soybean cyst nematode (SCN) and the wet weather that we have experienced so far this growing season. First, SCN is moved by anything that moves soil. Consequently, any field or area of a field that has flooded may have had the nematode introduced into the field. Random survey results from 1995-1996 indicate that approximately two-thirds of the corn-soybean fields in Iowa are infested with ...


Soybean Diseases In A Rainy Season, X. B. Yang Jun 1998

Soybean Diseases In A Rainy Season, X. B. Yang

Integrated Crop Management News

The excessive rains in late May and June have created disease-favorable conditions and resulted in soybean disease problems. This article summarizes the early-season disease problems encountered thus far and provides some answers to commonly asked questions. The disease information is from our field data, reports from growers and ISU extension staff, and plant samples submitted to the Plant Disease Clinic.


Scn Females On Roots; It's Time To Scout, Gregory L. Tylka Jun 1998

Scn Females On Roots; It's Time To Scout, Gregory L. Tylka

Integrated Crop Management News

The soybean cyst nematode (SCN) is an important, widespread soybean pest in Iowa that often goes unnoticed, particularly in years of adequate to excess rainfall. To date, SCN has been discovered in 84 of the 99 Iowa counties, and it is suspected to be present in many additional counties. The only consistent and reliable sign of an SCN infestation in the field is the presence of adult SCN females and cysts (dead females) on the roots of infected soybean plants. The adult SCN females and cysts appear as small, white- to yellow-colored objects, each approximately the size of a period ...


Corn Seedling Disease And Crown Rot, Gary P. Munkvold Jun 1998

Corn Seedling Disease And Crown Rot, Gary P. Munkvold

Integrated Crop Management News

Poor growing conditions have resulted in some predictable problems with corn emergence, many of which include infection by fungi. Pythium and Fusarium have been prominent this year in fields with emergence problems.


Soybean Damping-Off Prevalent, X. B. Yang, Michael D. Uphoff Jun 1998

Soybean Damping-Off Prevalent, X. B. Yang, Michael D. Uphoff

Integrated Crop Management News

The Department of Plant Pathology at ISU has received numerous reports of damping-off across Iowa. Both preemergence damping-off and postemergence damping-off have been found. The largest area having stand establishment problems is about 90 acres. We have identified Phytophthora or Pythium in some samples of diseased plants sent to the ISU Plant Disease Clinic.


Cobra For White Mold Suppression, X. B. Yang, Micheal D. Owen, Robert G. Hartzler Jun 1998

Cobra For White Mold Suppression, X. B. Yang, Micheal D. Owen, Robert G. Hartzler

Integrated Crop Management News

Many fields planted to soybeans this year had white mold problems in 1996, thus providing inoculum for infestations during the current season. Growers are looking for ways to manage white mold problems and one strategy may be to use a herbicide. Cobra (lactofen) has recently received a supplemental label for suppression of soybean white mold. In this article, we address questions related to using Cobra for white mold suppression.


Soybean Seed Coat Mottling, X. B. Yang Jun 1998

Soybean Seed Coat Mottling, X. B. Yang

Integrated Crop Management News

For last week's ICM newsletter, Michael Uphoff and I wrote an article on management of soybean diseases for specialty soybean. In the article we mentioned that soybean mosaic virus (SMV) can cause seed coat discoloration. This week, the ISU extension staff and a seed dealer reported emergence problems of regular soybean seeds that had SMV-like seed coat mottling. This article will address a few questions that should be useful in preventing such problems.


Disease Management For Specialty Soybeans, X. B. Yang, Michael D. Uphoff May 1998

Disease Management For Specialty Soybeans, X. B. Yang, Michael D. Uphoff

Integrated Crop Management News

Production of specialty soybeans, such as tofu soybeans, brings new opportunities for soybean growers. As more and more growers plant specialty soybeans, which are not commonly bred for disease resistance, we have received an increased number of questions on disease management. Common questions can be grouped into two areas: the first pertains to diseases that cause stand reduction and the second relates to seed quality.


Scouting For Soybean Seedling Diseases, X. B. Yang May 1998

Scouting For Soybean Seedling Diseases, X. B. Yang

Integrated Crop Management News

When soybeans start to emerge, a few of us may experience stand reductions caused by seedling diseases. Several fungi can cause stand establishment problems either before or after soybean emergence. Pythium, Phytophthora, Rhizoctonia, and Fusarium are fungi that cause seedling blight in Iowa. Research shows that the first three fungi account for about 90 percent of disease-related stand reduction problems in Iowa. Fusarium is a minor problem. Determining which fungi are the cause of a problem in a particular field is a main task of scouting.


Controlling Wheat Leaf Diseases, Gary P. Munkvold May 1998

Controlling Wheat Leaf Diseases, Gary P. Munkvold

Integrated Crop Management News

Now is the time to start thinking about controlling leaf diseases in wheat if necessary. Conditions have been wet enough in the southern Iowa wheat-producing areas to promote significant leaf disease development. Wheat can be affected by a number of foliar diseases caused by fungi, including Septoria leaf blotch, powdery mildew, and tan spot. There are also three different rust fungi that can infect wheat. Leaf rust, Puccinia recondita, is the most common rust disease and has the most destructive potential of the foliar diseases.


Alfalfa Leaf Diseases Reported, X. B. Yang, Gary P. Munkvold May 1998

Alfalfa Leaf Diseases Reported, X. B. Yang, Gary P. Munkvold

Integrated Crop Management News

Alfalfa is turning green early in this warmer-than-usual spring and the frequent rains have promoted foliar diseases in parts of Iowa. Last week, ISU extension field specialists-crops Brian Lang (northeast) and Virgil Schmitt (east) reported spring black stem, and Mark Carlton (south central) reported Leptosphaerulina leaf spot.


Alfalfa Seedling Diseases In 1998, Gary P. Munkvold Apr 1998

Alfalfa Seedling Diseases In 1998, Gary P. Munkvold

Integrated Crop Management News

Wet conditions have delayed new alfalfa seedings in many parts of the state, and these conditions also may lead to problems with soilborne fungi. Several genera of fungi can attack alfalfa seedlings, includingPhytophthora, Pythium, Aphanomyces, Fusarium, and Rhizoctonia. Traditionally, Phytophthora andPythium have been considered the primary pathogens, but recently Aphanomyces euteiches has been more widely recognized. According to a survey we did in 1994, Aphanomyces is more common thanPhytophthora in Iowa soils, and these two fungi should be considered equal threats to seedlings. Seedling diseases should be suspected when emergence is poor and/or there are obviously ...


Plan Your Disease Scouting, X. B. Yang Apr 1998

Plan Your Disease Scouting, X. B. Yang

Integrated Crop Management News

As crop scouts, we know that detecting a disease in the early stages of its development is critical to disease management. Early detection of a disease can help us make management decisions to minimize disease risk or to prevent disease problems before they take place.


Planting Date And Soybean Diseases, X. B. Yang Apr 1998

Planting Date And Soybean Diseases, X. B. Yang

Integrated Crop Management News

We know that planting date affects soybean diseases and that delayed planting is a useful management tool to reduce the risk of some diseases, especially in regions with a long planting season. However, research by Iowa agronomists shows that early planting increases the possibility of achieving maximum yield and that the level of success decreases as planting is delayed. Because of narrow planting windows for high yield, especially in northern Iowa, the value of delayed planting for disease management is less in Iowa than in other regions with a longer planting season.


Site-Specific Farming Shows Hidden Nature Of Soybean Cyst Nematode Yield Losses, Gregory L. Tylka, Carmen Sanogo, Dean Michael Tranel Apr 1998

Site-Specific Farming Shows Hidden Nature Of Soybean Cyst Nematode Yield Losses, Gregory L. Tylka, Carmen Sanogo, Dean Michael Tranel

Integrated Crop Management News

The soybean cyst nematode (SCN) is a serious and widespread pathogen of soybeans in Iowa. In fact, results of a recent random survey in Iowa indicate that SCN may be present in nearly two-thirds of the fields in the state. Unfortunately, many growers do not realize that their fields are infested with SCN. Why? Results of an Iowa State University, soybean-checkoff-funded research project using site-specific farming technology illustrate the hidden nature of SCN yield losses in Iowa fields.


Plant Oats Early To Avoid Diseases, Gary P. Munkvold Apr 1998

Plant Oats Early To Avoid Diseases, Gary P. Munkvold

Integrated Crop Management News

Oats in Iowa suffer from two major diseases, crown rust and barley yellow dwarf virus. Crown rust appears as orange leaf pustules and also causes yellowing and death of the leaves. Severely affected plants are stunted and produce little grain. The disease usually first appears in late May and can remain active throughout the rest of the season. Spores can be windblown long distances, but in Iowa some initial infections are the result of spread from local buckthorn shrubs. Buckthorn is the alternate host of the crown rust fungus, Puccinia coronata.


Scn In At Least 85 Iowa Counties, Gregory L. Tylka Apr 1998

Scn In At Least 85 Iowa Counties, Gregory L. Tylka

Integrated Crop Management News

Recently, data from several sources were compiled to determine the known distribution of the soybean cyst nematode (SCN) in Iowa. These data included results of analyses of more than 3,500 samples submitted to the Iowa State University (ISU) Plant Disease Clinic from 1994 to 1998 and nearly 400 samples collected from randomly selected sites in a survey conducted in Iowa from 1995 to 1996. Presently, SCN has been found in 85 of 99 Iowa counties. The counties where SCN has not yet been confirmed are located primarily in northeast and south central Iowa.


Corn Seed Treatments In 1998, Gary P. Munkvold Mar 1998

Corn Seed Treatments In 1998, Gary P. Munkvold

Integrated Crop Management News

The snow will be gone soon and it will be time to plant corn. El NiƱo promises to bring us a cool, wet spring, and this means seedling diseases. If you don't know which fungicidal seed treatment is on your corn seed, now is a good time to have a look at those labels on the bags and check it out. Recent trends in corn seed treatment are continuing in 1998--most seed has been treated with Maxim+Apron this year instead of the traditional, standard fungicide Captan.


Questions On White Mold Control, X. B. Yang Feb 1998

Questions On White Mold Control, X. B. Yang

Integrated Crop Management News

This winter two questions on soybean white mold have been frequently asked by growers and agronomists in agribusiness: (1) Can white mold fungus infect soybean seed and spread with the seed? and (2) What are the latest findings on the use of chemicals, especially Cobra, to control white mold by foliar spray? Plant pathologists in the north central region have been working on the answers to these questions for the past two years. Although final answers are yet to come, significant progress has been made. In this article I will address the two questions by using the latest research results.