Soybean aphid populations are increasing in some fields that were previously treated with foliar insecticides for soybean aphid. Soybean fields should continue to be scouted until the R6.5 growth stage, even if they were previously treated. This post-treatment scouting will allow you to catch potential resurgence of aphid populations. When determining whether to treat an aphid infestation at this time of year, pay particular attention to plant growth stage (the economic threshold of 250 aphids per plant is valid through R5, but yield loss can occur into early R6), whether or not the aphids have wings or "wing pads" (some aphids are already moving to buckthorn, but we don't know what fraction of the population will stay on soybean), and pre-harvest intervals of insecticides. The recent soybean aphid scouting guide provides more information. Be on the lookout for two-spotted spider mites too. Certain insecticides applied to control aphid populations can increase (flare) populations of two-spotted spider mites. The spider mite fact sheet provides more information. If a field needs to be treated again, it is advisable to switch to a different class (mode of action) of insecticide to prevent or delay the development of pest resistance to insecticides. For more information, review the guide to insecticide resistance and resistance management.
Recently in the Soybean Category
by Robert Koch, Extension Entomologist
In July 2014, the Minnesota Department of Agriculture (MDA) published a series of best management practices (BMPs) for agricultural insecticides (link to BMPs). These BMPs were created in response to seasonal detections of chlorpyrifos in several rivers and streams in the agricultural areas of Minnesota from 2010 to 2012. Subsequently, MDA determined chlorpyrifos to be a "surface water pesticide of concern" which initiates BMP development. Some MDA samples had concentrations violating water quality standards established by the Minnesota Pollution Control Agency (MPCA) to protect aquatic life, which led the MPCA to list three water bodies as impaired due to chlorpyrifos.
Soybean aphids can now be found in many soybean fields. In some fields (but certainly not all fields) in southern Minnesota, soybean aphid populations are approaching levels requiring insecticide application to prevent economic losses. This critical soybean aphid population level, referred to as the economic threshold, is an average of 250 aphids per plant AND aphids on more than 80% of plants AND aphid populations increasing. Many fields are well below this level and do not require insecticide application for aphids at this time. Scouting is required to determine which fields require or may soon require treatment and which fields do not. A guide for soybean aphid scouting in Minnesota was recently posted (http://z.umn.edu/soybeanaphidscouting).
By Dean Malvick
A number of different root and leaf diseases have been appearing in soybean and corn fields across Minnesota. Most are of minor concern at this point, but some have been more problematic. This article focuses on diseases that have been reported or may be favored by weather conditions and have raised questions or concern.
Most of the soybean and corn crop is emerged and growing well across Minnesota. Seedling disease problems in scattered soybean and corn fields have been reported in early June and more are expected due to wet and flooded fields. Abundant (or excessive) rainfall and fluctuating temperatures and have created excellent conditions for seedling diseases. This is a good time to check fields for seedling disease problems and efficacy of seed treatments.
Infection of seedlings before or after emergence can result in dead plants, rotted and discolored roots, stunted and discolored plants, and wilting. The problems often occur in patches in fields. Seedling infection can also lead to damage that may not fully develop until mid to late summer, as with Phytophthora root and stem rot and sudden death syndrome. Disease can cause serious damage, but it is just one of many stresses that seedlings are encountering. Careful scouting and diagnosis are often required to identify the cause of a problem.
Jeff Coulter, Extension Corn Agronomist, Seth Naeve, Extension Soybean Agronomist, Dean Malvick, Extension Plant Pathologist, and Fabian Fernandez, Extension Nutrient Management Specialist
With the recent heavy rains, many corn and soybean fields have areas where crops are experiencing flooded or saturated conditions. This article discusses agronomic and disease issues for corn and soybean exposed to prolonged periods of high soil moisture and cool temperatures.
As June 1 looms in the not-too-distant future, large areas of land intended for small grains or corn remain unplanted in Northwestern Minnesota. Likewise, there are localized areas in East-central and South-central Minnesota where the corn crop has not yet been planted. With recent rainfall, and a May 31 crop insurance cut-off date around the corner, some producers are considering switching to soybeans.
By Lizabeth Stahl and Lisa Behnken, Extension Educators in Crops
Access to results for many of the U of MN crops research trials conducted across the state has now become streamlined with the launch of the new, U of MN Extension Crops Research website. This one-stop shop can be accessed through the U of MN Extension Crops webpage at www.extension.umn.edu/crops under "Research Reports".
The website contains results for small plot and on-farm crops research and demonstration trials conducted across Southern MN from 2003 to 2013. You can also access research results for crops trials conducted at Research and Outreach Centers located across the state by clicking on the respective link. Statewide results for weed science research can be accessed through the "Applied Weed Science" link, and results for the Minnesota hybrid and variety trials can be accessed through the "Minnesota Field Crops Variety Trials" link.
The Research Reports webpage supplements U of MN Crops websites such as the "Corn", "Soybean", "Small Grains", "Forages", or "Sugarbeets" websites, or the "Nutrient Management", "Pest Management", "Ag Drainage", "Climate and Weather", and "Tillage" websites, where you can find research-based information and resources to help with specific crops-related decisions.
By Robert Koch, Extension Entomologist
Recent cool and wet conditions may increase the risk of seedcorn maggot infestation in some soybean and corn fields. Seedcorn maggots are small (1/4 inch long), white maggots (fly larvae) that feed on germinating seeds. The maggots can tunnel into seed, which may result in seed death, and can injure the emerging plant tissues, which can affect plant growth or lead to damping off. Such injury can result in stand loss or weakened plants. For example, if the growing point of soybean is killed, "Y-plants" can result when branching develops at the cotyledons. Yield from "Y-plants" may be reduced if competing with neighboring healthy plants. Seedcorn maggot injury can be difficult to distinguish from other problems such as Pythium and other seedling diseases.
Fields at greatest risk are those with decaying organic matter, such as a recently incorporated cover crop or manure. Risk of injury is greater when cool and wet conditions slow germination and emergence, which increases the window of time plants are susceptible to attack. Rescue treatments are not available for this pest. However, preventative tactics can be utilized to protect seed and plants in high-risk situations. Seed-applied and soil insecticides can offer effective protection of germinating plants from seedcorn maggot (be sure to follow instructions on product label). In addition, degree-day models are available to guide decisions about adjusting planting date to avoid periods with high larval abundance (UW seedcorn maggot degree-days).
When significant stand loss occurs, replanting may be required, but this option should be considered carefully. Information is available to guide replant decisions in soybean (U of MN Extension soybean replant guide) and corn (U of MN Extension corn replant guide).
By Lizabeth Stahl, Extension Educator in Crops
Benefits of a preemergence (PRE) herbicide application in soybean were demonstrated through the "PRE Challenge" - a series of on-farm research and demonstration trials conducted across southern MN in 2012 and 2013. In these University of Minnesota Extension trials, made possible through financial support of the Minnesota Soybean Research and Promotion Council, cooperators compared a postemergence-only herbicide program to a program that included a PRE herbicide application.
By Lizabeth Stahl, Extension Educator in Crops
Does glyphosate perform as well today as it did when you first used it? When producers were asked this question at University of Minnesota Private Pesticide Applicator Training sessions across southern Minnesota in 2014, 87% of the respondents said "No". This percentage is up significantly from 2009, when 55% of respondents answered "No" to this question. Increasing issues with resistance to glyphosate is likely, at least in part, behind reported reductions in weed control. To address issues of reduced weed control with glyphosate, diversification is key.
By Lizabeth Stahl and Lisa Behnken, Extension Educators in Crops
University of Minnesota Extension has recently launched a U of MN Extension Crops YouTube video site. It can be accessed through the newly updated U of MN Extension Crops webpage at www.extension.umn.edu/crops under "Social Media".
By: Mike Boersma, Extension Educator, Murray and Pipestone counties
The University of Minnesota Winter Crops Day and Small Grains Program is a great opportunity to hear the latest University-based research and information about corn, soybean, and small grain production. Whether you are a producer or an Ag professional who works with producers, this program is sure to provide relevant and practical information to help you be successful. The morning will focus on various aspects of corn and soybean production while the afternoon will focus on small grain production in southern Minnesota. The program will be held at the Slayton Pizza Ranch on Tuesday, February 25th. Registration will begin at 8:30 am, with the program running from 9:00 am to 4:00 pm.
The annual Extension Drainage Design Workshops will be held in four locations in 2014: January 29 - 30, SDSU Extension Regional Center, Sioux Falls, SD; February 11 - 12, North Dakota State College of Science, Wahpeton, ND; March 5 - 6, University of Minnesota - Crookston, Crookston, MN, and March 18 - 19, Holiday Inn, Owatonna, MN. The workshops are a collaborative effort between the University of Minnesota, North Dakota State University, and South Dakota State University Extension.
The 2-day workshops start at 8:00 a.m. and end at 5:00 p.m. on day two. The workshops will focus on planning and design of agricultural tile drainage systems to meet both profitability and environmental objectives. The course content is taught in a hands-on manner with lots of discussion time.
Each workshop is intended for those interested in a more complete understanding of the planning and design principles and practices for drainage and water table management systems, including: farmers, landowners, consultants, drainage contractors, government agency staff and water resource managers. Planning topics include legal aspects, basics of drainable soils, agronomic perspectives, doing your own tiling, land evaluation tools, wetlands, and conservation drainage concepts and techniques. The design topics begin with basic design considerations and progress through individual small team projects, with several hands-on problem-solving examples covering basic design and layout principles, water flow calculations, drain spacing, sizing, and grades. Design principles for lift stations and conservation drainage practices are also considered.
Registration for the four workshops sessions is now available at: www.regonline.com/2014drainage The registration price is $225 (price goes up to $300 about 3 weeks before the start of each workshop), and each workshop is limited to about 65 participants. These workshops have typically filled quickly, so register early to guarantee a spot. Due to seating limitations, on-site registration will not be available on the day of the event. Detailed agendas and additional information will follow shortly and be posted to the registration site.
How-to information, expert advice, practical tips
By Jodi DeJong-Hughes, Extension Educator - Crops and Conservation Tillage Conference Coordinator
Roll up your sleeves for some practical, hands-on information that will save you soil, time, fuel -- and money. Conservation tillage is the focus of the ninth annual University of Minnesota Extension Conservation Tillage Conference and trade show Feb. 17 and 18, at the Holiday Inn and Suites, St. Cloud, MN. This conference emphasizes proven farmer experience and applied science. Straight from the trenches, learn how heavier, colder soils aren't necessarily the challenge they're made out to be. And, what have long-time no-tillers and reduced-tillage farmers learned that could spare you the same lessons?
The unusual weather this season in Minnesota has created favorable conditions for various diseases in corn and soybean crops. Some diseases have been appearing since June due in part to delayed planting and crop growth and abundant rainfall in many areas. This article focuses on diseases that have been recently been confirmed and have raised concern. In corn fields, above average levels of common rust are being reported and Goss's wilt was confirmed in two fields. In soybean, Phytophthora root and stem rot and the less important but often noticed leaf diseases bacterial blight and Septoria brown spot are widespread. This is a good time of the year to scout fields for crop diseases.
By Robert Koch & Marla Spivak, Extension Entomologists
Honey bees and native bees forage in and near soybean and cornfields, especially during dry weather. When treatment decisions are being made for pests of these crops, it is important to consider minimizing the risk to these pollinators. Bees are the most important pollinators of our fruits, vegetables and crops like alfalfa hay that feed our farm animals. Honey bees and the thousands of native bee species all rely on the flowers they pollinate for good nutrition and health. Bees are being pushed to the tipping point by various factors, such as disruption of natural habitats, diseases and parasites, and widespread overuse of pesticides.
By Jeffrey L. Gunsolus, Extension Agronomist - Weed Science
The wet weather pattern this spring and early summer has left a significant number of acres, especially in southeastern MN, unplanted. Current estimates in southeastern MN project 30% of the tillable acres have not been planted and on many of these acres weeds such as giant ragweed, common lambsquarters and waterhemp are thriving.
Although weeds are beneficial from an erosion control perspective their rapid growth will make seedbed preparation for planting cover crops very difficult and weed seed production potential will challenge even the best weed management tactics available in 2014.
By Lizabeth Stahl and Jill Sackett, Extension Educators
The challenging spring of 2013 resulted in wide-spread planting delays across the state and a significant amount of acres that remain unplanted at this time. If the decision has been made to take the "prevented planting" option for insurance purposes, the question remains about what to do with these acres. Leaving the ground bare greatly increases the risk of not only soil erosion, but also the risk of "Fallow Syndrome" the following year.
By Robert Koch, Extension Entomologist
On June 11, 2013, we found soybean aphids on soybean at the Rosemount Research and Outreach Center near Rosemount, MN. Not many beans were out of the ground there, but in the two fields we sampled, we found aphids. We sampled one commercial soybean field at the VC growth stage (unifoliate leaves unfolded) and found 7.5% of plants infested with 1 to 9 aphids on each infested plant. The other field we sampled was a small plot trial, also at the VC growth stage, and had 10% of plants infested with 2 to 3 aphids on each plant.
By Lizabeth Stahl, Extension Educator - Crops
Volunteer corn has become one of the more prevalent weeds in fields across the Midwest. Conditions experienced in 2012, however, have combined to create almost a perfect storm in some fields for potentially high volunteer corn populations in 2013.
The weather has put us in a bind. Significant amounts of planting have yet to be completed, which has led to questions on the "correct" course of action. There will be no one "correct" course of action and with fields unsuitable for planting and more rain in the forecast there will be no easy decisions. One choice could be to utilize prevented planting, a choice that is appropriate for some and will lead to many other decisions to be made. A second option is to switch corn acres to soybeans; this may also be a wise and appropriate decision for some acres. Remember when planting soybeans after June 10th it is generally recommended to drop 0.5 RM from your typical full season varieties. The final choice is to stay the course and plant corn, a perfectly viable option for some acres.
A full set of delayed planting resources can be found at: http://z.umn.edu/lateplanting
By Lizabeth Stahl, Extension Educator - Crops, and Jeff Gunsolus, Extension Agronomist - Weed Science
With very tight windows of opportunity to plant this year, preemergence herbicides may not have been applied as planned. Application of a residual herbicide prior to planting or emergence of the crop, in both corn and soybean, is a great weed management strategy overall and also a key tool in managing against herbicide resistance. What are some of our options if soybeans emerged before a preemergence herbicide application was made?
By John Wiersma
Northwest Research and Outreach Center
High pH, highly calcareous soils, common in western Minnesota, restrict the availability of soil Fe needed for optimum soybean growth and yield. On such soils, the amount of Fe fertilizer applied must surpass a threshold before there is sufficient available Fe in the soil solution to induce a positive growth response. Only a limited number of management tactics designed to improve the availability of Fe have been studied with soybean. These include variety selection, seeding density, seed-applied or in-furrow materials, and foliar treatments.
By Daniel Kaiser
Extension Soil Fertility Specialist
Management of Iron (Fe) deficiency chlorosis (IDC) in soybean is seemingly and endless topic of research in soybean growing areas with high pH, calcareous, parent materials. We are just finishing a three-year summary of a series of IDC management strip trials that began in 2010. Our main focus for this work was to study the variability in response for a tolerant and susceptible variety to an oat companion crop and a 6% EDDHA-Fe treatment applied in-furrow (we used Soygreen at a rate of 3 lbs of product per acre). The field areas were selected to have some variation in the severity of IDC.
Extension Soil Fertility Specialist
I know there are still questions on the application of sulfur for soybean. Between me and a number of other researchers in Minnesota, we have been working on a number of projects focusing on sulfur management on corn, soybean, and spring wheat. Recently the soybean research has been fully summarized so I want to take a minute or two to highlight some of the findings to outline where we are at with the current guidelines for fertilizer management on soybean.
By Lizabeth Stahl, Extension Educator - Crops
Much of the seed planted this year will have been treated with a fungicide, insecticide and/or nematicide. As when working with any pesticide, care should be taken when handling treated seed so that exposure to the handler, non-target organisms, and the environment is reduced or prevented as much as possible.
Extension Soil Fertility Specialist
With spring finally approaching it is a good time to address some questions on soil testing that came up of the winter concerning testing soils in a field moist state versus the standard dried samples that are run through soil testing labs. First I would like to make it clear that the issue of drying of a soil sample mainly pertains to potassium. Most other tests routinely run through the lab are not affected by drying of the sample. The reason why potassium is different is due to its chemistry in the soil. We currently have finished the second year of potassium studies looking at both testing methods but will be continuing this work for the foreseeable future to gain a better understanding of what is going on within the soil.
By Lizabeth Stahl
The University of MN Field Crop Trials Bulletin is now available in print and electronic forms. The new publication, dated January 2013, provides results from U of MN trials conducted in 2012 across the state. The varieties tested are from both public and private breeding programs and include U of MN developed forage, grain, and oilseed crop varieties.
Spider mites are the concern today. Symptoms have become more obvious in some fields, especially along field edges, drought pockets and drier area in the region. Is this a "tornado watch" or "warning"? A watch in most fields, but we have touchdown (warning), with damage in some (more drought stressed conditions). You need to scout now. Here are some additional precautions and suggestions to consider.
- We are entering the critical time for soybean growth--pod set and fill, determining yield.
- When/If you pull the trigger and apply an insecticide now, this early in the season, plan on multiple application for multiple pests (aphids). You'll remove all beneficial insects and open the door to other pests.
- When making multiple applications it is imperative that you choose multiple modes of action.
- Canopy penetration is critical for good control.
- Do not cheat on insecticide rates.
- Do not cheat on water (gallons/acre applied).
- Do not cheat on pressure--keep PSI up.
Read this article for more information on managing spider mites.
How quickly crop conditions have changed from the wet weather of May.
Extreme heat and lack of rainfall throughout June has resulted in USDA Crop reports having been dramatically revised to reflect deteriorating crop progress throughout the U.S. Corn Belt. At the moment, conditions appear not quite as severe in SW Minnesota as in other regions but, that could change soon. I hope it is for the better as the result of rainfall.
Dry conditions threatening to generally impact final yields across the U.S. Corn Belt have historically had significant impacts on "old crop" and "new crop" prices. We have certainly seen that in the last few weeks. If market demand for corn or soybeans remain the same and stocks are tight, a relatively small change in expected supply leads to a larger change in prices.
We've been getting calls about spider mites in soybeans, not surprising given our high temps and the dry conditions in some locations. As temps get into the 90's, spider mite reproduction and development rates increase significantly. Drought also exacerbates spider mite populations, and when drought conditions are relieved by rain, spider mite populations may not necessarily decrease. Consequently, even after drought conditions pass, best to continue scouting for spider mites damage.
Spider mites are tiny and only large females are visible to the naked eye (unless you've got really good eyesight!). The best way to see spider mites is to shake a plant over a piece of white paper - any moving pieces of dirt are likely spider mites... So to scout for something that small, it's best to look for damage. Spider mite damage will first appear as small yellow spots (stippling) on lower leaves. There is currently no solid treatment threshold in soybeans, but If stippling reaches mid-canopy leaves, a treatment is likely necessary. Pyrethroids may flare spider mite populations, spreading mites and increasing their populations.
A good source for information on spider mite biology, scouting and thresholds was prepared last year by Bruce Potter and Ken Ostlie and is available at:
With most of the soybean and corn crop emerged and growing across Minnesota - it is a good time to assess fields for seedling disease problems and the potential benefits or failures of seed treatments. The recent fluctuating temperatures and abundant rainfall that resulted in surplus topsoil moisture in about 21% of the state last week (USDA-NASS data) have created good conditions for seedling diseases and root infection by a complex mix of pathogens in many fields. Scattered problems with seedling diseases have been reported.
By Liz Stahl and Jeff CoulterGrowers are finding high populations of volunteer corn in their fields this spring. Factors likely contributing to this include lodging in many fields last fall due to poor stalk quality and drought conditions, and higher harvest losses due to low grain moisture at harvest. Other factors that can lead to high populations of volunteer corn the following year include storm damage and ear droppage. The question arises: When are populations of volunteer corn high enough to warrant control?
University of Minnesota Soil Fertility Specialist
Research on Iron Deficiency Chlorosis (IDC) has been identifying methods to manage the problem for soybeans. Since 2010 research has been conducted using strip trials within farmers' fields. Currently we are looking for a 5 acre area to conduct a field study looking at the effect of Soygreen and oat cover crops on areas of the field that range from no-IDC to severe IDC. Our goal is to determine the economic benefits of the treatments on varying IDC severity within fields planted with two soybean varieties with varying tolerances to IDC.
By Jennifer Obst, Minnesota Agricultural Experiment Station, 612-625-4741
A comprehensive comparison of most crop varieties grown in Minnesota is now available in print and electronic forms. Minnesota Varietal Trials 2012, published by the Minnesota Agricultural Experiment Station, provides the results of the 2011 University of Minnesota evaluation of more than 1000 individual entries of plant varieties.
By Daniel Kaiser
Extension Soil Fertility Specialist
A new nutrient management website has been launched that houses most of the current fertilizer suggestions and data from the University of Minnesota. This website was made possible by funding from the Minnesota Agricultural Fertilizer Research and Education Council and was put together through a joint effort for several researchers from the University of Minnesota who's research focuses on nutrient management issues for several crops growth throughout the state of Minnesota. We would like to thank the AFREC program because without them this effort would not have been possible
Soybean Yield Loss Estimates from Early Frost
Seth Naeve - Extension Soybean Agronomist
Few resources are available to producers and agricultural professionals relative to yield losses from late- season frost injury to soybean plants. A study investigating the risks and benefits of long-season soybean varieties was established in 2008. This work was carried out by the Naeve Soybean Production Project, and was funded by the Minnesota Soybean Research & Promotion Council. While we don't have all of the answers that folks search for after a late-season frost, a small piece of this research effort is described below.
In 2009, 2010, and 2011 soybean plots were established to investigate the yield effects of early frost on a range of soybean maturities. Three varieties with maturities of RM 0.8, 2.0, and 2.8 were examined in 2009. These were planted at a normal seeding date (around May 1) and at a late planting date (around May 21). Frost was simulated with applications of Liberty herbicide at a rate of 32oz per acre in 10 gallons of water on September 7 (early) or September 21 (late). In 2010 and 2011, five varieties ranging from MG 0.8 to 2.8 were planted at a single planting date (early May) and treated to simulate frost on three dates (approximately September 7, 14, and 21).
By Seth Naeve and Dave Nicolai University of Minnesota Extension
A hard frost occurred early Thursday morning (Sept 15th) across much of central and southern Minnesota. The complete effects of this frost or freeze event may not be known for some time. However, most soybean and corn fields have not reached physiological maturity. Yield and quality in these fields were likely affected.
written by Dr. Jeff Stachler, Weed Scientist, UMN and NDSU
Scouting fields for weeds throughout the growing season is extremely important to maintaining herbicide effectiveness and planning for future weed control decisions. Scout fields now and at harvest to determine the effectiveness of this season's weed control practices. If weeds are present now, determine why they are present. If weeds are present due to herbicide resistance, then weed control and cropping practices must be different next season and beyond.
By Dean Malvick
Questions about which soybean diseases will be problems this year in Minnesota come up often. Although there are no good predictive systems, the wet weather conditions this summer are favorable for sudden death syndrome (SDS) and Phytophthora root and stem rot. Phytophthora rot occurs across MN. SDS occurs most often in southern MN, but appears to be spreading north each year.
update prepared by Dr. Ian MacRae, UMN Extension Entomologist, NWROC-Crookston
Many field projects are underway and we're scouting small grain and soybean fields to stay on top of what is happening with aphid populations in these crops. Following are comments based on what our field visits are revealing in northwest Minnesota.
3:30 PM to 5:30 PM
Dinner provided at 6:00 PM
Whom should attend? Sugarbeet and Soybean Growers, Consultants, Agronomists, Retailers, and Others
What is the tour about? Viewing plots for Managing glyphosate-resistant waterhemp throughout the crop rotation, especially sugarbeet and soybean.
By Doug Holen and Phil Glogoza, University of Minnesota Crop Extension Educators.
Producers have been pushed to accomplish as much planting possible in the little time given as calendar dates roll by in a late spring start. The goal has been to get the seed in the ground when fields are ready for equipment and between rain events. It has been common across the state in previous years for producers to ground roll fields within hours of planting soybeans. However, the push to plant between rain events and other delays this year has left many fields unrolled. The question is, "Can I still roll without causing significant damage to the plants or stand?"
By Dave Nicolai and Seth Naeve
Originally published in Ag News Wire
With only 28 percent of corn acres planted prior to May 9 in Minnesota, growers face the difficult decision of when to begin planting soybeans in order to maintain adequate yields.
Soil conditions are of primary importance when considering delayed planting.
Soil conditions and soil temperature
Soil conditions at and after planting usually make a difference in how successfully the crop is established. Soil compaction and smearing is a concern when pulling implements and the planter through, or driving on, wet soil.
To limit soil compaction, keep axle loads under 10 tons and properly maintain air pressure in the tires. Not only does this help the soil, but it will help your tractor run more efficiently and with less slippage. On wet soils, use the lightest tractor that can get the job done.
Soybean has delicate seed, so it benefits when planted about 1 1/2 inches deep, modestly firmed into the seed furrow, covered by relatively loose soil, and into soils with temperatures of 60 to 70 degrees. As of May 9 , soil temperatures at the 2-inch depth averaged 61 and 56 degrees, respectively, at University of Minnesota Research and Outreach centers in Lamberton and Waseca.
The lack of oxygen in saturated soils and the formation of a soil crust of even modest strength can almost eliminate soybean emergence. Therefore, it is important to pay attention to the five-day forecast prior to planting. Planting in cool and wet conditions may lead to poor germination and seedling diseases such as pythium. These problems are magnified by extended cold and rainy periods after planting.
University of Minnesota Extension research indicates that, under ideal conditions, soybeans in southern Minnesota should be planted at about 140,000 live seeds per acre (see Table 1). Soybeans grown in central and northwestern Minnesota require harvest stands of approximately 125,000 to 150,000 plants per acre to maximize yields. This is likely due to shorter-statured soybeans with fewer total nodes that are often produced in these regions. Increased seeding rates are required in central and northwestern Minnesota.
|Maturity group II soybeans||140,000 live seeds per acre|
|Maturity group I soybeans||150,000 live seeds per acre|
|Maturity group 0 soybeans||160,000 live seeds per acre|
|Maturity group 00 soybeans||170,000 live seeds per acre|
Planting date and soybean yield
Since early-May plantings usually result in maximum yields, lower yields should be expected for later plantings (see Table 2). Planting soybeans in Minnesota on May 10 results in only a 2-percent yield loss; on May 15 in a 3-percent yield loss, and on May 20 in a 6-percent yield loss (or 94 percent of normal yield).
|Planting date||Yield loss (%)||Yield potential (%)|
For more educational information and tools, visit www.soybeans.umn.edu, a cooperative effort among the University of Minnesota, University of Minnesota Extension, and the Minnesota Soybean Research and Promotion Council. More information about delayed crop planting can be found at www.extension.umn.edu/agriculture/crops/late-planting.
Waterhemp is an annual weed species in the pigweed family that is capable of producing greater than 1 million seeds per plant and due to a limited number of effective herbicides, especially in sugarbeet and soybean, is difficult to control compared to most weed species. In addition to the production of large quantities of seeds, continual germination throughout the growing season and an increased frequency of herbicide-resistant biotypes adds to the degree of difficulty in keeping this weed species under control. The good news is that the longevity of waterhemp seeds in the seedbank is relatively short compared to most species (1 to 12% survival after 4 years), meaning complete control (zero seed production) of all plants over a three to four year time period should significantly reduce the waterhemp seed bank densities, allowing the farmer to take control of this difficult weed problem.
An early corn and soybean harvest and good weather conditions are keeping the window of opportunity open for fall dandelion control this year. Fall is an excellent time to target several herbaceous perennials including: alfalfa, Canada thistle and dandelion. A fall application is more effective than a spring application because systemic herbicides such as glyphosate, 2,4-D, Express, Basis and Synchrony tend to accumulate in greater amounts in a perennial plant's roots or rhizomes after a fall application. Movement to the below ground roots and rhizome buds increases herbicide effectiveness and possibly decreases winter hardiness of the plant.
Extension Soil Fertility Specialist
With the recent flooding or late season hail there may be questions on whether a credit can be taken from soybeans not harvested for the next year's crop. Soybeans are a high protein crop which means they can contain a large amount of nitrogen. Average vaules of nitrogen removed in soybean grain are reported at around 3.8 lbs of N per bushel (Source IPNI) for a total of 190 lbs of N in a 50 bu/ac soybean crop. In comparison corn grain would remove about 0.90 lbs of N per bushel and a total of 180 lbs of N in a 200 bu/ac crop. Can all of this nitrogen be counted on if the soybeans cannot be harvested and are plowed under if they cannot be harvested?
Heavy rain fell across much southern Minnesota on September 22nd
and 23rd and left large areas of Minnesota corn and soybean fields
submerged. Flood waters covered, perhaps
100,000 acres for several hours as rain water moved from fields into creeks and
rivers. Longer term flooding of fields
affected tens of thousands of acres of cropland. In most instances, drainage tile, where
present, were unable to prevent ponded waters.
In other cases, streams swollen by
4 -12 inches of rain falling on fields, roads and cities came out of
their banks and flooded fields.
Dean Malvick, Department of Plant Pathology, St. Paul
The soybean crop is growing well across most of Minnesota. As of July 25, 80% of the state's ~7.4 million acres of soybeans was flowering and 25% was setting pods. Most of the soybean crop in Minnesota was rated in good (58%) or excellent (27%) condition. With the frequent rains this season, however, disease problems are appearing in some fields and others may be brewing. The leaf diseases downy mildew, bacterial blight, and Septoria brown spot are common now in Minnesota, but fortunately none of these diseases typically cause significant yield reductions. Many areas in Minnesota have also had favorable conditions for development of Phytophthora root and stem rot, stem canker, white mold, and sudden death syndrome.
You are invited to a field day located along highway 71 between Olivia and Blomkest on the southeast corner of the intersection of U.S. Highway 71 and Kandyohi/Renville county line road. Discussions will focus on recent research on iron deficiency chlorosis and a tour of the research plot at this location. Registration for the event will begin at 9 am with speakers starting at 9:30.
Authors: Dimitre Mollov and Jennifer Flynn
When crops or plants are not growing well and look diseased or less vigorous than healthy plants, an accurate diagnosis of the problem may be critical to reducing and managing it. The Plant Disease Clinic at the University of Minnesota in St. Paul is open year-round to diagnose crop and plant problems and to assist with other plant testing questions. The Plant Disease Clinic welcomes samples from anyone and offers a wide variety of diagnostic and testing services.
After the recent stretch of rainy weather we are currently in a period of excellent conditions for finalizing postemergence weed control in soybean. As crop stages progress, postemergence soybean herbicide options decrease due to growth stage or days before harvest restrictions.
By Lizabeth Stahl and Bill Wilcke
Extension Educator - Crops and Extension Agricultural Engineer
Soybean moisture levels of 16 to 20% or more at harvest have been reported throughout the state as this challenging harvest season continues. If storage temperatures are below about 60F, soybeans at 13% moisture can usually be kept for about 6 months without having mold problems. At a higher moisture content, how long can soybeans be stored before mold becomes a concern?
By Dean Malvick, Department of Plant Pathology
Cool weather and low rainfall have held the soybean crop back in parts of Minnesota this summer. Now, significant diseases are a concern in some areas. Several diseases have started to appear recently that can significantly damage soybeans, especially sudden death syndrome (SDS), brown stem rot (BSR), and white mold. These diseases are favored by weather conditions that have occurred in large areas of Minnesota this season. The information we gather now can help to explain why yield may be low in some fields and can assist with targeting disease management where these diseases occur most often. There are no effective fungicide or other treatments that can be used this season to reduce damage from these diseases.
SDS has been reported at significant levels in Dodge, McLeod, and Waseca counties, and it is undoubtedly also appearing in other areas in Minnesota. Based on results from previous years, SDS probably occurs across much of the southern half of Minnesota, but it could occur anywhere in the state. Foliar symptoms of SDS have been developing for at least the past two weeks. The last two weeks of August and the first week of September is a good time to scout for SDS. Look for this disease first in low or compacted areas of fields and near field entry points. Initial symptoms are yellow areas on leaves, and these yellow areas turn into brown patches. Reports have indicated different levels of disease severity among some varieties. This would be a good time to look for different factors that could affect SDS severity, including soybean variety, tillage, drainage, crop rotation, and planting date. The map of the confirmed distribution for SDS in Minnesota, as well as more information and photos for SDS and other soybean diseases, can be found at the Minnesota Crop Diseases web site (www.extension.umn.edu/cropdiseases/soybean/index.html).
Foliar and stem symptoms of BSR are also starting to appear. BSR occurs in fields throughout Minnesota, including all areas where SDS occurs. When scouting fields or attempting to diagnose whether plants are infected with SDS or BSR, keep in mind that the foliar symptoms can look very similar for these two diseases. The key for BSR is to split the bottom 6" of the soybean stems and look for brown pith, especially at the nodes. Plants with BSR will have brown pith, but plants with SDS will have white pith. Keep in mind that plants with BSR always develops brown pith, but foliar symptoms (brown tissue between veins) do not always develop. The only way to know how much BSR is in a field is to split stems, and internal BSR stem infections alone can cause yield loss. BSR tends to be more severe when temperatures are cool (60- 80°F) during reproductive growth stages. When leaf symptoms develop, they can be most severe when soil has been wet at early flowering to pod fill growth stages and dry during maturation. The conditions in large areas of Minnesota appear to have been favorable for BSR this season.
White mold may also be significant in some parts of Minnesota based on growing conditions this year. We have had reports of white mold damaging and killing in several areas of Minnesota. This disease is favored by cool temperatures and rainfall from mid- July through August. All of Minnesota has had cool conditions, and the areas that received enough rain to maintain wet soil for short periods in July and early August are set to develop white mold. Look for scattered and patches of dead and dying plants, and the presence of white moldy growth and sclerotia (black to gray round to oblong structures up to 1/4") on and inside the stems. As with the other diseases, look to see if you can associate the more severe areas with factors that may affect white mold such as soybean variety, manure or fertility history, tillage, row spacing, or high plant population.
Finally, downy mildew is common in a number of areas. Although this soybean leaf disease rarely if ever reaches levels that damages yields in Minnesota, it can be fairly easy to see. Downy mildew typically only infects leaves at this time of the season, although later it can infect pods. Symptoms of downy mildew on the tops of leaves are irregular yellow to brown spots, and the bottom of the leaves under the spots have tan to gray tufts of fungal growth that can be seen easily with a hand-lens.
Meet at and depart from Plummer Co-op Creamery
(Cenex Station) 1 pm
Thursday, September 10 ----- Hawley, MN
Meet at and depart from RDO Equipment 9:30 am
Is glyphosate less effective than 10 years ago?
Can you recognize the presence of glyphosate-resistant weeds in a field?
by Phillip Glogoza, Extension Educator, Crops
Management decisions on whether to treat soybean aphids will be affected by the soybean growth stage in a field during the next two weeks. As plants progress to the later reproductive stages (e.g., R5, R6, R7, etc.) risk of yield loss from aphids declines. Currently, the soybean crop ranges from R3 to R5. Insecticide treatments for R5 stage soybeans may respond positively to soybean aphid treatments when populations exceed threshold, however the level of the yield response is less predictable. Early R5 treatments are more likely to realize a positive response than late R5 treatments. Treatments for aphids are generally not recommended beyond the R6 growth stage.
By Ken Ostlie and Bruce Potter
Reports of spider mite infestations continue from both soybean and corn, particularly from areas with prolonged drought. Even if you've received rain recently, check for mite activity along field edges to determine if you've got a building problem. You may need to factor spider mites into a soybean aphid spray decision.
The article is available on the web at: http://www.extension.umn.edu/agriculture/soybean/pest/managing-two-spotted-spider-mites-on-soybeans/.
Well so much for the relatively arthropod pest- free growing season.
by Dr. Ian MacRae, U of MN Extension Entomologist
There has been increasing pressure to apply insecticide and tank mixed pesticides at lower thresholds based on claims of increased yield benefits. While increased commodity prices can stimulate the desire to decrease risk tolerance and increase the use of pesticides, this is not always a paying proposition.
by Dr. Ian MacRae, U of MN Extension Entomologist
.... Low populations of Soybean Aphid (SBA) have been reported throughout NW MN and NE ND. Populations are still low and generally not on more than 30% of the plants. The cooler weather will slow reproduction for a few days but it is predicted to warm up by the weekend, at which time we'll start to see some more population growth and dispersal across fields. Although most fields are well below treatment levels so far, it is time to start scouting the soybean fields, getting a handle on what populations you may have and tracking progress and population growth.
by Dr. Charla Hollingsworth, U of MN Extension Plant Pathologist
In 1954, the first detection of the soybean cyst nematode (SCN) occurred in North Carolina. Since that time, the nematode has become the most important disease issue of soybean in the world. Spread with soil, this microscopic roundworm continues to gain ground in Minnesota soybean-producing areas. Essentially anything that can move small particles of soil will also transport this nematode.
by Phillip Glogoza, Extension Educator - Crops
Soybean rust was found in 392 counties in the United States in 2008. This is the highest number of counties reporting the disease since it was first discovered in the continental U.S. in 2004. Soybean growers in Alabama were encouraged to use fungicides on at risk beans in late August, many neighboring states reported mostly low infection levels throughout the month of September as the crop matured.
Glyphosate-resistant biotypes of giant and common ragweed and common waterhemp have been confirmed in Minnesota and are listed on the International Survey of Resistant Weeds web site at: http://www.weedscience.org/in.asp Both species appear to be resistant to approximately four-times the labeled use rate of glyphosate (4X).
In the short time frame presented to us during the growing season, separating glyphosate nonperformance due to resistant weed biotypes from other factors is an inexact and qualitative process but a quick response could help reduce the spread of glyphosate resistant weeds and set-up long-term management plans.
We are into the fourth year of a soybean date planting trial at Crookston investigating how two different relative maturity soybean varieties respond to planting date. Results for 2006 - 2008 show maximum soybean yield when planting in the May 1 - 15th window of opportunity. Previous planting date trials from the University of Minnesota also show an optimum planting window of May 10 - 20 to achieve maximum yield (Table 1).
Large populations of volunteer corn are being reported in some fields in Minnesota this year. What impact the volunteer corn will have on this year’s crop yield and the viable management options available will depend upon in which crop the volunteer corn is present. Making the assumptions that the majority of the volunteer corn present is glyphosate resistant and that glyphosate resistant crops were planted in the field this year, your only management option in corn at this time is cultivation. In soybean you have the herbicide options of the ACCase inhibiting herbicides such as: Select Max (clethodim), Fusilade DX (fluazifop-P), Fusion (fluazifop-P & fenoxaprop) and Assure II (quizalofop); note Poast Plus (sethoxydim) is not as active as the other herbicides on volunteer corn. The ACCase inhibiting herbicides are generally targeted on 12- to 24-inch tall volunteer corn. The ALS herbicide, Raptor can also effectively control smaller (2 to 8 inch) volunteer corn.
Regional Extension Educator-Crops
Soggy fields and submerged crops can be found in areas throughout the state due to recent rainfall events. What effect will these late-season wet conditions and even flooding have on corn and soybeans as we wait for field conditions to improve and harvest to resume?
Wet soil conditions this spring, pressure from corn rootworm and European corn borer, and plants attempting to a fill large number of kernels per ear have set some fields up for potential stalk rot problems. Although some of the fungi causing stalk rots are a player in the natural process of recycling nutrients and organic matter back into the soil, decay of stalk pith prior to harvest can increase lodging potential. Harvest delays increase the chance of lodging due to stalk rots and lodged plants decrease harvestability, leading to ears being left in the field.
To check for stalk rot, stalks can be split (check for stalk tissue disintegration) or squeezed between your fingers (check if stalks are easily crushed) or pushed from vertical (severely stalk rotted plants will kink or lodge). Fields with stalk quality issues should be targeted for harvest as soon as is feasible because of increased lodging potential. Fields with heavy infestations of European corn borer should also be targeted for harvest as soon as is feasible.
Corn grain quality can also be a concern when wet conditions delay harvest. Be on the lookout for ear rots and if grain becomes molded, be sure to test for mycotoxins prior to feeding to livestock.
In soybean fields where pods were submerged by standing water for a significant time period, seed quality is a concern. Wet conditions combined with warm temperatures increase the risk of damage from fungal pathogens. If areas were submerged for several days, stems may weaken or rot, increasing the chance of lodging and harvest losses. Prior hail damage or previous stem diseases may predispose plants to further injury. Pod shatter prior to harvest is also of concern, especially if soybeans go through several cycles of drying and re-wetting.
If soybeans were submerged in areas of the field, consider segregating these potentially lower quality soybeans. Segregation may be particularly beneficial if soybeans were intended to be sold to a specialty market where premiums are based on soybean quality.
Delayed harvest will also influence the ability to conduct fall tillage operations and fertilizer applications. The main focus is, of course, to get crops out of the field. As field conditions improve and harvest resumes, keep an eye on crop status when deciding which fields to harvest next to help maximize crop quality and yield.
S. L. Naeve and D.R. Hicks
Agronomy and Plant Genetics
University of Minnesota
A major portion (about 90 percent) of the Minnesota corn acres are planted but only ten percent has emerged. For soybeans, only 28 percent of the acres are planted and only a very few (1%) have emerged. Cold seed zones do not promote germination and emergence.
Paul Peterson, Jim Linn, and Dale Hicks
University of Minnesota Extension Service
Frost touched much of the state's corn and soybean acreage this past weekend. The degree to which the frost was a killing frost varies considerably, but a complete killing frost appears to have been the exception, not the rule. Where frost injury occurred without complete kill, it is too early to consider forage harvest because additional yield and forage quality accumulation is likely from surviving plant parts. However, where these crops were/are completely killed by frost before reaching optimum grain or even forage harvest maturity, harvesting as forage is a viable option. In addition, based on the delayed maturation of corn and soybeans to date, chances are good that there will many acres of these crops that will receive a killing frost before reaching maturity, so harvest as forage may still be one of the better options as the growing season plays out.
Dale R. Hicks
Department of Agronomy and Plant Genetics, University of Minnesota
The growing season continues to be abnormally cold and now the cool temperatures of August 21 have caused frost injury to crops in Minnesota. This report gives an assessment of what I think is the situation.
Minnesota Extension Engineer
Because of wet conditions during harvest last fall, a number of farmers currently have shelled corn or soybeans in their bins that are too wet for safe storage into spring and summer. What moisture levels are safe for storage? Crop storability is a function of both temperature and moisture. The colder the storage temperature, the higher a crop's moisture can be before molds and insects cause quality loss. During winter, if stored crops are cooled to less than 30F, they can be held at fairly high moisture levels with minimal risk of storage. During spring and summer, we lose the ability to keep crops below 30F (unless we choose to spend money on refrigeration) and we need to reduce moisture content to avoid spoilage. Corn should be dried to 14 to 15% moisture for storage into spring, 14% for storage into summer, and 13% for longer-term storage. Soybeans should be 12 to 13% moisture for storage into spring, 12% for storage into summer, and 11% for longer-term storage.
If stored corn or soybeans are wetter than the values just listed, and the storage bin is only equipped with a duct-type aeration system and a small fan that delivers less than 0.5 cfm/bu (cubic feet of air per minute per bushel of grain in the bin), the crop will probably mold this spring or summer. Crops should be sold, fed, or moved out of the bin and dried to a safe moisture level before the weather gets too warm.
Using gas-fired dryers in late winter or early spring is an option for both corn and soybeans. After drying, the crop should be cooled to less than 50F for summer storage, so make sure drying is completed before average outdoor temperatures get above 50F. Expect energy costs for gas fired drying to be about $0.01 to $0.02 per bushel per percent point of moisture removed and total drying costs (energy plus labor, depreciation, repairs, etc.) to be $0.02 to 0.04 per bushel per point. Labor, equipment, and transportation costs for moving crops to the dryer and back to storage will add a few more cents per bushel. Soybeans can be dried in gas-fired dryers, but the seeds will split if dried too fast or at too high a temperature, so a much lower drying temperature should be used for soybeans than for corn. If any of the soybeans will be used for seed, drying temperature should be kept under about 110F to avoid killing the seed embryo.
If a bin is available that has a full perforated drying floor and a drying fan that can deliver about 1 cfm/bu, natural-air drying can be another option for slightly wet beans and corn. The University of Minnesota Extension Service bulletin, Natural-Air Corn Drying in the Upper Midwest, BU-6577, gives a good overview of natural-air drying and provides suggestions for spring drying. Spring drying must be started early because if a person waits too long, the weather will get too warm and the crop at the top of the bin will mold before it dries and the crop at the bottom of the bin will get drier than it needs to be. The wetter the crop is, the earlier you need to start. For corn wetter than 19% moisture, start watching the weather in mid-March, and as soon as it stops snowing and average outdoor temperatures stay above freezing, turn on the drying fan and let it run until the drying front moves through the top of the bin. For 17 to 19% moisture corn, start drying around April 1, and for 15 to 17% corn, start drying around April 15.
For natural-air drying of soybeans, use the same dates listed in the previous paragraph for corn, but reduce moisture values by about 2 percentage points. In other words, for soybeans wetter than 17%, start drying in mid-March. For soybeans that are 14 to 15% moisture, it might make sense to control the fan - either manually or by using a humidistat, so that the fan only runs when the relative humidity is less than about 70%.
For more information on soybean drying, see the drying, handling, and storage chapter in the University of Minnesota Extension Service Minnesota Soybean Field Book, MI-7290.
Extension Plant Pathologist
The "Dreaded" Root Rots Of Soybeans
Finally, much of Minnesota is experiencing more than one warm, sunny day in a row. The soybeans, and other crops, were stuck in a slow growth mode for the last month due to the rainy, overcast conditions. But now the crops should start developing more rapidly. Fortunately, Pythium root rot is no longer a concern since it likes cool wet soils and preys on newly germinated soybean seeds and small seedling. However, Fusarium, Phytophthora, and Rhizoctonia root rots are still a threat to soybeans. The warm conditions contributing to the rapid growth of soybeans may actually result in more noticeable root rot symptoms. Now would be a good time to dig seedling in wet, poorly drained areas of fields to look for root lesions caused by the fungal pathogens. Lesions on roots that appear red, reddish brown, or brown are most likely caused by Fusarium or Phytophthora (see Figure 1). Reddish brown lesions that occur on the stem near the ground level are probably caused by Rhizoctonia (see Figure 2). Watch stands in those areas for stand loss. There is not much you can do this year about the diseases. It is probably too late to benefit from a replant if stand loss has occurred. It would be worth while to identify what root rot diseases predominate in your fields and plan for managing them in the future.