Soybean Pest Management
November 7 & 8, 2002
St. Louis, Missouri
USDA North Central Region Pest Management Center
United Soybean Board
Missouri Department of Agriculture
Agricultural Information Research Service, Inc.
Iowa State University
Authors and Contributors
I. Lead Editor:
Dr. George S. Smith
Missouri Department of Agriculture
II. Associate Editor
Dr. David Pike
III. Layout and Content
Ms. Lynnae Jess
Dr. Michael Schmidt
Plant, Soil and General Agriculture
Southern Illinois University
Carbondale, IL 62901
Dr. Terry Niblack
Dept. of Crop Sciences
University of Illinois
Urbana, Illinois 61801
Dr. Craig R. Grau
University of Wisconsin
482 Russell Laboratories
Dr. Anne E. Dorrance
The Ohio State University
Dr. Glen L. Hartman,
USDA/ARS, University of Illinois, Urbana
Dr. Reid Frederick,
Fort Detrick, Maryland
Table of Contents
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Soybean Pest Management:
Priority Issues for Research, Regulatory and Education . . . . . . . . . . . 4
Key Soybean Pest Management Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Soybean Production in the Midwest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Soybean Diseases: Executive Summaries . . . . . . . . . . . . . . . . . . . . . . . . 12
A. Soybean Cyst Nematode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
B. Phytophthora Root Rot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
C. Sclerotinia Stem Rot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
D. Sudden Death Syndrome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
E. Soybean Rust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Soybean Diseases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Soybean Insects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Weeds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Organic Soybean Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Tables 1 & 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Attendees . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
I. Executive Summary
The purpose of a Pest Management Strategic Plan (PMSP) is to communicate, from an
industry perspective, the role of pesticides and pest management strategies in crop production.
To obtain broad-based industry input, PMSPs are developed for a commodity through the use of
workshops which bring together producers, crop consultants, commodity groups and pest
management specialists from across the production region. Although PMSPs were originally
intended for use by the Environmental Protection Agency (EPA), they have also proved valuable
to the United States Department of Agriculture (USDA), Land Grant Universities, and pest
management stakeholders at all levels.
This PMSP was prepared at a workshop held on the 7th and 8th of November, 2002, in St
Louis. Thirty two participants, representing diverse aspects of soybean pest management and
production regions, attended the meeting. Though it is not all-inclusive, this document is meant
to be generally representative of pest management challenges faced by soybean producers in the
North Central Region. In addition to providing input on pests and pest control methodologies,
workshop attendees identified research, education and regulatory issues that impact producer
profitability and environmental quality. As part of their final task at the meeting attendees
prioritized the issues that they thought were the most critical to soybean pest management in the
As mentioned, the original intent of this report was to provide the EPA with the pest
management perspectives of soybean producers, consultants, and other pest management
specialists. As such, it primarily reflects the comments and inputs of those parties who attended
the workshop. As with any group of individuals, the scope of knowledge as well as opinions of
participants vary greatly, and in its current form this document captures that scope and diversity.
The editors and reviewers of this document have taken significant measures to excise faulty
or misleading information, but it has not been our intent to remove or alter information which
was provided at the workshops that does not harmonize with “conventional wisdom”. This
Strategic Plan should be viewed as a work in progress; future versions will undoubtably result in
an improved product.
Throughout the text of this document an effort has been made to identify regional differences
in pests, their treatment, and the research, educational, or regulatory issues producers in those
regions would like to see addressed. The “toolbox” approach we have used has focused on crop
protection products and crop production tactics that are important for the economic management
of key pests of soybean in the 12 north central states. For many pests, there were significant
variations throughout the region regarding which pests were considered “risk drivers” for
pesticide use or for grower implementation of other “non-pesticide” practices.
Soybean diseases are a major threat to profitable soybean production in the Midwest and
ongoing “non-pesticide” pest suppression research was credited with mitigating economic losses.
The continued need for breeding programs for host resistance to diseases and nematodes was a
theme that pervaded the discussions of all other control tactics. In addition, the following issues
were perceived as important disease issues for soybean production.
Although there is little use of foliar fungicides for disease control in the North Central
region, all participants were aware of the high risk posed by soybean rust; especially if the
more virulent specie were to become established in the United States. Producers and
consultants expressed concern about the need to rapidly respond to this disease with accurate
information on products, timing, price and pre-harvest intervals (PHI).
Many products being tested for soybean rust were from the triazole family of fungicides.
This triggered concern because the long PHIs associated with these fungicides in wheat may
also indicate an excessively long PHI for soybean.
The search and screening for, and deployment of novel resistance genes for management of
soybean cyst nematode, sudden death syndrome, Phytophthora root and stem rot, white mold,
and soybean rust were a high priority item for producers.
Nematicides were generally not deemed to be critical tools for the soybean production in the
North Central states, but their continued registration in the southern soybean belt was noted.
Although fungicides were not being used to a significant extent for white mold control, (an
economic disease primarily in the states of Wisconsin, Minnesota and Michigan), many
participants viewed the fungicide Topsin M as a key tool and expressed the need for more
research into application timing and an educational focus on predictive models for disease
Seed treatment fungicides were viewed as essential complements to host resistance/tolerance
for management of Phytophthora.
Three soybean insects, bean leaf beetle, soybean aphid, and spider mites, were considered the
key drivers of insecticide use in the North Central region while three essential insecticides were
identified in the soybean pest management “toolbox”.
Firs t, spider mites tend to be a problem pest somewhere in the North Central states on an
annual basis and a key pest across most of the region once every eight to 10 years. The
insecticide considered essential for spider mite control is the organophosphate insecticide
dimethoate. The organophosphate insecticide chlorpyrifos is the second choice of
producers in years of heavy spider mite outbreaks when inventories of dimethoate are
exhausted. These two products were considered absolutely essential for economic control of
Second, for control of soybean aphid and bean leaf beetle the pyrethroid insecticide,
permethrin, is an essential product. Permethrin is the choice for producers because of
availability, low use rates, and price. Soybean aphid is a new threat to soybean production
and its equilibrium with the soybean agroecosystem has not been established, but in some
areas 30-50% of fields have been sprayed.
Within some states or areas other insects are treated on an infrequent but recurring basis.
S Continued carbofuran registration was considered critical to manage economic
grasshopper infestations in the western soybean belt.
S Japanese beetles, an economic problem in much of Michigan, Illinois, Indiana, Ohio, and
eastern and central Iowa, are managed with the same suite of insecticides that are
effective against bean leaf beetle.
S Soybean stem borer is becoming problematic in Kansas, western Missouri, southern
Nebraska, northern Oklahoma, and South Dakota. This pest was a priority for soybean
research into the most effective control methods.
Herbicides are the dominate type of pesticides used on soybean. Economic infestations of
weeds are ubiquitous throughout the North Central region. Principal risk drivers across the
region that dictate the herbicide program used by producers include foxtails, waterhemp,
shattercane, kochia, velvetleaf and lambsquarters. State-specific risk drivers include Palmer
amaranth in Kansas, common and giant ragweed in Ohio, and eastern black nightshade in North
Dakota, and Johnsongrass south of the Missouri River. Producers listed the following issues as
Glyphosate is now the dominant herbicide applied to soybean in the North Central region.
S Concern was expressed that because of the overwhelming popularity of Round Up Ready
soybean, (70% to 80% of the soybean acreage), that a lack of competitiveness in the
market may be having a deleterious effect on breeding programs for non-GMO varieties,
non-GMO seed availability, and the development of new soybean herbicides.
S There was considerable concern about the potential development of resistance to
glyphosate. Some anxiety was expressed that many producers may not be aware of the
risks and costs involved with resistant weeds that could result from regular use of
glyphosate products if they fail to take precautions.
Two herbicides that are not applied directly to soybean were deemed critical for effective
and economical weed management in soybean; 2,4-D and atrazine.
S 2,4-D was viewed as an essential tool for early season burndown of winter annuals,
perennial weeds, and broadleaf weeds.
S Atrazine’s efficacy in controlling many of the key broadleaf and grass weeds in corn
greatly mitigates weed pressure when fields are rotated to soybean and complements
resistance management programs.
Winter annual weeds and perennial weeds are viewed as becoming more problematic in
soybean due to increased no-till practices and the trend away from residual herbicides or the
use of lower rates of residual herbicides in corn the preceding year. Producers indicated that
research into efficacious management of winter annuals was needed.
II. Soybean Pest Management: Priority Issues for Research, Regulatory and
1. All Pests
University researchers, non-governmental organizations, consultants and producers are
encouraged to work together closely with on-farm research and demonstrations.
Producers recommended that a coalition between land grants, consultants, suppliers,
dealers and registrants be developed to promote effective resistance management and
pest management systems.
2. Diseases and Nematodes
A. Soybean Cyst Nematode Research and Education:
Producers indicated that development of alternative sources of resistance should be
pursued, especially Chinese germplasm.
Resistant varieties are expected to lose their resistance so there is a need to keep currently
registered products for control. However, in the North Central region, nematicides are
not generally viewed as an essential pest management tool for SCN.
In the southern soybean belt, there is a strong need to keep nematicides registered due to
the wider diversity of nematode populations.
There is a need to continue support for, and refinement of screening methods to
determine SCN resistance in soybean varieties.
There is the perception that up to 20% of ‘resistant varieties’ are really susceptible -
researchers should seek to establish methods by which farmers may know if a
“resistant” variety is really resistant.
There is a need for new, quicker methods of identifying diversity in nematode
populations to preempt future problems. The new “race”scheme is viewed positively but
producers and seedsmen need information on its proper use and interpretation for making
SCN management decisions.
Need to transfer research information to producers effectively, such as improving
producer awareness of problems, different susceptibility of varieties, etc, as farmers
currently depend on seed companies for this information.
B. Sclerotinia Research:
Researchers should develop a predictive model to alert producers when to control (with
Topsin M) sclerotinia. This is especially needed with irrigated soybeans.
Coniothyrium minitans is an example of a promising biological control agent that is a
potential alternative for control of S. sclerotiorum. Further research on this agent would
Researchers need to investigate and develop more tools for control of resistance, i.e. how
plant structure (large leaf vs. narrow leaf) affects severity.
Some current research is investigating mapping one or more genes that confer
physiological resistance to S. sclerotiorum. Application of a biotech approach to control
of sclerotinia would be very helpful.
Research is needed to investigate the efficacy of new dry bean and sunflower fungicides
to see if they can be used on soybeans (other diseases such as downy mildew).
C. Sudden Death Syndrome Research:
Researchers should evaluate soybean varieties for resistance to SDS.
Researcher should find ways to develop reliable assays to identify resistance to SDS.
Researchers are encouraged to incorporate SDS resistance genes in soybean genome.
D. White Mold Research:
Accelerate research on resistant varieties and determine how plant architecture is related
to resistance or disease severity.
Researchers are encouraged to develop predictive models to time white mold treatments
(Topsin-M) more effectively.
Researchers need to evaluate the efficacy of fungicides now being used on dry beans and
sunflowers to see if they can be used on soybeans (other diseases such as downy
Producers indicated that research on the impact of irrigation on white mold is important.
Coniothyrium minitans is an example of a promising biological control agent that is a
potential alternative for control of S. sclerotiorum. Further research on this agent would
be helpful. This is an area for biotech approaches. Some current research is investigating
mapping one or more genes that confer physiologic resistance to S. sclerotiorum.
E. Phytophthora Root Rot Research:
Researchers should continue to explore new products, especially seed treatments for
Phytophthora. Seed treatments (metalaxyl and mefenoxam) are utilized in regions where
P. sojae is an annual problem.
IR-4 should investigate new seed treatments for control of water molds.
F. Soybean Rust Regulatory and Education:
It is important to educate farmers on early identification of soybean rust. The fungus is
airborne, and has a life cycle of 4-9 days in South America, and there are four different
strains. Two biotypes can cause 20-40% losses and two may cause 40-80% losses.
Researchers and regulatory agencies are encouraged to label existing compounds for rust
A. Bean Leaf Beetle Research and Regulatory:
Increasing the REI for pyrethroids could be a hardship for producers with workers in the
field, irrigation workers, and with researchers in plots. Producers recommend
maintaining a 24hr REI.
Some organophosphates are needed so that insecticide classes can be rotated to forestall
resistance, (and also for control of potential outbreaks e.g. spider mites). In addition,
supplies of individual products may run out during a pest outbreak, so other products are
needed to fill in.
Researchers should investigate bean leaf beetles as a vector of bean pod mottle virus and
determine the dynamics of the spread of bean pod mottle.
B. Soybean Aphid Research:
Researchers are encouraged to develop solid information about economic thresholds.
Research is needed to determine appropriate rates of currently available products.
Research is needed to determine optimal treatment timing and effect on beneficial
C. Western Corn Rootworm Research:
A better understanding of the biology of the western variant is necessary to provide
rationale for control of the Western corn rootworm in corn-soybean rotations.
More information is requested on whether WCRW adults are carriers of Bean Pod Mottle
Virus and other soybean virus diseases.
A. Winter Annual Weeds Research:
Research on life cycles is needed so that producers know when and how best to control
winter annual weeds, especially henbit, chickweed, marestail (horseweed).
It is also important for producers to know what insect or disease pests are harbored or
hosted by winter annuals.
Researchers should evaluate winter annual weeds as secondary hosts and attractants for
insects and diseases and determine their potential impact on soybean production.
B. Annual Grasses Research and Education:
Research is needed to determine which grasses will develop tolerance or resistance to
glyphosate. Included in these studies should be an effort to determine how the frequency
of applications affects resistance or shifts in weed populations. It also may be necessary
to seek approval of tank mixes to control these grasses.
Producers indicated a need for more information on the effect of row widths and the
impact of reduced herbicide rates and treatment frequency on weed control.
More information is also needed on the rates of glyphosate and the interaction between
weed size, environmental conditions, and weed control. Product formulation and species
diversity may also be considerations in these studies.
Producers indicated a need to alleviate antagonism in tank mixes that commonly occur
with products such as Select, Fusilade, Assure and Fusion.
Producers also felt that information currently available to researchers, regarding weed
shift study results, needs to be communicated to producers.
Educate producers on rates of glyphosate uses (efficacy of reduced rates) vs weed growth
size vs environmental conditions.
C. Perennial Grasses and Sedges Research and Regulatory:
Research herbicides for control of Johnsongrass in rights-of-way (reduce movement to
Research is needed to determine which herbicides may control horsetail.
Research is needed to evaluate application timing - efficacy of spring vs fall application
of foliar applied herbicides.
Researchers are encouraged to find ways to encourage states to control Johnsongrass
D. Annual Broadleaf Weeds Research and Regulatory:
Producers indicated a need to keep atrazine use in corn prior to soybeans for overall weed
management in rotations.
The use of 2,4-D and the maintenance of its registration as a tool for use ahead of
soybean planting is deemed very important.
Producers indicated a need to have information on the role of temperature, humidity, and
time of day on various post-applied products.
Producers indicated a lack of information on how best to control weeds in wheel tracks.
Improving efficacy while controlling drift (application technology- spray tips and various
spray systems, both ground and air) is an increasing concern.
Producers indicated the need for additional research on spray additives for the most
effective control of post-emergence weeds.
Producers wished to convey to all audiences the need to maintain research on non-GMO
plant breeding and herbicides.
Producers also wished to encourage chemical companies and the EPA to continue
researching and registering new chemistries to provide additional tools for problem weed
management. It is particularly important to have the herbicides necessary where resistant
weeds have developed.
Research is needed on the effect of additives to tank mixes; which ones work well and
how they work.
Research is also important to determine the weed shifts that are due to lack of tillage and
weeds moving into fields from road sides.
E. Perennial Broadleaf Weeds Research:
Producers indicated a need to develop a system approach for control of perennial
broadleaf weeds (to include tillage and conventional pesticide use).
Producers indicated that research is necessary to develop methods of control for trumpet
creeper, Virginia creeper, pokeweed, and mulberry.
F. Herbicide Resistant Weeds Research and Education:
2,4-D is a critical tool to have available to control many herbicide resistant weeds.
Maintaining this registered use is very important to producers.
Producers need to use multiple modes of action to control weeds. This is especially true
with Round Up Ready soybeans. An educational effort to assist producers in more easily
selecting appropriate techniques is needed. This approach should also consider tillage
Weed resistance problems have been worsened by farm programs and chemical
promotional programs. Studies should be conducted to evaluate the negative impact of
these programs and determine how they might be mitigated.
Weed shifts are occurring with the use of some herbicides. Resistant weeds are typically
a result of “poor management”, although some seeds from adjacent fields or from
blowing pollen may create the problem. Producers would like to have better ways to
know which weeds are present and how to appropriately select the herbicide and treat