Integrated Management of Important Soybean Pathogens of the United States in Changing Climate

Abstract Soybean (Glycine max L.) is a major crop grown in the United States but is susceptible to many diseases that cause significant yield losses each year. Consistent threats exist across both northern and southern production regions and include the soybean cyst nematode, charcoal rot, and seedling diseases. In contrast, significant soybean diseases like Phytophthora stem and root rot, sudden death syndrome, and Sclerotinia stem rot (white mold) are intermittent threats that can be heavily influenced by environmental factors. Additional threats to soybean production that have emerged in recent years as more common problems in soybean production include root-knot and reniform nematodes, frogeye leaf spot, and Diaporthe diseases. Disease in any crop will only occur when the three components of the disease triangle are present: a susceptible host, a virulent pathogen, and a conducive environment. If an environment is becoming more conducive for a particular disease, it is important that farmers and practitioners are prepared to manage the problem. The information in this review was compiled to help assist agriculturalists in being proactive in managing new soybean diseases that may be emerging in new areas. To do this, we provide: 1) an overview of the impact and disease cycle for major soybean diseases currently causing significant yield losses in the United States, 2) a comprehensive review of the current management strategies for each soybean disease, and 3) insights into the epidemiology of each pathogen, including the likelihood of outbreaks and expansion to additional geographic regions based on current trends in climate change.

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Soybean yield loss estimates due to diseases in the United States and Ontario, Canada from 2015-2019

Plant Health Progress ◽

10.1094/php-01-21-0013-rs ◽

2021 ◽

Author(s):

Carl A. Bradley ◽

Tom Allen ◽

Adam J. Sisson ◽

Gary C. Bergstrom ◽

Kaitlyn M. Bissonnette ◽

...

Keyword(s):

United States ◽

Soybean Cyst Nematode ◽

Economic Loss ◽

The United States ◽

Plant Diseases ◽

Future Research ◽

Yield Losses ◽

Sclerotinia Stem Rot ◽

Survey Period ◽

Soybean Diseases

Soybean [Glycine max (L.) Merrill] yield losses as a result of plant diseases were estimated by university and government plant pathologists in 29 soybean-producing states in the United States and in Ontario, Canada, from 2015 through 2019. In general, the estimated losses that resulted from each of 28 plant diseases or pathogens varied by state or province as well as year. Soybean cyst nematode (SCN) (Heterodera glycines Ichinohe) caused more than twice as much loss than any other disease during the survey period. Seedling diseases (caused by various pathogens), Sclerotinia stem rot (white mold) (caused by Sclerotinia sclerotiorum [Lib.] de Bary), and sudden death syndrome (caused by Fusarium virguliforme O'Donnell & T. Aoki) caused the next greatest yield losses, in descending order. Following SCN, the most damaging diseases in the northern U.S. and Ontario differed from those in the southern U.S. The estimated mean economic loss from all soybean diseases, averaged across the U.S. and Ontario, Canada was $45 U.S. dollars per acre ($111 per hectare). The outcome from the current survey will provide pertinent information regarding the important soybean diseases and their overall severity in the soybean crop and help guide future research and Extension efforts on managing soybean diseases.

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Suppression of Soybean Yield Potential in the Continental United States by Plant Diseases from 2006 to 2009

Plant Health Progress ◽

10.1094/php-2010-1122-01-rs ◽

2010 ◽

Vol 11 (1) ◽

pp. 5 ◽

Cited By ~ 138

Author(s):

Stephen R. Koenning ◽

J. Allen Wrather

Keyword(s):

United States ◽

The United States ◽

Plant Diseases ◽

Soybean Rust ◽

Yield Potential ◽

Stem Rot ◽

Yield Losses ◽

Sclerotinia Stem Rot ◽

Soybean Yield ◽

The Impact

Research must focus on management of diseases that cause extensive losses, especially when funds for research are limited. Knowledge of the losses caused by various soybean diseases is essential when prioritizing research budgets. The objective of this project was to compile estimates of soybean yield potential losses caused by diseases for each soybean producing state in the United States from 2006 to 2009. This data is of special interest since the 4-year period summarized in this report, permits an examination of the impact of soybean rust that was first reported in the United States in 2004. Thus, in addition to the goal of providing this information to aid funding agencies and scientists in prioritizing research objectives and budgets, an examination of the impact of soybean rust on soybean yield losses relative to other diseases is warranted. Yield losses caused by individual diseases varied among states and years. Soybean cyst nematode caused more yield losses than any other disease during 2006 to 2009. Seedling diseases, Phytophthora root and stem rot, sudden death syndrome, Sclerotinia stem rot, and charcoal rot ranked in the top six of diseases that caused yield loss during these years. Soybean yield losses due to soybean rust and Sclerotinia stem rot varied greatly over years, especially when compared to other diseases. Accepted for publication 21 October 2010. Published 22 November 2010.

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Soybean Yield Loss Estimates Due to Diseases in the United States and Ontario, Canada, from 2010 to 2014

Plant Health Progress ◽

10.1094/php-rs-16-0066 ◽

2017 ◽

Vol 18 (1) ◽

pp. 19-27 ◽

Cited By ~ 121

Author(s):

Tom W. Allen ◽

Carl A. Bradley ◽

Adam J. Sisson ◽

Emmanuel Byamukama ◽

Martin I. Chilvers ◽

...

Keyword(s):

United States ◽

Soybean Cyst Nematode ◽

Yield Loss ◽

Research Policy ◽

Economic Loss ◽

Macrophomina Phaseolina ◽

The United States ◽

Yield Losses ◽

Soybean Yield ◽

Soybean Diseases

Annual decreases in soybean (Glycine max L. Merrill) yield caused by diseases were estimated by surveying university-affiliated plant pathologists in 28 soybean-producing states in the United States and in Ontario, Canada, from 2010 through 2014. Estimated yield losses from each disease varied greatly by state or province and year. Over the duration of this survey, soybean cyst nematode (SCN) (Heterodera glycines Ichinohe) was estimated to have caused more than twice as much yield loss than any other disease. Seedling diseases (caused by various pathogens), charcoal rot (caused by Macrophomina phaseolina (Tassi) Goid), and sudden death syndrome (SDS) (caused by Fusarium virguliforme O’Donnell & T. Aoki) caused the next greatest estimated yield losses, in descending order. The estimated mean economic loss due to all soybean diseases, averaged across U.S. states and Ontario from 2010 to 2014, was $60.66 USD per acre. Results from this survey will provide scientists, breeders, governments, and educators with soybean yield-loss estimates to help inform and prioritize research, policy, and educational efforts in soybean pathology and disease management.

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Modeling the relationship between estimated foliar fungicide use and soybean yield losses due to foliar fungal diseases in the United States

10.1101/744581 ◽

2019 ◽

Author(s):

Ananda Y. Bandara ◽

Dilooshi K. Weerasooriya ◽

Shawn P. Conley ◽

Carl A. Bradley ◽

Tom W. Allen ◽

...

Keyword(s):

United States ◽

The United States ◽

Positive Phase ◽

Yield Losses ◽

Soybean Yield ◽

Soybean Production ◽

Foliar Diseases ◽

Quadratic Curve ◽

Foliar Fungicide ◽

The Relationship

ABSTRACTFungicide use in the United States to manage soybean diseases has increased in recent years. The ability of fungicides to reduce disease-associated yield losses varies greatly depending on multiple factors. Nonetheless, historical data are useful to understand the broad sense and long-term trends related to fungicide use practices. In the current study, the relationship between estimated soybean yield losses due to selected foliar diseases and foliar fungicide use was investigated using annual data from 28 soybean growing states over the period of 2005 to 2015. At a national scale, a significant quadratic relationship was observed between total estimated yield losses and total fungicide use (R2 = 0.123, P < 0.0001) where yield losses initially increased, reached a plateau, and subsequently decreased with increasing fungicide use. The positive phase of the quadratic curve could be associated with insufficient amount of fungicides being used to manage targeted diseases, application of more-than-recommended prophylactic fungicides under no/low disease pressure, application of curative fungicides after economic injury level, and reduced fungicide efficacy due to a variety of factors such as unfavorable environmental conditions and resistance of targeted pathogen populations to the specific active ingredient applied. Interestingly, a significant quadratic relationship was also observed between total soybean production and total foliar fungicide use (R2= 0.36, P < 0.0001). The positive phase of the quadratic curve may suggest that factors like plant physiological changes, including increased chlorophyll content, photosynthetic rates, water use efficiency, and delayed senescence that have been widely reported to occur after application of certain foliar fungicides could have potentially contributed to enhanced yield. Therefore, the current study provides evidence of the potential usefulness of foliar fungicide applications to mitigate soybean yield losses associated with foliar diseases and their potential to positively impact soybean production/yield at national and regional scales although discrepancies to the general trends observed at national and regional scales do prevail at the local (state) level.

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Effect of Fungicide and Timing of Application on Soybean Rust Severity and Yield

Plant Disease ◽

10.1094/pdis-93-3-0243 ◽

2009 ◽

Vol 93 (3) ◽

pp. 243-248 ◽

Cited By ~ 54

Author(s):

T. A. Mueller ◽

M. R. Miles ◽

W. Morel ◽

J. J. Marois ◽

D. L. Wright ◽

...

Keyword(s):

United States ◽

The United States ◽

Field Trials ◽

Soybean Rust ◽

Growth Stages ◽

Yield Losses ◽

Treatment Timing ◽

Progress Curve ◽

Significant Yield ◽

Rust Severity

Soybean rust, caused by Phakopsora pachyrhizi, is a devastating foliar disease of soybean that may cause significant yield losses if not managed by well-timed fungicide applications. To determine the effect of fungicide timing on soybean rust severity and soybean yield, field trials were completed in Paraguay (four locations), the United States (two locations), and Zimbabwe (one location) from 2005 to 2006. Treatments at each location included applications of tebuconazole, pyraclostrobin, or a combination of azoxystrobin + propiconazole, and in some locations pyraclostrobin + tebuconazole at the following soybean growth stages (GS): (i) GS R1 (beginning flowering), (ii) GS R3 (beginning pod), (iii) GS R5 (beginning seed), (iv) GS R1 + R3, (v) GS R3 + R5, and (vi) GS R1 + R3 + R5. Soybean yields from plots treated with fungicides were 16 to 114% greater than yields from no fungicide control plots in four locations in Paraguay, 12 to 55% greater in two locations in the United States, and 31% greater in Zimbabwe. In all locations, rust severity measured over time as area under the disease progress curve (AUDPC) was negatively correlated (r = –0.3, P < 0.0001) to yield. The effectiveness of any given treatment (timing of application and product applied) was often dependent on when rust was first detected and the intensity of its development. For example, when soybean rust was first observed before GS R3 (two locations in Paraguay), the plants in plots treated with a fungicide at GS R1 had the lowest AUPDC values and highest yields. When soybean rust was first observed after GS R3, plants treated with a fungicide at GS R3 and/or GS R5 had the lowest AUDPC values and highest yields with a few exceptions.

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Dissecting the economic impact of soybean diseases in the United States over two decades

10.1101/655837 ◽

2019 ◽

Cited By ~ 1

Author(s):

Ananda Y. Bandara ◽

Dilooshi K. Weerasooriya ◽

Carl A. Bradley ◽

Tom W. Allen ◽

Paul D. Esker

Keyword(s):

United States ◽

Soybean Cyst Nematode ◽

Research Policy ◽

Economic Loss ◽

The United States ◽

Soybean Rust ◽

Soybean Yield ◽

Southern Blight ◽

Soybean Diseases ◽

The U.S

ABSTRACTSoybean (Glycine max L. Merrill) is a key commodity for United States agriculture. Here we analyze the economic impacts of 23 common soybean diseases in 28 soybean-producing states in the U.S., from 1996 to 2016. From 1996 to 2016, the total estimated economic loss due to soybean diseases in the U.S. was $81.39 billion, with $68.98 billion and $12.41 billion accounting for the northern and southern U.S. losses, respectively. Across states and years, soybean cyst nematode, charcoal rot, and seedling diseases were the most economically damaging pathogens/diseases while soybean rust, bacterial blight, and southern blight were the least economically damaging. Significantly positive linear correlation of mean soybean yield loss with the mean state-wide soybean production (MT) and mean soybean yield (kg ha−1) indicated that high production zones are more vulnerable to soybean diseases-associated yield losses. Our findings provide useful insights into how research, policy, and educational efforts should be prioritized in soybean disease management.

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Quantifying Alfalfa Yield Losses Caused by Foliar Diseases in Iowa, Ohio, Wisconsin, and Vermont

Plant Disease ◽

10.1094/pdis.2002.86.3.269 ◽

2002 ◽

Vol 86 (3) ◽

pp. 269-277 ◽

Cited By ~ 39

Author(s):

F. W. Nutter ◽

J. Guan ◽

A. R. Gotlieb ◽

L. H. Rhodes ◽

C. R. Grau ◽

...

Keyword(s):

United States ◽

Remote Sensing ◽

Disease Severity ◽

Yield Loss ◽

Disease Incidence ◽

The United States ◽

Yield Losses ◽

Fungicide Treatment ◽

Foliar Diseases ◽

Significant Yield

Although foliar diseases of alfalfa occur throughout the United States wherever alfalfa is grown, little work has been done to quantify yield losses caused by foliar pathogens since the late 1980s. To quantify the yield losses caused by foliar diseases of alfalfa, field experiments were performed in Iowa, Ohio, Vermont, and Wisconsin from 1995 to 1998. Different fungicides and fungicide application frequencies were used to obtain different levels of foliar disease in alfalfa. Visual disease and remote sensing assessments were performed weekly to determine the relationships between disease assessments and alfalfa yield. Visual disease assessments of percentage of defoliation, disease incidence, and disease severity were performed weekly, approximately five to six times during each alfalfa growth cycle. Remote sensing assessments also were obtained weekly by measuring the percentage of sunlight reflected from alfalfa canopies using handheld, multispectral radiometers. Yield loss estimates were calculated as the yield difference between the fungicide treatment with the highest yield and the nonfungicide control, divided by the yield obtained from the highest yielding fungicide treatment × 100. Over the 4-year period, significant alfalfa yield losses (P ≤ 0.05) occurred on 22 of the 48 harvest dates for the four states. The average significant yield loss for the 22 harvests was 19.3%. Both visual and percentage of reflectance assessments were used as independent variables in linear regression models to quantify the relationships between assessments and alfalfa yield. From 1995 to 1998, visual disease assessments were performed for a total of 209 dates and remote sensing assessments were performed on 198 dates from the four states. Yield models were developed for each of these assessment dates. There were 26/209, 26/209, and 17/209 significant yield models based on percentage of defoliation, disease incidence, and disease severity, respectively. Most of the significant models were for disease assessments performed on or within 1 or 2 weeks of the date of alfalfa harvest. When the significant models were averaged, percentage of defoliation, disease incidence, and disease severity explained 51, 55, and 52% of the variation in alfalfa yield, respectively. There were a total of 68/198 significant alfalfa yield models based on remote sensing assessments, and the significant models (averaged) explained 62% of the variation in alfalfa yield. Alfalfa foliar diseases continue to have a significant negative impact on alfalfa yields in the United States and remote sensing appears to offer a better means to quantify the impact of foliar diseases on alfalfa yield compared with visual assessment methods.

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Modeling the relationship between estimated fungicide use and disease-associated yield losses of soybean in the United States II: Seed-applied fungicides vs seedling diseases

PLoS ONE ◽

10.1371/journal.pone.0244424 ◽

2020 ◽

Vol 15 (12) ◽

pp. e0244424

Author(s):

Ananda Y. Bandara ◽

Dilooshi K. Weerasooriya ◽

Shawn P. Conley ◽

Tom W. Allen ◽

Paul D. Esker

Keyword(s):

United States ◽

Production Systems ◽

Regional Scale ◽

The United States ◽

Annual Data ◽

Yield Losses ◽

Soybean Production ◽

The Relationship ◽

The U.S ◽

Seedling Diseases

Use of seed-applied fungicides has become commonplace in the United States soybean production systems. Although fungicides have the potential to protect seed/seedlings from critical early stage diseases such as damping-off and root/stem rots, results from previous studies are not consistent in terms of seed-applied fungicide’s ability to mitigate yield losses. In the current study, the relationship between estimated soybean production losses due to seedling diseases and estimated seed-applied fungicide use was investigated using annual data from 28 soybean growing states in the U.S. over the period of 2006 to 2014. National, regional (northern and southern U.S.), state, and temporal scale trends were explored using mixed effects version of the regression analysis. Mixed modeling allowed computing generalized R2 values for conditional (R2GLMM(c); contains fixed and random effects) and marginal (R2GLMM(m); contains only fixed effects) models. Similar analyses were conducted to investigate how soybean production was related to fungicide use. National and regional scale modeling revealed that R2GLMM(c) values were significantly larger compared to R2GLMM(m) values, meaning fungicide use had limited utility in explaining the national/regional scale variation of yield loss and production. The state scale analysis revealed the usefulness of seed-applied fungicides to mitigate seedling diseases-associated soybean yield losses in Illinois, Indiana, North Carolina, and Ohio. Further, fungicide use positively influenced the soybean production and yield in Illinois and South Dakota. Taken together, use of seed-applied fungicide did not appear to be beneficial to many of the states. Our findings corroborate the observations made by a number of scientists through field scale seed-applied fungicide trials across the U.S and reiterate the importance of need base-use of seed-applied fungicides rather than being a routine practice in soybean production systems.

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