Duration: 10/01/2021 to 09/30/2026

Administrative Advisor(s):

NIFA Reps:

Non-Technical Summary

Statement of Issues and Justification

Plant-parasitic nematodes are economically important pests of agricultural crops produced in the North Central Region (NCR). Most notably, the NCR is the dominant region in the U.S. for corn, soybean and small grain production. In addition, the NCR is home to large production areas of several vegetable crops (e.g. sugar beets, cucurbits, potatoes). The presence of plant-parasitic nematodes in these production systems can cause substantial economic losses, in some cases exceeding $1 billion US. The long-term goal of this committee is to provide environmentally sustainable, effective and economic management of plant-parasitic nematode in the NCR.

 

The need as indicated by stakeholders

Access to unbiased data is the cornerstone for successful plant-parasitic nematode management by stakeholders (crop consultants, industry professionals, growers, breeders, Extension professionals, etc.). Plant-parasitic nematodes are some of the most economically damaging pests of agronomically produced crops in the midwestern United States. Heterodera glycines, the soybean cyst nematode (SCN), has been estimated to be the greatest yield-limiting pest of soybeans in the United States and Ontario for more than a decade (Wrather and Koenning 2006; Allen et al. 2017) responsible for an estimated 123 million bushels lost annually, or $1.2 billion in revenue lost each year, from 2010 – 2014. In addition, other nematodes (e.g. Rotylenchulus reniformis, Belonolaimus longicaudatus, and Meloidogyne, Helicotylenchus, Hoplolaimus, Paratrichodorus, and Pratylenchus spp.) account for an estimated 11 million bushels of soybeans lost each year over this same period.

In addition, plant-parasitic nematodes are considered to be among the top 10 most destructive diseases of corn in the United States and Ontario (Mueller et al. 2020). From 2016 – 2019, an estimated 270 million bushels of corn were lost as a result of plant-parasitic nematodes affecting corn production in the United States and Ontario. Nematodes included species belonging to the genera Belonolaimus, Helicotylenchus, Hoplolaimus, Longidorus, Meloidogyne, Paratrichodorus, Pratylenchus, Tylenchorhynchus, and Xiphinema. Many of these same nematodes also are known to be destructive to other field crops in the region including wheat and alfalfa as well as regionally important vegetable crops (Society of Nematologists Crop Loss Assessment Committee 1987; Koenning et al. 1999). In an effort to increase food security and information access, this project will address both applied and fundamental questions pertaining to yield loss attributed to plant-parasitic nematodes in all of the above mentioned economically important crops in the region.

 

The importance of this work and what the consequences are if it is not done

The NCR spans a large geographical region from north to south and east to west which makes for a wide diversity of nematode species throughout the region. This diversity of nematode species is also the result of soil edaphic factors, rotations, climatic conditions, and management methods. Yield losses due to plant-parasitic nematodes in many areas are often erroneously attributed to other causes such as nutrient deficiencies, poor soil quality, or other diseases. Lack of understanding of the impacts of plant-parasitic nematodes on crop production means less effective management, lost bushels and lost revenue.

One of the best examples of the impacts of nematodes on production is SCN. For more than 20 years, the PI 88788 source of resistance has been used to manage SCN in soybean varieties. Today, PI 88788 is present in approximately 95% of soybean varieties. The repeated use of this same source of resistance over an extended period of time has led the reduced effectiveness of the PI 88788 source of resistance on many field populations. In field trials in Iowa, by simply rotating to the Peking source of SCN resistance vs PI 88788, a grower can increase their profitability by as much as $200 per acre (Tylka 2020). More typically, a grower has the potential to increase yields by 15-20 bushels per acre by simply changing from a PI 88788 variety to a variety with the Peking source of SCN resistance.

Though awareness of plant-parasitic nematodes has increased slightly among stakeholders in recent years, this increase has largely been attributed to industry marketing of products for plant-parasitic nematode control. Our committee has provided access to unbiased data regarding many of these products. As new products are developed, it is essential that coordinated research spanning across state lines provides answers to these and other stakeholder questions. Meaningful data comparisons can only be extrapolated through such coordination and synchronization of experimental designs across multiple states in the NCR. This type of coordinated research allows for understanding of how environmental variability impacts nematode management, biology, and other factors which ultimately allows for successful development of new plant-parasitic nematode control strategies.

 

Technical feasibility of the research

As the primary nematology expertise of the NCR, the participants of this technical committee are capable of completing all proposed research as the objectives proposed utilize standard nematology techniques. As nematology experts, participants of this committee are capable of incorporating new nematode management technologies and ideas into a well-defined production system. Several members of this committee have substantial Extension appointments and are well-positioned to share committee findings with the public. Similarly, most committee members are also co-PIs on the United Soybean Board funded grant “SCN Coalition” to provide educational materials on SCN management to growers and agriculture industry stakeholders. To improve our ability to quantify economic impact, we have recruited Ray Massey and Ryan Milhollin, agricultural economists from the Univ. of MO with significant experience in quantifying the costs and returns associated with decisions farmers make under uncertainty.

 

The advantages for doing the work as a multistate effort

By working as a coordinated, multistate effort, data regarding geographical differences in nematode management and biology can be readily extrapolated and compared. This information in turn offers a broader understanding of plant-parasitic nematode interactions with their hosts and the soil environment, thereby allowing for more valuable insight into novel management strategies for improving yield and minimizing economic losses. For example, though SCN is present throughout the NCR (Tylka and Marett 2017), the response to some nematode-protectant seed treatments in areas may be attributed to interaction effects with additional geographically-restricted pathogens (Bissonnette et al. 2020). Understanding how soil edaphic factors, pest biology, agronomic practices, and other management strategies impact plant-parasitic nematodes is important at both the local geographical level and a regional level. Such work requires a multistate, coordinated effort by nematologists and plant pathologists to integrate novel strategies for nematode pest management. With the decrease in faculty in nematology and plant pathology at local land-grant institutions, collaborative nematology research is essential to maintain forward progress in the field and to continue providing relevant research results to stakeholders.

 

What the likely impacts will be from successfully completing the work

Increasing environmentally sustainable crop production through reducing yield loss caused by plant-parasitic nematodes is a key impact from this project. In corn and soybean alone, plant-parasitic nematodes are estimated to cause more than $1.5 billion US in economic losses annually (Allen et al. 2017, Mueller et al. 2020). Based on 2017 crop production data (UDSA NASS 2017), more than 8 million acres are chemically treated for nematode control in the NCR. This project will improve our understanding of integrated plant-parasitic nematode management in the near- and long-term through applied and fundamental research combined with outreach activities.

Related, Current and Previous Work

This renewal proposal for NC1197 describes research that expands and supplements our current knowledge of plant-parasitic nematode management. The multistate project proposed herein is a longstanding collaboration among NCR nematologists and plant pathologists whose goal is to solve the perpetual challenges faced due to plant-parasitic nematodes. Complete accomplishments are listed under the previous five years of yearly reports documented by this committee. A subset of these accomplishments include:

1. Evaluated thousands of SCN resistant soybean cultivars and breeding lines for their efficacy of resistance to SCN.
2. Tested nematode-protectant seed treatment efficacy across a wide range of geographies.
3. Determined root-lesion nematode host range of commercial crops and cover crops to improve management recommendations.
4. Established the second SCN Coalition, a public-private partnership to bring awareness to stakeholder about the effects of SCN on soybean production.
5. Developed new tools for molecular detection and diagnostics of key plant-parasitic nematodes of importance in the region.
6. Disseminated research-based information to tens of thousands of stakeholders via extension bulletins, electronic communications, and on-site visits.

While other multistate committees are currently addressing plant-parasitic nematodes (NE1640 and W4186), those projects give substantial effort to nematodes and crops relevant to the Northeast and Western regions. For example, W4186 examines Meloidogyne chitwoodi, a species that is absent from the NC region. While some of the nematode taxa examined will overlap, the crops and agricultural systems differ substantially among these regions. There is some overlap with the NCERA137 committee on soybean diseases, which includes monitoring of plant-parasitic nematodes on soybeans. Despite this overlap, our committee pursues research on nematodes beyond soybeans. Similarly, their committee focuses on a broad range of pathogens to soybean. Given the overlap with NCERA137, we will attempt to coordinate an annual meeting with that group during the upcoming project period to best coordinate our research directions. 

Previous work

The integration of nematode-resistance into commercial cultivars has been a longstanding challenge. No commercial corn hybrids are known to have nematode resistance and most SCN resistance in commercial soybean cultivars is still derived from the same source of resistance, PI 88788. McCarville et al. (2017) studied field populations of Heterodera glycines in the NCR and found that repeated use of the PI 88788 source of resistance has resulted in a widespread shift in virulent field populations of the nematode capable of elevated reproduction on varieties utilizing this resistance source. In collaboration with plant breeders and agronomists, members of this committee conducted germplasm analyses for resistance to Heterodera glycines in field and greenhouse trials across multiple states in the NCR testing more than 2000 commercial and novel resistance sources for their potential use in soybean breeding programs. (Chen 2020; Ravelombola et al. 2019; Qi et al. 2019)

While Heterodera glycines is an important plant-parasitic nematode affecting soybeans and related crops in the NCR, other plant-parasitic nematode genera are present in these same production systems. In an effort to better understand the role of other nematode genera in crop losses, researchers in KS and WI explored the host range of numerous Pratylenchus species that are known to occur in production fields in the region. Most notably, P. thornei was found to be host to both wheat and soybean with other species of Pratylenchus being host to either corn or wheat or in some cases both (Ozbayrak et al. 2019; Sakai et al. 2019; Sakai and MacGuidwin 2019). Going further, NC1197 participants in WI have begun the development of an error model for Pratylenchus penetrans populations affecting field crop production (MacGuidwin and Bender 2016).

Understanding the role of cultural practices in parasitic-nematode management is critical to the implementation of effective integrated pest management strategies. Many growers in the NCR have begun to introduce cover crops into production systems. In their marketing, several of these cover crops have been touted for their potential to control a variety of plant-parasitic nematodes, making the question of how cover crops impact plant-parasitic nematode populations of vital importance. During the previous project period, researchers in the NCR have explored the role of cover crops as nematode hosts in field and greenhouse trials (Acharya et al. 2019; Harbach et al. 2020). In addition, members of this committee continue to study the interaction among plant-parasitic nematodes and other soil-inhabiting organisms, both pathogenic and non-pathogenic (Grabau et al. 2018; Grabau et al. 2019; Kobayashi Leonel et al. 2017; Melakeberhan et al. 2018; Neher et al. 2019).

Notably, this committee has evaluated nematode protectant seed treatments in six states over the five previous years of this project (Bissonnette et al. 2018, 2020; Beeman and Tylka 2018, 2019; Jensen et al. 2018, 2018; da Silva et al. 2016). Each year, new treatments have become available on the market and this committee has been committed to evaluating these products in field and greenhouse trials in multiple states and across multiple environments. Of the seed treatment trials focusing on SCN, results have shown few significant decreases in SCN or increases in yield in any experiment.

This committee has also led efforts in local and regional nematode diagnostics. In the previous project period, multiple nematode species were found to be associated with agronomically important crops in the region and a new nematode species was described (Acharya et al. 2016; Akintayo et al. 2018; Baidoo et al. 2017, 2017; Huang and Yan 2017; Yan et al. 2016, 2017). Importantly, continued survey work on SCN distribution and population diversity revealed an expanding range where SCN is present in the NCR (Tylka and Marett 2017), but stability in the percentage of fields with SCN present in states where SCN has been long established.

Objectives

1. Develop, evaluate, improve, and integrate management techniques for plant-parasitic nematodes in the north-central region (NCR) to increase grower profitability.
   
2. Examine impact of plant parasitic nematodes on cropping system sustainability through analysis of interactions among nematodes, plant health, biological and abiotic soil conditions, and other pests/pathogens.
   
3. Develop and disseminate research-based information on the biology and management of plant-parasitic nematodes of economically important crops in the NCR.
   

Methods

Objective 1: Develop, evaluate, improve, and integrate management techniques for plant-parasitic nematodes in the north-central region to increase grower profitability.

A. Evaluate interactions of plant-parasitic nematodes with germplasm of economically important plants.

Germplasm screening for SCN resistance utilizing standard protocols (Niblack et al. 2009) will be conducted. This process will allow for the development of a diverse SCN screening population which in turn can be used in novel soybean breeding strategies such as gene stacking technology or through the integration of wild soybean genes into cultivated genomes. Additional evaluations of public and private company cultivars for SCN resistance will continue in greenhouse and field trials. A crop-centered focus will be placed on other regionally important plant hosts which will also be screened for resistance to plant-parasitic nematodes.

B. Assess intraspecific variability in nematode virulence and pathogenicity.

SCN populations will continue to be evaluated for virulence using the HG type test on a standard set of resistance sources from their states (Niblack et al., 2002). In addition, these evaluations will be used to determine the future utility of new resistance sources for SCN as they become available. We will also determine the virulence of populations of other plant-parasitic nematodes through a combination of greenhouse and field experiments. This is typically accomplished through comparison of the initial and final numbers of nematodes on a particular plant variety.

C. Evaluate new commercial products and innovative strategies for the control of SCN, root-lesion and other plant-parasitic nematodes.

Various products are currently marketed as providing protection against plant-parasitic nematodes. For example, several nematode protectant seed treatments, with diverse modes of action, are currently available for control of plant-parasitic nematodes. It is very likely that additional products will become available to growers who will require unbiased information regarding the efficacy of these products. Our committee has historically served as an important source of data regarding new nematode control products. These data are presented to growers via multiple formats (field days, winter grower meetings, web casts, direct advice to crop consultants, electronic and paper-based guides). We will continue to evaluate new products using laboratory, greenhouse and field experiments. Experiments will assess the efficacy of products and interactive effects between different products and also against different pathogens. We will also collect yield data from these field experiments across the region and subject them to meta-analysis.

D. Develop innovative methods to detect and quantify plant-parasitic nematodes.

The quantification of plant-parasitic nematodes relies on extraction from soil and roots, typically followed by identification and enumeration with a light microscope. While extraction procedures can be standardized for a targeted pest, they are often laborious and time-consuming. The microscopic identification of plant-parasitic nematode species requires extensive training. In this objective, we will develop molecular techniques for the identification and quantification of economically important plant-parasitic nematodes, making the process of detecting and quantifying plant-parasitic nematode species more efficient. In addition, as new information about SCN virulence genes becomes available, analysis of virulent SCN populations will be integrated into detection strategies.        

Objective 2: Examine impact of plant parasitic nematodes on cropping system sustainability through analysis of interactions among nematodes, plant health, biological and abiotic soil conditions, and other pests/pathogens.

A. Investigate pest and disease interactions involving plant-parasitic nematodes.

Plant-parasitic nematodes often interact with other pathogens to produce new or enhanced symptoms. This objective will examine the effect of other pests and pathogens on both nematode reproductive success and the ultimate effect of nematodes on plant health. For example, evaluating integrated management strategies to examine interactions between SCN and the soybean pathogen Fusarium virguliforme. Furthermore, possible interactions among nematode species will be examined in various cropping systems. Experiments will be conducted in both field and greenhouse settings.

B. Determine the temporal and spatial dynamics of nematodes in relation to plant and soil health.

Soil samples will be collected from experiments at appropriate time intervals, and nematodes will be identified, enumerated and assigned to herbivore, bacteriovore, fungivore, predator or omnivore trophic groups (Okada and Kadota 2003; Yeates et al. 1993) and colonizer-persister (c-p) groups (Bongers 1990). Data will be processed to describe nematode diversity and community abundance (Shannon and Weaver 1949), ecosystem disturbance, fertility and index and decomposition pathways (Bongers 1990; Bongers et al. 1997), and the structure and function of the soil food web (Ferris et al., 2001). In addition to nematode community analysis, crop yield will be collected at the end of the season. The integrated agrobiological, ecological and environmental efficiency of the agronomic practices relative to soil health will be determined using recent modifications of the fertilizer use efficiency (Melakeberhan and Avendaño 2008). Principal component analysis showed distinct correlation patterns among crops grown in different soil types with nematode community indices and soil physiochemical properties.

Objective 3: Develop and disseminate research-based information on the biology and management of plant-parasitic nematodes of economically important crops in the NCR.

We will coordinate our efforts to produce a consistent message regarding the importance of plant-parasitic nematodes and effective control strategies. We will conduct these outreach activities through traditional outlets such as grower meetings. This committee will also extend its efforts into amplifying the messaging of the SCN Coalition to bring awareness to SCN and its management strategies with intentions to transform the SCN Coalition into a soybean nematode coalition in the future. In addition, members of this committee will work closely with the University of Missouri Agricultural Economist to evaluate the farm-level economic impacts of plant-parasitic nematodes in the NCR. Economic analysis will focus on the impacts of utilizing different sources of SCN resistance and SCN seed treatments in production systems, based on grain yield difference between varieties with the different sources of resistance with and without seed treatment, grain prices, and the expenses involved. Estimation of net income changes from various SCN management decisions will follow standard procedures of the Commodity Costs and Returns Handbook (American Agricultural Economics Association Handbook, 2000). For all research-based materials, we will coordinate the distribution of extension publications (e.g., the Crop Protection Network), webcasts and press releases throughout the NCR.

Measurement of Progress and Results

Outputs

• Peer-reviewed research journal articles on nematode biology, ecology and management in economically important crops in the NCR as they relate to plant-parasitic nematodes.
• Improved methodology for the detection of plant-parasitic nematodes in soils and substrates.
• Unbiased data through Extension and other publications on the management of plant-parasitic nematodes.
• A database of germplasm with resistance or tolerance to plant-parasitic nematodes.
• Provide updated state, regional, and/or national map resources for the occurrence and distribution of nematodes of importance in the region

Outcomes or Projected Impacts

• Genetic resources developed to increase options for breeders and growers to manage plant-parasitic nematodes.
• Improved accuracy in species-specific diagnosis of plant-parasitic nematode issues as measured by turnaround time for processing of samples.
• Increased profitability for growers through reduced plant-parasitic nematode damage.
• Increased awareness of plant-parasitic nematodes and strategies for control of these important and often overlooked crop pests.
• Unbiased information regarding commercial products available to growers for nematode management

Milestones

(2022):A. Identify coordinators for each sub-objective. B. Identify potential extramural funding for each sub-objective. C. Begin laboratory and greenhouse experiments for objectives 1 & 2.

(2023):A. Continue laboratory and greenhouse experiments for objective 1 & 2. B. Apply for extramural funding. C. Begin 1st year of field experiments for objectives 1 & 2. D. Perform preliminary analysis of 2022/2023 data.

(2024):A. Continue laboratory and greenhouse experiments for objectives 1 & 2. B. Conduct 2nd year of field experiments for objectives 1 & 2. C. Summarize findings for stakeholders (Objective 3) based on 2022 and 2023 data.

(2025):A. Continue laboratory, greenhouse and field experiments for objectives 1 & 2. B. Analyze data from 2022-2024. C. Summarize findings for stakeholders (Objective 3) based on 2022-2024 data.

(2026):A. Complete laboratory, greenhouse and field experiments for objectives 1 & 2. B. Analyze data from 2016-2019. C. Summarize findings for stakeholders (Objective 3) based on 2022-2025 data. D. Coordinators for each sub-objective will begin formatting data for appropriate peer-reviewed journal.

(2027):A. Conclude data analysis. B. Submit and revise manuscripts to peer-reviewed journal regarding objectives 1 & 2. C. Summarize findings for stakeholders (Objective 3) based on complete data analysis.

Projected Participation

View Appendix E: Participation

Outreach Plan

Objective 3 directly addresses our plan for outreach. Our audience includes growers, commodity groups, crop consultants, agribusinesses, regulatory agencies, and scientists in industry, government and academia. We will tailor our outreach to the most appropriate audience. For example, the SCN-resistant soybean cultivar information will be of greatest use and interest to growers and agribusinesses. In some individual states/provinces, this information will be disseminated in hard-copy form, published and disseminated by commodity groups. Individual states/provinces will publish applied research results annually through extension outlets, including traditional extension publications, bulletins and newsletters, and web sites. Again, these reports will be gathered for region-wide public access via the internet. Highlights of research findings and links to publications will be shared on social media platforms (twitter and facebook). Information generated through the fundamental research will be disseminated through refereed research journals such as the Journal of Nematology, Plant Disease, Plant Health Progress, Phytopathology, and other scientific publications. Specific outreach goals are detailed in the timelines.

Organization/Governance

The recommended Standard Governance for multistate research activities includes the election of a Chair, a Chair-elect, and a Secretary. All officers are to be elected for at least two-year terms to provide continuity. Administrative guidance will be provided by an assigned Administrative Advisor and a NIFA Representative.

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