Brief Summary of Minutes of Annual Meeting

SHORT-TERM OUTCOMES:

CA: Walnut. Several multi-pathogen resistant accessions were identified and will be moved into further testing and prepared for nursery production. In orchard trialing, one rootstock accession performed superior to commercial comparatives in regards to vigor and early yield and is currently in preparation for release.
CA: Preplant soil treatments. An economically feasible application method for the allyl iso thiocyanate (AITC) -containing “Dominus” was developed for reducing preplant population densities of P. vulnus. When coupled with postplant applications, this treatment was competitive with soil fumigation with 1,3-dichloropropene (1,3-D) or combinations of 1,3-D and chloropicrin.
FL:  Identified calla lily as a host to Florida populations of the root-knot nematode species Meloidogyne incognita, M. javanica, M. enterolobii, and M. floridensis.  Identified fluopyram resistance in sting nematode.  Identified the ornamental plant fungicide Broadform and the insecticide Kontos as having excellent activity against foliar nematode.
GA (USDA-ARS): Local adaptation of a parasite to its pest host has been rarely studied in agricultural systems. ARS scientists in Tifton, GA in collaboration with scientists from the University of Virginia evaluated attachment of the bacterium Pasteuria penetrans to its nematode host, root-knot nematode (Meloidogyne arenaria), both within and between peanut fields. In only one of four years they found that Pasteuria had greater attachment to its local host compared to distant hosts; therefore, there was no strong support for local adaptation of Pasteuria to root-knot nematodes. This work paves way for future research in biologically based disease management strategies and furthered our understanding of this important predator-prey relationship.
HI: Documented that the use of energy sorghum as cover crop with high biomass production and nematode allelopathic compounds improved soil food web structure and suppressed plant-parasitic nematodes in the subsequent 5 months of eggplant crop in a strip-till cropping system. The effects are progressively improved in a healthier soil. Verified that biopesticides for organic sweetpotato production against sweet potato insect pests or plant-parasitic nematodes performed well in healthier soil managed by winter cover crop mix in North Carolina, or virulent green manure like velvet bean in Hawaii. This supports our hypothesis that prescription of soil health practices could lead to effective organic pest management strategies.
MSU: The Soybean Cyst Nematode Profit Checker tool was developed, validated, and made available to soybean growers in conjunction with the SCN Coalition. The tool estimates the impact of SCN on a field basis and provides the information necessary for active SCN management. Soybean cyst nematode active management information was provided to the SCN Coalition for its website, publication of numerous web-based publications and video development. The activities resulted in many media impressions, video views and statistically valid positive impacts in soybean grower SCN management understanding and practices. In a commercial soybean field, planting soybean PI 437654 as a SCN trap crop after wheat and before corn in 2023 resulted in a 10 Bu/A soybean yield increase compared to the fallow control.  Michigan potato tuber yields in four root-lesion nematode high-risk fields were significantly lower where remotely monitored site temperature was consistently five degrees Celsius higher than sites that were consistently five degrees Celsius lower when active carbon was less than 300 ppm. In one field, northern root-knot nematode populations were consistently associated with sites where active carbon was less than 25 pp.
PA:  Identified one additional plot in a Penn State-owned forest affected by beech leaf disease (BLD).  Expanded local BLD transmission studies. This year we had two sites and collected samples as far as 300 feet away from any BLD infected tree.  
RI:  Identified shifts in plant-parasitic nematode populations after repeated use of fluopyram, suggesting the likelihood of significant resistance development in Tylenchorhynchus claytoni.
TN: Root-knot nematode invasion of cucumber seedlings was not affected by the presence of microplastic particles mixed into the soil substrate.  An artificial soil mix used as substrate for a new rooftop garden at the University of Tennessee contained several species of bacteria-feeding Rhabditidae and Cephalobidae. Samples were taken directly from bags as they were opened to release the soil mix. 

OUTPUTS: 

FL:  One refereed publication, 8 presentations at scientific meetings, 2 trade journal publications, 12 presentations to grower groups, 1 field day, 1 grower workshops, 2 in-service trainings for extension agents, 3 extension volunteer training events, 4526 nematode diagnostic samples
GA (USDA-ARS): 2 refereed articles, 2 abstracts (Society of Nematologists, Beltwide Cotton Conferences), 3 presentations (Society of Nematologists, Embrapa/University of Florida/USDA-ARS, University of Costa Rica), and ~300 diagnostic samples evaluated for free-living and plant-parasitic nematodes.
HI: A total of 3 peer-reviewed refereed journal articles, 1 Ph.D. dissertation, 5 extension articles, 2 invited presentations, 4 guest lectures to new farmers, 13 conference presentations, 1 public media (pod cast), 7 field days/workshops presentations or displays; and secure 1 extramural grant and 2 intramural grants. All of which are related to “Sustainable Management of Nematodes in Plant and Soil Health Systems.”
MSU: Our publications on the application of the Soil Food Web (SFW), Fertilizer Use (FUE) and Integrated Productivity Efficiency (IPE) models as diagnostic tools for understanding cause-and-effect relationships of host-parasite interactions as well as management decisions have been viewed and downloaded 14,777 times since 2021. 
MSU: Made two research presentations at annual science society meetings.  Author of three research-outreach abstracts. Served on the SCN Coalition Work Group. Edited the SCN Coalition Newsletter.  Participated in two public sector/private sector grower research planning meetings.  Assisted in development of the SCN Profit Checker Tool.
NY: In New York, 15 garlic samples were assessed for the presence of bloat nematode (Ditylenchus dipsaci).  One grower was identified with on-going issues with bloat nematode and advice was given on management.
PA:  Conducted one (1) Webinar- 695 sign-ups with stakeholders from at least 34 states; two Canadian provinces; and one Mexican state. Estimated Impact: at least 5,442,246 acres of land.  Co-created three (3) educational BLD videos. Invited speaker to present research outcomes at PA DCNR Bureau of Forestry Winter Meeting. One referred article and two abstracts (listed under Publications), three presentations and one press article.
RI:  Presented 3 seminars to growers with attendance size between 50 and 200 people per presentation.  Diagnosed 470 nematode samples. 

ACTIVITIES:   

Objective 1:  Develop and integrate management tactics for control of plant-parasitic nematodes including biological, cultural (such as rotation or cover crops and plant resistance), and chemical controls.

CA: Walnut. In this team effort of researchers from UC Davis, UC Merced, UC Riverside, CSU Fresno, USDA-ARS and UCANR, several multi-pathogen resistant accessions were identified. For example, one accession was resistant against Pratylenchus vulnus, Meloidogyne incognita, Agrobacterium tumefaciens, Phytophthora spp., and grew vigorously under nematode-infested conditions. These accessions were prepared for nursery production and broad-scale field testing as completed trees for their growth habits, yield potential, and sustainable host plant resistance. 
CA: Pistachio.  Field and microplot experiments were conducted to determine the damage potential of Pratylenchus vulnus on pistachio. Low levels of infection were determined in commercial UCB1 rootstock clones but after multiple years of incubation, population density levels comparable with other tree nut crops were detected. In microplots, increasing population densities of P. vulnus at planting of pistachio damaged the trees. Care needs to be taken when pistachio plantings follow walnut that notoriously leaves behind population densities of P. vulnus that can damage pistachio.
GA (USDA_ARS): A field trial to determine the economic value of growing nematode-resistant vs. a susceptible cultivar in continuous and rotated (with cotton) peanut was established in Tifton, GA in May 2024 and sampled four times throughout the growing season to assess the nematode community.  A series of greenhouse experiments to identify sources of resistance to Meloidogyne arenaria and Pratylenchus brachyurus are underway to identify sorghum cultivars that are poor hosts for Pratylenchus brachyurus and/or Meloidogyne arenaria.  Screening peanut cultivars for resistance to Meloidogyne arenaria and Meloidogyne hapla was performed in 2024 in collaboration with peanut breeders from USDA-ARS and the University of Georgia. Further molecular characterization of resistance is underway.
HI: Develop and integrate management tactics for control of plant-parasitic nematodes including biological, cultural (such as rotation or cover crops and plant resistance), and chemical controls.  We developed a sorghum cover crop-based biofumigation method in a strip- and low-till system to manage plant-parasitic nematodes (including Meloidogyne spp. and Rotylenchulus reniformis) through biofumigation and soil health improvement effects. This effect is progressively effective if soil health is improved over time. We are currently developing another biofumigation approach using papaya seed waste as post-plant soil drenching treatment.
MSU: We maintain two long-term studies applying various combinations of regenerative agricultural practices (RAPs) such as tillage, cropping system, cover crop and/or nutrient amendments that test adaptation of soybean cyst (SCN) and changes in nematode community structure (NCS), nutrient cycling and soil health. We also maintain northern root-knot nematode (NRKN) cultures from different regions of Michigan soils with varying degrees of soil health conditions. Following recent publications, we are focusing on using the SFW model to elucidate the specificity of associations between NRKN populations’ parasitic variability (PV) and soil microbiome.  
MSU: Worked as a member of the Soybean Cyst Nematode Coalition Technical Committee in the development, evaluation and implement of the SCN Profit Checker to for SCN Active Management, including crop rotation, resistance source rotation and seed treatment.  Validated the potential of soybean PI 437654 as trap crop for SCN management.   
RI:  Examined the effect of alternative chemistries on turfgrass-parasitic nematodes and on trees impacted by BLD.

Objective 2: Determine the ecological interactions between nematode populations, nematode communities, ecosystems and soil health.

GA (USDA_ARS): A project to investigate the contribution of predatory nematodes in suppressing Meloidogyne incognita was established and the first iteration of the experiment completed in 2024. The experiment will be repeated in 2025. Progress was made regarding studies to identify the host and environmental factors that influence the attachment of Pasteuria penetrans to Meloidogyne arenaria through the publication of a journal article in Evolutionary Applications (Do biological control agents adapt to local pest genotypes? A multiyear test across geographic scales). Regarding soil type and crop plant influence, a field trial was established in June 2024 that was sampled over the growing season for P. penetrans and M. arenaria. Vetch was planted in this field in late 2024 to assist in maintaining population densities of M. arenaria over the winter.
HI: Through multiple field trials conducted in Alabama, Hawaii and North Carolina, we documented that healthier soil could lead to better sweetpotato yield improvement and occasionally plant-parasitic nematode suppression through bionematicides application. We determined that the efficacy of cover crop biofumigation and other biological based nematicides (e.g. MeloCon, Chitocide) were more effective in conjunction with soil health improvement (as indicated by nematode metabolic footprint) through cover cropping.
MSU: A major focus of our efforts this year has been analysis of NCS, nutrient cycling and soil health data with the SFW model. Specifically, how the RAPs influence the measured parameters and how the data relate to the disturbed and enriched, stable and enriched, stable and depleted, and depleted and degraded soil health conditions that the model describes. Consequently, we anticipate to establish cause-and-effect relationships that explain the outcomes and potentially benefit the environment.  
MSU: Used remote ecosystem sensing and site history sampling to demonstrate the associations among temperature stability, active carbon, nematode population densities and tuber yield in commercial potato fields in Michigan.
TN: Effects of commonly used agricultural microplastics on soil nematodes were studied with the materials LDPE or PHA/PLA ground to less than 250μm in diameter, mixed into a sand substrate at densities of 0 to 2% by weight. Cucumber seedlings grown in small Conetainer tubes filled with the mix + 500 Meloidogyne incognita eggs per tube. After 10 days plants were harvested and roots stained to observe Mi juveniles therein. The presence of microplastics had no effect on root invasion.

Objective 3: Detect and evaluate the distribution and movement of invasive and emerging nematode pests.

FL:  Continued a survey of botanical gardens in Florida to determine the distribution and ornamental plant hosts of foliar nematodes Aphelenchoides spp. Continued research on the host status of rice, strawberry, cotton, and soybean to the foliar nematode Aphelenchoides pseudobesseyi. Evaluated the susceptibility of calla lily to different species of root-knot nematode common in Florida.
PA and RI:  Continued surveys across states to determine the spread and susceptibility of various beech cultivars to beech leaf disease, determining that American beech is usually more susceptible that European beeches in the short-term, but continued progression of the disease does not indicate that any significant resistance to the pathogen is present at this time.
TN: Rooftop gardens are becoming more popular for both aesthetic and environmental reasons, but the presence of nematodes in these gardens has never been assessed. The recent completion of the Agriculture and Natural Resources Building at the University of Tennessee, includiong a large rooftop garden, presents an opportunity to study the development of nematode communities in a presumed nematode-free environment. Initial samples in summer and fall of 2024 from unplanted fresh substrate, including that directly from the bag, were checked for nematodes. Several species of Rhabditidae and Cephalobidae were detected, temporarily cultured, and preserved for both light microscopy and molecular analysis for identification. At least one rhabditid produced abundant dauer juveniles in culture.

Objective 4:  Outreach, Public Relations and Extension - Compile and present/ publish guidance on nematode management and management effects on soil health for different crops under different conditions.

GA (USDA-ARS): We are involved in the Fertilize 4 Life initiative, which is an agreement involving USDA-ARS, Embrapa, USDA-FAS, the University of Florida, and the International Fertilizer Development Center. Money received from this agreement is aiding ARS researchers in Tifton, GA to advance soil health assessments in the United States and Brazil. We are determining site-specific effects of agricultural conservation practices on biological, physical, and chemical soil health indicators and soil functions.
FL:  Provided nematode IPM education for turfgrass professionals at numerous seminars and webinars in Florida, Georgia, California, Texas, and nationwide, to a combined audience of >1200 stakeholders. Published two trade journal publications to educate clientele and revised 5 extension publications.
HI: We were invited to present at a symposium during the American Society of Plant Biology Conference entitled “Promoting sustainable food systems of the future: Industrial to Indigenous perspectives on regenerative agriculture,” where we shared a topic on “Prescription of soil health for farmers in Hawaii: Perspective from nematodes.” We were also invited to present a similar topic to 50 faculty, students, and post-doctorates at the Department of Plant and Environmental Protection Sciences, University of Hawaii at Manoa.  We continue to share cover crop and soil health management strategies to 4 cohorts of new farmers through GoFarm Hawaii New farmers’ training program throughout 2024. A total of 48 farmers participated through new farmers’ online learning platforms. More than 168 audience (scientists, students, farmers etc) attended our outreach activities, 250 attended our invited presentations. We published 5 extension articles in Haina’Ai with >1000 subscribers.
MSU: Because our application of the SFW, FUE and IPE models go beyond the yes and no answers to objective-dependent questions (tactical) into identifying if what is getting done is resulting in suitable and sustainable (strategic) outcomes, they face considerable intra- and cross-disciplinary gaps and barriers hindering broad application of the models and getting funds from in-state to federal level agencies. Building on the 14,777 views and downloads of the publications describing the models’ concepts, we will continue the long-term project objectives as planned and promote utilization of the models.
MSU:  Represented nematology at the 2024 Michigan Potato Industry Research Planning Conference.  Served as a reviewer of the monthly SCN Coalition Newsletter.  Participated in the SCN Coalition designed to add root-lesion, root-knot and reniform nematodes to the project’s activities, in addition to transferring the initiative to the next generation of nematologists.
VT: Nematode community indicators are being used as a baseline reference to evaluate the use of microbial indicators intended to inform farmers about management effects on soil health. In summer 2024, the suite of biological  metrics was measured three times (planting, mid-season, harvest) in 25 fields across Vermont that varied in management practices including annual or perennial crops, cultivation and manure application. Results will help inform indicator choices by the newly formed Soil Health Research and Extension Center at UVM.

MILESTONES:

CA:  Continued development of nematode resistant germplasm, with the future release of a number of promising cultivars immenent. 
GA (USDA-ARS): Tested nematode management practices for potential to induce suppressive soils.
GA (USDA-ARS): Adjusted cover- and rotation-crop experimental designs based on previous results.
GA (USDA-ARS): Continued experiments to examine non-target effects of nematode treatments on soil biology.
GA (USDA-ARS): Adjust and expand germplasm resistance screening in peanut and sorghum.
HI: Initiate or continue long-term experiments to examine new soil amendment materials and techniques against Meloidogyne spp. in vegetables, and other nematodes on crops.
HI: Evaluate the effects of identified non-host or nematode-suppressive rotational crops against different nematodes in multiple states under field conditions.
HI: Conduct grower education, annual short courses, webinars, field days
MSU: Our application of the SFW, FUE and IPE models have achieved over 3,600 views and downloads yearly.
MSU:  Conducted grower education programs through the Soybean Cyst Nematode Coalition and made farm visits for development of PI 437654 as a trap crop for SCN.
MSU: Integrated cover- and rotation-crops into soybean and potato nematode management systems through the SCN Coalition website and Michigan Potato Industry research and outreach initiative.
PA and RI: Screening for BLD continues and new locations within known areas and new areas were identified.
RI: Continue screening new potential nematacides with less environmental risk for efficacy.
TN: Analyze data on soil amendment materials and techniques against Meloidogyne spp. (microplastic effects)
TN: Continue screening for new and emerging nematode pathogens (dispersal of nematodes into pristine environments)

Refereed Articles:

Bird, G., B. Basso, R. Price. M. Otto and F. Warner. 2024. Relationships among temperature stability, nematodes, and potato tuber productivity. Proceedings of the 2024 Annual Meeting of the Society of Nematologists. Lake City, Utah.

Bird, G., B. Basso, M. Otto, and R. Price. 2024. Relationships among thermal stability, potato tuber yield, soil health indicators and nematodes. Proceedings of the 2024 Annual Meeting of the Potato Association of America. Portland, Oregon.

Darling, E., Palmisano, A., Chung, H. and Quintanilla, M. 2023 A new biological product showing promising control of the northern root knot nematode, Meloidogyne hapla, in greenhouse tomatoes. Journal of Nematology.

Fourie, H., Dehennin, I., Cortada, L., Korthals, G. deGoede, R., Neher, D.A., Bert, W., and Hodda M. 2025. Education and environmental nematology. Chapter 19 in Kakouli-Duarte, T. and du Preez, G. (eds) Nematodes as Environmental Indicators: from Theory to Practice. CABI. (in press)

Goraya, M., Kantor, C., Vieira, P., Martin, D., Kantor, M. Deciphering the Vectors: Unveiling the local dispersal of Litylenchus crenatae ssp. mccannii in the American beech (Fagus grandifolia) forest ecosystem. 2024. PLoS ONE 19(11): e0311830. https://doi.org/10.1371/journal.pone.0311830

Howland, A.D., Quintanilla, M. 2023. Plant-parasitic nematodes and their effects on ornamental plants. Journal of Nematology. https://doi.org/10.2478/jofnem-2023-0007.

Markel, S., G. Tylka, G. Bird, A. Tenuta, C. Bradley, D. Mangel, H. Lopez-Nicora and T. Watson. 2024. How a science-driven marketing-forward approach is addressing an evolving crisis. Proceedings of the 2024 Resistance Management Conference. Rothamsted Research, England.     

Faske, T.R., Mueller, J., Becker, J.O., Bernard, E.C., Bradley, C., Bond, J., Desager, J., Eisenback, J., Grabau, Z., Hu, J.H., Kemerait, R., Koehler, A., Lawrence, K., Mehl, H., Rudolph, R.E., Sikora, E.J., Thomas, S., Walker, N., Wheeler, T., Wrather, A.J., Ye, W.M. & Zhang, L. 2023. Summarized distribution of the southern root-knot nematode, Meloidogyne incognita, in field crops in the United States. Plant Health Progress 24 (4): 522‒524.

Neher, D.A. and Darby, B.J. 2025. General community indices that can be used for analysis of nematode assemblages. Chapter 3 in Kakouli-Duarte, T. and du Preez, G. (eds) Nematodes as Environmental Indicators: from Theory to Practice. CABI. (in press)

Neher, D.A. Nematodes as indicators of soil health. Chapter 11 in Norton, J., Schimel, J., and Lindo, Z. (eds) Measuring and Assessing the Biological Health of Soils. Burleigh Dodds Science Publishing, Cambridge, UK. BDSP-BK-2024-0187 (in revision).

Pate, S., Kelly, H.M., Bernard, E. & Schumacher, L. 2023. Roundworms and dead-man's fingers: Parasitic nematodes of soybean and Xylaria necrophora. Phytopathology 113 (9S).

Paudel, R., Balkwill and K.-H. Wang. 2024. Allelopathic effects of sorghum/sorghum-sudangrass hybrids against Rotylenchulus reniformis. Plant Disease (https://doi.org/10.1094/PDIS-08-24-1668-RE).

Pugh de los Reyes, M., K.-H. Wang, and I. Shikano. Age-dependent efficacy of putative dead-end trap crops Barbarea verna and Lepidium sativum on diamondback moth, Plutella xylostella. Arthropod-Plant Interactions 18: 1227–1236.

Pitiki, M., R. Paudel, J. Mew, and K.-H. Wang. 2024. Examining susceptibility of white clover, buckwheat, black oat and forage radish as a long-term cover crop mix to Meloidogyne incognita. Nematropica 54: 41-48 (https://journals.flvc.org/nematropica/article/view/135613).

Thapa, S., Darling, E., Cole, E., Poley, K., and Quintanilla, M. 2023.  Distribution of plant parasitic nematodes in Michigan corn fields.  Journal of Nematology. https://doi.org/10.2478/jofnem-2022-0015.

Waldo, B. D., Mendes, M. L., and Crow, W. T. 2024. Subsurface seep irrigation effects omnivorous nematode vertical distribution in lysimeters. Plant Health Progress 25:185-192.

Westphal, A., Maung, Z.T.Z., Buzo, T., Brown, P.J., Leslie, C.A., Browne, G.T., Ott, N.J., McClean, A., and Kluepfel^, D.A. 2024. Identifying walnut rootstocks with resistance to multiple soil-borne plant pathogens. Eur. J. Hortic. Sci. 89, online: https://doi.org/10.17660/eJHS.2024/008

Westphal, A., Maung, Z.T.Z., Buzo, T. 2024. Susceptibility and sensitivity of pistachio rootstocks to Pratylenchus vulnus. Eur. J. Hortic. Sci 89, online https://doi.org/10.17660/eJHS/011

Extension articles:

Larger, K., B. Wiseman, J. Uyeda, L. Wong, M. Pitiki, R. Manandhar, K.-H. Wang. 2024. Sustainable pest management for small-scale organic sweet potato production in Hawaiʻi. HānaiʻAi 54: December 2024 (in press).

Trump, A. and K.-H. Wang. 2024. Using cover crops and soil aeration to mitigate impact of phytophthora in macadamia orchards. HānaiʻAi 54: June 2024. 7 pp. https://gms.ctahr.hawaii.edu/gs/handler/getmedia.ashx?moid=73343&dt=3&g=12

Wong, L., K.-H. Wang and B.S. Sipes. 2024. Benefits of an entomopathogenic fungus, Metarhizium, for enhancing sweetpotato growth and sweetpotato weevil suppression. HānaiʻAi 54: June 2024. 6 pp. https://gms.ctahr.hawaii.edu/gs/handler/getmedia.ashx?moid=73341&dt=3&g=12

Wang, K.-H., I. Shikano, and J. Uyeda. 2024. IPM for edible crops in Hawaii. HānaiʻAi 54: June 2024. 2 pp. https://gms.ctahr.hawaii.edu/gs/handler/getmedia.ashx?moid=73305&dt=3&g=12

Wang, K.-H, Q. Cytryn, R. Paudel, and B.S. Sipes. 2024. Shelterbelt trees and cacao pollinators. HānaiʻAi 53: March 2024 https://gms.ctahr.hawaii.edu/gs/handler/getmedia.ashx?moid=73209&dt=3&g=12

Dissertations:

Paudel, R. 2024. Harnessing the power of sorghum-sudangrass hybrids to transform soil health in annual row crop systems: A narrative from nematodes and beyond. University of Hawaii at Manoa, Honolulu, HI. December 22, 2024.