Brief Summary of Minutes of Annual Meeting

Objective 1. Develop, evaluate, improve, and integrate management techniques for plant-parasitic nematodes in the North Central Region to increase grower profitability.

Evaluation of SCN-resistant soybean lines and varieties:

Soybean varieties and breeding lines described as resistant to the soybean cyst nematode (SCN), Heterodera glycines, were evaluated by researchers in Iowa, Kansas, North Dakota, and Ontario for effects on SCN reproduction and soybean yields. Differences in yield and in ability to suppress reproduction of the nematode were detected among the varieties. Research in Arkansas examined soybean lines and varieties known to be resistant to SCN for resistance to the reniform nematode, Rotylenchus reniformis, and the southern root-knot nematode, Meloidogyne incognita. These two nematodes cause greater yield loss than SCN in Arkansas and much of the southern United States. At least 50 breeding lines with moderate or high resistance to SCN were found to possess a high level of resistance to the reniform nematode. Work is underway in Arkansas in collaboration with University of Missouri scientists to identify soybean genotypes resistant to all three nematodes – cyst, reniform, and southern root-knot nematode.

Scientists in Kansas and Wisconsin studied root-lesion nematodes (Pratylenchus spp.) and its effects on corn, soybean, and wheat cash crops and also cover crop plants. The host preferences of root-lesion nematode populations collected from commercial corn and wheat production fields in Kansas were investigated in replicated greenhouse trials. Populations of the nematodes were tentatively identified as Pratylenchus alleni, P. neglectus, P. scribneri, and P. thornei. Corn and wheat were good hosts for Pratylenchus alleni and P. neglectus, soybean and wheat were good hosts for P. thornei, and corn was a good host for P. scribneri.  Among cover crops, pea and vetch were moderately good hosts for P. thornei, and rye was a moderately good host for P. alleni. Therefore, caution should be used when growing pea, vetch, and rye as cover crops in fields infested with these nematode species because nematode population densities may increase.

Researchers in Wisconsin developed a composed error model to establish the impact of the root-lesion nematode, Pratylenchus penetrans, on soybean. The model was based on five data sets with 6,506 pairwise comparisons of the difference in nematode population densities associated with the corresponding difference in yield.  The model implied a nearly 2% loss in bushels per acre for every 100 nematodes per 100cc of soil present at planting. 

Evaluation of nematicidal seed treatments for management of SCN:

The effects of nematode-protectant seed treatments on SCN population densities and soybean yields were studied in field experiments in Iowa, Kansas, Missouri, North Dakota, and South Dakota. Experiments with SCN were conducted in all five states, and experiments with root-lesion nematode (Pratylenchus) were conducted only in Kansas.

Results of the experiments with seed treatments and SCN in all four states were variable, with few significant reductions in SCN numbers and few increases in soybean yields detected.

In the two experiments with root-lesion nematode on corn in Kansas, seed treatments and in-furrow applications of fluopyram both were studied.  Reductions in early season nematode population densities in corn roots were associated with one of four in-furrow application rates of fluopyram and with the standard Counter 20G treatment, but not with seed treatments.

Corky ringspot disease (CRS) on potato is caused by Tobacco rattle virus, which is vectored by stubby-root nematodes. In April 2017, an experiment was conducted in a field where CRS and Paratrichodorus allius were found to assess the efficacy of 10 experimental chemical treatment regimes on Yukon Gold potatoes. Overall, treatments with Vydate showed consistently significant reductions in disease incidence and severity of the CRS disease.

Assess intraspecific variability in nematode virulence and pathogenicity

The Wisconsin Soybean Marketing Board provides free soil testing for SCN to farmers in Wisconsin. Ten years ago, several SCN populations in the samples that were tested had elevated reproduction on SCN HG type indicator line PI 88788 (female index over 40).  Results of testing in 2017 found the level of reproduction on PI 88788 to be similar to a decade ago. The average female index on PI 88788 has not changed in the past 10 years for the state as a whole or for just the counties with the highest soybean acreage. The most common HG type was 2.5.7.

In Ohio, more than 40 SCN populations collected from 28 counties where HG typed.  Results showed that 95% of the populations were HG type 2.5.7, but several populations were HG type 1.2.3.5.6.7.  And in North Dakota, 131 soil samples were collected from 10 major soybean-producing counties; 34 samples were found to be infested with SCN. The HG types 0 and 7 were common but types 2.5.7 and 1.2.5.7 were detected.

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

A SYBR Green I-based qPCR assay was developed in North Dakota to discriminate, identify, and quantify P. penetrans in field soil. Meanwhile, a diagnostic method for direct quantification of P. allius from soil DNA using TaqMan probe and SYBR Green real-time PCR assays was developed to assist the potato industry in management of this important virus vector. This is the first efficient molecular method for direct detection and quantification of the root-lesion nematode Pratylenchus penetrans and the stubby root nematode Paratrichodorus allius from field soil DNA.

A multiyear collaborative study was initiated in Illinois to examine the potential for tile drainage to serve as a dispersion source for plant-parasitic nematodes and to determine whether bioreactors placed at the end of the tile lines affect transport. Results from initial sampling of the tile line suggest that plant-parasitic nematodes are not exported from fields via tile drainage systems. Samples taken from immediately before entry into the bioreactor were devoid of nematodes of all trophic groups, but a large abundance of unidentified copepods were present in samples collected from the inlet to the bioreactor.

Root-lesion nematodes, Pratylenchus spp., are more common in Wisconsin soybean fields than SCN.  And about 20% of the samples in which Pratylenchus spp. are present contain male nematodes. So Wisconsin researchers studied 55 male-positive populations of Pratylenchus from 49 counties to determine which amphimictic Pratylenchus species occur in the state. Males were sequenced using three different primers. For some of the populations, single-female in vitro cultures were initiated, and both males and females were examined morphologically and molecularly.  Only males from the original sample were identified molecularly for other samples.  Ninety-one percent of all samples were identified as P. penetrans.  This species is distributed throughout the state in fields with a wide range of soil texture and cropping history.

Meloidogyne incognita and four other root-knot nematode species in Arkansas (M. haplanaria, M. hapla, M. marylandi, and M. partityla) were found and identified molecularly.  

 Objective 2. Determine interactions of nematodes with other pests and pathogens and the impact of nematodes on plant and soil health.

Scientists in Michigan conducted research using nematodes as indicator to demonstrate the challenges and potential roadmaps towards managing harmful and beneficial nematodes in the same environment. The effects of cover (oil seed radish and mustard), rotation (corn and soybean), and main (sugar beet) crops on soil biophysiochemistry in sandy clay loam and loam soil were studied over two growing seasons. The crops had no effect on nematodes. Nematode abundance and community indices varied by sampling time, growing season and/or soil type. Principal component analysis showed that the crops distinctly separated by soil type and only a few nematode community indices and/or soil physiochemical parameters overlapped with crop.  Soil food web (SFW) analysis showed depleted and degraded conditions in the sandy loam soil and disturbed and approaching enrichment in the loam soil. The study suggests a roadmap to get to agrobiologically suitable soil conditions to meet industry priorities for healthy soils. Secondly, the effects of plant (PC) and animal (AC) based compost at 1, 1.5 and 2× the standard nitrogen (N) rate on processing carrot ‘Cupar’ were studied over three growing seasons. Most measured parameters varied by compost source and/or rate, but an increase in SFW structure with time was most consistent. Thirdly, the effects of amending soils either with or without bio-mix and 0, 318, or 454 kg composted chicken manure on potato cyst nematode (PCN, Globodera spp.) were studied at eight potato fields in each of Mollisol and Andisol soil groups in the highlands of Guatemala. The bio-mix (BioCopia) consisted of Guatemalan isolates of Purpureum and Bacillus applied at 1.8 kg/m² to suppress harmful nematodes. The Mollisols are at 3,200 m to 3,353 m and Andisols around 2,896 m altitude. There was no significant correlation of soil pH and percent organic matter with either yield nor the number of cysts across amendments, but yield, soil pH and organic matter were positively and significantly correlated in Andisols, suggesting differences between the soil groups. As part of assessing integrated efficiency of the soil amendment treatments and potential sustainability of the outcomes, cyst (x-axis) and yield (y-axis) were expressed as a percent of control and fitted to the fertilizer use efficiency (FUE) model, and the data fell into Quadrant B – soil amendments are increasing cyst population density and yield in both soil groups. The data suggest the need for additional measures for managing PCN without compromising biological processes that increase organic matter or yield response.    

A multi-investigator project including a mycologist, nematologist, entomologist and soil scientist was initiated at the University of Illinois to examine the effects of N management schemes in a conventionally managed, tiled corn production system on soil health properties. Soil samples were taken from two nitrogen rates along the tile lines and subdivided for measurement of mycorrhizal fungi, nematode communities, arthropod communities, and soil chemical and physical properties. Analysis of these data include identification of changes in plant-parasitic nematode populations (identified to genera) and free-living nematodes (identified to family) at five time points from planting to harvest. Data from this project will be combined with an ongoing project using remote sensing to reduce N inputs.

Georeferenced samples in Wisconsin revealed that the distribution of Pratylenchus penetrans is aggregated within fields. Data from 11 commercial fields were used to study the relationship between nematodes and 30 edaphic factors. Three models were developed: one for nematode density in 100 cm³ soil, one for nematode density in root fragments contained within 100 cm³ soil, and one for the nematodes occupying both soil and root habitats in 100 cm³ soil.  Each model contained some unique variables, but there were common factors among two of the three models including a positive influence of manganese and elevation and a negative influence of total nitrogen and potassium. The model confirmed farmer perceptions that nematode population densities are greater on the tops of hills and in areas with low levels of nitrogen fertilizer. To our knowledge, the influence of manganese on root-lesion nematodes has not been reported before. 

Research is underway in both North Dakota and South Dakota to study the interactions between the SCN and Fusarium spp. Work in North Dakota showed that overall, high population densities of SCN may increase the damage from these root rot fungi when the fungal inoculum levels are low to moderate. Also, there are experiments being conducted in Dr. Heike Bucking’s laboratory at South Dakota State University studying interaction between SCN and mycorrhizae.

In Ohio, research focused on investigating the use of Pseudomonas spp. to control SCN.  A third year of microplot studies is underway.   More than 10 different strains of Pseudomonas alone and in combinations are being tested.  Previous work indicated that some strain combinations were better at reducing SCN than others as a soil drench and as a seed coat.   Another set of microplot studies is investigating how corn in rotation with soybean can affect SCN populations.  Using the Nested Associated Mapping Maize lines (inbred maize lines), it has been observed that some maize lines can impact SCN, either through induced or delayed hatching.  A third year of microplot studies is currently underway to determine the impact maize roots can have on SCN and whether maize genetics can be manipulated to reduce SCN in non-soybean cropping seasons.

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

The results of the aforementioned surveys to determine the presence of root-lesion nematodes and SCN population densities and/or its virulence phenotypes (HG type) were shared with farmers and crop advisors. Similarly, results of field experiments with nematode-protectant seed treatments and soil-applied nematode management products were shared with crop farmers and crop advisors. And lists of SCN-resistant varieties and/or their performance were compiled and shared with farmers.

Many scientists involved in this project taught classes and also gave presentations to farmers and agribusiness personnel and crop advisors using results of the research conducted in the project. And most of the scientists involved in the project are participating in the SCN Coalition, a national effort to mitigate yield loss caused by SCN, to address the loss of effective resistance conferred by PI88788, and to increase active management of SCN. Greater detail and more information about the SCN Coalition are available online at TheSCNCoalition.com.

            Also, Nathan Schroeder secured irreplaceable electron micrographs produced by Dr. Burton Endo during his 30-year career with the USDA studying ultrastructure of economically important plant-parasitic nematodes, including SCN. Much of these data were never published, and the micrographs were left unorganized and unprotected until Schroeder saved them. The micrographs will be digitized and those that had previously been unpublished will be made publicly available.

EXTRAMURAL FUNDING FOR PROJECT ACTIVITIES

Federal Grants Programs:

• USDA/NIFA/SCRI grant titled “Enhancing Soil Health in U.S. Potato Production Systems”, multi-state, approximately 8 million over four years, approximately $550,000 to Wisconsin.
• USDA-NIFA-Specialty Crop Research Initiative, $94,829 to North Dakota.
• NIH-NIGMS grant titled “Stress-induced phenotypic plasticity in elegans,”$1,368,350 to Illinois.
• NSF, REU Site grant titled “Phenotypic plasticity research experience for community college students,” $302,850 to Illinois.
• USDA-SBIR: Phase II – “System for biological control of soybean cyst nematode”, $200,000 to Ohio.

State Grants Programs:

• North Dakota Department of Agriculture/USDA Specialty Crop Grant Program: $54,033 for FY18.
• Ohio Department of Agriculture: Specialty Crop Grant Program: $120,000 for FY18-19.

National Commodity Organizations:

• United Soybean Board – to all states involved in the SCN Coalition: $260,000 for FY18 and $586,880 for FY19
• United Soybean Board – $586,880 total for FY18, $15,000 to Wisconsin

Regional Commodity Organizations:

• North Central Soybean Research Program - to all states involved in the SCN Coalition: $321,805 for FY18 and $300,000 for FY19

State Commodity Organizations:

• Illinois Corn Growers Association: $75,000 for FY18
• Iowa Soybean Association: $139,798 for FY18
• Kansas Soybean Commission: $69,000 for FY18
• Nebraska Corn Board: $55,000 each for FY18, FY19
• North Dakota Soybean Council, Northern Plains Potato Growers Association, and Sugarbeet Research and Education Board of MN and ND: $135,960 for FY18
• Ohio Soybean Council: $50,000 for FY18
• South Dakota Soybean Research and Promotion Council funding of $77,576 for FY18
• Wisconsin Potato and Vegetable Growers’ Association: $12,000 for FY18
• Wisconsin Soybean Marketing Board: $39,362 for FY18

Refereed journal articles

Akintayo, A., Tylka, G., Singh, A.K., Singh, A., Ganapathysubramanian, B., and Sarkar, S. 2018. A deep learning framework to discern and count microscopic nematode eggs. Scientific Reports 8:9145. DOI:10.1038/s41598-018-27272-w

Androwski R.A., Flatt K.M., and Schroeder, N.E. 2017. Phenotypic plasticity and remodeling in the stress-induced C. elegans dauer. WIREs Developmental Biology. 6:e278. doi: 10.1002/wdev.278

Baidoo, R., Yan, G.P., Nagachandrabose, S., and Skantar, A.M. 2017. Developing a real-time PCR assay for direct identification and quantification of Pratylenchus penetrans in soil. Plant Disease 101: 1432-1441.

Baidoo, R., Yan, G.P., Nelson, B., Skantar, A.M., and Chen, S. 2017. Use of chemical flocculation and nested PCR for Heterodera glycines detection in DNA extracts from field soils with low population densities. Plant Disease 101: 1153-1161.

Beeman, A.Q. and Tylka, G.L. 2018. Assessing the effects of Ilevo and Votivo seed treatments on reproduction, hatching, motility, and root penetration of the soybean cyst nematode, Heterodera glycines. Plant Disease 102:107-113. dx.doi.org/10.1094/PDIS-04-17-0585-RE

Bissonnette, K.M., Marett, C.C., Mullaney, M.P., Gebhart, G.D., Kyveryga, P., Mueller, T.A. and Tylka, G.L. 2018. Effects of Clariva Complete Beans seed treatment on Heterodera glycines reproduction and soybean yield in Iowa. Plant Health Progress 19:1-8. doi.org/10.1094/PHP-08-17-0043-RS

Clifton, E.H., Tylka, G.L., Gassmann, A.J., and Hodgson, E.W. 2018. Effects of host-plant resistance and seed treatments on soybean aphid (Aphis glycines Matsumura), soybean cyst nematode (Heterodera glycines Ichinohe), and soybean yield. Pest Management Science DOI: 10.1002/ps.4800

Habteweld, A.W., Brainard, D.C., Kravchenko, A.N., Grewal, P.S. and Melakeberhan, H. 2018. Effects of plant and animal waste-based compost amendments on soil food web, soil properties, and yield and quality of fresh market and processing carrot cultivars. Nematology 20, 147-168.

Han, Z., Thapa, S., Reuter-Carlson, U., Reed, H., Gates, M., Lambert, K.N., and Schroeder, N.E. 2018. Immobility in the sedentary plant-parasitic nematode H. glycines is associated with remodeling of the neuromuscular system. PLOS Pathogens. (In Press)   

Huang, D., Yan, G.P., Gudmestad, N., and Skantar, A. 2017. Quantification of Paratrichodorus allius in DNA extracted from soil using TaqMan Probe and SYBR Green real-time PCR assays. Nematology 19: 987-1001.

Huang, D., and Yan, G.P. 2017. Specific detection of the root-lesion nematode Pratylenchus scribneri using conventional and real-time PCR. Plant Disease 101: 359-365.

Huang, D., Yan, G.P., and Skantar, A.M. 2017. Development of real-time and conventional PCR assays for identifying stubby root nematode Paratrichodorus allius. Plant Disease 101: 964-972.

Hung X.B., and Schroeder, N.E. 2018. Post-embryonic ventral nerve cord development and gonad migration in Steinernema carpocapsae. Journal of Nematology 50:27-32.

Jensen, J.P., Beeman, A.Q., Njus, Z.L., Kalwa, U., Pandey, S. and Tylka, G.L. 2018. Movement and motion of soybean cyst nematode, Heterodera glycines, populations and individuals in response to abamectin. Phytopathology 108:885-891. dx.doi.org/10.1094/PHYTO-10-17-0339-R

Jensen, J.P., Kalwa, U., Pandey, S., and Tylka, G.L. 2018. Avicta and Clariva affect the biology of the soybean cyst nematode, Heterodera glycines. Plant Disease dx.doi.org/10.1094/PDIS-01-18-0086-RE

Kobayashi Leonel, R., Mueller, D., Harbach, C.J., Tylka, G.L. and Leandro, L. 2017. Susceptibility of cover crop plants to Fusarium virguliforme, causal agent of soybean sudden death syndrome, and Heterodera glycines, the soybean cyst nematode. Journal of Soil and Water Conservation 72:575-583. doi:10.2489/jswc.72.6.575

McCarville, M.C., Marett, C.C., Mullaney, M.P., Gebhart, G.D. and Tylka, G.L. 2017. Increase in soybean cyst nematode virulence and reproduction on resistant soybean varieties in Iowa from 2001 to 2015 and its effects on soybean yields. Plant Health Progress 146-155. dx.doi.org/10.1094/PHP-RS-16-0062

Melakeberhan, H., Maung, Z.T.Z., Lee, C-L., Poindexter, S., and Stewart, J. 2018. Soil type-driven variable effects on cover- and rotation-crops, nematodes and soil food web in sugar beet fields reveal a roadmap for developing healthy soils. European Journal of Soil Biology 85, 53-63.

Qi, M., Zheng, W., Zhao, X., Hohenstein, J., Kandel, Y., O'Conner, S., Wang, Y., Du, C., Nettleton, D., MacIntosh, G., Tylka, G., Wurtele, E., Whitham, S., and Li, L. 2018. QQS orphan gene and its interactor NF-YC4 reduce susceptibility to pathogens and pests. Plant Biotechnology Journal doi.org/10.1111/pbi.12961

Salazar, M.M. and Schroeder, N.E. 2018. Using a gall index to explore root-knot nematode biology and epidemiology. Plant Health Instructor. (In Press).

Tylka, G.L., and Marett, C.C. 2017. Known distribution of the soybean cyst nematode, Heterodera glycines, in the United States and Canada - 1954 to 2017. Plant Health Progress 18:167-168. dx.doi.org/10.1094/PHP-05-17-0031-BR

Walsh, E., Elmore, J.M., and Taylor, C.G. 2017. Root-knot nematode parasitism suppresses host RNA silencing. Molecular Plant-Microbe Interactions 30: 295-300.

Wei, J.-Z., Siehl, D.L., Oral, J., Taylor, C.G., and Wu, G. 2017. An enterotoxin-like binary protein from Pseudomonas protegens with potent nematicidal activity. Applied and Environmental Microbiology 83: e00942-17.

Yan, G.P., Plaisance, A., Chowdhury, I., Baidoo, R., Upadhaya, A., Pasche, J., Markell, S., Nelson, B., and Chen, S. 2017. First report of the soybean cyst nematode Heterodera glycines infecting dry bean (Phaseolus vulgaris L.) in a commercial field in Minnesota. Plant Disease 101:391.

Yan, G.P., Plaisance, A., Huang, D., Chowdhury, I.A., and Handoo, Z.A. 2017. First report of the new root-lesion nematode Pratylenchus sp. on soybean in North Dakota. Plant Disease 101:1554.

Yan, G.P., Plaisance, A., Huang, D., and Handoo, Z.A. 2017. First report of the spiral nematode Helicotylenchus microlobus infecting soybean in North Dakota. Journal of Nematology 49:1.

Yan, G.P., Plaisance, A., Huang, D., Handoo, Z.A., and Chitwood, D.J. 2017. First report of a new, unnamed lesion nematode Pratylenchus sp. infecting soybean in North Dakota. Plant Disease 101: 1555.

Ye, W., Foye, S., MacGuidwin, A.E., and Steffan, S. 2018. Incidence of Oscheius onirici (Nematoda: Rhabditidae), a potentially entomopathogenic nematode from the marshlands of Wisconsin, USA.  Journal of Nematology 50: DOI: 10.21307/jofnem-2018-004

Abstracts

Acharya, K., Yan, G.P., Plaisance, A., and Berti, M. 2017. Reducing soybean cyst nematode, Heterodera glycines populations by planting cover crops in infested soils. American Phytopathological Society North Central Division Meeting, Champaign, Illinois, June 14-16.

Baidoo, R. and Yan, G.P. 2017. Developing a real-time PCR assay for direct identification and quantification of soybean cyst nematode, Heterodera glycines, in soil. Pages 38-39 in Abstracts of 56^th Annual Meeting of the Society of Nematologists, Williamsburg, Virginia, August 13-16. 

Baidoo, R. and Yan, G.P. 2017. Molecular detection and quantification of root-lesion nematode, Pratylenchus penetrans from soil using real-time PCR. Phytopathology 107:S5.55.

Basnet, P., and Byamukama, E. 2018. Reproduction of Heterodera glycines types on weed hosts: field pennycress, henbit and purple deadnettle in South Dakota. North Central American Phytopathological Society Meeting, Fargo, ND. 3/12-3/14.

Bissonnette, K., Marett, C., Mullaney, M., Gebhart, G., and Tylka, G.L.  2017. Effect of a bionematicide seed treatment containing Pasteuria nishizawae on Heterodera glycines reproduction and soybean yield in Iowa in 2014 to 2016. Phytopathology 107(S5):167. doi.org/10.1094 / PHYTO-107-12-S5.165

Chowdhury, I.A., Yan, G.P., and Plaisance, A. 2017. Evaluating virulence types of soybean cyst nematode populations in infested fields in North Dakota. Proceedings of the North Dakota Academy of Science 71:27. 109^th Annual Meeting of North Dakota Academy of Science, Grand Forks, ND, April 28-29.

Chowdhury, I., Yan, G.P., and Plaisance, A. 2017. Plant-parasitic nematodes on corn (Zea mays) and their association with abiotic factors in North Dakota. Pages 48-49 in Abstracts of 56^th Annual Meeting of the Society of Nematologists, Williamsburg, Virginia, August 13-16.

Harbach, C.J. and Tylka, G.L. 2017. Investigating the interactions of the soybean cyst nematode with cover crops under greenhouse conditions. Phytopathology 107(S5):167. doi.org/10.1094 / PHYTO-107-12-S5.165

Huang, D., Yan, G.P., Plaisance, A., Gudmestad, N.C., Whitworth, J., Frost, K., Brown, C.R., Hafez, S.L., Handoo, Z.A., and Skantar, A.M. 2017. Molecular detection, identification and quantification of Paratrichodorus allius from nematode individuals, communities and soil DNA. Pages 70-71 in Abstracts of 56^th Annual Meeting of the Society of Nematologists, Williamsburg, Virginia, August 13-16.

KC, A., Yan, G.P., Plaisance, A., Underdahl, J., Friskop, A., and Elias, E. 2017. Varietal screening of wheat crop against root-lesion nematode in North Dakota. American Phytopathological Society North Central Division Meeting, Champaign, Illinois, June 14-16.

Ozbayrak, M., Todd, T., Harris, T., Powers, K., Sutton, L., Higgins, R., Mullin, P. and Powers, T.O.  2018.  DNA barcoding of Pratylenchus from agroecosystems in the Northern Great Plains of North America.  Proceedings of the Annual Meeting of the Society of Nematologists, Albuquerque, NM, page 81.

Plaisance, A., Yan, G.P., Peterson, D., and Gudmestad, N. 2017. Chemical applications to control stubby root nematodes and corky ring spot disease of potato. Proceedings of the North Dakota Academy of Science 71:39. 109^th Annual Meeting of North Dakota Academy of Science, Grand Forks, ND, April 28-29.

Saeed, I. A., Pack, G.D., Zhu, J., and MacGuidwin, A.E. 2018. Distribution of Pratylenchus penetrans in sand and loamy sand soils in relation to edaphic factors. Nematropica

Saikai, K., and MacGuidwin, A. 2018. Modeling the damage function of Pratylenchus penetrans on soybean using a nested error component model.  Journal of Nematology 50:

Sanchez, A., Alverez, G.I., Sipes, B.S., Kakaire, S., Lee, C.-L., Sacbaja, A., Chen, C. and Melakeberhan, H. 2018. Assisting smallholder farmers in adopting integrated nematode-soil health management: IV – Changes in cyst nematode population density and potato yield. Society of Nematologists 57th Annual Meeting Abstracts: 89-90.

Thapa, S., Gates, M.K. Reuter-Carlson, U., and Schroeder, N.E. 2018. Epidermal seam cell lineages are associated with pyriform body shape in cyst and root-knot nematodes. Society of Nematologists Annual Meeting. Albuquerque, NM.

Upadhaya, A., Yan, G.P., Plaisance, A., Secor, G., and Robinson, A. 2017. Effects of co-inoculation with Pratylenchus penetrans and Fusarium oxysporum on potato emergence, growth and yield. Page 120 in Abstracts of 56^th Annual Meeting of the Society of Nematologists, Williamsburg, Virginia, August 13-16.

Upadhaya, A., Yan, G.P., Plaisance, A., Pasche, J., and McPhee, K. 2017. Pin nematode: a potential threat to pea production in North Dakota. Proceedings of the North Dakota Academy of Science 71:45. 109^th Annual Meeting of North Dakota Academy of Science, Grand Forks, ND, April 28-29.

Upadhaya, A., Yan, G.P., Plaisance, A., and Pasche, J. 2017. Plant-parasitic nematodes on field pea and their association with soil edaphic factors in North Dakota. American Phytopathological Society North Central Division Meeting, Champaign, Illinois, June 14-16.

Yakha, J.K., Kafle, A., Byamukama, E., Mathew, F., and Bucking, H. 2018. Plant microbe interactions - A new strategy to reduce soybean cyst nematode infestations. North Central American Phytopathological Society Meeting, Fargo, ND. 3/12-3/14.

Yan, G.P. and Baidoo, R. 2017. Molecular detection of soybean cyst nematode in North Dakota. Phytopathology 107:S1.9. http://dx.doi.org/10.1094/PHYTO-107-1-S1.1. Soybean Cyst Nematode Conference, Coral Gables, Florida, December 13-15.

Yan, G.P., Huang, D., and Plaisance, A. 2017. Developing real-time PCR assays for identification and quantification of stubby root nematode Paratrichodorus allius in soil. Page 3 in SCRI Potato Necrotic Virus Project Abstracts in Annual Meeting WERA89, San Diego, CA, March 8-9.

Yan, G.P., Huang, D., Plaisance, A., Gudmestad, N.C., Whitworth, J., Frost, K., Brown, C.R., Ye, W., Crow, B., and Hafez, S.L. 2017. Species and population densities of stubby root nematodes from multiple states in the United States. Phytopathology 107:S5.96.

Yan, G.P., Plaisance, A., Huang, D., and Handoo, Z.A. 2017. First detection of two new, unnamed root-lesion nematodes Pratylenchus spp. on soybean in North Dakota. Phytopathology 107:S5.99. https://doi.org/10.1094/PHYTO-107-12-S5.1, American Phytopathological Society Annual Meeting, San Antonio, TX, August 5-9.

Yan, G.P., Plaisance, A., Huang, D., and Handoo, Z.A. 2017. First detection of the spiral nematode Helicotylenchus microlobus on soybean in North Dakota. Phytopathology 107:S5.99.

Extension Publications

Bissonnette, K.M. and Tylka, G.L. 2017. Seed treatments for soybean cyst nematode. Iowa State University Extension Publication CROP 3142, 1 p.

Byamukama, E. and Tande, C. 2018. Has your soil been tested for SCN? What is your latest number? SDSU Extension iGrow online http://igrow.org/agronomy/soybeans/has-your-soil-been-tested-for-scn-what-is-your-latest-number/

MacGuidwin, A., Smith, D., and Conley, S.P. 2018.  Fall is still a good time to sample for SCN and other plant parasitic nematodes.  Wisconsin Crop Manager September Issue

Markell, S. and Yan, G.P. 2017. Soybean cyst distribution in North Dakota. North Dakota State University Cooperative Extension Service Publication - Crop and Pest Report. Issue 2: Pp 3-5.

Markell, S., Harveson, R., and Pasche, J. 2017. Dry Edible Bean Disease Diagnostic Series. North Dakota Cooperative Extension Service Publication PP1820. 32 Pp.

Markell, S., Yan, G.P., Nelson, B., Pasche, J., and Harveson, R. 2017. Soybean cyst nematode soil sampling (PP1820-5) in: Dry Edible Bean Disease Diagnostic Series. North Dakota Cooperative Extension Service Publication PP1820. Pp. 11-12.

Mueller, D., Robertson, A., Sisson, A., Tylka, G., and Licht, M. 2017. Corn Diseases. Iowa State University Extension and Outreach. IPM 0005, 48 pp.

Pasche, J., Yan, G., Nelson, B., Markell, S., and Harveson, R. 2017. Soybean cyst nematode (SCN) (PP1820-4) in: Markell, S., Harveson, R., and Pasche, J. Dry Edible Bean Disease Diagnostic Series. North Dakota Cooperative Extension Service Publication PP1820. Pp. 9-10.

Tylka, G.L. and Mullaney, M.P. 2017. Soybean cyst nematode-resistant soybeans for Iowa. Iowa State University Extension Publication PM 1649, 27 pp.

Tylka, G.L., Gebhart, G.D., Marett, C.C., and Mullaney, M.P. 2017. Evaluation of soybean varieties resistant to soybean cyst nematode in Iowa – 2017. Iowa State University Extension, publication IPM‑52, 23 pp.

Yabwalo, D., Geppert, R., and Byamukama, E. 2018. 2017 soybean foliar fungicide and nematicide seed treatment trial summaries. iGrow online.

Book chapters

Bird, G.W., Zasada, I.A., and Tylka, G.L. 2018. Role of population dynamics and damage thresholds in cyst nematode management. Pages 101-127 in R.N. Perry, M. Moens, and J.T. Jones, eds. Cyst Nematodes. CAB International.

Blok, V.C., Tylka, G.L., Smiley, R.W., de Jong, W.S. and Daub, M. 2018. Resistance breeding. Pages 174-214 in R.N. Perry, M. Moens, and J.T. Jones, eds. Cyst Nematodes. CAB International.

Little, C., Bandara, A.Y., Todd, T.C., and Perumal, R. 2018.  Diseases of sorghum: stalk, root and other diseases.  Pp. in W. Rooney (ed.).  Achieving Sustainable Cultivation of Sorghum Volume 1: Genetics, Breeding and Production Techniques. Burleigh Dodds Series in Agricultural Science.

MacGuidwin, A.E. 2018. Nematodes important to agriculture in Wisconsin, in Plant Parasitic Nematodes in Sustainable Agriculture of North America Vol. 2 – Northeastern, Midwestern, and Southern U.S.A., Subbotin, Sergei A., and Chitambar, John J. (eds), Springer.

Marion, O. H., Jacob, J., Brown, P., and Yan, G.P. 2017. Wheat pests: introduction, rodents and nematodes, in P. Langridge (ed.), Achieving sustainable cultivation of wheat Volume 1: Breeding, quality traits, pests and diseases, 2017, Burleigh Dodds Science Publishing, Cambridge, UK (ISBN: 978 1 78676 016 6; www.bdspublishing.com), pp. 443-466.