Brief Summary of Minutes of Annual Meeting

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.

Four themes of studies have been completed as part of providing growers with the most recent information on nematode management in the Midwest cropping systems. These included replicated field (IA, MN, ND, ON) and greenhouse (KS, MN, ND, ON) trials evaluating the status of commercially available soybean varieties and new breeding lines of different maturity groups against soybean cyst nematode (SCN) populations or HG Types.  These trials are conducted in collaboration with breeders and agronomists.  A total of 177, 131, 88, 40, and 50 cultivars were evaluated in IA, KS, MN, ND, and ON, respectively.  Field trials were naturally infested with SCN, whose HG type characterizations are on-going under controlled conditions.  The greenhouse studies included HG Type 7, HG Type 2.5.7, and HG Type 1.2.3.5.6.7 (KS) and HG type 1 and HG type 2 (MN) known for their variable virulence to PI 88788, major resistance source in the majority of soybean varieties in the US. In MN, a few lines were identified as resistant to HG type 1 and HG type 2.  Information generated from these trials has been provided to stakeholders (see Objective 3). 

The second theme is identifying impact of alternative hosts used as cover crops on managing SCN and other nematodes. In IN, screening of several cover crops against an HG type 2.5.7 population of SCN under greenhouse conditions showed none or very few cysts developed on these cover crops. In MN, about 120 pennycress lines from the Minnesota breeding program were tested for resistance to SCN.  SCN reproduced in all of them less than the susceptible soybean variety (Sturdy), but no highly SCN-resistant line was found. Tests for reproduction and pathogenicity of SCN on camelina, another cover crop, showed no reproduction.

The third theme is screening the status of cereal crops against Pratylenchus spp. (root-lesion nematode). The host preferences of root-lesion nematode (RLN) populations collected from commercial corn and wheat production fields in Kansas were investigated in replicated greenhouse trials.  Populations represent four molecular (COI) clades tentatively identified as Pratylenchus alleni, P. neglectus, P. scribneri, and P. thornei.  Both corn and wheat appear to be optimal hosts for all populations except P. scribneri, for which wheat was a poor host, and one population of P. neglectus, for which corn was a poor host.  Sorghum and soybean were generally poor hosts for all populations except P. thornei.  In ND, 15 hard red spring wheat and five durum wheat varieties were screened in clay loam soil infested with P. neglectus. The varieties evaluated showed a range of RF values from 0.5 to 5.4 for the first experiment, and 0.1 to 4.1 for the second experiment. None of varieties were consistently classified as resistant, and the durum variety Mountrail was consistently classified as susceptible. More experiments will be conducted to confirm the resistance level of each variety.

The fourth theme is identifying nematodes other than SCN present in the fields from where samples are submitted or collected. In the course of processing 1,200 soil and plant samples submitted to the Purdue Nematology Laboratory, new and uncommon nematodes in IN were discovered. These include two new nematode in corn (Vittatidera zeaphila) and turf (Heterodera iri) and uncommon on soybean (Meloidogyne hapla), mint (Longidorus sp.), corn (Trichodorus sp.) and alfalfa (Ditylenchus spp.).

 B. Assess intraspecific variability in nematode virulence and pathogenicity.

Understanding the presence and distribution of SCN HG types in production landscape and the biology of the HG types are major challenges. The team has been applying multi-pronged approaches. These include collecting soil from field studies, surveys, and samples submitted for analyses by growers and screening for SCN presence, and building cultures from the positive samples for HG typing under greenhouse conditions using indicator varieties (IA, IN, KS, MN, SD, OH, ON). The results vary by state. For example, in KS, 67% and 15% of SCN populations exhibit a female index (FI) on PI 88788 greater than 10% and 30%, respectively.  Nearly two-thirds of the Kansas SCN populations exhibit an FI greater than 30% on PI 88788-derived cultivars. In MN, 131 out of 200 soil samples collected across Minnesota in July 2013 were positive for SCN. Out of the positive samples, 89 populations were tested for their virulence phenotypes. In OH, over 40 populations were screened and over 95% of them had a female index >10% for HG type 2.5.7.   In ND, samples from 28 fields were assessed and positive for SCN. Theses populations were HG type 7 (36%), HG type 2.5.7 (25%), HG type 5.7 (18%), HG type 0 (14%), and HG type 2.7 (7%), showing the SCN populations in ND that can successfully reproduce on PI 88788, the most widely used source of resistance. In SD, 73 SCN populations were established from SCN-positive fields. Based on the SCN population differential set (FI >10%), HG types 0, 2.5.7 and 7 were the most predominant populations. Overall, 63% of the SCN populations tested had FI>10% on PI548316, 25% on PI88788 and 19% on PI 209332. No SCN populations had FI > 10% on PI437654. These results indicate some of the SCN populations can reproduce on PI88788, the most commonly used source of SCN resistance genes.  In WI, 44 Hg types have been established from 146 soil samples representing 22 counties in 2016.  The majority of the SCN populations were adapted to the PI88788 source of resistance, as has been the case in previous years.  Thirty-three percent of the SCN populations tested had a FI greater than 30 for PI 88788.

Another aspect has been a more basic approach to understand the biology from hatching mechanisms of SCN to causing infection (IL).  Studies show that SCN is more likely to hatch in the presence of soybean root exudates. A pre-hatch developmental timeline was developed. Developmentally synchronized eggs were used to test the effect of soybean-root exudates on the rate of pre-hatch development. No difference was found in pre-hatch development between nematodes exposed to water versus soybean root exudate.  Further examination of the effect of the commonly used hatching stimulant ZnCl₂ on subsequent infection and reproduction of SCN showed that ZnCl₂ has a deleterious effect on subsequent infection. Specifically, SCN that hatched in ZnCl₂ produced significantly fewer females and offspring.  

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

Nematode population density suppression using biological formulations and combination of corn-soybean rotation (ON), and nematicides (IA, IN, MN, ND, SD, WI) were tried. In ON, testing in-vivo commercial biological control products for suppressing SCN populations affords possible environmentally safer alternatives. Results from commercial soil additives are incomplete at this time for reporting. Investigation of newly-isolated Pseudomonas for the control of SCN is ongoing (OH).  Identification of different SCN active bacteria strains under greenhouse conditions are being tested under microplot conditions.  A consortium of four different SCN-active Pseudomonas was shown to reduce SCN reproduction by as much as 30% when applied as a soil drench.

  Three corn hybrids grown in 3 rotation sequences were compared to resistant soybean varieties and fallow unplanted check in microplots. The 5-year study is near completion and results are beginning to indicate advantageous differences among hybrids for SCN suppression. Research conducted in Ohio also showed that certain corn varieties can also impact SCN reproduction.  A screen of the Nested Associated Mapping Lines (NAM) of maize representing over 20 different maize lines showed that different maize lines could impact SCN reproduction when planted in rotation with soybean.   The results were replicated in the lab, greenhouse and under microplot conditions.  How, certain maize lines affect SCN hatching is still unknown but raises the possibility that certain corn varieties when planted in rotation with soybean could prove advantageous for SCN control.

An additional study was initiated in 2016 to test the effect of trap cropping SCN during their reproductive cycle. Susceptible soybeans were planted and destroyed using 3 different planting cycles and compared to a resistant check. Results indicate trends in SCN population suppression and project was expanded in 2017.

The effects of several nematicides applied to the soil and/or as seed treatment for managing SCN (IA, IN, MN, SD) root-lesion (WI) and corky ringspot of potatoes (ND) were studied under greenhouse and/or field conditions. The results from the soybean studies were largely negative.  For example, after several experiments in IA there were no significant differences in soybean yields or in SCN reproductive factors (final SCN egg population density ÷ initial SCN egg population density) between Clariva Complete Beans and CruiserMaxx Advanced plus Vibrance or between Poncho/Votivo + Ilevo and Poncho/Votivo in any of the experiments in 2016. In IN, evaluation of several seed treatment products from two chemical companies against an HG type 2.5.7 population of SCN showed no significant under greenhouse conditions. In SD, seed treatments of Clariva Complete Beans, Ilevo, Avicta complete beans were compared to a CruisserMaxx treatment and a non-treated control (naked seed) on SCN resistant cultivar (S12H2-PI88788 source) and a SCN-susceptible cultivar (S10P9).  Nematicide seed treatments did not significantly increase yield or reduce SCN numbers compared to non-treated seed for the two soybean cultivars. However, the resistant cultivar had numerically higher grain yield than the susceptible cultivar. In WI, soybean seed treatment with a Bayer product (# 6: Ilevo plus “something”) significantly reduced Pratylenchus penetrans numbers at 52 days after planting compared to the control in growth chamber studies. In ND, corky ringspot disease on potato is caused by Tobacco rattle virus that is vectored by stubby-root (Paratrichodorus allius) nematodes. It can result in up to 55% of potatoes from a harvest to be unmarketable. In April 2016, a field where corky ringspot and its vector were found was used to test the efficacy of 10 experimental chemical treatment regimes on Yukon Gold potatoes. Treatments utilized contact and systemic insecticides, nematicides, and biological agents such as Movento, Majestene, Vydate, Dyne-Amic, Velum Prime, and Serenade. Overall, treatments with Vydate showed consistent significant reductions in disease incidence and severity.

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

Sampling to detect nematodes from soil, where multi-taxa presence is the norm, and identifying them, and establishing their relationship with their plant hosts and the soil environment in a timely manner are major challenges managing nematodes.  In WI, the question of sampling tested on four commercial fields for sampling using two criteria: 1) the fields had a history of potato and the potato early dying disease but had not been fumigated for at least two years, and 2) the fields had been mapped for electrical conductivity or another measure of soil factors.  Samples were collected in the spring before tillage or planting in a uniform pattern either covering the entire field, or a portion of the field that represented variation in soil factors. Relationships among soil factors and potato pathogens were conducted using regression and correlation analyses for those fields with greater than 50% of the sampling locations positive for the pathogen.

Morphometrics is the most common way of identifying most nematodes, which is tedious and difficult when distinguishing SCN and other members of the H. schachtii sensu stricto group as well as the root-lesion genus. In ND, new molecular tools have been developed to detect SCN, stubby-root and root-lesion nematodes. The first molecular assay detects low population densities of SCN in field soils and differentiating it from other species. The assay was validated using 35 field soil samples. Grinding the field soil coupled with PCR inhibitor removal by AlNH₄(SO₄)₂.12H₂O treatment of soil DNA extracts followed by nested PCR enabled SCN detection as low as 12 SCN eggs/200 g soil. The PCR assay not only provides a sensitive method for SCN detection at low densities but also provides a discrimination method for SCN from other closely related nematodes.  The second assay detects stubby-root.  A rapid and reliable molecular diagnosis of this nematode targeting ITS rDNA has been established. The PCR assays amplified DNA of stubby root nematodes isolated from 18 soil samples, which were confirmed as P. allius by sequencing. Both conventional PCR and real-time PCR assays amplified target nematodes from nematode individuals and also complex nematode communities. The third molecular assay detects Pratylenchus scribneri, a plant-parasitic root-lesion nematode causing economic damage to various crops. Conventional and real-time PCR assays with new species-specific primers were used. Both PCR assays identified P. scribneri and distinguished it from P. penetrans and P. neglectus isolated from field samples. The developed PCR assays are suitable for use in diagnostic laboratories and detection of field infestations with this nematode species.

Breeding soybeans for adaptation to environment and emerging pests and concurrent development of molecular marker selection tools is of major importance in Canadian agriculture. The ON team is working closely with multi-disciplinary teams and institutions to identify new and unique resistant sources for incorporation into breeding of Early Maturing soybean varieties and Food Grade types that are lacking yield protection from SCN infestations.

2. Determine interactions of nematodes with soil microbiota and other pests and pathogens on plant and soil heath.

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

The interactions of SCN and sudden death syndrome (SDS) in soybean (IN, ON) and potato early die (PED) caused by P. penetrans and Fusarium oxysporun (SD) or Verticillium dahlia (WI) in potato production were investigated.  In IN, most of the fields with SDS symptoms were infested with high population of HG type 2.5.7 of SCN.  In ON, SCN population densities of 4,000-5,000 eggs/100g soil natural infestation in the field showed significant inverse correlation between SDS severity and soybean yield. 

In ND, a microplot study was carried out in 2016 to evaluate the effects of P. penetrans and F. oxysporum separately and in combination on emergence, growth and yield of the potato cultivar Red Norland. P. penetrans (200, 800 or 2,000 nematodes per 5 kg of soil) and F. oxysporum (5, 10 or 20 colonized barley seeds per 5 kg soil) were either inoculated individually or co-inoculated.  Preliminary results showed that presence of both pathogens at the high level can cause more negative effects on potato emergence, growth, yield, and disease incidence and severity compared to presence of only one pathogen at the same level.  In WI, yield of potato was correlated with the initial inoculum of lesion nematodes, the percentage of stems infected with Verticillium during modseason, and disease progress in nonfumigated plots.  Only disease was correlated with yield in the fumigated plots.  Disease, in turn, was correlated with the initial level of nematodes in both fumigated and nonfumigated plots.

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

The relationship between nematode population density and yield loss continues to be continues to be challenging. In WI, P. penetrans applied at 0 – 100 nematodes per 100 cc soil from three field plots showed no significant correlations between nematode and yield possibly due to low inoculum density.

Achieving soil heath using many agronomic practices including cover and rotation crops and soil amendments is a cross-cutting priority in US Midwest cropping systems.  Many Brassica such as oilseed radish and mustard, cereals such as oats, wheat and corn, and legumes such as vetch, soybean and beans, are among the commonly used cover- and/or rotation-crops. The main challenge is variable outcomes within and across cropping systems.  Ongoing are studies in MN and MI. In studies have been established in 2016 at four field locations to study the effect of oilseed cover crops, pennycress and camelina on SCN population dynamics in fields planted with SCN-susceptible and resistant soybeans. Soil samples were taken at soybean planting, midseason, and harvest in 2016 for SCN population measurement. Data are being processed. In MI, a major emphasis has been to understand the sources of variable responses when aiming to achieve healthy soils in vegetable and field crop production systems. Using nematode community analysis and the soil food model, it has been well-established that soil type is a major source of variable responses and that the one-size-fits-all approach to making management recommendations should be reconsidered. 

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.

          Dissemination of research information is one of the strengths of the team.  Regardless of Extension appointments, all team members interact with growers and stakeholders during organized field days, season and annual commodity group reporting times and professional meetings, and print and electronic media.  Annual field day presentations ranged from hundreds (IL, IN, KS, MN, ND, SD, WI) of farmers and crop consultants to 70,000 direct mail outreach in IA.  In addition, electronic outreach include updating corn and soybean producers through radio and print media on latest of corn and soybean parasitic nematodes (IN), informing relationship between beneficial and harmful nematodes in MI (http://msue.anr.msu.edu/news/plant_parasitic_and_beneficial_nematode_distribution) to listing of SCN-resistant soybean varieties in MN (http://www.maes.umn.edu/sites/maes.umn.edu/files/2016_soybean_final.pdf.), KS (http://www.agronomy.k-state.edu/services/crop-performance-tests/soybean/), ON (http://www.gosoy.ca), and IA (https://store.extension.iastate.edu/Product/pm1649-pdf) online.

Research Publications:

Acharya, K., Tande, C. and Byamukama, E. 2016. Determination of Heterodera glycines virulence phenotypes occurring in South Dakota. Plant Disease 100:2281-2286.

Beeman, A. Q., Z. Njus, S. Pandey, and G. L. Tylka. 2016. Chip technologies for screening chemical and biological agents against plant-parasitic nematodes. Phytopathology 106:1563-1571.

da Silva, M. P., Tylka, G. L., and Munkvold, G. P. 2016. Seed treatment effects on maize seedlings coinfected with Fusarium spp. and Pratylenchus penetrans. Plant Disease 100:431-437.

Grabau, Z. J., and Chen, S. 2016.  Influence of long-term corn-soybean crop sequences on soil ecology as indicated by the nematode community.  Applied Soil Ecology 100:172-185.

Han Z., Boas, S., and N.E. Schroeder. 2016. Unexpected variation in neuroanatomy among diverse nematode species. Frontiers in Neuroanatomy. 9: 1-11. doi:10.3389/fnana.2015.00162

MacGuidwin, A. E., and B. E. Bender. 2016. Development of a damage function model for Pratylenchus penetrans on corn.  Plant Disease 100:764-769.

Morriss, S.C., Studham, M.E., Tylka, G.L., and MacIntosh, G.C. 2017. Validation of a hairy roots system to study soybean-soybean aphid interactions. PLoS ONE 12(3): e0174914. doi.org/10.1371/journal.pone.0174914.

Wise, K. A., J. Faghihi, J., and V.R. Ferris. 2016. Effect of soybean cyst nematode resistant cultivars on an HG type 2 population of Heterodera glycines and sudden death syndrome in Indiana soybean. Crop, Forage, and Trufgrass management, 2(1), 3.

Yan, G. P., Plaisance, A., Huang, D., and Handoo, Z. A. 2016. First report of the lance nematode Hoplolaimus stephanus from a soybean field in North Dakota. Plant Disease 100: 2536. http://dx.doi.org/10.1094/PDIS-07-16-1012-PDN.

Yan, G. P., Plaisance, A., Huang, D., Liu, Z., Chapara, V., and Handoo, Z. A. 2016. First report of the root-lesion nematode Pratylenchus neglectus on wheat (Triticum aestivum) in North Dakota. Plant Disease 100: 1794. http://dx.doi.org/10.1094/PDIS-02-16-0260-PDN.

Abstracts:

Beeman, A. Q., Njus, Z. L., Pandey, S. and Tylka, G. L. 2016. A scanner assay developed to quantify nematode population movement and its applications for nematicide screening. Journal of Nematology 48:302-303.

Beeman, A. Q. and Tylka, G. L. 2016. Soybean aphid feeding affects soybean cyst nematode egg hatching in vitro. Journal of Nematology 48:303.

Bissonnette, K. and Tylka, G. 2016. Survey of internet resources on the soybean cyst nematode. Phytopathology 107:S1.1, http://dx.doi.org/10.1094 / PHYTO-107-1-S1.1

Bissonnette, K. and Tylka, G. 2016. Grower perceptions of SCN: The 1990s versus 2015. Phytopathology 107:S1.1, http://dx.doi.org/10.1094 / PHYTO-107-1-S1.1.

Byamukama, E., Tande, C., and Acharya, K. 2016. Partnering with the state soybean commodity board to promote diagnosis and management of SCN in South Dakota. National Plant Diagnostic Network 4^th National Meeting, Washington DC.

Chen, S.  2016.  Increase in virulence of Heterodera glycines on soybean over time in the past two decades in Minnesota.  Journal of Nematology 48:309-310.

Grabau, Z.J., B.P. Werling, and H. Melakeberhan. 2016. Plant-parasitic nematodes and nematode community composition in selected Michigan vegetable fields. Joint Meeting of the Society of Nematologists and Organization of Tropical America Nematologists. 95.

Grabau, Z.J., Z.T.Z. Maung, C. Noyes, D. Baas, B.P. Werling, D.C. Brainard, and H. Melakeberhan. 2016. Short-term effects of cover cropping on root-lesion nematode, stunt nematode and soil ecology in Michigan carrot production. Joint Meeting of the Society of Nematologists and Organization of Tropical America Nematologists. 94.

Grabau, Z.J., Z.T.Z. Maung, C. Noyes, D. Baas, B.P. Werling, D.C. Brainard, and H. Melakeberhan. 2016. Cover cropping affects plant-parasitic and free-living nematodes in Michigan carrot production. American Phytopathological Society Annual Meeting. 0000

Han, Z., and N.E. Schroeder. 2016. The role of the neurotransmitters serotonin and GABA in plant-parasitic nematodes. Society of Nematologists Annual Meeting. Montreal, QC.

Hoerning, C., Wyse, D. L., Chen, S., Wells, M. S., Gesch, R. W., and Forcella, F.  2016.  Influence of winter annual cover crops on soybean cyst nematode populations.   2016 ASA Annual Meeting Abstracts 42-7.

Huang, D. and Yan, G. P. (2016). Real-time and conventional PCR assays for identifying the stubby root nematode Paratrichodorus allius. Phytopathology 106:S4.114. http://dx.doi.org/10.1094/PHYTO-106-12-S4.1.

Huang, D. and Yan, G. P. (2016). Specific detection of the root-lesion nematode Pratylenchus scribneri using conventional and real-time PCR. Phytopathology 106:S4.114. http://dx.doi.org/10.1094/PHYTO-106-12-S4.1.

Jensen, J. and Tylka, G. 2016. Nematicide seed treatments alter Heterodera glycines development within roots. Phytopathology 107:S1.1, http://dx.doi.org/10.1094 / PHYTO-107-1-S1.1.

Jensen, J. P., Njus, Z. L., Pandey, S., and Tylka, G. L. 2016. Video analysis software to measure nematode movement with applications for accurate screening of nematode control compounds. Journal of Nematology 48:335-336.

McCarville, M. T., C. C. Marett, M. P. Mullaney, G. D. Gebhart, and G. L. Tylka. 2016. Adaptation of soybean cyst nematode populations to the PI 88788 source of resistance from 2000 through 2015 in Iowa and its effects on soybean yields. Phytopathology 106:S4.4.

Mennan, S., Z.T.Z. Maung, J. Gronseth, P.D. Reeb, A.L.M. Smucker, J. Qi, and H. Melakeberhan. 2016. Soil type, soil group and ecoregion based strategies for scalable soil health management in Michigan agriculture.  32^nd Symposium of the European Society of Nematologists Meeting. 111.

Mennan, S., J. Gronseth, P.D. Reeb, A.L.M. Smucker, A. Adelaja, J. Warbach, J. Qi, and H. Melakeberhan. 2016. What do soil property and nematode assemblage analyses suggest about integrated soil health management in Michigan agriculture? Joint Meeting of the Society of Nematologists and Organization of Tropical America Nematologists. 140.

Thapa. S, Patel, J.A., Reuter-Carlson, U., and N.E. Schroeder. 2016. Embryonic and post-embryonic development of Heterodera glycines encysted and egg-mass eggs in different hatch stimulant. Society of Nematologists Annual Meeting. Montreal, QC.

Tylka, G. L. 2016. Integrated management of Heterodera glycines in the Midwestern United States. Journal of Nematology 48:377-378.

Tylka, G. 2016. Soybean cyst nematode: current status, challenges and opportunities. Phytopathology 107:S1.1, http://dx.doi.org/10.1094 / PHYTO-107-1-S1.1.

Tylka, G., Gebhart, G., Marett, C. and Mullaney, M. 2016. The Iowa State University SCN-resistant soybean variety trial program. Phytopathology 107:S1.1, http://dx.doi.org/10.1094 / PHYTO-107-1-S1.1.

Yan, G. P. and Plaisance, A. (2016). Vermiform plant-parasitic nematodes on soybean in North Dakota and their relationship with soybean cyst nematode. Phytopathology 106:S4.104. http://dx.doi.org/10.1094/PHYTO-106-12-S4.1.

Yan, G. P., Plaisance, A., Huang, D., and Handoo, Z. A. (2016).  First detection of the stubby root nematode Paratrichodorus allius on potato in North Dakota and on sugarbeet in Minnesota. Phytopathology 106:S4.125. http://dx.doi.org/10.1094/PHYTO-106-12-S4.1.

Extension publications:

Byamukama, E. and Tande, C. 2016. Test for the soybean cyst nematode before planting soybeans this spring. iGrow Crops Newsletter.

Byamukama, E. Mathew, F., Tande, C., Strunk, C. 2016. Scout and soil test for the soybean cyst nematode. iGrow Crops Newsletter.

Faghihi, J., and V.R. Ferris. 2016. Nematode Updates - Now is the Best Time to Sample for SCN. pest and crop newsletter,  https://extension.entm.purdue.edu/pestcrop/2016/Issue24/

Faghihi, J., and V.R. Ferris. 2016. Nematode Updates - Corn Parasitic Nematodes. pest and crop newsletter,  https://extension.entm.purdue.edu/pestcrop/2016/issue7/

Faghihi, J., and V.R. Ferris. 2016. Sampling for plant parasitic nematodes Agpro Farm Journal April 18, 2016

Faghihi, J., and V.R. Ferris. 2016. Nematode Updates - Sampling for Plant Parasitic Nematodes: Your Result is as Good as the Sample You Provide. pest and crop newsletter,  https://extension.entm.purdue.edu/pestcrop/2016/Issue2/

Grabau, Z.J., B.P. Werling, R. Goldy, B. Phillips, and H. Melakeberhan. 2016. Plant parasitic nematode distribution in Michigan vegetable soils. http://msue.anr.msu.edu/news/plant_parasitic_and_beneficial_nematode_distribution. Posted 04/25/2016.

Khan, M., Arabiat, S., Yan, G. P., and Chanda, A. K. 2016. Stubby root nematode and sampling in sugarbeet. North Dakota Extension Bulletin A1821, North Dakota State Univ., Fargo, ND. 4 p. (online at https://www.ag.ndsu.edu/pubs/plantsci/rowcrops/a1821.pdf).

MacGuidwin, A.E., Bender, B., and Saeed, I. 2016. Predicting potato early dying in Wisconsin potato fields.  Proceedings of Wisconsin’s Annual Potato Meeting,   29:51-52.

MacGuidwin, A. E., Bender, B., Saeed, I., VanHaren, R., LaPorte, L., and Coloma Farms. 2016. Soil mapping for variable rate fumigation.  Proceedings of Wisconsin’s Annual Potato Meeting, 29:53-57.

MacGuidwin, A. E. 2016. Adaptations of plant-parasitic nematodes to extreme conditions in agricultural fields – manipulating the soil environment to foil nematode pests.

Markell, S., Nelson, B., Pasche, J., and Yan, G. P. 2016. Soybean cyst nematode and the threat to dry beans. Northarvest Bean Grower Magazine. 22 (5): 16-17.

Merzdorf, J. V. 2016. Extension Purdue nematologist: Cool, wet spring may increase risk of needle nematodes Agcom news release June 9, 2016Rush, T. A., and A. E.MacGuidwin. 2016. Impact of concurrent infection by Pratylenchus penetrans and Fusarium verticilliodes on corn seedlings. 

Sisson, A., Mueller, D., Abendroth, L., Hartzler, B., Hodgson, E., Licht, M., Mallarino, A., McGrath, C., Pope, R., Robertson, A., Sawyer, J., Schaefer, K., and Tylka, G. 2016. Corn and Soybean Field Guide. Iowa State University Extension and Outreach. IPM 001, 158 pp.

Tylka, G.L. and M. P. Mullaney. 2016. Soybean cyst nematode-resistant soybeans for Iowa. Iowa State University Extension Publication PM 1649, 26 pp. https://store.extension.iastate.edu/Product/pm1649-pdf.

Tylka, G.L., G.D. Gebhart, C.C. Marett, and M.P. Mullaney. 2016. Evaluation of soybean varieties resistant to soybean cyst nematode in Iowa – 2016. Iowa State University Extension, publication IPM‑52, 24 pp. https://store.extension.iastate.edu/Product/ipm52-pdf.

Tylka, G. 2016. Don't forget SCN sampling on your list of spring chores. Iowa State University Integrated Crop Management News (15 April 2016).

Tylka, G. 2016. SCN females now visible on soybean roots. Iowa State University Integrated Crop Management News (22 June 2016).

Tylka, G. 2016. More SCN-resistant soybean varieties than ever, but diversity of resistance is lacking. Iowa State University Integrated Crop Management News (18 October 2016).

Tylka, G. 2016. What’s the situation with SCN in your fields? Iowa State University Integrated Crop Management News (31 October 2016).

Tylka, G. 2016. Performance of SCN-resistant soybean varieties in Iowa in 2016. Iowa State University Integrated Crop Management News (27 December 2016).

Book chapters:

Todd, T.C., G.L. Windham, and D.I. Edwards.  2016.  Diseases caused by nematodes.  In G.P. Munkvold and D.G. White (eds.).  Compendium of Corn Diseases (Fourth Edition).  Pp. 117-129.

Tylka, G. L. 2016. Soybean cyst nematode, pp 99-101 in A Farmer’s Guide to Soybean Diseases. D. Mueller, K. Wise, A. Sisson, D. Smith, E. Sikora, C. Bradley, and A. Robertson, eds. APS Press, The American Phytopathological Society, St. Paul MN, USA.