Brief Summary of Minutes of Annual Meeting

Project/Activity Number:     W4186

Project/Activity Title:           Variability, Adaptation and Management of Nematodes Impacting Crop Production and Trade

Period Covered:                    2021

Date of This Report:                  1/12/2022      

Annual Meeting Date(s):      November 15-16, 2021

Venue:  University of Hawai’i, Hawaii

Brief summary of minutes of annual meeting:

Kathy Lawrence discussed her latest research on nematode-resistant [reniform and root-knot nematode (RKN)] cotton varieties and nematicides applications. Use of reniform-resistant cotton increased yield by 877 kg/ha and reduced nematode population by 83%. The effect on yield was less significant in case of RKN resistant cotton.

Louise-Marie Dandurand discussed status of potato cyst nematode (Globodera pallida) in Idaho. DSSAT (Decision Support System for Agrotechnology Transfer) growth model was used to predict potato yield reduction in relation to initial G. pallida population. US varieties are susceptible to G. pallida. Various breeding programs are underway to integrate resistance into potato. A 3-year rotation experiment involving litchi tomato and barley is currently underway.

Cynthia Gleason updated progress on development of tools for molecular identification of Meloidogyne chitwoodi. Efforts are underway to develop race-specific primers through various approaches including whole-genome sequencing.

Shahid Siddique gave an update about the progress on characterization of PSY peptides in M. javanica. Whole genome sequencing of M. javanica wild-type strain (VW4) and resistant-breaking strain (VW5) is currently underway. Tools for genetic transformation of M. hapla are being developed.

Simon Niels Goren is a new faculty member at UCR. He updated the group about his research plans to work on plant toxins and the evolution of host-parasite interactions.

Phil Roberts updated on RKN resistance trait in carrots. Resistance markers were developed against M. hapla in carrot cultivar “Homs”. Ongoing efforts in resistance screening against M. javanica and M. incognita were discussed.

Haddish Melakeberhan discussed parasitic variability in M. hapla. A look at the enrichment index and structure index-based Soil Food Web model shows that conditions that favor presence of M. hapla also favor presence of other nematodes. Haddish discussed nematode management strategies using Soil Food Web (SFW) and Fertilizer Use Efficiency (FUE) models.

Russel Ingham talked about RKN infection problems in potato. He discussed nematode suppression by green manure cover crops.

Steve Thomas presented for Jacki Beacham who could not attend the meeting. Ditylenchus dipsaci was found last year from New Mexico. Garlic but not alfalfa often has stem nematode. Temporal studies were conducted on Vitis vinifera for M. incognita detection and to determine the optimal time for nematicide application.

Brent Sipes updated on issues related to poor survival of native plants in areas around the University of Hawaii Campus. Various native plants were tested for infection by RKN and reniform nematodes. In general, a lot of variation was observed for nematode reproduction factor on native plants for reasons not clear. A survey of M. enterolobii was conducted on Asian vegetables and Asian perennials that are potentially imported as rooted plants. Meloidogyne enterolobii was never detected.

Business

Business Meeting: Nov 15, 2021

Following items were discussed,

Location: Davis was selected as a location for 2022 meeting. Shahid will check potential dates (beginning to mid November 2022).

Officer’s Election: Haddish Melakeberhan was elected as secretary unanimously. Louise-Marie Dandurand volunteered to be the new secretary in year 2022.
Kathy Lawrence will move to become the chair.
Shahid Siddique will move to become the vice chair.

Reports: Reports for 2021 should be sent to Cynthia Gleason before Christmas.

New Members: Chair Kathy Lawrence will write to Peter DiGenarro (University of Florida), Chris Taylor (Ohio State University), Triston Watson (Louisiana State University), Travis Faske (University of Arkansas), Inga Zasada (USDA, Corvallis, OR) and Zhang Lei (Purdue University) inviting them to join the group.

Project Renewal: Project renewal is due in 2023. So, we will have to think about renewing the project already next year. Phil Roberts will send previous project proposal to the group.

Objective 1:   Characterize genetic and biological variation in nematodes relevant to crop production and trade.

Plant-parasitic nematodes are a large diverse group of roundworms that cause significant agricultural crop losses. These losses are estimated to be at least $8 billion in the United States and $80 billion worldwide. Therefore, it is important to understand and characterize the genetic and biological variation of plant parasitic nematodes. These variations may affect nematode virulence and/or host range, with implications relevant to crop production and trade. The following activities have been performed regarding objective 1.

Several researchers in the project work on potato-nematode interactions.  Washington/Oregon/Idaho produce the majority of the potatoes grown in the USA. Meloidogyne chitwoodi is a major problem for potato producers in this region because the nematode causes tuber defects that can significantly diminish the value of the crop. There are different isolates of M. chitwoodi present in the region that differ in virulence and host range. Therefore, nematode management strategies are impacted by the specific isolate present. Researchers at Washington State University have sequenced the genomes of three M. chitwoodi isolates and have developed molecular diagnostic tools, such as molecular beacon assays, for M. chitwoodi.  

Another important potato nematode is the pale cyst nematode, Globodera pallida. This quarantine pathogen is found only in a small section of Idaho, but its potential spread threatens the entire US potato industry. Researchers at the University of Idaho have recently initiated a project to determine the genetic diversity found in Globodera spp. They will then work on development of resistant potatoes suitable for US growers and the potato industry by finding appropriate sources of resistance that encompass the genetic diversity found in Globodera spp. Populations from Chile and Peru are being characterized for genetic diversity by various sequencing efforts.

Objective 2:  Determine nematode adaptation processes to hosts, agro-ecosystems and environments.

A number of actions have been performed under objective 2 (studying nematode adaptation to climatic conditions, cropping systems, and/or soil properties).  For example, researchers at Michigan State University have analyzed the parasitic variability (PV) of the Northern root-knot nematode (M. hapla) populations in Michigan. Meloidogyne hapla is a major RKN found in temperate climates. One question was whether PV exists in M. hapla because it is adapted to diverse soil health conditions. In order to answer this question, M. hapla distribution by soil groups (mineral and muck) and soil health conditions, as described by the nematode community analyses-based soil food web (SFW), was characterized in 15 fields (6 muck and 9 mineral soils) across three vegetable production regions of Michigan. A second question was whether there is an association, or the lack of, between the presence of M. hapla and specific biophysicochemical conditions. The Michigan researchers performed principal component analyses among M. hapla presence, soil groups, and nematode abundance parameters and showed general similarity between mineral and muck soils. On-going analyses are going to help determine relationships among PV, soil health, microbiome and soil physicochemical parameters. This information will set the foundation for more targeted investigations to understand any links between M. hapla’s PV and its soil environment.

A major research focus at Michigan State University has been on modifications of the soil food web and fertilizer use efficiency models. These may be used as diagnostic tools to get in-depth and systematic understanding of cause-and-effect relationships and to extract potential practical applications of research outcomes. Michigan researchers have recently published how the soil food web model can be used to translate complex biophysicochemical soil health outcomes into practical applications and the fertilizer use efficiency model to assess the sustainability of the outcomes.

Another aspect of objective 2 has been to look at distribution of nematodes in terms of adaption to various hosts. For example, the University of Hawaii has surveyed native plants in areas around University of Hawaii Campus for susceptibility to RKN and reniform nematodes. For reniform nematodes, the native plant Ipomoea appeared to be a good host, but most native plants seemed to be poor hosts to these nematodes. The observed variation of resistance in seedlings may reflect the variation in the seed germplasm. In addition, there was also concern that the quarantine nematode M. enterolobii may have been recently introduced into Hawaii. A survey of Asian vegetables and Asian perennials (Earpod, Guava, Mango, Avocado, Jabong, Breadfruit, Jackfruit, Banana, Cacao, Papaya, Jaboticaba, Pineapple, Cherimoya etc.) was conducted. Fortunately, M. enterolobii was not detected in any samples.

In New Mexico, researchers have studied nematodes from samples that were taken as part of a rangeland research project evaluating the displacement of native grasses by an invasive grass planted by a local utility company. Morphological identification of the fixed specimen has been on-going with the assistance of Paul DeLey (UC-Riverside). A new nematode genus and species was discovered at 3 locations within the experiment site. The new genus appears closely related to the family Anguinidae (a diverse plant parasitic family mostly infecting grasses) but differs in a key diagnostic character from all known species of that family.

Objective 3:  Develop and assess nematode management strategies in agricultural production systems.   

There is a continued need for new safe, effective, and inexpensive nematode control options. A number of studies presented below have been performed to address objective 3, the development and assessment of nematode management strategies.

Starting with chemical controls, nematicides offer an effective means of nematode management, but as companies develop new nematicides, it is important to investigate the effectiveness of their formulations or their application methods. Research at Auburn University focuses on chemical management strategies to reduce root-knot and reniform populations on cotton. The objective of their research was to integrate additional fertilizer and nematicide combinations into current practices to establish economical nematode management strategies while promoting cotton yield and profit. Microplot and field trials were run to evaluate fertilizer and nematicide combinations applied at the pinhead square (PHS) and first bloom (FB) plant growth stages to reduce nematode population density and promote plant growth and yield. Cost efficiency was evaluated based on profit from lint yields and chemical input costs. For example, in M. incognita field trials, a nematicide seed treatment + nematicides (28-0-0-5 + Vydate^® C-LV + Max-In^® Sulfur) applied at the pinhead square (PHS) and first bloom (FB) plant growth stages supported the largest lint yields and profit per hectare at $784. These results suggest that combinations utilizing fertilizers and nematicides in addition to current fertility management show potential to promote yield and profit in R. reniformis and M. incognita infested cotton fields.

In New Mexico, researchers have been studying nematicide treatments in relation to wine grape yield. The goal of their vineyard research was to study M.  incognita management and wine-grape yield response to fluensulfone (Nimitz®) compared to spirotetramat (Movento®) and an untreated control. Interestingly, neither of the nematicides were effective in improving yield greater than that in the untreated control in this second year of the study. Mean RKN recovery from the soil was lower in the Nimitz®-treated plots compared to the untreated control at only one of the three vineyards.

In order to better understand how different vineyard drip irrigation strategies result in differences in roots and RKN distributions in the soil, an assessment was conducted in New Mexico in the spring of 2021. The study revealed that roots and RKN were very closely correlated with the location of the drip emitters at the vineyard with the single drip line, whereas they were equitably distributed in the 4’ x 4’ area around the vine at the vineyard with two drip lines, 12” on either side of the vine row. This may help explain the improved efficacy of control of the RKN at the vineyard with the single drip line versus the poor control at the vineyard with a more broadcast distribution of RKN. Currently University of New Mexico researchers are conducting temporal studies to determine the optimal time for nematicide application. Every two weeks for the next two years, soil and roots from multiple sites in a vineyard will be sampled. RKN juvenile populations in the soil and roots and soil temperatures are being continuously recorded and will be used to try and determine a degree day reference for nematicide applications in vineyards.

To move away from synthetic nematicides, researchers at the University of Idaho have looked at plants as the sources of novel chemistries for the development of bionematicides. They continue to evaluate potential nematicidal compounds isolated from the trap crop Solanum sisymbriifolium. High levels of solamargine have been extracted from roots of this trap crop. Fractions extracted from this plant have been found to be highly toxic to G. pallida, and reduce hatch, infection and reproduction of the nematode. Solanum sisymbriifolium is also resistant to RKN, indicating that it has broad spectrum nematode resistance.

Other approaches to nematode control, aside from chemicals, include host plant resistance, green manures, and biological controls. In terms of green manure, work from Oregon State University determined the reproduction of the Columbia RKN (CRKN, Meloidogyne chitwoodi) for green manure plants.  Four mustard cultivars were good hosts for the nematode, but not as good as wheat. An oilseed radish (Terranova) and one sorghum x sudagrass hybrid (Sordan 79) were both nonhosts. When infested soil was amended with green vegetation, wheat-amended pots had few live nematodes, but the fewest live juveniles were recovered from sudangrass-amended pots in which live J2 were reduced over 92% compared to wheat-amended pots. However, none of the amendments had any effect on the ability of the surviving J2 to reproduce when a good host (wheat) was planted in the amended soil.

Efforts to move away from nematicide use in potato have also been undertaken. Researchers at Washington State University engineered the bacteria Bacillus subtilis to produce and secrete the defense elicitor called Pep1. By treating the potato plants with B. subtilis that secretes the Pep1 defense elicitor, the plants became more resistant against M. chitwoodi. They have also treated tomato with B. subtilis that secretes the Pep1 and found protection against M. hapla, indicating that the transgenic bacteria can provide protection to a variety of plants against RKN.

Aside from synthetic and natural treatments, genetic resistance to plant parasitic nematodes would provide another option for nematode control. Currently, resistance to pale cyst nematodes in commercially relevant potato varieties for US growers does not exist. Through collaborations with breeders and plant geneticists, University of Idaho-based research has focused on breeding resistance into russet type potatoes for the US industry. Clones with partial resistance have been developed, and future efforts are focused on pyramiding different sources of resistance to achieve higher levels of resistance to G. pallida. In addition to the development of resistance through traditional breeding efforts, University of Idaho researchers have initiated a project to understand the plant-nematode interaction of Solanum sisymbriifolium. They studied the differential expression of genes in nematodes infecting S. sisymbriifolium. A transcriptome analysis of G. pallida revealed differences in expression of genes important for detoxification as well as parasitism, which gives insights into the mechanism of plant resistance. In addition, field trials have been established to develop a 3-year rotation plan for use in G. pallida infested fields. The rotation compares the use of resistance or a trap crop in rotation with a susceptible potato variety and evaluates G. pallida population decline for each of the rotation plans.

Carrots are one of the highest fumigant users. To reduce fumigant usage, researchers at the University of California at Riverside (UCR) have conducted an analysis of RKN resistance traits in carrot to identify and characterize novel resistance genes and their interactions with root-knot nematode species and populations. Resistance traits effective against Meloidogyne incognita were genetically mapped in the carrot genome using greenhouse generated phenotypes from infection assays and single nucleotide polymorphism (SNP) markers from genotyping-by-sequencing. Several sources of resistance in carrot germplasm from Brasilia, South Africa and India were determined to be conferred by at least five genome locations across carrot chromosomes. Candidate genes for the resistance determinants were identified.

Because there are not many naturally resistant crops to plant parasitic nematodes, researchers have also looked to engineer plant resistance. Researchers at the University of California, Davis have studied the plant-nematode interaction at the molecular level so that the information can be used to develop new tools of resistance. They have recently identified several PSY-like peptides in RKNs. The MigPSY peptides have a highly conserved region shared with the bacterial pathogen Xanthomonas oryzae pv. Oryzae (Xoo) peptide called RaxX.  Rice plants have a defense receptor protein called XA21 that binds to RaxX and triggers a plant defense response. Therefore, the UCD researchers hypothesized that the XA21 dependent immune response may also be activated by MigPS. They found that rice plants with XA21 (called KitaakeX) had fewer young nematode females, indicating slower or blocked nematode development. They also observed that KitaakeX showed a 37% reduction in the number of eggs per plant compared to wild-type plants. Together, these results suggest that XA21 expression in rice confers resistance to the RKN M. javanica. While these preliminary experiments indicate that rice plants constitutively expressing the XA21 are resistant to nematodes, the underlying mechanism behind this resistance response is unknown.

Publications

Refereed Journal Articles:

• Bali, S., Zhang, L., Franco, J., Gleason, C., Biotechnological advances with applicability in potatoes for resistance against RKN,(2021) Current Opinion in Biotechnology, 70: 226-233.
• Bali S., Hu S., Vining V., Brown C., Mojtahedi H., Zhang L., Gleason C., Sathuvalli V. (2021) Nematode genome Announcement: Draft genome of Meloidogyne chitwoodi, an economically important pest of potato in the Pacific Northwest. Molecular Plant Microbe Interactions, 34(8):981-986.
• Beckmann J.F., Dormitorio T., Oladipupo, S. O., Terra, M. T. B., Lawrence, K., Macklin, K.S., Hauck, R. (2021) Heterakis gallinarum and Histomonas meleagridis DNA Persists in Chicken Houses Years after Depopulation, Veterinary Parasitology, DOI: https://doi.org/10.1016/j.vetpar.2021.109536
• Divykriti C, Hasan MH, Matera C, Chitambo O, Mendy B, Mahlitz D, Naz AA, Szumski S, Janakowski S, Sobczak M, Mithöfer A, Kyndt T, Grundler FMW, Siddique S (2021). Plant parasitic cyst nematodes redirect host indole metabolism via NADPH oxidase‐mediated ROS to promote infection. New Phytologist, 232: 318-331.\
• Hassan, Mohannad K., Kathy S. Lawrence, Edward J. Sikora, Mark R. Liles, and Joseph W. Kloepper (2021) Enhanced biological control of RKN, Meloidogyne incognita, by combined inoculation of cotton or soybean seeds with a plant growth-promoting rhizobacterium and pectin-rich orange peel. Journal of Nematology 53:1-17. DOI: 10.21307/jofnem-2021-058
• Hesse, C. N., I. Moreno, O. Acevedo Pardo, H. Pcheco Fuentes, E. Grenier, L. M. Dandurand, I. A. Zasada (2021) Characterization of Globodera ellingtonae populations from Chile utilizing whole genome sequencing. Journal of Nematology 53:1-9. https://doi.org/10.21307/jofnem-2021-08
• Kantor, M.R., Z.A. Handoo, A.M. Skantar, M.N. Hult, R.E. Ingham, N.M. Wade, W. Ye, G.R. Bauchan, and J.D. Mowery (2021) Morphological and molecular characterization of  Punctodera mulveyi n. sp. (Nematoda: Punctoderidae) from a golf course green in Oregon, USA, with a key to species of Punctodera. Nematology 23: 667-683. DOI::http://doi.org/10.1163/15685411-bja10068\
• Klink, Vincent P., Omar Darwish, Nadim W. Alkharouf & Katherine S. Lawrence (2021) The impact of pRAP vectors on plant genetic transformation and pathogenesis studies including an analysis of BRI1-ASSOCIATED RECEPTOR KINASE 1 (BAK1)-mediated resistance. Journal of Plant Interactions, 16:1, 270-283, DOI: 10.1080/17429145.2021.1940328.
• Land, Caroline J., Gary E. Vallad, Johan Desaeger, Edzard Van Santen, Joe Noling, and Kathy Lawrence (2021) Supplemental fumigant placement improves root-knot and Fusarium wilt management for tomatoes produced on a raised bed, plasti-culture system in Florida’s Myakka fine sand. Plant Disease https://apsjournals.apsnet.org/doi/pdf/10.1094/PDIS-03-21-0543-RE
• Lartey, I., A. Kravchenko, T. Marsh and H. Melakeberhan (2021) Meloidogyne hapla occurrence relative to nematode trophic group abundance and soil food web conditions in soils and regions of selected Michigan vegetable production fields. Nematology 23: https://DOI.org/10.1163/15685411-bja10091
• Lawaju BR, Groover W, Kelton J, Conner K, Sikora E, Lawrence KS (2021) First report of Meloidogyne incognita infecting Cannabis sativa in Alabama. Journal of Nematology. 2021 May 1;53:e2021-52. doi: 10.21307/jofnem-2021-052.
• Pillai, S. S., and L. M. Dandurand (2021) Effect of steroidal glycoalkaloids on hatch and reproduction of the potato cyst nematode Globodera pallida. Plant Disease https://doi.org/10.1094/PDIS-02-21-0247-RE
• Pillai, S. S., and L. M. Dandurand. (2021) Potato cyst nematode egg viability assessment and preparasitic juvenile screening using a large particle flow cytometer and sorter. Phytopathology, 111(4), 713-719. https://doi.org/10.1094/PHYTO-06-20-0255-R
• Powers TO, Harris TS, Higgins RS, Mullin PG, Powers KS. Nematode biodiversity assessments need vouchered databases: A BOLD reference library for plant-parasitic nematodes in the superfamily Criconematoidea. Genome. 2021 Mar;64(3):232-241. doi: 10.1139/gen-2019-0196. Epub 2020 Jun 11. PMID: 32526150.
• Solo N., J. Kud, A. Caplan, J. Kuhl, F. Xiao, and L. M. Dandurand (2021) Characterization of the superoxide dismutase (SOD) from the potato cyst nematode, Globodera pallida. Phytopathology. https://doi.org/10.1094/PHYTO-01-21-0021-R
• Marhavy P, Siddique S (2021). Histochemical staining of suberin in plant roots. Bio-protocol, doi: 10.21769/BioProtoc.3904
• Melakeberhan, H., G. Bonito and A.N. Kravchenko (2021) Application of nematode community analyses-based models towards identifying sustainable soil health management outcomes: A review of the concepts. Soil Systems 5, 32. https://doi.org/10.3390/soilsystems5020032
• Nyaku, S. T., V. R. Sripathi, K. Lawrence, and G. Sharma (2021) Characterizing repeats in two whole-genome amplification methods in the reniform nematode genome. International Journal of Genomics. https://doi.org/10.1155/2021/5532885.\
• Palomares-Rius JE, Hasegawa K, Siddique S, Vicente CSL (2021). Protecting our crops-approaches for plant parasitic nematode control. Frontiers in Plant Science, 2: 726057
• Sanchez, WinDi, David Shapiro, Geoff Williams, and Kathy Lawrence (2021) Entomopathogenic nematode management of small hive beetles (Aethina tumida) in three native Alabama soils under low moisture conditions. Journal of Nematology 53:1-14. DOI: 10.21307/jofnem-2021-063
• Sato K, Uehara T, Holbein J, Sasaki-Sekimoto Y, Gan P, Bino T, Yamaguchi K, Bino T, Yamaguchi K, Ichihashi Y, Maki N, Shigenobu S, Ohta H, Franke B, Siddique S, Grundler FMW, Suzuki T, Kadota Y, Shirasu K (2021) Transcriptomic analysis of resistant and susceptible responses in a new model RKN infection system using Solanum torvum and Meloidogyne arenaria. Frontiers in Plant Science, 12: 680151
• Skantar A, Handoo Z, Kantor M, Hafez S, Hult M, et al. 2021. First report of Cactodera milleri Graney and Bird, 1990 from Colorado and Minnesota. Journal of Nematology 53:2021-38
• Velasco-Cruz, C., G. Giese, D. Saldaña-Zepeda, J. Beacham (2021) Modeling nematode population dynamics using a multivariate poisson mixture model. Journal of Applied Statistics: https://doi.org/10.1080/02664763.2021.1935800
• Zhang L. and Gleason, C., (2021) Transcriptome analyses of pre-parasitic and Parasitic Meloidogyne Chitwoodi Race 1 to identify putative effector genes, Journal of Nematology, 53:e2021-84.

 Other:

• Turner, A. K., Lawrence, K. S., Gordon, K., Dyer, D., Lawaju, B., Rondon, M., Norris, C. 2020. Management strategies utilizing seed treatments to combat yield loss from reniform nematode on cotton. Report No. 15:N010. The American Phytopathological Society, St. Paul, MN. https://www.plantmanagementnetwork.org/pub/trial/PDMR/reports/2021/N010.pdf 
• Turner, A. K., Lawrence, K. S., Gordon, K., Dyer, D., Lawaju, B., Rondon, M., Norris, C. 2020. Soybean seed treatment combinations for decreasing reniform nematode population density in North Alabama. Report No.  15:N009. The American Phytopathological Society, St. Paul, MN. https://www.plantmanagementnetwork.org/pub/trial/PDMR/reports/2021/N009.pdf 
• Turner, A. K., Lawrence, K. S., Gordon, K., Dyer, D., Lawaju, B., Rondon, M., Richburg, J., Norris, C. 2020. Nematicide and cotton variety combinations for decreasing reniform nematode populations in North Alabama. Report No.15:N016. The American Phytopathological Society, St. Paul, MN.  https://www.plantmanagementnetwork.org/pub/trial/PDMR/reports/2021/N016.pdf 
• Turner, A. K., Lawrence, K. S., Gordon, K., Dyer, D., Lawaju, B., Rondon, M., Norris, C. 2020. Nematicide and cotton variety combinations for decreasing RKN populations in Central Alabama. Report No. 15:N017. The American Phytopathological Society, St. Paul, MN. https://www.plantmanagementnetwork.org/pub/trial/PDMR/reports/2021/N017.pdf 
• Kathy S. Lawrence, Austin Hagan, Randy Norton, Jiahuai Hu, Travis R. Faske, Robert B Hutmacher, John Muller, Ian Small, Zane J. Grabau, Robert C. Kemerait, Doug Jardine, Paul Price, Thomas W. Allen, Calvin D Meeks, John Idowu, Lindsey D. Thiessen, Seth A. Byrd, Jerry Goodson, Heather Kelly, Terry Wheeler, Thomas Isakeit and Hillary L. Mehl. 2020. Cotton Disease Loss Estimate Committee Report, 2020.         Proceedings of the 2020 Beltwide Cotton Conference Vol. 1: 117-119. National Cotton Council of America, Memphis, TN. http://www.cotton.org/beltwide/proceedings/2005-2020/index.htm
• Kara Gordon, Kathy S. Lawrence, Drew Schrimsher and Brad Meyer. 2020. A Cost-Effective Prescription Management Strategy Utilizing Fertilizers and Nematicides to Combat Yield Losses from Rotylenchulus reniformis on Cotton. Proceedings of the 2020 Beltwide Cotton Conference Vol. 1: 169-171. National Cotton Council of America, Memphis, TN. http://www.cotton.org/beltwide/proceedings/2005-2020/index.htm
• Bisho Ram Lawaju and Kathy S. Lawrence. 2020. Evaluation of Salibro as a New Nematicide for Cotton Production Systems.  Proceedings of the 2020 Beltwide Cotton Conference Vol. 1: 458-463. National Cotton Council of America, Memphis, TN. http://www.cotton.org/beltwide/proceedings/2005-2020/index.htm
• Drew Schrimsher, Brad Meyer, Kathy S. Lawrence, Bisho Ram Lawaju, Marina Rondon, Will Groover, David R Dyer and Kara Gordon. 2020. Cotton Cultivar Response to CLRDV as Influenced By Planting Dates.  Proceedings of the 2020 Beltwide Cotton Conference Vol. 1: 388-391. National Cotton Council of America, Memphis, TN. http://www.cotton.org/beltwide/proceedings/2005-2020/index.htm
• Travis R. Faske, Thomas W. Allen, Zane J. Grabau, Jiahuai Hu, Robert C. Kemerait, Kathy S. Lawrence, Hillary L. Mehl, John Mueller, Paul Price, Lindsey D. Thiessen, and Terry A Wheeler. 2020. Beltwide Nematode Research and Education Committee Report on Field Performance of Seed and Soil-Applied Nematicides, 2019. Proceedings of the 2020 Beltwide Cotton Conference Vol. 1: 192-196. National Cotton Council of America, Memphis, TN. http://www.cotton.org/beltwide/proceedings/2005-2020/index.htm

Extension publications:

• Ingham. R.E. 2021. Nematode management with oxamyl and Velum Prime. Potato Progress 26 (1): 6-8.
•  Melakeberhan, H. and S. Kekaire (2021). Managing nematodes, cover Crops, and soil health in diverse cropping systems: MSUE Extension Bulletin (E3457). https://www.canr.msu.edu/resources/managing-nematodes-cover-crops-and-soilhealth-in-diverse-cropping-system

Book chapters:

Lawrence, Kathy S. 2021. Reniform nematode (Rotylenchulus reniformis) and its interactions with cotton (Gossypium hirsutum) Chapter 14: pages 94-100 in Integrated nematode management: state of the art and visions for the future. eds Richard Sikora, Johan Desaeger and Leendert Molendijk for CABI. DOI: 10.1079/9781789247541.0014