Brief Summary of Minutes of Annual Meeting

Kaloshian reported on effector-triggered immunity. S. Siddique shared results of research on PSY peptides. V. Klink related work on the early defense processes with xyloglucans. K. Lawrence reported on resistance and nematicides for nematode control. S. Hafez relayed identification of sever first reports of nematodes in Utah, and California. R. Ingham shared results of test with the harpin protein for nematode control. P. Roberts discussed allelic dosage and additive effects of resistance against nematodes. A. Borgmeier highlighted nematode diversity in a prairie corridor. H. Melakeberhan presented results of soil health and nematode adaptations to environments. C. Gleason discussed work on induced resistance, immune-stimulants, and diagnostics. B. Sipes share work on improvement of entomopathogenic nematode living bombs and nematicides.Loper shared that these are different times and thanked the project on their efforts, noting this is a broad project with aspect from molecular to the field. The 2020 report had particularly good impact statements. It would be good to feature collaborative efforts in this year’s report such as between Washingtion, Wisconsin and USDA; Idaho and Nebraska; Michigan and Hawaii; and Alabama and Mississippi. NIFA Kansas City is 95% staffed with two new Multistate Program Leaders.Fayad has been assigned as MPL to our project and wanted to reiterate J. Loper’s comments.

Business

Officer Election: C. Gleason will rotate from Vice Chair to Chair. K Lawrence will rotate from Secretary to Vice Chair. S. Siddique was elected Secretary by acclamation.

2021 Meeting Site: Hawaii will host the meeting assuming pandemic restrictions are not prohibitive. Davis, California will serve as the backup site if issues arise with travel to Hawaii.

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

 Plant-parasitic nematodes are a large diverse group of nematodes that cause significant agricultural loses globally.  In economic terms, annual crop losses due to plant-parasitic nematodes are estimated to be least $8 billion in the United States and $80 billion worldwide. Due to their significant, detrimental effects in agricultural systems, it is critical that scientists study nematode species associated with crop production and trade, and in doing so, investigate the genetic and biological variation within a nematode species. Intraspecies variation can significantly impact nematode management strategies. With this in mind, the following activities have been performed regarding objective 1.

Researchers at the University of California at Riverside (UCR) have conducted an analysis of root-knot nematode resistance traits in carrot and cowpea to determine presence of novel resistance genes and variation within and between root-knot nematode species for virulence to the resistance traits. In carrot, high resistance was found in carrot lines from Brasilia, South Africa and India to Meloidogyne incognita and M. javanica. Resistance to M. hapla in a carrot entry from Syria was found effective against nine out of ten different M. hapla isolates collected from different cropping systems and agro-ecologies. In cowpea, analysis was continued of the genome-level organization of root-knot nematode resistance traits, identified on four of the 11 cowpea chromosomes. Researchers have established an Agrobacterium rhizogenes-transformed hairy root system for cowpea plants to study resistance traits.

Several researchers in the project work on potato-nematode interactions.  Potatoes rank as one of the four most important staple crops on a global scale, and Washington/Oregon/Idaho produce a significant portion of the potatoes grown in the USA. Meloidogyne chitwoodi (also known as the Columbia root-knot nematode) is major problem for potato producers in this region. The nematode infects the potatoes and causes tuber defects that can significantly diminish the value of the crop. The different pathotypes of M. chitwoodi have been an on-going issue. Researchers at Washington State University have performed genomic and transcriptomic analyzes of different races/pathotypes of M. chitwoodi. This has led to insights into its intraspecies genetic diversity. Additional molecular diagnostic tools for M. chitwoodi and other potato-infecting root-knot nematodes are being developed.

 Using information about nematode variability has also been important for cyst nematode diagnostic assays. Together with a Nebraska based biotechnology MatMaCorp, researchers at University of Nebraska are continuing to validate a 4-cyst nematode diagnostic assay for single J2s in the soil. The assay features simultaneous identification of four different Heterodera species known from the Great Plains regions. The assay uses a rolling-circle style amplification that produces a detectable signal within an hour and can be performed in the field. Its performance in community DNA soil extractions is currently being tested.

 Cyst and root-knot nematodes are the most economically important plant parasitic nematodes in the USA. Researchers at Michigan State University have focused on both the soybean cyst nematode (SCN) and the Northern root-knot nematode (NRKN). Research has looked at SCN adaptation by simulating Midwest cropping systems and changes in soil conditions over time. After almost two decades after SCN was introduced, the research into the effects of tillage, rotation and crop species (e.g. till or no-till and corn (C), SCN-resistant (R), SCN-susceptible (S) monocropping or RCRC, SCSC rotation) shows that SCN is barely detectable and less so in no-till than in tilled plots. The focus on NRKN started with characterizing its distribution in soil types across regions and testing parasitic variability (PV) of populations isolated from the field under greenhouse conditions. About half a dozen NRKN populations are being characterized for PV by assessing their ability to induce galling in a series of experiments. The data provide insights into how nematodes establish and adapt in new locations.

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, work at Michigan State University has focused on understanding the distribution, parasitic variability (PV) and adaptation of soybean cyst (SCN) and northern root-knot nematodes (NKRN) in Michigan cropping systems. The goal has been to understand how SCN and NRKN PV relate to the biological and physiochemical conditions in the environment in which they survive. Studies have been undertaken to understand how SCN adaptation relates to changes in soil biophysiochemical conditions. Cropping systems seem to have the greatest influence on the soil food web. Now soil microbiomes have been incorporated into the soil analysis. Investigations are continuing in order to study how changes in soil microbiomes relate to soil health and potential SCN adaptation. Meanwhile, NRKN PV seems to be associated with soil types, but its occurrence relative to soil health conditions remains unknown. Preliminary analyses suggest that soils in which NKRN has been observed seem to have degraded and depleted soil food web conditions. This work lays down a foundation for more targeted investigations to understand the potential links between NKRN’s PV and ecosystem to microbiome level changes in its soil environment.

 Another project in objective 2 has been to study nematode adaptation, at the community level, in different geographic locations. At the University of Nebraska, researchers are examining changes in the soil nematode community within native and unplowed grazing lands that feature varying levels of disturbance and management regimes. By using DNA barcoding, the project has looked at the biodiversity of nematode communities. This data will be important for gaining an understanding of the prairie ecosystem and how the nematode communities in one prairie space compare to communities form other prairie spaces in the Midwest.

 Lastly, within in this objective, new nematode records have been made. There was a first report of Ditylenchus dipsaci from alfalfa in New Mexico. New Mexico alfalfa hay production ranked as the fourth largest cash commodity in the state $125 million with 160,000 planted. It is a critical agricultural industry that supports the dairy and cattle producing industries, which are the two top yielding agricultural commodities in New Mexico.The alfalfa cyst nematode Heterodera medicaginis was found in samples from Kansas, Montana, and Utah. This is the first time that the alfalfa cyst nematode has been found in North America. The cactus cyst nematode, Cactodera cacti, was found in Idaho and Colorado, a first for these two states. There was a first report of Cactodera milleri from Quinoa fields in Colorado. 

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

There are many approaches for controlling plant parasitic nematodes in agriculture. Although chemical nematicides are often used, research is needed to investigate new formulations or application methods. Other approaches to nematode control include host plant resistance, green manures, and biological controls. Overall, 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.

Conventional potato growers primarily rely on nematicides to control root-knot nematodes on potato. Several trials were conducted at Oregon State University to test new management strategies using nematicides to control tuber damage from Meloidogyne chitwoodi. After harvest, tubers were peeled and examined for M. chitwoodi infection. Any tuber with six or more infection sites was considered a cull. Employ (Plant Health Care, Inc., Raleigh, NC) contains 1% Harpinαβ, a protein that is said to activate a natural defense mechanism in host plants referred to as systemic acquired resistance (SAR). Various applications (seed piece dipping, foliar treatments) were made at planting or after plant emergence  to plants that had been inoculated with M. chitwoodi eggs. None of the treatments had any effect on the number of J2 or eggs recovered.

Work on nematicides at the University of Idaho looked at the efficacy of new non-fumigant chemistries and formulations and several combinations of fumigants + non-fumigants  on potato fields to determine management strategies for Pratylenchus species and Meloidogyne chitwoodi. Treatments with Velum Prime and Vydate C-LV have showed significant increase in yield when applied to lesion nematode-infested soil. 

Efforts to move away from nematicide use in potato have also been undertaken. In one project in this objective, potato roots were treated with the defense elicitor peptide called Pep1. Treatment with a plant peptide enhanced potato resistance against Meloidogyne chitwoodi. To develop an easy method to deliver this peptide to potato, researchers at Washington State University engineered the bacteria Bacillus subtilis to produce and secrete Pep1. By treating the potato plants with B. subtilis that secretes the Pep1 defense elicitor, the plants became more resistant against M. chitwoodi. This indicates that a “probiotic” bacterial treatment of potatoes may help growers combat M. chitwoodi.

An alternative to method of nematode control in potato is to use cover crops. Several cover crops are being marketed in the Pacific Northwest to be grown as green manure crops to suppress nematodes and soil borne fungal diseases. One important factor for success is for the crop grown prior to incorporation to be a poor or non-host for Columbia root-knot nematode (CRKN, Meloidogyne chitwoodi). The host status of most of these crops is not currently known. In a trial performed by Oregon State University researchers, three-week-old seedlings were inoculated with 5,000 CRKN eggs. Plants were harvested 55 days later, eggs were extracted from roots, and the Reproductive factor (Rf = final population/initial population) was determined. Good hosts were determined as plants with an Rf of 1.00 or greater, poor hosts as those with an Rf from 0.01 to 1.00 and non-hosts as those with an Rf less than 0.01. Caliente 199, Caliente Rojo, Caliente 61 and Trifecta Power Blend were determined to be good hosts and were not different from wheat (the good host standard). Caliente 119, Kodiak, Pacific Gold, White Gold and a blend of Nemat and Caliente 61 were good hosts but had Rf values less than wheat. Nemat alone and in blends with Caliente 199 or Caliente Rojo were poor hosts while Terranova and Sordan 79 were non-hosts. This data will help growers chose the best cover crops for CRKN control.

In addition to infecting potato, plant-parasitic nematodes are also a major pest of turfgrass in the United States, yet there are few options for successful management. Most current management strategies rely on the use of a limited number of chemical nematicides, so finding a new management option for nematode suppression would be extremely valuable for turfgrass managers. The goal of this study at Auburn University was to evaluate a new nematicide, fluazaindolizine (Reklemel™ active), for its ability to reduce plant-parasitic nematode population density and improve turfgrass quality. Greenhouse evaluations performed at demonstrated multiple rates of fluazaindolizine reduced B. longicaudatus population density, and one of the two M. incognita trials showed multiple rates of fluazaindolizine reduced nematode population density. Reklemel was also effective at reducing population density of both B. longicaudatus and M. incognita in microplot settings for both 2018 and 2019, and a significant improvement in turf quality was observed for both visual turfgrass ratings and NDVI. Field trials demonstrated a significant reduction for both B. longicaudatus and M. incognita population density by multiple rates of fluazaindolizine, but no significant differences in turf quality ratings were observed. Overall, fluazaindolizine shows promise as a chemical nematicide for plant-parasitic nematode management on turfgrass.        

Cotton can also be infected by nematodes, and researchers at Auburn University have studied Fusarium oxysporum f. sp. vasinfectum (FOV) and Meloidogyne incognita infections on cotton. FOV and M. incognita combine to form the Fusarium wilt disease complex of cotton, which has been causing losses in the cotton industry around the world for more than 125 years. The goal of this study was to evaluate the use of fluazaindolizine (Reklemel™ active), for its ability to lower M. incognita population density, its effects on FOV, and its usefulness in management the FOV-nematode disease complex. The objectives of this study were 1) evaluate the impact of ReklemelTM on the growth of FOV isolates in vitro and 2) assess cotton growth, yield, and disease incidence with the application of ReklemelTM under greenhouse and field conditions. In greenhouse testing, ReklemelTM significantly reduced M. incognita population density but had no significant effect on Fusarium wilt incidence. However, in the field, ReklemelTM reduced both M. incognita population density and Fusarium wilt incidence. This reduction in FOV incidence was not observed with the treatment of Velum TotalTM which had statistically similar reductions in M. incognita egg population density.

Rotylenchulus reniformis another important nematode that causes yield loss in cotton across the mid-south and southeastern region. Researchers at Auburn University wanted to quantify the yield loss due to Rotylenchulus reniformis and document any yield increase from the addition of a nematicide. Field trials were established in two adjacent fields, one was infested with R. reniformis and one where R. reniformis was not detected. In both fields, seven cotton cultivars were planted with and without Velum Total (1.02 L/ha). Across the cultivars, addition of the nematicide increased seed cotton yields by an average of 6% in the R. reniformis infested field and an average of 8% in the non-infested field. The nematicide reduced R. reniformis eggs per gram of root by an average of 92% in 2017 and 78% in 2018 across all cotton cultivars. 

Research on new nematicides has also been performed in mint fields. Several plant parasitic nematodes infect mint, and researchers at the University of Idaho, Parma research and extension center worked to determine the efficacy of new chemical compounds against Pratylenchus sp., Meloidogyne hapla and Paratylenchus species infecting mint. Results from some of the products tested [Velum Prime (fluopyram), Movento 240 SC (spirotetramat), and Vydate-L (oxamyl)] showed moderate efficacy against lesion nematode over time, but little impact against NRKN or pin nematodes. In addition to the mint trials, work in Idaho also looked at nematicides on greenhouse tomatoes. They found that the efficacy of some new numbered products from Gowan for management of Meloidogyne incognita showed promising results. 

Meanwhile, in New Mexico, work has progressed on nematicide trials in vineyards. Wine distribution, sales, and consumption in New Mexico generates ~$876.7 million in annual economic activity. In 2017, the industry generated ~$51.6 million in state and local taxes, and $55.4 million in federal taxes. Nematodes can cause premature vineyard decline, reduced vine vigor, and increased fungal infection and virus transmission with yield losses of >60% due to nematodes (Teliz et al., 2007). Recent developments of new nematicides necessitate investigations into these new chemistries their integration with New Mexico cultural practices. A field study at the University of New Mexico was initiated in the spring of 2020 to measure Meloidogyne incognita management and wine-grape yield response to fluensulfone (Nimitz^®) compared to spirotetramat (Movento^®) and an untreated control.  As anticipated, yields were not significantly improved by either of the spring nematicide treatments at any of the vineyard sites evaluated. This was the first year of the trial, and treatments applied this year have the best opportunity to influence grape yields more directly in 2021.

In order to be effective, the nematicidal treatments in vineyards must be applied to the soil environment during the time when there is the highest probability that the vulnerable life stage of the pathogen will also be present in the soil matrix. However, little is known about the seasonal population dynamics of Meloidogyne incognita race 3 (southern root-knot nematode -SRKN) in wine grape vineyards of southern New Mexico. To investigate this, a monitoring study has been initiated this year that will attempt to track soil temperature, soil presence of SRKN juveniles and SRKN egg production on the roots of grapevines of varying rootstocks in a vineyard in Dona Ana County, NM. This information will contribute to improved efficacy of chemical management tools that target the particular life-stage of this nematode in the ever-growing number of vineyards in this region.

Lastly, there has been work performed at the University of Hawaii to study nematicide treatments to control nematodes in pineapple. Chemical approaches to management of plant-parasitic nematodes was a common approach amongst producers, and multiple preplant chemicals, including fumigant nematicides such as 1,3-D, methyl bromide, EDB, fenamiphos, and postplant organophosphates and carbamates, were incorporated into the pineapple cropping system. Many of these chemicals have been removed from the market and are no longer available for use in any cropping system. Consequently, replacement options are needed. The efficacy of preplant crown dips with abamectin or fluopyram was tested on pineapple establishment and growth in soil infested with Rotylenchulus reniformis. Plants not infected with nematodes grew better than plants treated with abamectin, fluopyram, or left untreated. Nematode populations were low in all treatments. These chemicals may not have utility as preplant dips in pineapple.

Researchers in Hawaii have also studied Entomopathogenic nematode (EPNs) as a method of insect control. EPN live bombs hold promise as a novel biocontrol agent delivery method, however the bombs have not performed well. Laboratory experiments with 0.2 g, 2-2.5 cm mealworm larvae yielded an average of 7,842 IJ S. feltiae over a 27-day period. The mealworms produced 3,555 IJ of H. indida and 7,035 Oscheius sp. Not all of the mealworm larvae were successfully infected by the EPN. The number of cadavers recovered from an infection court varied from 100 to 10% infection. Infection averaged 71% with S. feltiae, 97% with H. indica and 100% with Oscheius. IJ emergence also varied by time. Two peaks of IJ of S. feltiae were observed, the first at 15 days and a second at 22 days after placement into the infection court. A similar peak was observed at 15 days in H. indica and Oscheius. From the literature, emergence of S. feltiae peaks at 15 days in Galleria mellonella. Emergence of H. indica has a similar peak at 14 days in Temnorhynchus baal larvae. The rate of emergence of Oscheius is not as clear. The first peaks observed in the current experiment fit the behavior of S. feltiae and H. indica, however the second peaks are puzzling. In the next set of experiments, insect death at 24 and 48 hours after introduction to the infection court will be noted. This work will help us understand how to improve EPN as a biocontrol tool.

Biotechnology offers new approaches to nematode control and will reduce the reliance on nematicides, which are often expensive. In a biotechnology project from UCR, researchers have identified a negative regulator of root-knot nematode immunity in Arabidopsis and have shown that the absence of this gene results in over 50% decrease in RKN infection. To assess the role of this gene in tomato, they developed CRISPR-Cas9 constructs to target the tomato putative ortholog(s) of the Arabidopsis gene.  Several primary tomato transformants were obtained and a few made it to maturity. A number of putative transgenic plants were lost due to lack of daily care because of the pandemic lockdown. Sequence analysis indicated that the CRISPR edited plants had point mutations and were all heterozygous for the mutations. All transgenic plants that made it to maturity were able to set fruits with seeds. The seeds will be planted to obtain homozygous mutants for evaluation with RKN.  Additional tomatoes are being transformed to obtain several independent CRISPR edited lines for future studies. These “biotech” tomatoes may have novel root-knot nematode resistance.

With the view that it is important to identify additional biological mechanisms that can be used to develop novel and durable crop resistance against nematodes, researchers at Davis are interested in further understanding the mechanisms by which plants recognize and defend themselves against nematodes. Basal plant immune responses (also known as PAMP-triggered immunity, PTI) can help defend plants against nematodes. However, mechanisms that underlie the activation of PTI in plant-nematode interactions remain unclear. Davis researchers and their collaborators previously identified a plant receptor (NILR1) that is involved PTI activation upon nematode infection. However, the identity of nematode PAMP whose perception is mediated by NILR1 remains unknown. They are now focusing on isolating nematode-derived peptides whose perception is mediated by NILR1 and how the activation of NILR1 is linked to downstream immune signaling. The research plan focuses initially on the model plant Arabidopsis thaliana and its interaction with cyst nematode and root-knot nematode. However, the knowledge gained will be transferred to crop plants during the subsequent years, particularly to rice, soybean (Glycine max), almond (Prunus dulcis), tomato (Lycopersicon esculentum) and sugar beet (Beta vulgaris).

Biotechnology has also provided breakthrough in understanding soybean cyst nematode resistance. A Glycine max (soybean) hemicellulose modifying gene, xyloglucan endotransglycoslase/hydrolase (XTH43), is expressed within an Heterodera glycines-induced nurse cell known as a syncytium developing within the soybean root undergoing a defense response. Transgenically expressing XTH43 in Gossypium hirsutum (upland cotton) resulted in an 18% decrease in galls, 70% decrease in egg masses, 64% decrease in egg production and a 97% decrease in second stage juvenile (J2) production as compared to transgenic controls, but did not significantly affect root mass. The results demonstrate XTH43 expression functions effectively in impairing the development of M. incognita (Niraula et al. 2020a). XTH is a secreted protein. Secreted proteins move through the cell in various ways involving two major pathways, the anterograde and retrograde transport. The universal eukaryotic conserved oligomeric Golgi (COG) complex, functioning in retrograde trafficking maintains the correct Golgi structure and function. The COG complex is composed of 8 subunits COGs1-4 compose Sub-complex A while COGs5-8 compose Sub-complex B. Functional transgenic studies demonstrate at least one paralog of each COG gene family functions in G. max during H. glycines resistance (Lawaju et al. 2020). Anterograde transport can culminate through the action of the exocyst. The G. max exocyst is encoded by 61 genes: 5 EXOC1 (Sec3), 2 EXOC2 (Sec5), 5 EXOC3 (Sec6), 2 EXOC4 (Sec8), 2 EXOC5 (Sec10) 6 EXOC6 (Sec15), 31 EXOC7 (Exo70) and 8 EXOC8 (Exo84) genes. At least one member of each gene family is expressed within the syncytium during the defense response. Syncytium-expressed exocyst genes function in defense while some are under transcriptional regulation by mitogen-activated protein kinases (MAPKs) (Sharma et al. 2020). G. max has 32 mitogen activated protein kinases (MAPKs) with nine of them exhibiting defense functions to H. glycines. RNA seq analyses of transgenic G. max lines overexpressing (OE) each defense MAPK has led to the identification of 309 genes that are increased in their relative transcript abundance. Here, 71 of those genes have measurable amounts of transcript in H. glycines-induced syncytia undergoing a defense response. The 71 genes have been grouped into 7 types, based on their expression profile. Overexpression experiments that increase the relative transcript abundance of the candidate defense gene reduces the ability that the plant parasitic nematode Heterodera glycines has in completing its life cycle while, in contrast, RNAi of these genes leads to an increase in parasitism. The results provide a genomic analysis of the importance of MAPK signaling in relation to the secretion apparatus during the defense process defense in the G. max-H. glycines pathosystem and identify additional targets for future studies (Niraula et al. 2020).

Refereed Journal Articles:

Avelar, Sofia, Roberto Ramos-Sabrinho, Kassie Conner, Robert L. Nichols, Kathy Lawrence, and Judith K. Brown. 2020. Characterization of the Complete Genome and P0 Protein for a Previously Unreported Genotype of Cotton Leafroll Dwarf Virus, an Introduced Polerovirus in the United States. Plant Disease 104:780-786. doi.org/10.1094/PDIS-06-19-1316-RE

Anjam, M. S., Shah, S. J., Matera, C., Rozanska, E., Sobczak, M., Siddique, S., and Grundler, F. M. W. 2020. Host factors influence the sex of nematodes parasitizing roots of Arabidopsis thaliana. Plant Cell Environ 43:1160-1174.

Dyer, David R., William Groover, Kathy S. Lawrence. 2020. Yield loss of cotton cultivars due to Rotylenchulus reniformis and the added benefit of a nematicide. Plant Health Progress 21:113-118. https://doi.org/10.1094/PHP-10-19-0073-RS

Groover, W., K. S. Lawrence, and P. Donald. 2020. Temporal distribution of plant-parasitic  nematodes on select bermudagrass sites in Alabama. Nematropica 50:77-85. https://journals.flvc.org/nematropica/article/view/124876

Groover, W., and K. S. Lawrence. 2020. Plant health evaluations of Belonolaimus longicaudatusand Meloidogyne incognita colonized bermudagrass using remote sensing. Journal of Nematology 52:1-13. DOI: 10.21307/jofnem-2020-109.

Groover, Will, David Held, Kathy Lawrence, and Kendra Carson. 2020. Plant growth-promoting rhizobacteria: a novel management strategy for Meloidogyne incognita on turfgrass. Pest Management Science DOI 10.1002/ps.5867.

Gutbrod, P., Gutbrod, K., Nauen, R., Elashry, A., Siddique, S., Benting, J., Dormann, P., and Grundler, F. M. W. 2020. Inhibition of acetyl-CoA carboxylase by spirotetramat causes growth arrest and lipid depletion in nematodes. Scientifc Reports 10:12710.

Hamada, N., Yimer, H. Z., Williamson, V. M., and Siddique, S. 2020. . Chemical hide and seek: nematode’s journey to its plant host. Molecular Plant, 13 (2):1-2.

Handoo, Z. A., Skantar, A. M., Kantor, M. R., Hafez, S. L., and Hult, M. N. 2020a. Molecular and morphological characterization of the amaryllis lesion nematode, Pratylenchus hippeastri (Inserra et al., 2007), from California. J Nematol 52:1-5.

Handoo, Z. A., Skantar, A. M., Hafez, S. L., Kantor, M. R., Hult, M. N., and Rogers, S. A. 2020b. Molecular and morphological characterization of the alfalfa cyst nematode, Heterodera medicaginis, from Utah. J Nematol 52:1-4.

Hiltl C, Siddique S. New Allies to Fight Worms. Nature Plants, 6: 598-599.

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. 2020. 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 (in press).

Kranse O, Beasley B, Adams S, da Silva AP, Bell C, Lilley C, Urwin P, David Bird D, Miska E, Smant G, Gheysen G, Jones J, Viney M, Abad P, Maier TR, Baum TJ, Siddique S, Williamson V, Akay m, Eves-van den Akker S (2020). Towards genetic modification of plant-parasitic nematodes: delivery of macromolecules to adults and expression of exogenous mRNA in second stage juveniles. G3:GENES, GENOMES, GENETICS. ** IN PRESS **.

Lawaju BR, Prakash P, Lawrence GW, Lawrence KS, Klink VP. 2020. The Glycine max conserved oligomeric Golgi (COG) complex functions during a defense response to Heterodera glycines. Frontiers in Plant Science doi: 10.3389/fpls.2020.564495.

Niraula PM, Lawrence KS, Klink VP. 2020a. The heterologous expression of a soybean (Glycine max) xyloglucan endotransglycosylase/hydrolase (XTH) in cotton (Gossypium hirsutum) suppresses parasitism by the root knot nematode Meloidogyne incognita. PlosOne 15:e0235344. doi: 10.1371/journal.pone.0235344.

Niraula PM, Sharma K, McNeece BT, Troell HA, Darwish O, Alkharouf NW, Lawrence KS, Klink VP. 2020b. Mitogen activated protein kinase (MAPK)-regulated genes with predicted signal peptides function in the Glycine max defense response to the root pathogenic nematode Heterodera glycines PlosOne, https://doi.org/10.1371/journal.pone.0241678).

Powers, T., Harris, T.S., Higgins, R.S., Mullin, P.G. and Powers, K.S., 2020. Nematode biodiversity assessments need vouchered databases: A BOLD reference library for plant-parasitic nematodes in the superfamily Criconematoidea. Genome, (ja). https://doi.org/10.1139/gen-2019-0196

Sharma, Keshav, Prakash M. Niraula, Hallie A. Troell, Mandeep Adhikari, Hamdan Ali Alshehri, Nadim W. Alkharouf, Kathy S. Lawrence & Vincent P. Klink. 2020. Exocyst components promote an incompatible interaction between Glycine max (soybean) and Heterodera glycines (the soybean cyst nematode). Scientific Reports 10:15003. doi.org/10.1038/s41598-020-72126-z

Singh, R. R., Verstraeten, B., Siddique, S., Tegene, A. M., Tenhaken, R., Frei, M., Haeck, A., Demeestere, K., Pokhare, S., Gheysen, G., and Kyndt, T. 2020. Ascorbate oxidation activates systemic defence against root-knot nematode Meloidogyne graminicola in rice. Journal of Experimental Botany 71:4271-4284.

Subedi, Pratima, Kaitlin Gattoni, Wenshan Liu, Kathy S. Lawrence, and Sang-Wook Park, 2020. Current utility of plant growth–promoting rhizobacteria as biological control agents towards plant-parasitic nematodes. MDPI Plants 9: 1167. DOI:10.3390/plants9091167

Velasco-Cruz, C., G. Giese, D. Saldaña-Zepeda, J. Beacham. 2020. Modeling nematode population dynamics using a multivariate poisson mixture model. Journal of Applied Statistics. (in review)

Waisen, P., Z. Cheng, B.S. Sipes, J. DeFrank, S.P. Marahatta, and K.-H. Wang. 2020. Effects of biofumigant crop termination methods on suppression of plant-parasitic nematodes. Applied Soil Ecology 154:103595. https://doi.org/10.1016/j.apsoil.2020.103595

 Zhang, L. and Gleason C., “Enhancing potato resistance against root-knot nematodes using plant elicitors delivered by bacteria.” Nature Plants, 6, pages 625–629

Extension publications:

Cynthia Gleason and Sagar Sathuvalli “Genetic Diversity in Columbia Root-Knot Nematode, and a Request for Help in Research” Potato Progress Vol XX, No. 13, 2020

Lei Zhang and Cynthia Gleason “Loop-Mediated Isothermal Amplification for the Diagnostic Detection of Meloidogyne chitwoodi,” Potato Progress Vol XX, No. 1, 2020

Book chapters:

Lawrence, Kathy S. 2020. Reniform nematode (Rotylenchulus reniformis) and its interactions with cotton (Gossypium hirsutum) Chapter 14: pages XX-XX in Integrated nematode management: state of the art and visions for the future. eds Richard Sikora, Johan Desaeger and Leendert Molendijk for CABI. (In press.)

Lawrence, K. S. and G. W. Lawrence. 2020. Plant-Parasitic Nematode Management Chapter 12: pages 164-180 in Conservation Tillage Systems: Production, Profitability and Stewardship. eds J. Bergtold, R. Raper, G. Hawkins, and K. Iversen. CRC Press LLC.

Roberts, P.A. 2020. Integrated management of root-knot and other nematodes in food legumes. Pp.1-9 in Integrated nematode management: state of the art and vision for the future. Sikora, R., et al., (eds.). (In press).

Published Abstract:

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 CottonConference Vol. 1: 117-119. National Cotton Council of America, Memphis, TN. http://www.cotton.org/beltwide/proceedings/2005-2020/index.htm

Heather Kelly, Rachel R. Guyer, Shelly Neill Pate, Thomas W. Allen, Tessie H. Wilkerson, P. D. Colyer, Thomas Isakeit, Robert C. Kemerait, Kathy S. Lawrence, Hillary L. Mehl, Paul Price, Alejandro Rojas, Lindsey D. Thiessen and Terry A. Wheeler. 2020. Report of the Cottonseed treatment committee for 2019. Proceedings of the 2020 Beltwide Cotton Conference Vol. 1: 393-402. National Cotton Council of America, Memphis, TN. http://www.cotton.org/beltwide/proceedings/2005-2020/index.htm

Kathy S. Lawrence, Tyler Sandlin, Andy Page, Tyson B Raper, Heather Kelly, Brad Meyer and Nathan Silvey. 2020.  Cotton Cultivar Disease Incidence, Severity, and Yields When Challenged with Verticillium Wilt in the Tennessee Valley Region, 2019. Proceedings of the 2020 Beltwide Cotton Conference Vol. 1: 112-116. 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

Marina Nunes Rondon and Kathy Lawrence. 2020. G143A Mutation in the Cytochrome B Gene Detected from Corynespora cassiicola Isolates in Alabama.  Proceedings of the 2020 Beltwide Cotton Conference Vol. 1: 202-206. National Cotton Council of America, Memphis, TN. http://www.cotton.org/beltwide/proceedings/2005-2020/index.htm

Shelly Neill Pate, Heather Kelly, Rachel R. Guyer, Thomas W. Allen, Tessie H. Wilkerson, P. D. Colyer, Kathy S. Lawrence, Thomas Isakeit, Robert C. Kemerait, Hillary L. Mehl, Paul Price, Alejandro Rojas, Lindsey D. Thiessen and Terry A. Wheeler. 2020. An Assessment of Seed Treatment Efficacy and Cotton Seedling Disease Presence Using Innovative Techniques. Proceedings of the 2020 Beltwide Cotton Conference Vol. 1: 327-328. 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

R. Dyer, K.S. Lawrence, W. Groover, D. Dyer, M. Rondon, K. Gattoni, W. Sanchez, K. Gordon. 2020. Evaluation of nematicide products for increasing cotton plant growth and yield and decreasing reniform nematode population density on cotton in North Alabama, 2019. Plant Disease Management Reports 14:N007. The American Phytopathological Society, St. Paul, MN.

https://www.plantmanagementnetwork.org/pub/trial/pdmr/reports/2020/N007.pdf

R. Dyer, K.S. Lawrence, W. Groover, D. Dyer, M. Rondon, K. Gattoni, W. Sanchez, K. Gordon. 2020. Evaluation of Salibro for increasing cotton plant growth and decreasing root-knot nematode population density and fusarium wilt incidence on cotton in central Alabama, 2019. Disease Management Reports 14:N006. The American Phytopathological Society, St. Paul, MN.

http://www.plantmanagementnetwork.org/pub/trial/pdmr/reports/2020/N006.pdf

Kara Gordon, K.S. Lawrence, W. Groover; D. Dyer; M. Rondon, W. Sanchez. 2020. Management strategies utilizing nematicides to combat yield loss from reniform nematode on cotton, 2019. Plant Disease Management Reports 14:N013. The American Phytopathological Society, St. Paul, MN. http://www.plantmanagementnetwork.org/pub/trial/pdmr/reports/2020/N013.pdf

 B.R. Lawaju, K.S. Lawrence, W. Groover, D. Dyer, M. Rondon, K. Gattoni, W. Sanchez, K. Gordon. 2020. Evaluation of fungicides for management of damping-off in cotton in north Alabama, 2019.Plant Disease Management Reports 14:CF054. The American Phytopathological Society, St. Paul, MN.  http://www.plantmanagementnetwork.org/pub/trial/pdmr/reports/2020/CF054.pdf

B.R. Lawaju, K.S. Lawrence, W. Groover, D. Dyer, M. Rondon, K. Gattoni, W. Sanchez, K. Gordon. 2020.  Combinations of seed treatments for seedling disease management in cotton in northern Alabama, 2019. Plant Disease Management Reports 14:CF053. The American Phytopathological Society, St. Paul, MN.  http://www.plantmanagementnetwork.org/pub/trial/pdmr/reports/2020/CF053.pdf

B.R. Lawaju, K.S. Lawrence, W. Groover, D. Dyer, M. Rondon, K. Gattoni, W. Sanchez, K. Gordon. 2020. Fungicide seed treatments for management of seedling disease in cotton in northern Alabama, 2019. Plant Disease Management Reports 14:CF052. The American Phytopathological Society, St. Paul, MN.  http://www.plantmanagementnetwork.org/pub/trial/pdmr/reports/2020/CF052.pdf

Marina Nunes Rondon, K.S. Lawrence, W. Groover; D. Dyer, B.R. Lawaju, K. Gordon. 2020. Nematicide seed treatments for reniform nematode management on soybean in north Alabama, 2019. Plant Disease Management Reports 14:CF038. The American Phytopathological Society, St. Paul, MN.  http://www.plantmanagementnetwork.org/pub/trial/pdmr/reports/2020/CF038.pdf