Barbara Shew
Research Assistant Professor Emeritus
Management of ornamental and peanut diseases
Gardner Hall 3404
Bio
Students:
- Ella Reeves, M.S. Fall 2020, Co-advised with Jim Kerns. Thesis title: Pythium spp. associated with root rot and stunting of winter crops in North Carolina.
- Alejandro Llanos Melo, M.S. 2020, Co-advised with Sara Villani. Thesis title: Evaluation of SDHI fungicides and host plant defense inducers for the management of plant pathogens in two different cropping systems.
- Emma Lookabaugh, Ph.D. 2017. Dissertation title: Integrated strategies for managing Pythium root rot and fungicide-insensitive strains of Pythium aphanidermatum in poinsettia. Current position: Technical Services, turf and ornamentals, BASF
- Michael Cannon, M.S. 2017. Thesis title: Sensitivity of Sclerotinia minor to common peanut fungicides
- Emma Lookabaugh, M.S. 2013. Thesis title: Understanding the impact of Pythium species on floricultural crops in North Carolina. Current position: Technical Services, turf and ornamentals, BASF
- Sarah Rurak, M.S. 2009. Thesis title: Evaluation of biological and other novel seed and soil treatments for organic peanut production. Current position: Ph.D. student, Cornell University
- Damon Smith, Ph.D. 2007, M.S., 2004. Thesis title: Biology and Epidemiology of Sclerotinia minor on Peanut (Arachis hypogaea L.). Current position: Assistant Professor, University of Wisconsin
- Laura Duffie, M.S. 2003. Effects of intercropping corn and peanut on peanut leaf spot management and the spatial and temporal epidemiology of Cercospora arachidicola. Current position: USDA-APHIS
Research
Pythium root rot
Our objective is to better understand how Pythium infections contribute to poor stands, stunting, and death of North Carolina’s winter-grown crops, including clary sage, winter wheat, and selected cover crop species. This work has involved widespread sampling from these hosts across the state, isolation and identification of the Pythium species infecting them, pathogenicity testing, and characterization of interactions between Pythium and environmental variables on selected hosts species.
North Carolina is a major producer of floricultural crops and Pythium is frequently diagnosed on floricultural samples submitted to the Plant Disease and Insect Clinic (PDIC). Greenhouses in North Carolina previously had not been systematically sampled for the presence of Pythium. The severity of the problem, the Pythium species involved, and the extent of mefenoxam resistance in greenhouse populations were unknown. To address these questions, graduate student Emma Lookabaugh collected herbaceous ornamentals exhibiting symptoms of Pythium root rot from 18 greenhouses in 14 counties in North Carolina. Isolates were identified to species by sequencing of the ITS rDNA region. More than half of the 277 isolates collected were resistant to mefenoxam. Resistant and sensitive strains were found within the same greenhouse and species. We plan to use the results of this research to provide mefanoxam resistance screening services to growers through the Plant Disease and Insect Clinic.
Peanut diseases
Peanuts are grown on about 90,000 acres in North Carolina. The crop is affected by several serious diseases, including leaf spots, southern stem rot, Sclerotinia blight, Cylindrocladium black rot, and Spotted wilt. My research aims to develop integrated disease management tactics that take advantage of host resistance and weather-based disease advisories to minimize the use of fungicides and other pesticides in peanut production. Currently, I am focusing on developing reduced input disease control methods that can be used on the new partially resistant cultivars Bailey, Sugg, Sullivan and Wynne. I work with peanut breeder Dr. Tom Isleib in evaluation of disease resistance in new breeding lines. I also work with Dr. David Jordan to understand the impacts of cultural practices on disease development and crop health.
Extension & Outreach
Plant Disease and Insect Clinic
I served as the Director of the Plant Disease and Insect Clinic at NCSU from 2009 – 2019. The clinic is staffed with two full-time plant disease diagnosticians, Shawn Butler and Mike Munster, and full-time entomologist, Matt Bertone. Graduate student Emma Lookabaugh diagnoses diseases of tomatoes and other crops. The clinic provides diagnostic training for County Agents and Master Gardeners and uses social media (Facebook, Twitter, and Blog) for outreach to a wide audience of Extension personnel, farmers, nurseries, and homeowners.
Peanuts
As part of a team that includes Dr. David Jordan in Crop Science, entomologist Dr. Rick Brandenburg, and county extension personnel, I have extension responsibilities for peanut diseases. We prepare educational materials, conduct field testing, and participate in grower meetings, demonstrations and field days. In addition, in cooperation with the North Carolina State Climate office, I provide daily peanut disease advisories for peanut growers in North Carolina.
Peanut Portal – Comprehensive website for peanut information and updates
Peanut Information – Peanut production guide
Agricultural Chemicals Manual
Peanut Risk Management – See how production practices affect pest problems
Peanut Disease Photos
Peanut Disease Advisories – Click on this link to view today’s weather based disease advisories and for information on how to interpret advisories. You may contact Dr. Shew to receive daily advisory emails.
Peanut Scouting Manual – IPM Center
Selected Publications
- Lookabaugh, E.C. Whipker, B., and Shew, B. B. 2017. Evaluation of Poinsettia Cultivars for Resistance to Pythium Root Rot Caused by Pythium aphanidermatum. HortTechnology doi: 10.21273/HORTTECH03817-17.
- E. C. Lookabaugh, A. Thomas, B. B. Shew, S. C. Butler, and F. J. Louws. 2017. First Report of Black Leaf Mold of Tomato Caused by Pseudocercospora fuligena in North Carolina. Plant Disease doi.org/10.1094/PDIS-06-17-0897-PDN.
- Lookabaugh, E., Shew, B., and Cowger, C. 2017. Three Pythium species isolated from severely stunted wheat during an outbreak in North Carolina. Plant Health Progress 18:169-173.
- B.R. Lassiter, G.G. Wilkerson, D.L. Jordan,* G.S. Buol, B.B. Shew, R. Brandenburg,
A. Herbert Jr., and P. Phipps. 2017. Development and Deployment of a Composite Pest Risk
Assessment Decision Support System for Peanut (Arachis hypogaea L.) in the Virginia-Carolina Region. Crop Forage Turfgrass Manage. doi:10.2134/cftm2017.08.0054 - A. M. Koehler, E. C. Lookabaugh, B. B. Shew, and H. D. Shew. 2017. First Report of Pythium Root Rot of Stevia Caused by Pythium myriotylum, P. irregulare, and P. aphanidermatum in North Carolina. Plant Disease 101:1331.
- Junsopa, C., Jogloy, S, Saksirirat, W, Songsri, P, Kesmala, T, and Shew, B.B. 2017. Genotypic diversity of Jerusalem artichoke for resistance to stem rot caused by Sclerotium rolfsii under field conditions. Euphytica 213:164.
- Jordan, D.L., Corbett, T., Bogle, C., Shew, B., Brandenburg, R. and Ye, W. 2017. Effect of previous rotation on plant parasitic nematode population in peanut and Crop Yield. Crop Management doi:10.2134/cftm2016.12.0086
- Junsopa, C., Jogloy, S., Saksirirat, W., Songsri, P, Kesmala, T., Pathanothai, A., Shew, B.B. 2016. Inoculation with Sclerotium rolfsii, cause of stem rot in Jerusalem artichoke, under field conditions. Eur. J. Plant Pathology Doi 10.1007/s/0658-016-089-1
- Boudreau, M.A., B. B. Shew, and L.E. Duffie. 2015. Impact of intercropping on epidemics of groundnut leaf spots: defining constraints and opportunities through a 7-year field study. Plant Pathology Doi 10.1111/ppa.12440.
- Lookabaugh, E.C., Ivors, K.M., Shew, B.B. 2015. Mefenoxam sensitivity, aggressiveness, and identification of Pythium species causing root rot on floriculture crops in North Carolina. Plant Disease 99:1550-1558.
- Isleib, T.G., Milla-Lewis, S.R., Pattee, H.E., Copeland, S.C., Zuleta, M.C., Shew, B.B., Hollowell, Sanders, T.H., Dean, L.O. Hendrix, K.W., Balota, M., Chapin, J.W., and Monfort, W.S. 2015. Registration of ‘Sugg’ Peanut. J. Crop Regist. 9:44-52
- Jordan, D.L., P. D. Johnson, T. Corbett, J. Schultheis, B. Shew, R. Brandenburg, W. Ye. 2014. Peanut response to crop rotations including clary sage, snap bean, and sweet potato. Crop Manag. doi:10.2134/CM-2014-0038-RS
- Drake, W.L., D. L. Jordan, P. D. Johnson, B. B. Shew, R. L. Brandenburg, T. Corbett. 2014. Peanut response to planting date, tillage, and cultivar in North Carolina. Agronomy Journal 106: 486-490
- Isleib, T.G., B.B. Shew, S.R. Milla-Lewis, W.B. Dong, S.C. Copeland, C. Arellano. 2013. Stability analysis of incidence of tomato spotted wilt in virginia-type peanut cultivars and breeding lines. Peanut Sci. 40:24-30.
- Chahal, G.S., D.L. Jordan, B.B. Shew, R.L. Brandenburg, J.D. Burton, and D. Danehower. 2012. Interactions of Agrochemicals Applied to Peanut; Part 2: Effects on Fungicides. Crop Protectionhttp://dx.doi.org/10.1016/j.cropro.2012.05.008
- Partridge-Telenko, D.E., J. Hu, D. M. Livingstone, B. B. Shew, P. M. Phipps, and E. A. Grabau. 2011. Sclerotinia Blight Resistance in Virginia-Type Peanut Transformed with a Barley Oxalate Oxidase Gene. Phytopathology 101: 786-793.
- Ruark, S.J., and Shew, B.B. 2010. Evaluation of microbial, botanical, and organic treatments for control of peanut seedling diseases. Plant Dis. 84:445‐454.
Selected Technical Reports
- Shew, B.B. 2015. Response of peanut diseases in North Carolina to spray programs with labeled fungicides, 2014. Plant Dis. Mgt. Rep. 9
- Shew, B.B. 2015. Response of peanut diseases in North Carolina to in-furrow inoculation and fungicide applications, 2014. Plant Dis. Mgt. Rep. 9
- Shew, B.B. 2014. Evaluation of Abound, Convoy, and Folicur for stem rot control on stevia in North Carolina, 2014. Plant Dis. Mgt. Rep. 9
- Shew, B.B. 2013. Evaluation of experimental fungicides for peanut disease control in North Carolina, 2013. Plant Dis. Mgt. Rep. 8
- Shew, B.B. 2011. Evaluation of Abound plus Alto for control of peanut diseases in North Carolina, 2011. Plant Dis. Mgt. Rep. 6
- Shew, B.B. 2011. Evaluation of Fontelis and Topguard for control of peanut diseases in North Carolina, 2011. Plant Dis. Mgt. Rep. 6
- Shew, B.B. 2011. Evaluation of spray programs with labeled fungicides for the control of peanut diseases in North Carolina, 2012. Plant Dis. Mgt. Rep. 6
- Shew, B.B., B.B. 2010. Evaluation of Topguard and other fungicides for the control of peanut diseases in North Carolina, 2009. Plant Dis. Mgt. Rep. 4
- Shew, B.B., B.B. 2010. Evaluation of in-furrow and foliar fungicides for control of peanut diseases in North Carolina, 2009. Plant Dis. Mgt. Rep. 4
Education
B.S Plant Pathology Colorado State University 1976
M.S Plant Pathology North Carolina State University 1980
Ph.D Plant Pathology North Carolina State University 1983
Grants
The PDIC will continue to provide for the identification of plant diseases, insects, weeds, nematodes and abiotic problems through the cooperation of faculty and staff across several disciplines and in cooperation with the NC Department of Agriculture and Consumer Services. Diagnostic personnel will attend national and regional professional meetings and training on special topics and general plant pathology/ entomology/ nematology. The laboratory currently has a permit to receive samples from out of state and will continue to be available to process regional surge samples if the need arises. We will continue to submit all data on a daily basis for the duration of the project, as defined by the NPDN policies regarding data submission and sharing. NCSU Extension IT will interface with NPDN as necessary to resolve database issues. The PI and PDIC personnel will work to prepare key documents and protocols necessary for Star-D accreditation. We will continue to contribute to a weekly electronic pest information newsletter (Pest News) and to communicate specific Pest Alerts for new insects and diseases in our state as necessary. Informational materials will be communicated to our County Extension clientele and other first detectors by our website, social media, the Plant Pathology and Entomology Extension Portals. NCSU PDIC personnel will communicate pest and diagnostic information in web-based and in-person sessions, through the development of print publications (posters, handouts and brochures), and by frequent and timely updates on our social media sites. CEUs will be given in most training sessions. Clinic personnel will communicate pest information and diagnostic education to an estimated 400 Master Gardeners and CES agents via online meetings. We will coordinate with NCDA&CS to communicate pest threats, issue alerts, and information about intra-state quarantines as needed. We will participate in all regional and applicable subcommittee conference calls. At least one member of the laboratory will attend the SPDN regional meeting in 22017.
Through this cooperative work, NCSU and PPQ CPHST will employ a variety of advanced diagnostic methods and platforms for rapid, sensitive, and reliable detection, identification and characterization of fungal, oomycete, bacterial and viral plant quarantine and/or select agent pathogens. These platforms will include DNA-based methods such as PCR, real-time PCR, and digital PCR. Two other areas of evaluation are the serological technology CANARY that we continue to adapt to plant pathogen detection with MIT, and the loop-mediated isothermal amplification technology (LAMP) recently applied to plant pathogen detection by national and international researchers. We will utilize these advanced technologies for the detection of HLB, CC, CiLV, CBS and PPV. The NCSU researcher and technical staff will support the needs of the work above by working with CPHST Beltsville Laboratory scientists in Beltsville to supply needed materials to these projects and evaluate the platforms and reagents as supplied to the PPQ CPHST Beltsville Lab. The graduate student will enroll in appropriate graduate courses, conduct research on a diagnostic problem, diagnose designated samples submitted to the PDIC, participate in PDIC training and education programs, and attend diagnostic workshops conducted by APHIS in cooperation with NPDN. In addition, the graduate student will aid in the evaluation and validation of new protocols developed by the Beltsville researchers as described above.
The project has its general objective to apply cutting-edge technology in advanced diagnosis of plant quarantine and/or select agent plant pathogens, and to validate methods and novel platforms used in improving detection methods and processes. The project may also provide support for the development and validation of proficiency test panels for plant quarantine pathogens and diseases.
Poor control of peanut leaf spots, especially late leaf spot, appears to have increased in North Carolina the past few years. Poor leaf spot control has been seen in several fields across the state and sometimes has been severe enough to warrant early digging. Although some problems could be attributed to sprays delayed by rain and wet fields, and others to use of fungicides at inappropriately low rates or extended intervals, severe leaf spot also has been observed in fields where growers used solid control programs. The purpose of this research is to further document the prevalence of leaf spot control problems and to test for the for the presence of QoI (group 11) resistance in populations of leaf spot fungi in North Carolina.
This project aims to improve soybean management by providing accurate diagnosis of diseases, insects, or abiotic disorders of soybeans submitted by extension agents. This effort will help to reduce the cost of soybean production by targeting management based on accurate diagnosis of diseases and disorders of soybean.
1) This project will support efforts by cooperative extension agents to diagnose specific crop nutritional or disease problems in corn. 2) This project will fund a limited number of samples to be submitted by cooperative extension agents for analysis at the NCDA&CS Agronomic Division plant tissue lab, and at the NCSU Plant Disease & Insect Clinic.
The purpose of this project is to develop an enhanced web-based searchable version of the North Carolina Agricultural Chemicals Manual that will expand the user's ability to search for pesticide based on a wider set of criteria including best management practices, worker and environmental safety, compliance with organic production stands, and pesticide resistance management recommendations.
Previously we demonstrated that several management programs are suitable for use on the commonly grown cultivars Bailey, Sullivan and Wynne. Preliminary data indicate that these programs also are suitable for Bailey II, but additional research with this cultivar is needed to guide management programs in this cultivar. Likewise, previous work was initiated before the introduction of a new fungicide (Miravis) that may provide leaf spot control for up to 28 days after application. Based on cooperative fungicide trials, this fungicide appears to provide excellent leaf spot control and is likely to be used widely in disease control programs in North Carolina. However, questions about efficacy over extended intervals and best fit in local control programs remain. This proposal will: 1) Compare standard disease control programs on Bailey II and Sullivan; 2) Examine efficacy and timing of extended-interval fungicide applications on Sullivan
While good leaf spot control is still the rule in North Carolina, problems with poor control appear to be increasing. Conversations with county agents, consultants, and growers revealed that poor leaf spot control was seen in several fields across the state in 2017. In some cases, leaf spot and defoliation were severe enough to warrant early digging. Some of these problems could be attributed to sprays delayed by rain and wet fields, and others to use of fungicides at inappropriately low rates or extended intervals. However, severe leaf spot also was observed in fields where growers used solid control programs. Similar loss of control was observed in isolated cases in 2015 and 2016. The purpose of this research is to determine the levels of leaf spot control attained across North Carolina production areas, to document the prevalence of leaf spot control problems, and to expand studies examining efficacy of group 11 fungicides commonly used for leaf spot control.
Although there is considerable information available on the interrelationships of peanut pests and practices that influence their occurrence, development and management, many constraints are often addressed individually with limited understanding or consideration for other constraints in the system. Traditional methods of outreach in written or electronic formats do not inform users on interactions of practices and aggregate or cumulative risks in an easy manner. A risk tool developed at North Carolina State University allows practitioners to look at how changing a practice for one pest influences risks associated with other pests, including input costs associated with practices that may reduce risk for a single pest or group of pests. Developing the risk tool for African situations will provide an opportunity to develop detailed biotic and abiotic crop calendars that can be used by extension services and ministries of agriculture to relay timely alerts to farmers and their advisors. Once platforms are developed for Ghana and Malawi, other countries can develop the tool, GAP maps, and crop calendars for their production systems. How research outputs will enhance the competitively awarded research activities Once templates for the risk management tool are developed for each country and region within countries, GAP maps are produced and comprehensive crop calendars prepared, competitive projects can focus on validation of the models and predictive tools and implementation of research protocols that can improve the risk management tools. Ultimately, the combination of the initial development of the risk management tool, the validation of the tool and filling in gaps in research that can improve the tool will create greater understanding of peanut production systems and implementation of practices that minimize risk, increase yield potential, and improve quality and food safety.