Barbara Shew

Research Assistant Professor and Extension Specialist

Director, Plant Disease and Insect Clinic

• B.S., Colorado State University
• M.S., (Plant Pathology), N. C. State University
• Ph.D., (Plant Pathology), N. C. State University

Research Interests

Host resistance

Planting disease resistant cultivars is the most valuable strategy for reducing or eliminating pesticide applications while maintaining crop health and yield. Several commercial cultivars of viginia-type peanuts have partial resistance to one or two diseases.

We work closely with NCSU peanut breeder Dr. Tom Isleib to identify and characterize resistance to leaf spots, Sclerotinia blight, Cylindrocladium black rot, spotted wilt and other important diseases in advanced peanut breeding lines. Dr. Isleib and his cooperators recently have released two new multiple disease resistant cultivars, Bailey and Sugg.

We also work with Drs. Tom Stalker and Shyamlrau Tallury to identify useful sources of disease resistance in wild Arachis spp and in wild species-derived lines.

Disease advisories

Disease advisories are widely used in North Carolina and Virginia for timely application of fungicides for peanut disease control. Using a weather-based disease advisory can save one to three leaf spot sprays in a typical growing season compared to calendar-based sprays. Eliminating unnecessary leaf spot sprays reduces the likelihood of spider mite outbreaks during dry periods.

Weather-based advisories also are used to time fungicide applications for control of Sclerotinia blight. Disease control is most effective when fungicides are applied during periods when risk of infection is high.

Currently we are conducting studies to determine how to adjust disease advisories to account for resistance in new cultivars and to improve overally advisory performance.

Improving delivery of advisories through the use of modeled or networked weather data is another program goal.

Cultural practices

Integrated management of peanut diseases
A multi-disciplinary, multi-state project with Drs. Gail Wilkerson (PI), David Jordan, Rick Brandenberg, and Ph.D. student Bridget Robinson seeks to develop integrated approaches to pest management, and to weigh pest control practices as they impact all aspects of crop health. Results of these studies are being used to develop an Internet based Peanut Risk Management tool for growers.

Weed infection and diversity of Sclerotinia minor

We have found that many annual weeds commonly found in peanut fields during winter fallow are hosts of Sclerotinia minor, causal agent of Sclerotinia blight. It is possible that fungal populations are maintained on these weeds in the absence of a cultivated host. In addition to harboring peanut pathogens, weed hosts may help to maintain diversity in field populations of S. minor and TSWV. Our aim is to gain a better understanding the diversity of populations of S. minor found in peanut production areas. Interestingly, S. minor could be used for biocontrol of annual weeds in container-grown woody ornamentals. We are cooperating with Dr. Joe Neal to explore this possibility.

Organic production
There is growing demand for organic peanuts, but the potential for production of virginia-type peanut for the organic market has received little attention. We are investigating foliar disease management based on host resistance and application of approved fungicides. Stand establishment and seedling diseases have emerged as major impediments to organic production. Several biological agents and cultural methods were investigated by graduate student Sarah Ruark for use in organic production systems.

Project Personnel

Cooperators

NC State University:

• Dr. Tom Isleib, Crop Science
• Dr. Tom Stalker, Crop Science
• Dr. David Jordan, Crop Science
• Dr. Chris Reberg-Horton, Crop Science
• Dr. Shyamlrau Tallury, Crop Science
• Dr. Gail Wilkerson, Crop Science
• Dr. Rick Brandenburg, Entomology
• Dr. Ryan Boyles, State Climate Office
• Dr. Joe Neal, Horticulural Science

University of Georgia:

• Dr. Mark Boudreau

Virginia Tech:

• Dr. Pat Phipps

Extension

Plant Disease and Insect Clinic

Peanuts

As part of a team that includes Dr. David Jordan in Crop Science, Dr. Rick Brandenburg in Entomology, 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. I also work with the North Carolina Plant Disease and Insect Clinic to diagnose peanut diseases.         

• 2010 Peanut Information
• Agricultural Chemicals Manual
• Peanut Risk Management
• Peanut Disease Photos
• Tomato Spotted Wilt Index
• Peanut Disease Advisories -click on this link to view today's weather based disease advisories or contact Dr. Shew to receive daily advisory emails. Click on this link for information on how to interpret advisories
• Peanut Scouting Manual - IPM Center

Teaching

PP 506 (Epidemiology and Disease Control): Offered annually in the spring. Distance Education version offered in the fall starting in 2010. The class is co-taught with Drs. Mike Benson (coordinator; cultural practices, biocontrol) and Turner Sutton (fungicides). Lecture topics include disease progress curves and models of disease progress, disease assessment, spatial pattern of disease, sampling, disease gradients, design of epidemiological experiments, host resistance, and disease forecasting.

Recent Publications

• Click for a list of recent publications

Contact Information

Email: barbara_shew@ncsu.edu