Mary Ann Hansen


Program Focus

I am currently involved in several Extension-related research projects.

Current Projects

“Re-visiting Pierce’s Disease in Virginia Commercial Vineyards” – This project, funded by the College of Agricultural Sciences internal integrated grants program, will examine the spread of Pierce’s disease, an important yield- and quality-reducing disease of grape, in Virginia. Climatic changes have allowed an expansion of the geographic range of the insect vector of this disease. Our goal is to determine how widespread the disease has become in Virginia vineyards and to identify potential resistant varieties and other effective disease management practices. This project is led by Mizuho Nita; Elizabeth Bush and Boris Vinatzer are cooperators.

IPM Support for Pest Diagnostic Facilities—Plant Disease Clinic is a three-year project within the Virginia Tech-Virginia State in Partnership for the Advancement of IPM grant funded by the Extension Integrated Pest Management grants program, USDA-National Institute for Agriculture. Elizabeth Bush and I are cooperators on this project, which focuses on accurate pest identification for implementing appropriate pest avoidance, mitigation and control tactics in commercial crop production, as well as in home landscapes and gardens. Proper pest identification and control recommendations ensure pesticides are only used when they are likely to have an economic benefit or when plant health is at serious risk and alternative control measures are not available. This reduces negative effects of pest management and minimizes risk to human health, the environment and non-target organisms.


M.S., Plant Pathology, University of Wisconsin-Madison, 1984

B.S. with Honors, Plant Pathology, The Ohio State University, 1979


  • January 1993 – present: Instructor and Plant Clinic Co-Manager, Department of Plant Pathology, Physiology and Weed Science, Virginia Polytechnic Institute and State University, Blacksburg
  • November 1984 – December 1992: Diagnostician and Plant Clinic Manager, Virginia Polytechnic Institute and State University, Blacksburg

Courses Taught

  • PPWS 5034 – Plant Clinic Experience
  • PPWS 2104 – Plants, Genes and People
  • PPWS 6004 – Identifying Plant Pathogens - Contributed online module

Other Teaching and Advising

I enjoy classroom teaching and I also enjoy teaching adult audiences through Virginia Cooperative Extension programs. I teach workshops on plant disease diagnosis and disease management to local Virginia Master Gardener groups, VCE agents, grower groups and urban foresters.

Program Focus

The goal of my extension program is to provide timely and accurate diagnosis of plant problems to Virginia growers and homeowners. Non-commercial growers, commercial crop producers and lawn/landscape professionals depend upon accurate diagnosis of their crops’ disease and abiotic problems (e.g. chemical injury, environmental stress, cultural problems) to implement appropriate pest management tactics. Commercial growers must also avoid crop loss and poor crop quality to ensure profitability. Accurate plant diagnosis is the foundation for healthy lawns and landscapes, profitable crop production, and for development of an integrated pest management program that results in minimal impacts to the environment. Accurate diagnosis depends on an educated staff of Extension agents, Master Gardeners, and receptionists at the local county level. To that end, I also provide training in plant disease diagnosis, management and proper sample submission in support of local VCE county programs.

Current Projects

Virginia Tech Plant Disease Clinic (PDC) – The PDC provides diagnostic services for plant problems caused by pathogens and abiotic factors to VCE agents across the Commonwealth. The PDC processes approximately 1500 plant samples per year, in addition to email and digital image submissions. This service is free for all Virginia VCE agents. Reports, which include a diagnosis of the problem and information on disease control, are sent to agents electronically; agents  communicate results to the client. Electronic reporting has decreased the turnaround time for plant disease diagnosis and allows for rapid implementation of disease management practices.

  • Hong C., M. Hansen, E. Day. Rose rosette disease, VCE e-Book 450-620 (PPWS-10P). 2012. Virginia Cooperative Extension.
  • Norm D., M. Hansen, E. Bush, C. Hong. Boxwood Blight: A New Disease of Boxwood Found in the Eastern U.S. 2012. Virginia Cooperative Extension.
  • Oliver C., R. Cai*, B. Vinatzer, E. BUSH, M. Hansen. First Report of Bacterial Spot of Peony Caused by Xanthomonas sp. in the U.S. 2012. Plant Disease 96(4): 581.
  • Vaira, A. M., M. A. Hansen, C. Murphy, M. D. Reinsel, and J. Hammond. First report of Freesia sneak virus in Freesia sp. in Virginia, USA. 2009. Plant Disease 93(9):965.
Mary Ann Hansen
  • (540) 231-6530
  • 106 Price Hall
    Mail code: 0331
    170 Drillfield Drive
    Blacksburg, VA 24061