Mary Ann Hansen, Instructor (540) 231-6758 (540) 231-6758 (Lab)
maryannh@vt.edu/, Plant Pathology, Physiology, & Weed Science, Plant Clinic
My program’s goal 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.
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. 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.
 IPM Support for Pest Diagnostic Facilities—Plant Disease Clinic is a threeyear 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.
“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.