Plant Disease Clinic at Penn State provides diagnostic, management services

UNIVERSITY PARK, Pa. — The leaves on your favorite houseplant have been wilting and dropping off for weeks. Its stems are starting to bend. You've tried to bring it back to life by adjusting the room temperature, moving it to a different window, and not watering it as much. Yet, it's not improving.

That makes you wonder — could its condition be caused by something serious, such as an infection? With thousands of plant diseases that are bacterial, fungal or viral in nature, where can you turn to have the problem accurately diagnosed?

The Plant Disease Clinic in Penn State's College of Agricultural Sciences is a great place to start. The clinic, under the direction of the Department of Plant Pathology and Environmental Microbiology, is located in Buckhout Lab, where it provides clinical diagnoses of plant diseases for Pennsylvania's agricultural producers, gardeners and homeowners.

"It's important that plants are healthy because they are essential to our lives — they provide food, fiber and building materials for garments and shelter and give us beauty and enjoyment in the forms of gardens, landscapes, parks and natural areas," said Sara May, plant pathologist and clinic coordinator. "They also are crucial to our economy — agricultural crops and forest products are multibillion-dollar industries in Pennsylvania."

If left untreated, plant disease can have a devastating impact on society. Nothing underscores that statement more than Ireland's Great Famine of 1845. Late blight, a disease caused by a fungus-like pathogen that destroys a plant's leaves and edible roots, ravaged the country's potato and tomato crops, leaving many families starving and in economic ruin. The Great Famine is blamed for 1 million deaths and the emigration of 1.5 million people from Ireland.

Although not as catastrophic, Pennsylvania experienced a late blight outbreak in 2009. The disease resulted in the loss of thousands of tomatoes and potatoes in home gardens and commercial farms, which led to substantial economic losses for growers, May said.

"Fortunately, a lot of work is being done at Penn State to help protect and manage crops against diseases like late blight," she said. "Our vegetable pathologist, Beth Gugino, and our potato pathologist, Xinshun Qu, conduct research on fungicides used to manage late blight in tomatoes and potatoes. Majid Foolad, a professor of plant genetics, is working to breed tomato cultivars with resistance to important diseases like late blight. And, of course, we have our diagnostic clinic."

The Plant Disease Clinic accepts samples, free-of-charge, from anyone in Pennsylvania — from homeowners to commercial agricultural producers, including growers of field crops, vegetables, tree fruit, vineyards, Christmas trees and ornamentals. A submission form and instructions can be found on the clinic's website. Instructions include how to select and package plant disease material and directions on mailing. It's very important to follow these instructions in order for the staff to make a proper diagnosis, May noted.

"We look at many different types of plants, and each are susceptible to many different problems," she said. "If we don't have a good sample and enough information, then it often can be difficult to figure out what the problem is. Correct diagnosis is the first step in effective disease management."

That diagnosis begins with identifying the plant, reviewing its symptom history, assessing its appearance, and conducting diagnostic tests, which can range from viewing the samples under a microscope to culturing the infected plant tissue. May's goal is to have a diagnosis and treatment recommendations back to the client in about two weeks. She noted that sometimes the remedy is simple, and other times it's not. For example, not all diseases caused by fungi are managed the same.

"You can't just apply any fungicide that you find in a store," May said. "You need to know which fungus is causing the disease so you can determine which fungicide to use and which cultural management practices will work, such as using resistant cultivars, pruning out diseased parts of the plant, and planting in a different location to avoid soil-borne diseases."

When the clinic receives a sample with a very destructive disease — for example late blight or downy mildew, which affects cucurbits such as watermelon, squash or cucumbers — the clinic shares that information with state and national agencies, as well as agricultural industries, so action can be taken to prevent the pathogen's spread.

The Plant Disease Clinic complements the work of Penn State Extension. May said extension educators and Penn State Master Gardener programs in many counties are great resources and often can provide guidance on the spot.

Fact sheets about various plant diseases and information about diagnostic services can be viewed by visiting Penn State Extension's website at http://extension.psu.edu/pests/plant-diseases. Links to the Plant Disease Clinic and Department of Plant Pathology and Environmental Microbiology also are located on the page.

Media Contacts: 
Last Updated July 28, 2017