- May 11, 2026
- By Karen Shih ’09
Baskets overflowing with fruit, sticky fingers and red-stained grins mark the sweet joy of strawberry season in Maryland. Whether it’s families with young kids or couples on dates, eager customers walk the long rows at pick-your-own farms every May and June, savoring the juicy, ripe fruits along the way.
But an insidious rot, hidden beneath vibrant serrated leaves, could leave them all empty-handed. Greenery wilts, berries shrivel and eventually, whole plants die.
Fingering a cause isn't as easy as plucking a berry, however. A variety of pathogens could be the culprit—and knowing which one is critical to applying the right treatment.
That’s why last summer, a farm in distress turned to the University of Maryland’s Plant Diagnostic Lab, led by Director Ana Cristina Fulladolsa.
She's the equivalent of TV's Dr. House for greenery across the state, taking on the toughest mysteries confounding nurseries, farmers and landscapers who help make up the $1.76 billion horticulture industry in Maryland. As a member of the National Plant Diagnostic Network, the lab also works closely with state and federal agencies to monitor new diseases and pests and prevent outbreaks.
“Every day you're solving a puzzle,” said Fulladolsa, an assistant research professor in the Department of Entomology and Plant Science and Landscape Architecture. “It's great fun to be a diagnostician. With every sample is a new challenge and a new opportunity to learn something to help someone.”
Digging into the problem
In one corner of the lab, a single, spindly tree trunk juts out of a pot wrapped in a garbage bag. Atop a wooden table is an assortment of wan, squat evergreens with their roots exposed. Elsewhere, yellowed pine needles dry in a bag; petri dishes of brown leaves grow fuzzy white mold; a stem from a succulent awaits inspection beneath a microscope.
These are all Fulladolsa’s patients.
“Just like in a hospital or a clinic, we begin with triage,” said Fulladolsa, who has a team of four undergraduate interns. “What do we observe? What’s our primary hypothesis? What do we have to do next?”
Crop consultants and farmers know to start with UMD Extension for common questions; specialists can identify most problems based on their experience. (Individuals can contact the UMD Extension’s Home and Garden Information Center.) But when an issue is less straightforward, they can consult the Plant Diagnostic Lab, which has operated pro bono since it was created in 1979. Commercial growers across the state either send their samples through the mail or drop them off in person; Fulladolsa took over as the lab’s director in late 2024.
“I cannot say strongly enough how much we value our relationship with UMD Extension and the Plant Diagnostic Lab,” said Vanessa Finney, executive director of the Maryland Nursery, Landscape, and Greenhouse Association. “It would be ineffective and unaffordable for our businesses to have their own little labs. … Instead, they turn to the experts so they can get answers to treat issues effectively.”
The work is as seasonal as plants themselves; last year, Fulladolsa and her team processed 360 cases, with the busiest time starting in the spring and ending in the fall. In addition to the lab work, she also regularly presents to farmers and other horticulture professionals about what types of symptoms should be reported, making sure they know about the lab’s services.
The diseased strawberries arrived at the height of growing season last summer. A crop consultant brought in multiple affected plants, so Fulladolsa and her student assistants could cut into the crown—where the stems meet the root—to reveal brown discoloration.
Investigation of samples can go in many directions, but the first stop is always the microscope, to see if anything obvious appears under magnification. Then, the team may move on to microbial cultures detect possible bacterial growth. If that’s inconclusive, Fulladolsa could try a what looks like a COVID-19 strip—a serological test that involves mashing up the plant, dipping the strip in the pulp and seeing if a second line appears indicating a positive test, mostly for viruses. Other times, she’ll try a “moisture chamber”; it’s a Ziploc bag with a wet paper towel—where she can incubate and induce growth of fungal pathogens, which like heat. And if there’spest damage, she’ll loop in colleagues in the entomology department.
In the case of the strawberries, Fulladolsa’s examination turned up a fungus. Maryland farmers are familiar with Phytophthora (a fungus-like organism) that’s been cropping up in their plants for years. But she discovered that it was actually the fungus Neopestalotiopsis, previously known for more visible leaf and fruit damage, was also capable of causing crown rot. Both pathogens can be managed if caught early, but visually, there’s no way to tell which one is affecting the plant via a single symptom, so she put the word out that lab confirmation was needed for crown rot cases to ensure correct treatment.
“We don't want this to become a constant problem,” she said.
A sliced-open strawberry plant showing crown rot.
Protecting the state—and beyond
Whether as a stowaway egg mass on a container ship crossing the Pacific Ocean or as bacteria lingering on a guava brought back from a tropical resort, pathogens slip in daily that could threaten U.S. ecosystems and agriculture.
To better track and stop the spread of these pests and diseases, UMD’s Plant Diagnostic Lab works with federal and state agencies, including participating in the National Plant Diagnostic Network, established after the Sept. 11 attacks to prevent bioterrorism. The network provides trainings, holds a national data repository and provides federal funding to its members as a first line of defense against outbreaks.
By Fulladolsa
Fire blight on an apple tree
By Fulladolsa
Culture of the fungus Fusarium
By Fulladolsa
Nematode that causes beech leaf disease
In January, Fulladolsa was part of what she called “a true success story” when a central Maryland resident noticed that a grapefruit tree they had bought a few months earlier had started developing dark spots on its leaves. The resident sent photos of the ornamental tree in its pot to UMD Extension agent Amy Rembold, and the agent notified entomology Professor Paula Shrewsbury, who often works with Fulladolsa and looped in the Plant Diagnostic Lab.
“It looked alarming to me, and the symptoms were a big red flag,” said Fulladolsa. She suspected it was citrus canker, a federally quarantined disease that has infected groves throughout the Florida and has no cure. She immediately sent the photos to Kim Rice, program manager in the Maryland Department of Agriculture, whose office collected the plant and visited the nursery where the tree was purchased. The state tested a sample, and a test in a U.S. Department of Agriculture lab definitively confirmed citrus canker—all within 20 days, a quick turnaround for this type of problem.
UMD’s Plant Diagnostic Lab “serves as an extra eye for us,” said Rice. “We’ve always worked really closely with the university, and they are incredibly helpful and a great resource and partner.”
While Maryland doesn’t have a citrus industry like Florida, containing the disease is critical because it can persist in the environment and spread easily through wind, rain and contaminated equipment. (Local ornamental orange blossom trees could still be affected.) And this constant communication Fulladolsa and her lab are at the center of means that when a disease with major ramifications for local plants emerges, everyone will be ready to act.
“Early detection and monitoring is important,” said Fulladolsa. “Our services help safeguard our food and natural resources across the state and the country.”
By Mark Sherwood
UMD Research Changes Lives
At the University of Maryland, scientists and scholars come together to spark new ideas, pursue important discoveries and tackle humanity's grand challenges—improving lives in our communities and across the globe. See more examples of how UMD research changes lives at today.umd.edu/topic/research-impact.